NAUI Scuba Diver With Index

P U B L ISI S H E D B Y

National National Association Association of Underwater Underwater Instructors (NAU (NAUI) I) PRODUCT DEVELOPM ENT

 Je  Jed Livingstone P R O J EC T M A N A G E M E N T

Genny Sikes EDITORS

Peter Oliver Mike Mike Williams Williams WRITER

Susan Carroll REVIEWERS

Stefan Hogbom Bill Lidyoff Rudy Lutz Carl Meilahn Mike van Niekerk  Joe  Joe Rodriguez Stefano Ruia Mike Russell Michael Tong DESIGN AND LAYOUT

The Information Information Design Design Group, Group, Inc. Inc. PROOFREADING

Dorothy Dorothy Winkel Winkel PHOTOGRAPHY

Hjtaagflt. Hjtaagflt.

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JeffBozanic WayneHasson Karl Huggins  Je  Jed Livingstone Carl Meilahn David Meyer Tim O’Leary Scott Raish Diving Diving Unlimited Unlimited International (D (DUI) UI)

Copyright Copyright © 2000,2004, 2009, 2010 by the Nationa Nationall Association Association of Underwater Underwater Instructors (NA (NAUI) UI) All rights reserved reserved. No part of this publicat publication ion may be be reproduced, duced, stored stored in a retrieva retrievall system, or transmitted, in any form or by any means, means, electronic, electronic, mechan mechanica ical, l, photocopying, recording, or othe otherwise, rwise, without without prior written written permission from the publisher. Printed Printed in the United States of America

NAUI Scuba Diver

PREFACE  NAU  NAUI Scuba Scuba Diver  Diver  de  describes the gear, skills, skills, and basic concepts concepts of scuba diving. diving. Scuba diving diving is

a wonderful adventure sport. However, ever, like like any adventure sport, sport, there is a small but real risk risk that that you you can be injured injured any any time you enter the water to dive. Even if if you do everything right, even if your equipment equipment functions perfectly, there are always so some me risks in scuba diving. When you decide decide to become a scuba diver, you must do it of your own personal desire and be willi willing ng to accept the risks of the sport. This book is is written as a reference for all all students taking the NAUI Scuba Dive Diverr certifica certification tion course. rse. If you have any questions about the conte contents nts of this book, askyour NAUI instructor. instructor. Your instructor instructor will will let you know know in which which order theywould like like you to read the the informati information on contained contained in this book book.

HOW THIS BOOK IS ORGANIZED This book is organized into the followi following ng chapters and appendixes: appendixes: • Chapter One, “Introduction,” gives gives an overview overview of scuba scuba diving, certific certification, ation, NAUI, your obligations, obligations, and rewards from this exciting sport. sport. • Chapter Two, “Diving Equipment,” describes describes the the items of gear you will ill use in scuba diving. • Chapter Three, “Diving Skills,” describes the the skill skills s you need to master to be a safe scuba diver. • Chapter Four, “Diving Science,” describes the concept of pressure and the ways it affects your body under water. The chapter also describes the immediate and cumulativ cumulative e indirec indirectt effects of pressure. • Chapter Chapter Five, Five, “Decompression “Decompr ession,, Dive Tables, and an d Dive Computers,”describes the concept of ingassing and offgassing, dive tables and their their use, the NAUI Dive Time Calculat Calculator, or, and dive computers. • Chapter Six, “Dive Planning and Recording,” describes describes long term and short term dive plan plan ning, preparing preparing to dive, conducting your dive, and recording recording your dive. • Chapter Seven, “Problem Solving,” describes describes problem solving solving and explains why it is so important in scuba diving. diving. The chapter also describes describes how to assist other divers as well well as how how to rescue another another diver. • Chapter Eight, “Diving Environments,” describes describes factors that that affect the diving environment, such as water conditions, p physi hysical cal charact characteris eristics tics of of a site, site, waves waves and surf, and tides and cur rents. rents. The chapter also describes som some popular popular diving diving areas throughout the world, marin marine e life, life, and conservation. • Chapter Nine, “Diving Activities,” describe describes s some of the different conti continuin nuing g education education courses you can take once you are a certified certified diver, and special diving diving interests you can pursue. • Appendix A, “Answers to Review Questions,” includes includes the answers to the review questions found throughout throughout the book. • Appendix B, “Being a Responsible Diver,” includes guidelines guidelines to follow to be a responsible responsible and considerate diver. • Appendix C, “Checklists,” includes checklists for dive dive planning, planning, diving equipment, equipment, and a first aid kit. • Glossary defines the terms, acronyms, acronyms, and concepts used used in this this book.

Introduction

C O N V E R S IOI O N S U S E D I T H ISI S B O O K Unless exact exact equivelents are absolutely absolutely necessary table 1shows a list list of the conversions used used in this book. The first column shows the unit unit being converted. converted. The second second column shows shows the exact con version. The third column column shows the unit to which the conversion conversion was rounded rounded for ease ease of reading throughout this book.

Table 1 : C o n v e r s i o n s Unit

Equivalent

Rounded Unit

1bar

0.9869 atmosphere

1atmosphere

1bar

14.51 poundsper square inch inch (psi) (psi)

14.7 psi

1atmosph atmosphere ere

1.013 bar bar

1bar

200 bar

2902 psi

3000 psi

2 centimeters centimeters

0.79 inches

3/4 inch inch

10meters meters

32.81 feet

33 feet feet

20 meters

65.62 feet

66 feet

1inch

2.54 centimeters centimeters

2.5 centimeters centimeters

2 inches inches

5.08 centimeters centimeters

5centimeters centimeters

10feet feet

3.05 meters eters

3 meters eters

100feet feet

30.48 meters eters

30 meters eters

1kilogram

2.20 pounds

2pounds pounds

6.5 kilograms

14.33 pounds pounds

14pounds pounds

1pound

0.45 kilograms

0.5 kilograms

4 pounds

1.81 kilograms

2 kilograms

21“Celsius “Celsius

69.8°Fahrenheit

70°Fahrenheit

80°Fahrenheit

26.67°Celsius

27°Celsius

NAUI Scuba Diver

T A B LE LE O F C O N T E N T S

Second Stage Alternate Air Sources Gauges Maintenance Additional Diving Instruments Timing Devices Dive Computers Backup Instrumentation Maintenance Buoyancy Compensators Features Types Selection Maintenance Weights Weights and Weight Belts Belts Types of Weights Weights Weight Weight Belts, Harnesse Harnesses, s, and Weighting Systems Systems Quick Release of Weights Diving Suits Dive Skins Wetsuits Dry Suits Hoods Choosing the the Correct Suit Suit for the Conditions Maintenance Acces Accesso sory ry Equip Equipmen mentt Attachment Attachment Devices Devices Knives Gear Bags Dive Flags and Floats Logbooks First Aid Kits Other Accessories Conclusion

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26 26 27 30 31 31 31 32 32 32 32 33 34 34 36 36

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Preface

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HowThis Book is Organiz Organized ed

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Conversions Used in This This Book Book

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In M o c tio n 2 4

Learning Goals What is Scuba Diving?........................ What is Scuba Certification?

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What is NAUI? NAUI Courses

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NAUI Specialty Courses What are the Risks of Scuba? A Little Little Apprehe Apprehensio nsion n is Nor Norma mall

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Misconceptions About Diving What are Your Obligations? Attendance Health Fitness Use of Drugs and Alcoho Alcoholl What’s Next

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D i v ini n g E q u i p m e n t 1 2

iW m

Learning Goals Buying Equipment for Diving Basic Personal Equipment

14 14 15

Masks Snorkels Booties Fins Gloves Flotation Device Maintenance Cylinders Characteristics Valves Maintenance Regulators First Stage

15 16 17 18 19 19 19 20 20 22 23 25 25

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D i v ini n g S k i l lsl s 4 6 Learning Goals Snorkelin Snorkeling g Skill Skills s Preparing Your Gear for Use Donning Donning Your Your Gea Gearr Using Using Your Your Fin Fins

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48 48 48 49 50

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T a b l e o l C o n t e n tst s

Breathing through through Your Your Snorke Snorkell Surface Diving Clearing Water from Your Snor Snorkel kel Assembling Scuba Equipment Assembling Your Scuba Unit Unit Testing Your Scuba Unit Assembling Your Weight Be Belt Donning Scuba Gear Donning Your Diving Suit Donning Your Scuba Unit Donning Donning Your Weight Weight Belt Be lt Entering and Exiting the Water Checking Checking Your Equipment Equipment Boat and Platform Entries Beach Entries Boat and Platform Exits Beach Exits Mask Mask Skills Sk ills Clearing Water from Your Mask Removing Removing and Replacing Your Mask Mask Regulator Skills Breathing Under Water Breathing Breathing with a Flooded Flooded Mask Mask or without a Mask Clearing Clearing Your Your Regulato Regulatorr Recovering Your Regulator Breathing Breathing from a Free-Flowing Regulator Orally Inflating Your Buoyancy Compensator Compensator Switching from Your Regulator to Snorkel Monitoring Your Air Supply Buoyancy Skills Checking Checking Your Buoyancy at the Surfac Surface e Descending During the Dive Ascending Safety Skills Sharing Air with Another Another Diver Diver Independent Emergency Ascents General Guidelines Buddy System

52 52 54 55 55 57 58 59 59 59 60 6l 61 62 64 65 66 67 67 68 68 68

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Communication Underwater Communication Surface Communication Handling Your Scuba Equipment in the Water Removing and Replacing Your Scuba Unit on the Surface Surface and Under Water Water Removing and and Replacing Replacing Your Weight Belt on the Surface Surface and Under Water Water Navigation Skills Natural Navigation Compass Navigation Disassembling Your Scuba Gear Conclusion

82 82 84

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■ l i l i K

D iv in g S c ie n c e 9 2

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Learning Goals 94 Direct Effects of Pressure 94 Density and Its Effects 94 Buoyancy 97 What is Pressure 101 How Pressure Effects Volume..................102 104 How Pressure Effects Density Density How Pressure Affect Affects s Air Consumption 105 Your Body 106 How Pressure Affec Affects ts Your Air Spaces 106 The Anatomy of Your Lungs Lungs 112 Indirect Indirect Effects of Pressure Pressure 116 Ingassing and Offgassing 116 Decompression Sickness 116 Nitrogen Narcosis 117 Oxygen Toxicity 117 Carbon Monoxide Toxicity 118 Thermal Effects of Diving........................119 Humidity and Temperature 120 Scuba Cylinders and Temperature Temperature 120 ...............................

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l e c o m p r e s s l o i i,i , D i v e T a b l e s , a n d D ivi v e C o m p u tet e r s 1 2 2

Learning Goals Nitrogen and Diving Ingassing Nitrogen

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124 124 124

NAU I Scuba D i ver

Offgassing Offgas sing Nitroge Nitrogen n Residual Nitrogen Dive Table Overview Dive Table Terms Dive Table Rules Rules Dive Table Organiz Organizatio ation n Table 1- End-OfEnd-Of-Dive Dive Letter Group Group Table Table 22 -Surface Interval Interval Time (SIT) Table Table 3 -Repetitive Dive Timetab Timetable le Dive Planning Worksheet Planning Your Dive Finding Your Letter Group Recording Your Surface Interval and Findin Finding g Your New Letter Group Group Planning Your Repetitive Dive Recording Your Your Repetitive Dive Dive Maximizing Your Underwater Time Limiting Your Dive Time Planning Your Surface Intervals Limiting Your Your Depth Special Rules Decompression Diving Cold or Strenuous Dives Flying After Diving Altitude Diving Using the NAUI Dive Time Calcu Calculat lator or General General Organization Organization Using the Calculator Dive Dive Planning Planning with the the Calcula Calculator tor Sample Problems Using Dive Computers Dive Computer Terms Terms Displays Planning Repetitive Dives Safe to Fly Indicators Logging Your Dives Dive Computer Computer Rule Rules s Conclusion

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Short Range Planning

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Preparing to Dive

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Conducting Conducting Your Dive

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Site Survey

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Emergency Plan Activity Diving Your Plan

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Contingency Planning

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Reco Record rdin ing g You Yourr Dive Dive.. .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... ..1 155

04867768

Learning Goals

160

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134 135 135 136 137 137 137 137 137 139 139 139 139 139 139 140 141 142 142 143 146 146 146 147 147

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Long Range Planning

Diving Situations

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General Metho Method d of Resolving a Proble Problem m

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Heat Loss

160

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Overheating

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Cramps

162

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Entanglements

162

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Disorientation and Vertigo

163

Equipment Difficulties

163

Seasickness

164

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Choking and Coughing

164

Air Starvation

165

Summary

165

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Assisting Other Divers

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Establishing Buoyancy

166

Resting and Breathing

166

Providing Assistance

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Rescues

167

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At the Surface

167

Underwater

168

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In-Water In-Water Artificial Artificial Respiration

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Emergencies Emergencies and First Ai Aid d

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Be Prepared

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Basic First Aid

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Learning Goals

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CPR and Oxygen Adminis Administrat tration ion

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Aquatic Life Injuries

171

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Dive Planning and R e c o r d ini n g 1 4 8

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Safety Safety in Summary Summary

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Responsible Scuba Diving Practices

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Table of Contents

Diving Environment 174 Learning Goals Physical Characteristics of a Site Type Types of Site Sites s Entries and Exits Bottom Conditions Water Conditions Visibility Temperature Moving Water and Its Effects Effects Waves and Surf  Tides Currents Marine Life Animals That Bite Animals with Barbs Animals That Sting and Scrape Animals That Shock Conservation Diver Impacts Hunting Collecting ExploringWrecks Cleaning Up the Environment Boat Diving Popular Diving Areas California Cozumel Gulf Gulf Coast of Louisia Louisiana na and Texas Great Lakes Turks & Caicos Truk, Federated Federated States of Micron Micronesi esia a Galapagos Islands

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Leadership Courses Developing Special Interests Being a Responsible Diver

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199 200 201

A n s w e r s lb R e v ie w Q u e s tio n s 2 0 2

Chapter 1 Health and Fitness Chapter 2 Basic Equipment Cylinders Regulators, Alternate Alternate Air Sources, and Instrumentation Instrumentation Buoyancy Compensators Weight Belts Diving Suits Accessory Equipment

202 202 202 202 202

Chapter 3 Using Mask, Mask, Snorkel, and Fin Fins Assembling Scuba Gear Entries and Exits Mask Skills Regulator Skills Buoyancy Safety Safety Skills Skills Buddy System Communication Handling Scuba Equipment in the Water Water Navigation Chapter 4 Density and Its Effects Buoyancy Pressure Air Quantity in Balloon Air Consumption Consumption Squeezes and Block Blocks s Lungs and Breathing Indirect Effects of Pressure Thermal Effects Effects of Diving Diving Chapter 5 Ingassing and Outgassing Dive Table Rules

203 203 203 203 203 203 203 203 204 204 204 204 204 204 204 204 204 204 205 205 205 205 205 205 205

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Diving Activities 196

Learning Goals Getting Getting Involved in Cl Clubs ubs Furthering Your Education Specialty Courses The Advanced Scuba Diver Diver Course Course The Master Master Scuba Diver Course Training Assistant Specialty Course

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NAU I Scuba D i ver

Table 1 Table 2

Spare Equipment Emergency Items Personal Items First Aid Kit Checklist General Optional

205 205

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Table 3 Dive Planning Planning Worksheet Worksheet Sample Problems Dive Computers Chapter 6 Long Range Planning Short Range Planning Preparing to Dive Conducting Conducting Your Your Dive Dive Diving Your Plan Contingency Planning Recording Your Dive

205 205 205 206 206 206 206 206 206 206 206 206

Chapter 7 Diving Situations Assisting Other Other Divers Divers Rescues Emergencie Emergencies s and First Aid Aid Chapter 8 Physical Characterist Characteristics ics of a Site Site Water Conditions Water Movement Marine Life Conservation

206 206 207 207 207 207 207 207 207 207 207

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GETTING THE MOST OUT OF THIS BOOK Throughout this study book there will be sections that require your special attention. The following icons are used to mark these sections.

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Diver Etiquette NAUI Respo Responsib nsible le Boat Diving Prac Practic tices es The Code of the Responsible Div Diver er

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210 210 211

Indicates Indicates that that you should take note note of the informatio information, n, because it forms the basis for the final exam.

Indicates information that will help you complete complete the workbook.

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Checklists 212

m aw i Dive Planning Checklist Long Temi Planning Short Term Planning Preparing to Dive On-Site Planning Diving Equipment Checklist Primary Dive Gear Additional Dive Gear

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Indicates a warning or safety information.

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Indicates responsible diving practice.

Table of Contents

CHAPTER

MAUI Scuba Diver

LEARNING GOALS        o          i         t        c        u          d        o        r         t        n          I

In this chapter chapter you will: • Learn the meaning of the acronym SCUBA. SCUBA. • Learn about about scuba scuba certification. certification. • Be introduced to to NAUI Worldwide. • Learn about other NAUI courses. • Be introduced to some of the risks of scuba diving. • Understand Understand your obligations obligations for attendance, attendance, health, health, and fitness. • Understand Understand why why drugs, alcohol, alcohol, and diving diving do not mix. Scuba diving diving is is the most unique adventure sport sport on earth. In the underwater world, you can watch the the deli deli cate beauty of tiny fish as they dart around a colorf colorful ul tropical tropical reef. You can experience experience the thri thrillll of swimming swimming eye to eye with with sea turtles, whales, or manta manta rays (figure (figure 1-1). 1). With With very little little trai trainin ning, g, you can shoot underwater underwater video footage that will will dazzle dazzle your family family and friends. friends. As a scuba diver, you can see history as you discover fab ulous underwater treasures treasures and lost sunken cities. Scuba diving diving is an an adventure sport you can pursue almost anywhere anywhere in the world. From the shipwrecks shipwrecks of of the Great Lakes Lakes to the the tropical tropical reefs of Australia, Australia, from the kelp kelp forests forests of Califo Californ rnia ia to the rocky coast of the Mediterranean, where there is water, there is usua usually lly div div ing. As long as you are in good healt health h and have the proper equipment and training, you can enjoy diving.

F IGI G U R E 1 - 2 . W R E C K E X P L O R I N G M I G H T B E O N E O F T H E  A C T I V I T I E S Y O U W I L L E N J O Y .

F IGI G U R E 1 - 3 . D I V INI N G I N C O L D W A T E R C A N B E J U S T A S E N J O Y A B L E  A S D I V I N G I N W A R M W A T E R .

Although it it might might seem that there is a great deal of informatio information n you must must learn about diving, you do not not need to be an expert to enjoy enjoy it. You can experience all all the excitement of scuba diving diving by completing completing your NAUI Scuba Diver certific certification ation course. There are are dives dives that are more advanced and challeng challenges es you can choose to experienc experience e later, but the basics basics of diving will will enable you you to begin your your underwater underwater adventures. F IGI G U R E 1 - 1 . I M A G I N E T H E T H R I L L O F S W I M M I N G W I T H LA LA R G E  A N I M A L S U N D E R W A T E R !

4

Chapter 1- Introduction

To enjoy diving where you live, live, you wil willl need to to learn learn how to use the scuba equipment commonl commonly y used in your area. The equipmen equipmentt might appear appear intimidat intimidat ing at first, but it is very simple simple to use. Just Just like driving a car, you you don' don't need to understand understand every aspect of the the equipment equipment to be able to use it. Just Just remember that if you dive in other areas or pursue pursue certain certain specialized specialized type types of diving, you will will need need additional training training and equipment.

W H A T ISI S S C U B A D I V INI N G ? You might alread already y know that the word scuba stands stands for Self Contained Underwater Breathin Breathing g Apparatus. Apparatus. You scuba dive with a compressed air air cylind cylinder er or tank tank that you wear on on your back (figur (figure e 1-4). 4). The air air is supplied to your mouth through a regulator regulator that that reduces the high high pressure inside the tank tank to the same pressure as the water surrounding you. You will will hear divers divers referring to scuba scuba diving as recreatio recreational nal diving diving or sport sport diving. These terms are used interchangeably interchangeably to refer to scuba diving for for fun, as opposed sed to commercial diving diving work, which which professionals perform for pay. You might might also hear the term technic technical al diving. diving. This term refers refers to highly highly specialized divin diving g that

F IGI G U R E 1 - 5 . S K I N D IVI V I N G ISI S D O N E W I T H O U T A N Y U N D E R W A T E R B R E A T H INI N G A P P A R A T U S .

requires additional equipment and training to explore the more demanding areas of the underwater world. You will also hear the the term term skin diving. Skin diving diving involves diving wit without hout any underwater breathing appa ratus. In skin diving, you hold your your breath and and dive dive below the surface. Skin Skin diving diving is also known as free div ing or breath-hold breath-hold diving (figure (figure 1-5). Your NAUI NAUI Scuba Diver certifica certification tion course course will teach you to to become a beginning beginning scuba diver. Your instructor wil willl also teach you the the fundamentals of skin diving. Mastering the skills of skin diving will will make you you a much better scuba diver. diver.

WHAT IS SCUBA CERTIFICATION?

F IGI G U R E 1 4 . Y O U W E A R A C O M P R E S S E D A IRIR C Y L INI N D E R O N Y O U R B A C K W H E N Y O U S C U B A D I V E.E .

Because there there are no no laws governing recreationa recreationall scuba diving in most countries, countries, the professiona professionall instruc tors who work in the the scuba industry have agreed on cer tain minimum minimum standards standards of training training for sport sport divers. divers. You must meet these standards to receive a certifi certificat cation ion card. Your NAUI instructor will also add special training training specific to the the area in which you are learning learning to dive. dive. Your certificatio certification n card will will enable you you to receive receive scuba scuba diving services, services, such as renting a cylinder cylinder or enjoying a day of diving on a charter dive boat. boat.

NA UI Scuba Sc uba D i ver

       o          i         t        c        u          d        o        r         t        n          I

Your NAUI NAUI Scuba Diver certification certification course will teach you the fundamentals fundamentals of diving. You will ill learn learn the principles principles of selecting and operating your equip ment, ment, the effects of diving diving on your body, body, and basic infor infor mation about your local local diving diving environment. environment. Once Once you have completed completed the course course and your open water cer certif tifi i cation dives, you will be qualified to dive in conditions simi simila larr to those in which which you did your open water certification dives. Different levels of diving certification certification signify special knowledg knowledge in diving. diving. After you complete the NAUI Scuba Diver Diver certification certification course, course, you you will will beeligible eligible to take specialty courses to learn about the different special interest areas areas in diving. For example, you might want to take a course in rescue diving diving or or underwater photog raphy (figure (figure 1-6). 1-6). There are also also courses in underwa ter hunting and collecting, night diving, and many many other topics. Your instructor instructor probably learned learned to dive in a course course simila similarr to the one one you are taking now ow.. In addition, your instructor instructor completed completed addition additional al leadership leadership course courses s in running running organized dives and diver rescue techniques. techniques. Before being grante granted d an instructor ce certific rtification, ation, your instructor instructor also completed a demanding demanding course in instruc instructio tional nal techniques and was required to demon strate the required knowled knowledge ge and skills skills to a panel of experienced diving instructors.

F IGI G U R E 1 - 6 . O N E O F T H E S P E C I A LTL T Y C L A S S E S Y O U M I G H T W A N T T O T A K E I S U N D ER ER W A T E R P H O T O G R A P H Y .

Your NAUI Scuba Diver Certificatio Certification n card is just the the beginning of your adventu adventures res in diving. diving. It is your license to lear learn n more about the underwater world. There is no one who knows knows everything there is to know about diving, but in diving, you’ll find much of the fun is in the learning.

W H A T ISI S N A U I ? Your NAUI Scuba Diver certifica certification tion course is being being taught by an instructor certified through the National Association of Underwater Instructors, Instructors, more commonly referred to as NAUI or NAUI Worldwide (figure 1-7). NAUI was founded founded in i 9 6 0  and is is one of the oldest and most respecte respected diver certify certifying ing agencies in the world. You can take pride pride in your NAUI certifica certification tion becau because NAUI courses are among the most most thorough, routinel routinely y exceeding minimu minimum m industry industry standards. standards.

NAUI Courses In addition to teaching the the NAUI NAUI Scuba Scuba Diver certi fication course you are currently taking, NAUI instruc tors also teach courses to to further your your diving diving education. Two of the NAUI courses you can take to continue continue your education are: • Advanced Advanced Scuba Diver Diver • Master Scuba Diver

F I G U R E 1 - 7 . Y O U R I N S T R U C T O R I S C E R T IFIF IEIE D T H R O U G H T H E N A T I O N A L  A S S O C I A T I O N O F U N D B 1 W A T E R I N S T R U C T O R S ( N A U I) .

Chapter 1- Introduction

The NAUI Advance dvanced d Scuba Diver certifi certifica cation tion course improves roves your overall overall knowledge and skills skills in the water. water. It is designe designed for newly certifie certified d divers and introduces introduces you to the many different types types of activitie activities s avail availab able le to certified divers. The NAUI NAUI Master Scuba Diver certifica certification tion course course helps you acquire acquire leadership-level leadership-level academic academic knowledge knowledge and enables you to participa participate te in exciting exciting advanced div ing activities in a challenging course. Many people people find that diving diving changes their careers and even their lives. By gaining gaining diving diving experience experience and taking taking the progressive courses your NAUI faci facilility ty or instructor instructor offers, you can gain knowledge, skills, skills, and experience experience that will will prepare you you to earn your own certification as a NAUI instructor.

NAUI Specialty Courses NAUI instructors also teach many kinds of specialty specialty courses. Some of the NAUI specia specialty lty courses you can take cover: • Rescue Rescue diving • Wreck Wreck diving diving • Deep diving • Underwater Underwater photography and and video video

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F IGI G U R E 1 - 8 . S O M E T I M E S C O N D I T I O N S A R E S O B A D T H A T ITI T ISIS  A D V I S A B L E N O T T O D I V E .

• Ice diving diving • Cavern Cavern and cave diving • Underwater Underwater hunting and collecting collecting • Night diving diving • Technical Technical diving diving These course courses s are fun and emphasize emphasize the practic practical al application application of the know knowledg ledge you you wil willl gain in your NAUI Scuba Diver certifica certification tion course. course. Specialty courses courses give give you the the opportunity to learn learn these exciting activit activities ies safely and faster than if you tried to accumulate the same knowledge and experience experience on your your own. The more experience experience you can gain under under the supervision of a NAUI instructor, instructor, the more comfortable and confident you will be in the water.

W H A T A R E T H E R I SK SK S O F S C U B A ? In any sport, there are risks. Scuba diving, diving, as a sport, sport, has some risk risk and and you must understand this before you become a diver. diver. Most dives are very easy. However, on every dive there is always a chance chance that you wil willl need to exert yourself yourself greatly. At times, diving diving can be very strenuous. strenuous. This is particu particular larly ly true if you dive in cold water, dive in strong currents, or make beach beach entries through surf surf (figure 1-8). As in any activity, activity, the ultimate risk in diving is of being injured or killed. Serious injuries and deat deaths hs caused by diving diving are extremely rar rare e though, and most divers never suffer any type type of mishap. mishap. However, you need to recognize that that risk risk exists. As a diver, diver, you must bewilling illing to accep acceptt this risk and take take responsibility for  Expres esss your own actions. You will ill be asked to sign an Expr  Assumpt  Assumption ion of Risk Risk Associ Associat ated ed with with Diving Diving and   Related  RelatedActivi Activiti ties es which explains the risks of diving. Also, this textbook clear clearly ly explains explains each type type of risk asso ciated ciated with diving. diving. In addition, addition, your instructor instructor will explain the risks in diving in in general general and any risks that are unique to your local dive sites. If you are a minor, your parents will also have have to understand the risks you face in diving. diving. They will ill be be asked to sign your waiv waiver er and medical history>form.

NAUI Scuba Diver

 A L i e A p p r e h e n s i o n i s N o r m a l Mostpeople who have not spent much time time swim swim ming in the ocean or other open bodie bodies of water have a little little apprehension about learnin learning g to dive. You might have concerns about the the strange equipment, the marine marine life, life, and the environment. This is normal normal and to be expected. Diving is seldom seldom like it is portrayed portrayed in popular films films or television television shows. Once you become a diver, you will will quickly quickly begin to spot spot the the flaws in in most of the the movies mo vies that feature diving. When you go under water, water, you will will find that most most fish swim away from divers and that humans are are almost almost always the most dangerous creatures there. There are ways to minimize minimize the risks risks in diving. By knowing the risks, risks, you can deal with them and make make the probabil probability ity of problem problems s occurring occurring extremely small. This is one major objective of your NAUI Scuba Scuba Diver certification course.

The amount amount of air you have have in your your cylinder limits the amount of time time you spend spend under water on any given dive. Divers use use a submersible pressure gauge (SPG (SPG)) connected to their cylinder to monitor their air supply and help them determine when it is time time to surface (fi (fig g ure 1-9). Just Just as a person person driving driving a car monitors their fuel gauge, gauge, you will will monitor monitor your pressure pressure gauge under under water. However, you must monitor monitor your your pressure gauge more frequently frequently than you would a fuel gauge. gauge. As an an extra precaution, most most divers divers carry either either an additional additional regulator, which allows their dive buddy buddy to to share air during during an emergency, emergency, or a total totally ly independent independent backup backup air air supply. supply. If you are a responsib responsible le and reasonably reasonably cau tious diver, the risk of running running out of air under water is very slight. Another common common misconception is that diving diving equipment is unreliab unreliable. le. Few divers ever ever experience experience an equipment equipment failure failure in diving gear that has bee been n properly properly maintained. A poorly maintained regulator is more more likely likely to freeflow freeflow and deliver more more air air than you need need than to deliver no no air air at all. all. As part of your NAUI Scuba

One of the most popular misconceptions about div div ing is that you can easily easily run out of air under water. water.

Diver certification certification course, course, you you will will learn how to properly properly care for for your equipment and inspect it before each dive. dive. Occasiona Occasionally, lly, a piece of gear might become become loose loose or go out of adjustment u under nder water, water, but you will will learn learn how to deal with with these minor nuisances as part of of the course. Another common concern is that when you are diving diving in in the ocean, you you will will always be be under under the threat of a shark shark attack. Few divers ever ever have the opportunity opportunity to even see a shark shark during during normal normal scuba dives. dives. There are special special trips trips for experienced experienced divers that have the sole purpose of seeing and photographing photographing sharks. The opportunity opportunity to dive with with these unique creatures creatures is something something rare and special. In most cases when sharks do encounter divers, divers, they show littl little e or no interest interest in the divers divers unless they have been been baited with food. food. Divers who remain calm, calm, swim slowly, and stay under water water usually usually receive little little or no attention from a passing shark. shark. They, like like most most creatures under water, wil willl leave you alone iiff you do not not

OUT YOUR DIVE TO SEE HOW M UCH AIR YOU HAVE LEFT

harass them.

C h a p t e r 1 - I n t r o d u c tit i o n

W H A T A R E Y O U R O B L IGI G A T I O N S ? As a student enrolled in in the NAUI Scuba Scuba Diver certi certi fication course, you have certain obligations.

 A t t e n d a n c e You have an obligation to attend, participate in, and satisfacto satisfactorily rily complete every every classroom and water session session. Diving Diving is not complicated, but the know knowledge ledge and skills skills you learn build build throughout the the course. course. You must understand the simple simple concepts in divin diving g to be able to apply them them to the the diving diving you wil willl do in open open water. If you do not attend every train training ing session, session, your knowledge and skills skills wil willl be incomplete. If you do miss any sessions, sessions, it is is your responsibility to arrange with your instructor instructor to complete complete them satisfactor satisfactorily. ily. Be sure to take not notes es during all all classroom session sessions. Your instructor w will ill provide provide you with supplemental supplemental information that might not be in this textbo textbook. ok. In particular particular,, you will learn about about local diving diving techniqu techniques es during during the lectures lectures and open open water dives. dives. You will learn the skills of diving in a confine confineddwater setting. setting. These sessions might take place iin na swimming pool or a calm, clear clear body of water. water. Once Once you have learned the skills of diving and can demon demon strate them comfortably, your instructor will take you on a series of open open water dives where where you wil willl practice practice these skills under actual diving conditions. You will will need to complete knowledge knowledge examinations, plus confined and open open water water evaluations of your diving diving skills before fore your instructor wi willll issue you a NAUI Scuba Diver certification certification card. Even if you pass pass all the knowl edge and skill skill tests tests, but your your instruc instructor tor does does not believe that that you have the judgment needed needed to dive properl properly y or respon responsibly sibly,, it it is your instructor’s instructor’s obligation to withhold your certification. certification. You instructor will explain explain what you need need to do to complete complete your certific certificati ation on and will will help you to achieve that goal.

Health Health is the stateof being sound in body and mind and is a prerequisite for diving. To engage in diving, diving, you must:

• Have a sound heart and healthy healthy lungs. • Have clear clear ears and sinuses. sinuses. • Be free of any limiti limiting ng disease or serious ailment. ailment. • Be free of any condition condition that that can cause unconsciousness. Your instructor instructor will will askyou to complete complete a medical  history form before you can partici participate pate in the water ses sions for this course. If you indicate indicate any problems problems that might affect your ab abilit ility y to dive, you wil willl be asked asked to to have a medical examination and obtain written medical approval before starting your training. Your age and and overall physical physical condition might also cause your instructor to require that you see a physician for a physical examination examination before before diving. This is for your own well well being. However, regardless regardless of a physi cian cian’s ’s opinion, a NAUI instructor may well decline to train train you if you have an absolute absolutecontraindication (a medical condit condition, ion, such as asthma, diabetes, diabetes, or epilep sy) to diving. Women have special healt health h considerations, considerations, espe espe cial cially ly during during pregnancy. pregnancy. No definitive definitive studies studies have bee been n done on on the effects effects of increased increased air air pressure on an unborn child. child. Therefore, if a woman woman is pregnant, she should not dive. If a woman can engage engage in physical activities on land during menstrua menstruation, tion, it is usually usually all all right to par ticipate in in diving. If cramps or other effects effects of menstru menstru ation lim limit it a woman’s activity activity on land, it it is best best to not not dive when when these symptoms exist.

Fitness  Fitn  Fitnes esss is the abil ability ity to meet the the physical physical demands of a particular particular activity. You must must be fit to dive. dive. Initia Initially lly,, this means that you need good aquatic aquatic abil ability ity,, such as being able to swim at least least 200 meters (220 yards) non stop without without fins or or other aids. This demonstrates demonstrates the the aquatic aquatic fitness fitness needed needed to be comfortable in the water. water. Later, Later, you wil willl need to develop develop fitness for using fin fins s and performing other waterskills.

 Jus  Justt because you are in shape for some sports does not mean that that you are in in shape shape for diving, diving, because because different muscle muscles s are use used d in different ways ways.. Playing Playing sports such as baseball baseball does not necessa necessaril rily y keep you fit fit

NA UI Scuba Sc uba D i ver

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for diving. To be in shape shape for a particu particular lar activity activity requires requires regular participation participation in that activity. activity. The best way to stay stay fit for diving diving is to dive regular ly, or swim with mask, snorkel, and fins. Remember Remember that your ability ability to dive dive safely is decrea decreased sed by inactivity. inactivity. Before resuming diving diving after a layoff layoff of one one month or or longer, you should re-establish your skills skills and fitness by pool workouts before any open water water dives. Refresher Refresher courses offered by NAUI facil faciliti ities es and NAUI instructor instructors s also afford opportunities to polish polish skills, skills, add new knowl knowl edge to the basics, basics, and help restore fitness and skill skill pro ficiency. ficiency. Refresher courses courses are are highl highly y recomm recommended if you haven’t been been diving in a while. Divers take pride in their their health and fitness. fitness. It is essential essential to maintai maintain n your health health and fitness fitness if you want to enjoy the sport sport and reduce its risks.

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Good health and fitness are important for for diving safety, but use of drugs can lead to problems under water. Substanc Substances es such as alcohol, mari marijua juana na,, and cocaine, which alter alter your physiology physiology and affect affect your ability ability to think clearly, should never be used before diving.

Any such substanc substance e would be be partic particula ularly rly dangero dangerous us if taken before before diving. Avoid taking any any over-theover-the-count counter er or even prescription prescription drugs that that recommend you not operate operate machi achine nery ry.. Even if you are on medication prescribed by a physician, physician, its effects under pr pressu essure are probably unpredictable, especially especially side side effects effects.. Complete Complete your your treatment before diving. diving. Do not drink drink alcohol before diving. If you are ill ill and do not feel feel well enough to dive dive without without taking taking a drug, you should not dive, even if you feel fine with with medication. medication. The effects effects of drugs drugs can be changed by pressure pressure in unpredictabl unpredictable e ways. Medication Medication can mask the sym sympto ptoms ms of your illness illness,, but that that illness illness still exists.

 V e r i f y W h e t  Y o u H a v e L e a r n e d Review the following following questions questions about health and fitness: 1. Good Good health is a requirement requirement for div diving ing because because 2. A person should ref refrai rain n from divin diving g when 3. True or False: Only people people with problems problems in their their medical history should have a physical examina tion for diving. 4. The best way to maintai maintain n fitness for diving diving is to 5. If I f you are not feeling well but medication help helps s you feel better, you should refrain from diving because ______________________________

F IGI G U R E 1 - 1 0 D IVI V INI N G I S O N E O F T H E M O S T E X C I T ININ G A N D F O N  A C T I V I T I E S Y 0 0 W I L L E V E R E N J O Y .

You will will find that scuba scuba diving is one of the bes best activ activ ities that you you will will ever enjoy (figure (figure 1-10). By completing this Scuba Diver c certifi ertification cation course, you will ill beprepared to participate in diving advent adventures ures unlike anything you have experienced experienced before. Read this this bookcompletely, com plete theworkbook, and follow follow your your instmcto instmctor’s r’s directions and you will will be ready to leam how to dive.

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NAU I Scuba S cuba D i ver

LEARNING GOALS In this chapte chapterr you will: will: • Learn about the basic e equipment quipment you need to go skin diving. • Learn about scuba cylinders, cylinders, includ including ing types types and sizes, valves, maintena maintenance, nce, and inspections. inspections. • Be introduced to regulators and the equipment equipment usuall usually y attached to to the the regulator. • Learn about differ different ent types of diving instruments. • Understand the types of buoyancy buoyancy control control devices and how to select one that that meets your needs. • Learn about weighti weighting ng systems. • Be introduced to the many different types of div div ing suits for warmth and protection and learn how to choose oose the right right suit for your your diving diving con con ditions. • Learn about some the accessory equipment that that makes diving more enjoyable. You must use some some specializ specialized ed equipment equipment to go skin diving diving or scuba scuba diving. diving. When you first first put on on the the equipment nee needed ded, you wil willl probably probably feel awkward awkward before you enter the water. Keep in mind mind that each item serve serves a purpose rpose in the underwater environment. The gear is designed designed to to be be comfortable in the water, rather rather than on land. The sooner sooner you get in the water, the better the equipment equipment will will feel to you.

BUYING EQUIPMENT FUR UIVING You can buy diving equipment from a variety variety of outlets. However, ever, your best choice for purchasing purchasing equip ment is your loca locall dive shop or sporting goods store, if if it it has a dedicated dedicated diving section (figure (figure 2-1). 2-1). There are several reasons why you should buy your gear gear from a specialized specialized retailer, such as a NAUI NAUI affiliated affiliated dive store. These include: include: • You can see and wear the equi equipment pment in in the the store before before you buy buy it and possibly even try out simila similarr rental rental items items in the store store pool. pool. • Your local local retaile retailerr is able to help help you adjust item items s such as buoyancy compensators compensators (BCs (BCs)) and to

FIGURE 2-1. A DIVE RETAILER IS THE BES T CHOICE FOR PURCHASING EQUIPMENT.

measure measure you properly for custom-tailored custom-tailored wetsuits. wetsuits. • Local retailers can provide you you with the instruc tion needed when you purchase a specialized specialized piece of gear, such as a dive computer, video housing, or dry suit. • Your local retailer is usually able to service any gear that you buy a att their their shop. • Local retailers might rent or loan you equipment equipment while yours is in the sho shop for repair. • Your local retailer retailer is your only sourc source e for scuba scuba cylinder fills and last minute required items. Develo Develop a good relationship with with your loca locall diving retaile retailer. r. The salespeop salespeople le there there will ill be able to help you select select the right type type of gear gear for local local diving conditions and for your personal diving interest interests. s. Most newdivers divers wait until until they have have finished their course to buy all of their their scuba equipment. This is a good idea becaus because e you will will usually usually have the opportunity to to try several different different types of gear during during your course. However, most instructors w wililll require require that that you have cer tain tain personal items items of gear when you start your NAUI Scuba Diver certificati certification on course. course. These item items can include: • Mask • Snorkel • Booties Booties • Fins • Gloves

Chapter 2- Diving Equipment

B A SI S I C P E R S O N A L E Q U IP IP M E N T You can go skin diving under under optimal conditions with four four pieces of gear gear:: • Mask • Fins Fins • Snorkel • Flotati Flotation on device Because you wear most pieces pieces of dive gear directly directly on your body, the comfort comfort and fit fit of each item is extremely important.

Masks If you have ever opene opened your eyes eyes under water with with out a mask, mask, you know that it is impossible to see clearly clearly there. Our eyes are designed designed to focus in air. air. A scuba mask places places a layer layer of air air betweenyour eyes and the water, enabling enabling you to see underwater obje objects cts clearly. clearly. A scuba scuba mask differs from swimming goggles in that it it covers your nose. Having Having your nose covere covered enables you to equalize equalize the the pressure inside inside the mask, which increases increases as you dive deeper in the water. The air air pressure pressure inside the mask is equalized with with the water

pressure pressure outside the mask mask when you exhale exhale air air from from your nose nose into the mask. mask. The most important important consideration when when you select select a mask is whether the the mask mask fits your face. To check for fit: 1. Place Place the mask mask gently against your face without putting putting the strap over your head. 2. Inha Inhale le briefly briefly through your nose nose and hold your breath. If the mask sticks against against your face face and does not fall fall off when you look dow down, n, it is a good good fit. If you must must push the mask against your face or continue to inhale to get the mask to to stay on, it is not a well-fi well-fittin tting g mask. (However, this is not true for men with moustaches.) Keep looking looking for a mask that fits. Be sure to to try several different different masks, masks, even even if the first first one you try fits well. well. You might find another style that fits better. You can choose from many different different styles of masks masks.. Some of the features of masks are essential essential and others are optional (figure 2-2). 2-2). Essential features features include: • A tempered glass lens to help resist breaking breaking and avoid injury injury if the lens breaks breaks.. • A solid solid frame to hold the lens in position. • An adjustable, split split or or wide headstrap headstrap that fits fits over a wide portion of of your head.

Dive Mask Double Seal Split

Frame

Nose Pocket

F IGI G U R E 2 -2- 2 . S O M E F EAE A T U R E S O F YO YO U R M A S K A R E E S S E N T I A L .

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NAU I Scuba Sc uba D i ver

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• The ability ability to block off your nose to help help equalize the pressur pressure e in in your your ears. • Adouble featheredge seal to help help the mask fit fit to your face. There are many optional features you might want to consider consider when when you select your mask. Some popular optional features include: • Side windows windows to provide a wider field field of vision. vision. • Apurge valve to help clear clear water from the mask. • A low-volume mask that that fits fits closely closely to your your face to give give you a wider angle of vision. vision. It is also easier to clear of water. water. • Prescr Prescript iption ion lenses. New New mask lenses are covered covered with with a thin thin film film of lubricant lubricant.. You can use toothpaste to remo move ve this lubri lubri cant by using the following following procedure: procedure: 1. Put Put a litt little le toothpaste on the the inside of each lens of the mask. 2. Rub the toothpaste over the entire entire lens with with your fingers or a soft, wet cloth. 3. Rinse Rinse well with with fresh water. Washing Washing the lens lens with toothpaste helps keep the lens from fogging, fogging, which which occurs when condensation condensation forms on the inside of the lens. lens. Each Each time you don your mask mask for diving, you w will ill need need to to prepare prepare it so that it will will not fog because of the temperature differen difference ce inside inside the the mask compared to the surroundi surrounding ng water. The most common way to prevent fogging used to be to spit in in the mask, rub the saliva saliva on the lens, and then rinse the mask. mask. A better better alternative is to use commercially a ava vail il able anti-fog anti-fog sprays, drops, or creams. creams.

Snorkels Have you you ever noticed that you can lie lie face down down on the surface of the the water and float float completely motionless? It’s easy, and most people can do it. However, every time you need to breathe, breathe, you must lift lift your your head out of the water and that takes exertion exertion and gets tiring. tiring. A snorkel is the answer answer to this problem, problem, (figur (figure e 2-3). 2-3). A snorkel enables you to to breathe normally normally while you watch the beauty beneath you. Even litt little le kids can easily easily enjoy the activity. activity. The snorkel helps you conserve conserve energy energy - and the air air in your scuba scuba cylinder - any time

16

F IGI G U R E 2 - 3 . D I F F E R E N T T Y P E S O F S N O R K E L S .

F IGI G U R E 2 - 4 . A S N O R K E L E N A B L E S Y O U T O B R E A T H E A S Y O U E N J O Y T H E B E A U T Y B E N E A TH Y O U .

you are swimming on the surface (figure (figure 2-4). There are many different features features available available with snorkels. The basic snorkel is a “J ” shaped tube with a mouthpiece at the the curved end (figure (figure 2-5). Other fea tures that can be added added to the the basic snorkel include: • Flexible Flexible hosing to enable the snorkel to fit com fortably in your mouth. • Apurge valve to allow allow water to drain out of the bottom of the tube. • A swivel swivel mouthpiece mouthpiece so you can can adjust adjust the mouthpiece in your mouth and swivel it out of the way when you switch to a regulator. regulator.

Chapter 2- Diving Equipment

F IGI G U R E 2 -6- 6 . B O O T I E S P R O V I D E W A R M T H A N D P R O T E C T I O N F O R  Y O U R F E E T W H E N W A L K I N G O V E R R O U G H S U R F A C E S .

The inside diameter of the s snorkel norkel should be no less m than 2 centimeters (3/4 (3/4 inch inch). ). If the diameter is too too small, it is like breathing through through a straw straw.. If the diame ter is too large (over 2.5 2.5 centim centimeters eters or 1in 1inch ch), ), the snorkel is awkward awkward to clear. Also, avoid a snorkel that has any sharp sharp bends or angles.

Booties F IGI G U R E 2 -5- 5 . S N O R K E L S H A V E B O TH TH E S S E N T I A L A N D OPTIONAL FEATURES.

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• Baffles at the top of the “J ” tube to keep water from getting into the snorkel at the surface. • Amolded or soft mouthpiece mouthpiece for for added comfort. The two most important important things things to consider when selecting your snorkel are comfort and breathing breathing ease. ease. The mouthpiece mouthpiece must fit comfortably in in your your mouth and should not be twisted when you place place the tube or barrel of the snorkel snorkel over your left left ear. The snorkel itsel itselff should be between 30 and 35 centimeters (12 and 14 inches) inches) tall. tall. If your snorkel is too too short, short, it will constantly fill fill with water. water. If your snorkel is too long long,, it wil willl be harder to get a good good breath of fresh fresh air. air.

Booties provide protection and warmth for for your feet. feet. They also serve as shoe shoes s when you you are walk walking ing around a dive boat or dive site. Booties Booties are made from neoprene, which is synthetic synthetic rubber injected injected with a gas, gas, usually nitrogen, to make it spong spongy. y. The tiny gas cells in the rubber provide insulati insulation on for for your feet. The neoprene is usuall usually y covered covered with nylon to make make the bootie comfort able against against your skin skin and easy to put on and take off. The neoprene neoprene can be thin or thick thick for for warm-water or cold-water cold-water diving, diving, respectively. The bootie bootie should also have a sole sole to protect the bottom of your your foot from rocks and rough surfaces (figur (figure e 2-6). 2-6). You wear booties with with heel-strap fins fins and some times with full-foot fins. Some of the different different types of booties booties you can find find are: • Slip-on 3 millim millimete eterr (1/8 inch) inch) booties booties that com come up to your ankle ankle for warm-water warm-water diving.

NAU I Scuba Sc uba D i ver

F in

F I G U R E 2 -8- 8 . I F Y O U A R E W E A R I N G B O O T I E S W I T H Y O U R F I N S , B E S U R E T O T R Y T H E M O N A T T H E S A M E T IM IM E S O Y O U CHOO SE A FIN THAT IS THE RIGHT SIZE. F IGI G U R E 2 - 7 . F I N S C O M E ININ B O T H F U L L F O O T A N D H E E L STRAP STYLES.

• Booties with zippers that come up up over your ankle. ankle. The zipper should have a backi backing ng to prevent water from entering dire directly ctly through the zipper and to keep the zipper from rubbing rubbing your skin. skin. The bootie bootie should fit snugly but comfort comfortably ably on your foot. foot. If it it is too too large for your foot foot,, you will ill have a lot of water transfer in and out of your bootie during a dive and your foot will ill get cold. The excess room might might also preven preventt your fin from fitting fitting properly or make it loose enough to come off.

Fins Fins provide your means of propulsion or way to move yourself yourself through the water. Once Once you have all all your scuba gear gear on, on, it it is diff difficu icult lt and awkward to use your hands and arms to move through through the water. With With fins, you can can use the larger larger muscles muscles in in your legs legs for swimming and have your hands free for other other uses.  fin s  and There are two basic types of fins: fins: full-foo t fin heel-s heel-strap trapfin s  (figure 2-7). Full-foot fins are typically typically used used for snorkeling and in warm water. Your entire foot

is enclosed in the foo t pocket  of  of the fin. Heel-stra Heel-strap p fins fins also have a foot pocket, but the back of the pocket is open and an adjus adjustabl table e strap goes across the opening. You must wear booties with with heel-strap fins fins to protect your feet from blisters. blisters. You can use heel-strap fins for diving in any temperatu temperature re water. water. Fins Fins come in a range of sizes from small small to extralarge. large. The size of the fin determines the size of the footpocket and the blade length and width. The blade of the the fin fin is the flat flat portion portion that extends extends away from the foot pocket. You must must choose oose a fin that fits snugly snugly to your foot without cramping your toes toes or pinching your feet (figure (figure 2-8). If your fin is too too large, it will will be too too hard hard to kick, can can cause cramps, cramps, and can easil easily y be be lost. lost. You must pick the fin that that is right right for you and your level of physical conditioning conditioning.. You must be able to kick comfortably comfortably with your fins for long period periods. s. Fins that are too large and stiff stiff for your your leg muscles can cause your legs legs to cramp and will ill not be comfortable. comfortable. You might be more mor e comfortable with a shorter, shorter, more flexible fin. Fins come in many different different materials materials and styles styles depending depending on the manufacturer. The fin must with with stand exposure to sun, salt salt,, and sand, so you should purchase a good good qualit quality y fin that can withstand withstand hard use. use. Some fins come with a plastic insert in each foot foot

C h a p t e r 2 18234876 “ ' / .

F IGI G U R E 2 -9-9 . G L O V E S P R O T E C T YO YO U R H A N D S F R O M C O T S A N D A B R A  S I O N S A N D K E E P YO Y O U R H A N D S W A R M I N C O LDL D W A T E R .

pocket pocket.. The insert helps helps maint maintain ain the shap shape e of the foot pocket when your foot is not in the pocket. You should keep the inserts in the foot pockets pockets whenever you store your fins.

Gloves Gloves Gloves are considered considered basic gear in in many parts of the world. Gloves protect your hands from cuts and scrapes and and provide provide warmth in cold water (figure (figure 2-9). You wear gloves gloves in warm water to protect your hands from injury. injury. They can be made made out of cotton, a thin nylon material material,, or thin neoprene neoprene,, some with a leather or simulated-leather palm. You wear gloves or mitts in in cold cold water to keep your hands hands warm and to protect your hands from the envi envi ronment. Cold-water gloves are made from neoprene. neoprene. Your gloves gloves should fit fit snugly and allow allow you to move your fingers fingers easily. easily. You must be able to handle your equipment equipment while while wearing gloves gloves. Your instructor instructor might have you wear gloves gloves during your your confined confined water traini training ng so you learn learn how to work while wearing wearing gloves. gloves. You should not touch or handle handle the creatures you find under water just because because your gloves gloves are protecting you from the environment. In many case cases, s, you can hurt or kil killl plants or animals animals just by touching tthe hem. m. Coral reefs reefs are parti particu cular larly ly sensitive to touch and many corals are easily broken. Many fish are cove covered red with a protective slime, and removing the slime makes the fish subject to to infection infection or parasites. parasites.

F IGI G U R E 2 - 1 0 . Y O U S H O U L D R I N S E Y O U R E Q U I P M E N T W I T H F R ESE S H WATER AFTER EVERY DIVING DAY.

Me In som some areas of the world, you are no longer allowed to wear gloves gloveswhen diving diving (for (for example: example: Cozumel, Cozumel, Mexico). This is to ensure that you will ill not touch the reef and harm delicate corals corals to die. die.

Flotation Device Divers should wear some type of personal flotat flotation ion device for snorkeling snorkeling and skin diving. diving. The most com monly used used piece piece of flotation equipment is an inflatable inflatable vest that is is worn on the chest chest and is usuall usually y referred to as a skin diving diving or snorkeling snorkeling vest vest.. The vest is design designed to slip over your head and fasten at your waist with a strap. Most vests of this design design also have some type of oral inflation tube.

Maintenance Maintai Maintaining ning your basic skin diving gear, gear, as well as

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your scuba gear, gear, is simple. You should rinse your gear with fresh water after every diving diving day (figure (figure 2-10 2-10). ). Be sure that you do not leave your gear in the sun any more mo re than necessary necessary becau because se sunligh sunlightt and heat are V extremely extremely damaging to scuba gear gear and neopren neoprene, e, ail

At the end of a diving trip, soakyour gear gear overnight in fresh water and then rinse it thoroughly thoroughly with fresh water. Make sure the gear is dry before before you store it in a cool, dry area, like a closet. For extra protection, you can store your dry gear in a sealed, sealed, plastic plastic bag. No matter howwell you maint maintain ain your your gear, you will ill need need to replace some parts periodically periodically.. Fin Fin straps, straps, mask straps, and snorkel keeperswear out. You must

CYLINDERS When most people think of scuba diving, diving, they immediately think think of the cylinders that divers wear wear on their their backs. backs. Scuba cylinders a allo llow w you to store store large amounts amounts of air in a small space. space. Scuba cylinders ar are e also known as bottles or tanks. Every Every country country can can be expected to have standards regulating scuba scuba cylinders. In the United States States,, cylin cylin ders ders are regulated by the Department of Transportation (DOT) (DOT) and must be pressure tested tested accordi according ng to govern ment standards. standards. In Canada, cylinders cylinders are regulated by the Canadian Transport Commis Commission sion (CTC) (CTC),, which which has standards simila similarr to the United States Departmen Departmentt of Transportation.

inspect your gear regularly regularly,, and especially especially before before a dive trip, trip, to give you a chance chance to replace worn parts before they break.

 V e r i l y W t i a t Y o u H a v e L e a r n e d Review the following following questions questions on basic equipment: equipment: 1. The two most important important features features for the selection of your mask, mask, snorkel, booties, booties, and fins fins are: □ Com Comfort fort

□ Style Style

□ Fit

□ Color olor

□ Price Price

□ Materi Material al

2. One feature that that is not essential essential in a dive mask is: a. Purge valve b. Tempered glass c. Nose-blocking device d. Rigid frame 3. List two factors that that can can reduce the ease ease or efficiency of breathing through a snorkel:

Characteristics The air air in in a scuba cylinder cylinder is high highly ly compressed, so a cylind cylinder er must have strong walls walls to withstand the pressure. The pressure of cylinde cylinders rs ranges from 120 bar (1800 pounds per square inch [ps [psi]) i]) to 310bar (4500 psi). psi). One One bar is equal to approximately 14.7 psi or 1 atmosphere sphere (atm (atm). ). Mo Most st cylinders cylinders are made made of aluminum or steel.

 A l u m i n u m Aluminum Aluminum cylinders cylinders do not rust, rust, which which is an advantage over steel steel cylinders. However, ever, aluminum aluminum cylinders cylinders are more easily damaged damaged than steel steel cylinders cylinders on the outside and the threads threads where where the cylinder cylinder valve screws in must be inspected regular regularly ly for cracks and other problems. If water enters nters an aluminum aluminum cylinder, the cylinder corrodes and forms alumin aluminum um oxide. Once aluminu aluminum m oxide has formed, it it slows further further corrosion corrosion to the cylinder. cylinder.

Steel Steel cylinders cylinders are more resistant to exterior damage. damage. However, ever, if if water enters enters a steel steel cylinder, cylinder, the cylinder cylinder corrod corrodes es and form forms s rust that can quickly quickly ruin ruin a steel steel cylinder. cylinder. If you suspect suspect that water has entered

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Chapter 2- Diving Equipment

U.S. Markings

European Marking Marking s 2

Steel Cylinder(3AA=Steel) 1. Regulatory Agency 2. Type 3. Working Pressure(Bar) 4. Manufacturer  5. Test Date 6. Serial Number 

1. Gas Ty p e

8. Ser i al N u m b er  

2. Ow n e r

9. St an d ar d

3. S c ub ub a E qu qu i pm pm en en t

10. T es es t P re re ss ss u re re

4. S er er v ic ic e Pr es es s ur ur e

11. E WG WG T ra ra de de ma ma rk rk

5. EWG EWG Design Design Permit Permit

12. 12. RepeatTest RepeatTest

6. Co u n t r y o f

13. Em p t y W ei g h t

Man u f a c t u r e r

 Al um in um Cy li nd er (3AL=A (3AL=Aiuminum iuminum)) 1. Regulatory Agency 2. Type 3. Working Pressure 4. Serial Number  5. Manufacturer  6. Size 7. Test Date

14. Mi Mi n i m u m Vo l u m e

7. Manufactur er Symbo l 15. Galvanized

F IGI G U R E 2 1 1 . C Y L I N D E R M A R K I N G S P R O V I D E I M P O R T A N T INI N F O R M A T I O N A B O U T T H E C Y L I N D E R .

the cylinder, cylinder, an inter internal nal inspection inspection should be made made at a qualified facility.

Sizes Scuba cylinders come in many different sizes. In the metric metric system, the size of the c cyli ylinde nderr is is expressed as the volume the cylinder cylinder actua actually lly holds. In the United States, the size of the cylind cylinder er is is expressed as the volume of com compresse pressed d air the cylinder cylinder wil willl hold. Some metric metric sizes you may see when diving diving include: • A 12-lit 12-liter er cylinder made out of aluminum aluminum rated rated for a pressure of 200bar. • A 10-lit 10-liter er cylinder made out of aluminum aluminum rated for a pressure of 200bar. • A 10-liter cylinde cylinderr made out of steel rated for for a pressure of of 150bar. • An 18-liter cylin cylinder der made out of steel steel rated rated for a pressure pressure of 160bar. bar.

Some United States sizes you may see when divin diving g include: • An 80cubic foot cylinder cylinder made out of aluminum aluminum rated for for a pressure of 3000 3000psi. • A 63 cubic foot cylinder cylinder made out of alumin aluminum um rated for for a pressure pressure of 3000 psi. • A 72 cubic cubic foot cyli cylind nder er made out of steel rated for a pressure of 2475psi. • A 95 cubic foot cylinder cylinder made out of steel steel rated for a pressure of 2640psi.

Markings Markings are placed on the the shoulder of each cylin cylin der to provide important important pieces pieces of informatio information n about the cylinder cylinder (figure (figure 2-11). 2-11). The markings include: include: • The serial number of the the cylinder, which is unique for each cylinder cylinder made by a single manufacturer. • The The name of the the manufactur manufacturer er or their their symbol. • Government-required marks to signify signify that that the

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Cylinders can can also also be be covered covered with with a rubber or or plastic plastic net. The net protects protects the the exterior of the cylinder cylinder and its paint. You might also see see divers with two cylinders hooked together together with a manifold manifold sharing sharing a common valve.

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 V a l v e s Every cylinder cylinder must have have a valve to hold the air in the cylinder cylinder when it is not in use, use, to control the flow of of air air out of the cylinder, cylinder, and to provide an attachment point for the scuba regulator. A valve valve acts like like a water water faucet. You open open the the valve by turnin turning g a handle (knob) (knob) counterclockwise and close close the valve by turning turning the knob clockwise, as seen from from the top of the valve handle.

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F IGI G U R E 2 1 2 . T

V A LVL V ES E S A R E T H E M O S T C O M M O N T Y P E O F V A LVL V E

F O U N D I N T H E U N I T E D S T A T ES ES .

cylinder cylinder was manufactured anufactured according to its standards. • The service pressu pressure of the cylinder, cylinder, which which is the pressu pressure to which the cylinder can be filled filled (for example, 200 bar or 3000 psi) psi).. • A “+” “ +” mark on steel steel tanks, tanks, authoriz authorizing ing a 10 percent pressure over overfi fillll beyond the stamped service pressure. • The materia materiall of which which the cylinder cylinder is composed (for examp example, le, 3AL 3AL stand stands for a parti particula cularr alu alu minum alloy). • The The hydrostatic testing date of the cylind cylinder er (fo (forr example, example, 8/97 8/97signifies signifies that the cylin cylinder der was test ed in August of 1997 1997). ). In the United States, hydrostatic hydrostatic testing must be performed every five years. years. In Japan, Japan, hydrostatic testing must must be performed every three years. In Australia, Australia, hydrostatic hydrostatic testing must be done every year.

 A c c e s s o r i e s Cylinders Cylinders sometimes have boots on the bottom to protect the the bottom bottom of the cylinder cylinder and its environment. Some steel cylinder cylinders s have a rounded bottom and need a boot to be able to tempora temporaril rily y stand upright. upright. You must remove the boot boot on a cylinder cylinder periodi periodical cally ly to properly rinse the bottom of the cylinder. cylinder.

22

T

V a lv e s

The United States States “K” “ K” valve is one one valve you will see often when diving diving (figur (figure e 2-12). It is design designed like like a post post with an on/off knob. The first stage regulator regulator yoke fits over the post and the regulator is tightened against the post with with a screw. screw. These These valves are not usuall usually y used at pressures higher higher than than 200 bar (3000 psi) psi).. An O-ring O-ring or gasket gasket found on the cylinder cylinder valve makes a seal between the regula regulator tor and valve. valve. If the Oring is damaged or missing, the regulator wil willl not seal to the cylinder cylinder and air air will will escape. You should replace O-rings frequently frequently because of wear.

" J " V a lvlv es es A “J ” valve look looks s like the “K” “K” valve with a lever lever opposite the on/off knob. This lever lever is known as a reserve reserve mechanism. mechan ism. The mechanism is designed to begin to restrict ai airfl rflow ow at about 20 bar (300 psi) to 33 bar (500 psi) of pressure pressure in the cylinder. cylinder. When the mechanism is manu manual ally ly opened, the airflow airflow is no longer restricted.  submersiblee pres “J ” valves were popular befo before re submersibl  sure gauges gauges (SPG  (SPGs) s) were commonly used. The reser reserve ve mechanism had to be placed placed in in the up position at the start start of the dive. The lever lever was moved to a down posi tion by means means of a cord or rod when the diver noticed

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Ch apter 2- Diving Diving Equipm Equipm ent

F IGI G U R E 2 - 1 3 . D IIII U V A L V E S O R I G INI N A T E D I N E U R O P E A N D A R E CAPABLE OF OPERATING AT PRESSURES GREATER THAN 200 BAR (3000 PSI).

diffi difficul culty ty breathing. These These levers levers were easily easily bum bumped ped out of the the up position during during the dive and the diver would be using the last air air without without knowing it. You will see “J” “J ” valves in use, use, but the valve is always used with the reserve reserve lever in in the down position. The mechanism mechanism is rar rarely ely usedbecause divers now use use sub mersible pressu pressure re gauges gauges to monitor their their air air supply.

disk. This relief relief mechanism is necessary to to keep the cylinder cylinder from rupturing rupturing if if the cylinder beco becom mes extremely hot, or otherwise oveipressurized.

D I N V a lvl v e s

Maintenance

The DIN valve system system originated originated in Europe. The DIN valve valve has a large, threaded opening and the regula tor screw screws into the valve (figur (figure e 2-13). This system is capture d O-ring system. system.   While also known as the captured common in the rest of the world, DIN DIN valves are not commonly seen in the United States. States. The DIN valve is is stronger stronger and capable of operating at pressure pressures s higher higher than than 200 bar (3000 psi). psi).

Proper care of your cylinder cylinder includes rinsing rinsing the outside outside with fresh water after using the cylinder, having the cylinder visua visually lly inspecte inspected each year, and having the cylind cylinder er hydrosta hydrostatica tically lly tested tested as required by governm government ent standards.

Burst Bisks □

 pressuree Every cylinder valve valve is equipped ipped with a pressur relief disk  or  or burst disk. This disk is designed to allow the cylinder cylinder to vent excessiv excessive e pressure by bursting bursting the

F IGI G U R E 2 - 1 4 . Y O U R S C U B A C Y L I N D E R M U S T B E V ISI S U A L L Y INI N S P E C T E D  A T L E A S T O N C E P E R Y E A R .

Scuba cylinders must be inspe inspected cted internal internally ly and externally externally at least once per per year at a professional professional dive shop shop or a dive-equipm dive-equipment repair facil facility ity by a certified cylind cylinder er inspector. inspector. The cylinder cylinder is inspected for dents, nts, marring, marring, and fire or heat discoloration discoloration on the ou outsid tside e and for corrosion, water, and cracks inside (figure (figure 2-14)

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F I G U R E 2 -1- 1 6 . H Y D R O S T A T I C T E S T I N G S T A R T S B Y F ILI L L INI N G T H E S C U R A C Y L I N D E R W I T H W A T E R A N D P L A C I N G I T ININ A L A R G E R C Y L I N D E R D F W A T ER ER .

vgen Servlc* L .7.— 

fOUCAllON

decrease back within within set set limits limits when the pressu pressure is relieved, the cylinder cylinder can can no longer be used. sed.

F IGI G U R E 2 1 5 A V ISIS U A L C Y L I N D E R I N S P E C T I O N S T I C K E R ISI S P L A C E D O N Y O U R C Y L INI N D E R W H E N I T H A S P A S S ED ED ITS VISUAL INSPECTION.

If the cylinder passes sses the visual visual inspection, inspection, a visual visual cylinder cylinder inspection sticker is attached to the cylinder with the month month and year of the inspection noted on the sticker (fig (figure ure 2-15). If the cylinder cylinder does not pass the the visual visual inspection, it it might need to be cleaned or tum bled to remove oxidation. If the cylind cylinder er needs needs to to be tumbled, tumbled, it autom automatic aticall ally y needs eds hydrostatic testin testing. g.

Hydrostatic Testing a m

In the United States, States, hydrostatic testing is required every five years or whenever the cylinder cylinder must be cleaned by by tumbling. tumbling. Hydrostatic testing test tests s the cyli cylin n der for metal fatigue. During During hydrostatic testing, the scuba scuba cylinder is filled filled with water and placed placed in a larger sealed cylinder cylinder full full of water (figu (figure re 2-16). The pressure of the water in in the scuba scuba cylinder cylinder is increased to 5/3 the the service pressure of the cylind cylinder er and then then reduced to the pressure of the surrounding surrounding water. water. If the cylind cylinder’s er’s size size increases with with the increase increase of of pressure but does not

Storage You should store store cylinders for any long term with some pressure in the cylinder. cylinder. In steel steel tanks, keeping keeping som some air air in your cylinder cylinder ensures ensures that water cannot enter your cylinder and cause cause corrosion. corrosion. With alu alu minum tanks, this is not as much of a concern. Aluminum Aluminum tanks can can be stored stored empty empty and with the valves open open so that they will will not be a hazard in a fire. You should store store cylinders cylinders upright upright in a cool, dry, and protected locat location ion where they cannot be knocked knocked over. over. Never leave a cylinder cylinder standing standing by itself itself when when you are not holding it. You should should lay lay your cylinder down to prevent damage damage to it, the valve valve,, or inju injury ry to someone. When transporting a cylinder in a moving moving vehicle, place the cylinder cylinder on its side and secure it to prevent damage to the cylinder, cylinder, the valve, or the vehicle. vehicle.

Backpacks Backpacks are designed designed to hold a cylin cylinder der securely securely on a diver’s diver’s back. Backpacks are now usuall usually y incorpo rated directly directly in in the buoyancy compensator, compensator, but you might sti stillll see divers using a backpack and separate separate buoyancy control control device. The backpack must be used used

Chapter 2- Diving Equipment

with an easily easily adjustable harness with a quick-release quick-release buckle at the waist and at least least one at the shoulder. shoulder.

 V e r i f y W h a t l a H a v e L e a r n e d i        v      i        n       g    

Review the followin following g questions questions about cylinders: 4. What is the difference between a “J” “J ” valve valve and a “K” valve?

E        q      u     i         p     m     e     n     t      

5. The two types of metal metal used to make scuba scuba cylinders are and _____________________

6. In the United States, States, a visual visual inspection inspection is per formed and_a_hydro static test is performed performed . ____________________

________________

F IGI G U R E 2 1 7 . Y O U R S C U B A R E G U L A T O R D E LIL I V E R S A IRIR T O YO YO U O N D E M A N D A N D P R O V IDI D E S E A S Y B R E A TH T H INI N G UNDERWATER.

REGULATORS The scuba regulator  is  is a mechanical device that delivers air to you on demand demand (figur (figure e 2-17). One func tion of the regulator regulator is to reduce the high pressure of the the am bientt pressur pressure, e, or the pres air in the cylinder to the ambien sure surrounding your body, body, so you can breathe it. Regulators Regulators are composed of two main parts: the first first stage and the second stage. Regulator Regulators s also commonly have other pieces of equipment attached attached to them, includin including g addition additional al regulator regulator second stag stages and and gauges. F IGI G U R E 2 1 8 . T H E F I R S T S T A G E O F T H E R E G U L A T O R A T T A C H E S

First Stage The first first stage of most United United States type regulators fits over the pos postt of the cylinder valve using using a device com com bining bining the yoke yoke and yoke screw (figure (figure 2-18). Some use a DIN threaded threaded fitting. fitting. In the first first stage, the high-p high-pres res sure air from the cylinder is reduced to approximately 10bar (150 psi) above the pressure pressure surroundi surrounding ng the cylinder. The air from the the first stage stage is then delivered to the second stage through through a low-pressure hose. The first stage stage of your regulator regulator has a number of 

D I R EC E C T L Y T O T H E S C U B A C Y L INI N D E R .

outlets or ports to which which hose hoses s and pieces of equipment are attached. The first first stage must have at least one high-pressure port. This This port bypasses the mechanisms that reduce the pressure from the cylinder cylinder.. Your sub mersible mersible pressure gauge gauge is attached attached to this this port so you m can monitor your ai airr supply. supply. The following following hoses oses might

NAU I Scuba S cuba D i ver

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F I G U R E 2 - 1 9 . T H E M O U T H P I E C E IS A T T A C H E D T O T H E S E C O N D STAGE OF THE REGULATOR.

F IGI G U R E 2 -2- 2 0 . T H E M O S T C O M M O N A L T E R N A T E A IRI R S O U R C E ISI S A N OCTOPUS REGULATOR.

be connected to low-pressure ports in additio addition n to your prima primary ry second stage stage hose: • Apower-inflator power-inflator hose for your buoyancy buoyancy compensator. • An alterna alternate te second stage or octopus regulator. regulator. • A dry suit suit power-infl power-inflator ator hose, if if used.

Second Stage The second stage tage of your regulator regulator has a mouth piece attached to to it (fig (figur ure e 2-19). The second stage fur fur ther reduces the air air pressure from approxi approximately mately 10 bar (150 psi) psi) above the surround surrounding ing pressure to whatever the ambient pressure pressure is. Therefore, the air air you breathe is always always at the pressure needed needed by your body, no matter how deep you are are under the water. Some Some regulators offer higher performance than than others others and deliver deliver a greater volume of air air at deeper per depths regardless regardless of flow restrictions. This is important, important, because the deeper you go, the denser the air. air. If you plan plan to leam leam to do deep, wreck, wreck, cave, or ice divin diving g or do underwater hunting, hunting, you will will want want a high-perform high-performance ance regulator.

 A l t e r n a t e  A i r S o u r c e s It is standard practice that that you and your buddy be

26

FIGURE 2-21. SOM E ALTERNATE AIR SOURCES ARE COM BINED WITH THE P O W E R I N F LAL A T O R O F T H E B U O Y A N C Y C O M P E N S A T O R .

equipped equipped with alternate alternate air air sources sources in case of emer gency. An alternate alternate second stage can be attached to your primary primary regulator, or you can carry a source source of air totally separate from your scuba cylinder.

O c t o p u s R e g u l a tot o r s The most most common alternate alternate air air source is an an octo  pus  pu s regulato regulator  r  (figur  (figure e 2-20 2-20). The octopus regulator regulator is an additi additional onal second stage stage that allows allows you to share air from your cylinder cylinder with another another diver. diver. The hos hose e for the

Ch apter 2- Diving n g Equipm Equipm ent

F IGI G U R E 2 2 3 . T H I S ISI S A N O T H E R T Y P E O F C O N T I N G E N C Y S C U B A .

F IGI G U R E 2 - 2 2 . S M A L L S C U B A C Y L INI N D E R S W I T H T H E IRIR O W N REGOLATOR ARE CALLED PONY BOTTLES.

octopus regulator regulator should should be at least 10 centimeters centimeters (4 inches) inches) longer than a standard regulator hose. hose. The octopus pus regulator regulator is is inexpensive, convenient, and easy to use. However, it it is not a source of air air separate from your scuba cylinder, cylinder, so your remain remaining ing air air supply is depleted depleted much faster when when it it is is in emergency emergency use use by another diver and yourself. Another type type of alternate alternate air air source is a combina combina tion regulator and power-inflator for your buoyancy compensato compensatorr that fits on its power-inflator power-inflator hose hose (figur (figure e 2-21 2-21). These These units elimi eliminat nate e the extra hose for an octopus regulator and are easy to locate in in case of an emergen emergency. The air donor typic typicall ally y uses this alternate alternate air air source and gives their prima primary ry air air source to the the other diver.

Contingency Scuba Contingency Contingency scuba scu ba  or true alternate air air sources rces provide a totally totally independent independent regulator regulator and air air supply. supply. The two main main types of contingency scuba are:  pon y bottl bottle, e, which is a small scuba cylinder •A pony with a separate separate regulator regulator (figur (figure e 2-22 2-22). Pony bottles are commonly commonly used by wreck divers and divers divers who dive deep.

• Asmaller cylinder cylinder with an integrated first and second second stage stage mounted directly directly on the cylind cylinder er (figure 2-23). Contingency scuba provides provides an excellent excellent backup for yourself yourself if if you and your your buddy buddy getseparated under under water. Howeve However, r, contingency contingency scuba adds adds additiona additionall expense to your scuba equipment as well as extra bulk and weight.

P o s i tit i o n o l t h e  A l t e r n a t e M o u t h p i e c e The mouthpiece mouthpiece for your alternate air source source should be located on the front of your body (figu (figure re 224). The mouthpiec mouthpiece e for your alternate air air source source must must bevisible, easy to identify, and available available for immediate usewhen it is neede needed. An alternate alternate air air source will ill not do you or your buddy any good if it cannot be located immediately during an emergency.

Gauges Divers must rely on gauges gauges and instruments to tell them depth, epth, bottom bottom time, direction, direction, and air air supply, just as a pilot relies on instrumentation to fly a plane. The gauges gauges and instruments can be integrated into a console or worn separately. console streamlines your gauges into one Adive console unit. unit. The console is an enclosure molded with with slots to hold hold a submersible pressure gauge, depth gauge, gauge, and sometimes a compass.

NAU I Scuba Diver

mares B R A S S

F IGI G U R E 2 2 5 . T H E S U B M E R S I B L E P R E S S U R E G A U G E I S A R EQ E Q U IRI R E D P I EC EC E O F S C U B A E Q U I P M E N T .

F IGI G U R E 2 2 4 . Y O U R A L T E R N A T E A I R S O U R C E M O U T H P I EC EC E S H O U L D B E LO LO C A T E D O N T H E F R O N T O F Y O U R BODY AND BE CLEARLY VISIBLE.

psi) psi) when when the pressure pressure is reduced reduced to half, half, and soon. SPGs are sensitive instruments and you should should not subject them to shocks or abuse. If you notice a small leak leak from the hose or connecti connection on between the hose and and SPG, it is is not necessary necessary to end end your dive immediately. However, you should have the SPG SPG and hose serviced as soon aspossible to your NAUI Pro Pro Center or dive-equipment repair facilit facility. y. If you see water in your SPG, have it serv serv iced as soon soon as possible and do do not rely on it for diving diving until you do. SPGs can can also be integrated in dive dive computers and measure measure pressure electronic electronically. ally. In addition, someairintegrated dive computers can also monitor your breathing rate and predict how long the air in in your cylin cylin der will ill last based onyour breathing breathing rate (figure (figure 2-27).

S u b m e r s ibib lel e P r e s s u r e G a u g e  submersible blepressure pressure gauge  (SPG) The submersi  (SPG) is a required piece of equipment equipment for scuba diving. The SPG displays displays the amount of air pressu pressure re remaining remaining in your scuba cylinder cylinder in in the same way a fuel fuel gauge gauge shows ows how much gas gas you have have left in your ca car’s r’s gas tank. By look ing at your SPG frequently during your dive, you you will will know when your air air supply is getting low and it is time to end end your dive before before you run out of air. air. All mechanica mechanicall SPGs perform the function of measur ing the air pressure in your scuba cylind cylinder er (fig (figure ure 2-25). SPGs give a reading reading in bar or pounds per square inch inch (psi). (psi). For a typical alum aluminum inum cylinder, the SPG reads 200 bar (300 (3000 psi) psi) when the cylinder cylinder is full, full, 100bar (1500

Depth Gauge Your depth and th the e duration duration of of your dive at at any particu particular lar depth depth are limited by a number number of factors, so so you need to monitor your your depth when diving. diving. A depth depth gauge gives you a way to measure your your depth when you are under water (fig (figure ure 2-28). There are four types of depth gauges: • Capillar Capillary y tube • Bourdon Bourdon tube tube • Diaphragm mechanism • Electr Electroni onic c gauge The capilla capillary ry tube is a simple, simple, inexpensive inexpensive instru ment that consists of a clear clear piece of tubing sealed at

Chapter 2- Diving Equipment

05332874

iBS/lS

F IGI G U R E 2 2 6 . T H E S P G ' S I N T E R N A L M E C H A N I S M . F IGI G U R E 2 2 8 . A D E P T H G A U G E M E A S U R E S Y O U R D E P T H W H E N  Y O U A R E U N D E R W A T E R .

F IGI G U R E 2 -2- 2 7 . M O S T E L EC E C T R O N I C S U B M E R S I B LEL E P R E S S U R E G A U G E S A R E I N T E G R A T E O W I T H O IVI V E C O M P U T E R S .

one end. The tubing is marked with numbers numbers that correspond to your depth. As you descend in the water, water enters the tube and compresses the air air inside. inside. You read your depth depth by by looking looking at the air air and water interface interface inside the tube. tube. A capi capilla llary ry tube is very useful at shallow shallow depths (above (above 12 meter’s or 40feet), feet), but is not recom recom mended for for deeper depths, as the scal scale e size becomes too small for accurate readings. A Bourdon tube uses pressure to straigh straighten ten a curved metal tube. Bourdon Bourdon tubes can be open or closed, although although open tubes are rarely rarely seen today. The closed tube is filled with with air air and is enca encased sed in a housing fil filled led with oil. oil. The pressure from the surrounding surrounding water is

transmitted throug through h a flexible part part of the housing to the oil and then to to the tube. tube. The tube is attached attached to a linkag linkage e and and needle and as the pressure opens opens the tube, tube, the needle moves moves to show your your depth. Bourdon Bourdon tubes measure depth reasonably accurately. A diaphragm mechanism uses a metal diaphragm, which is attached attached to to a linkage. The linkage is attached attached to a needle. As the pressure pressure increases on the diaphragm, diaphragm, the needle moves to show your your depth. Diaphrag Diaphragm m gauges gauges can often be adjusted adjusted for thei theirr zero point. Electronic Electronic depth gaug gauges es are part of all all dive comput comput ers and most electroni electronic c dive timers. An electroni electronic c depth gauge measures your depth using using transducers, transducers, and then displays the depth depth digita digitally lly.. Electr Electroni onic c depth gauges are extremely extremely accurate and reli reliable. able. You must have a means of record recording ing the deepest deepest depth you reach on a dive. Capil Capillar lary y gauges do not have a means of recording recording your your deepest depth so you must remember to record record it on a slate during during your dive. Bourdon tube and diaphragm diaphragm gauges might have a sec ond needle that is pushed around the gauge by the depth needle attached to the linkage linkage.. The second needle stays at your your deepest depth while while the depth needle keeps show ing your current current depth depth. Electr Electroni onic c depth depth gaug gauges record record your maximum maximum depth depth in their their memory and then display the maximum maximum depth when you surface surface or on demand.

NA UI Scuba Diver Di ver

Compass When you you are swimming under under water and visib visibilit ility y is poor, a compass is an important important reference inst instrument, rument, if not essential. essential. Some divers use a compass on every dive, including wh when en diving in clear, clear, tropical tropical water. water. A compass pass can also be crit critic ical al on the surface iiff it is foggy and you cannot cannot see the beach or boat. A compass consists of a magnetized magnetized needle that that aligns itself with the the earth’s magnetic magnetic field. The need needle will ill point point towards magnetic magnetic north north as long as there are no magnetic magnetic influences influences nearby that can can cause the nee nee dle to deviate or turn away from its specified direction. This constant reference to magnetic north north enables you to know know your position or direction of travel under or above the water water relati relative ve to the north-seeking needle. A diving diving compass must: • Be fille filled d with liq liquid uid to withstand pressure and dampen needle movement under water. • Have Have a reference reference line, called called a lubber line, line, used used as the direction direction of travel. • Have a means, such as a ro rotat tating ing bezel, to show a select selected ed bearing or direction (figure 2 -2 9 ).

Maintenance Your regulator, alternate alternate air air source, and gauges are are your life-support system under water water and should should be carefully carefully maintained. Maintenance of your regulator first first and second stages, alternate alternate air air source, and gauges can be divided divided into into steps you can take as a user to keep your regulator regulator in top condition, condition, and step steps that must be perform performed by by a qualified qualified repair technician. You should replace the dust dust cap that fits over the inlet inlet to the first stage whenever your regulato regulatorr is off a cylinder. cylinder. The dust dust cap must be dry before before you fit it over the inlet inlet to the the first stage. The first stage stage contains preci preci sion moving parts and O-rings O-rings.. If water, sand, or dust dust get into the first first stage, they can damage the moving parts, affecting affecting the performance of your regulato regulatorr and making making it diffic difficult ult for for you to breathe. Some dust caps caps use an O-ring to create a seal with the first stage. If the dust cap requires an O-ring O-ring and it is missing, you wil willl see an empty groove in the cap. Be sure to replace replace the

F IGI G U R E 2 2 9 . D IVI V INI N G C O M P A S S E S A R E F I LLL L E D W I T H L IQIQ U I D TO TO W I TH T H S T A N D P R E S S U R E , A N D S H O U L D H A V E A LUL U B  B E R L INI N E A N D R O T A T INI N G B E Z E L

O-ring to ensure ensure that you are s sealing ealing the inlet inlet closed. closed. At the end of each each diving diving day, you should rinse your your regulator regulator with with fresh water to remove remove salt crystals or other impurities impurities (figur (figure e 2-30). Always be sure to let water run through the mouthpiece and exhaust tees on the second stage. However, you should should never press press the  purge button when running running water through the mouth piece. This could cause water to enter the the hose hose to the first first stage and get get into the first stage of tthe he regulator regulator from there. You should soakyour regulator (if it does not have have a DIN connector), connector), alternate air air source, source, and gauges ges overnight overnight in fresh water at the end of a dive trip, and then rinse them thoroughly. thoroughly. Let the the regulator dry com pletely and then then store it in a cool, dry place. Do not coil the hose hoses tightly tightly or allo allow w them to hang at an angle with weight on them, which which causes kinks kinks at at the hose ends. Hoses that have have been stressed can spring spring leaks leaks and must be replaced. replaced. At least once once per year, year, you should have your regula regula tor service serviced d by a certified repair repair technician. technician. Repair tech nicians nicians are trained by the manufacturers manufacturers in the proper proper metho methods ds to service their their regulators and also to spot spot prob prob lems and correct them them.. The repair technici technician an will will take the first and second second stages apart, clean clean all the metal parts, and replace the O-rings O-rings and other nylon or sili sili cone cone parts of the regulator. The repair technician technician will will

Ch apter 2- Diving Diving Equipm Equipm ent

also test and adjust the intermediate intermediate pressure pressure of your first stage during the service. During During an annual annual service, the repair technicia technician n wil willl also inspect inspect your submers submersible ible pressure gauge and high-pressure igh-pressure hose, depth gauge, and compass for proper operation. operation. Do not leave your gauges ges sitting sitting in the sun. The sun can cause the o oilil in a compass or depth gauge to expand and leak. leak. Also, Also, if you will will be traveling at high altitudes, altitudes, be sure to transport transport your gauges in a pressureproof contai container ner when at more than than 300 meters (1,000 (1,000 feet) above sea level. level.

 V e r i l y W h a t t b a H a v e L e s m e d Review the followin following g questions questions about regulators, alternate air air sources, sources, and and instrumentation: instrumentation: 7. The most important important crite criteri ria a when selecting a regulator is _____________________

8. You must must replace th the before before you rinse your regulator. regulator. 9. What is is an advantage to using an octopus regulator? _______

10. What is the primar primary y advantage for using contin contin gency gency scuba instead of an octopus regulator? regulator? 11. A depth gauge is usable usable only at shallow shallow depths. 12. Th The measures measures the air air pressure in your your cylinder. cylinder. _________________

_______________________________

 A D D I T I O N A L D I V I N G I N S T R U M E N T S Some additional additional diving diving instruments that you might want to consider consider using include a timing timing device, a com puter, and backup backup instrumentation. instrumentation.

Timing Devices Along with keeping keeping track track of your your depth under water, you must also keep track track of the time you stay stay under water. You can keep track track of your time under

F IGI G U R E 2 - 3 0 . Y O U S H O U L D R I N S E YO YO U R R E G U L A T O R A T T H E EN D OF EACH DIVING DAY.

water by using a watch, watch, an underwater timer, or a dive computer (figure 2-31). Watches usedfor diving diving must be designed to with stand pressure. pressure. They should should be rated for depths of at least 100 meters (300 feet). feet). Your Your watch watch should also have a way to measure measure elapsed time with with one of the followi following: ng: • A rotating bezel around the dial dial of the watch. • Astopwatch feature. feature. Underwater Underwater dive timers timers are designed to measure elapsed elapsed time time and have a valuable valuable feature not found in most dive watches. A pressure-activated pressure-activated switch switch starts the timer when you leave the surface and shuts off automat ica ically lly when you come back to the surface. The dive timer autom automatica atically lly records records the elapsed elapsed time of your dive without action on your part. With mo most st watches, atches, you must remember remember to set the recording recording mechanism at the start of the dive and check it it at at the end end of the dive.

Dive C o m p u t e r s Dive computers computers also measure the length of your bottom time as well well as many other items. Computers

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NAU I Scuba D i ver

F IGI G U R E 2 3 1 . W A T C H E S FO F O R D IVI V I N G M U S T R E D E S I G N E D TO TO W IT H S T A ND P R E S S U R E .

are the most most convenient method of keeping track of your bottom time as well well as your your depth. The dive computer combines your depth gauge, tim tim ing device, thermometer, and sometimes your sub mersible pressure pressure gauge in one unit. unit. Newdive computers are introduced every year, with mo more re features available. available. At a minimum, minimum, a typical typical dive computer re records cords or displays displays the following following information: • Maximum Maximum depth [jTI • Current depth epth • Actual dive time • Remaining allowable dive time Between Between dives, the computer computer can display display inform informa a tion from from your previous dives dives as well as the the amount of time that you have been been out of the water. water. The computer computer can also help you plan your your next dive by tellin telling g you how long you can can stay at different depths. See See Chapt Chapter er5 for fo r detailed information about  abou t  dive computers.

3

B a c k u p I n s t rur u m e n t a tit i o n Even the best best instruments instruments can sometimes sometimes fail fa il or malfuncti malfunction. on. Having an instrument fail fail does not neces neces sarily sarily mean an emerg emergenc ency, y, but it it can end your diving day unless unless you have a back backup. up. If you use a bottom bottom timer, you should back it up with a watch. If you use use a dive computer, computer, you should back it it up with with a second second computer computer or a watch and a depth depth gauge. If you use an air-integrated computer, computer, you should back it up with a submersible pressure gauge, depth gauge, and watch.

S!

Rinse your instruments instruments in clean, fresh water at the end of each diving diving day and have your instruments inspected inspected and serviced on once ce per year by a qualified qualified repair technician. technician. Instruments are highly highly reliable, but they can go out of calibr calibrati ation. on. Also, O-ring O-ring seals can wear out and must be be replaced or water can can flood flood the instrument. If salt water get gets into an instrument and and stays inside, the instruments are quickly ruined. Do not subject watches to extreme changes in tem perature, such as by wearing them in a hot shower shower follow ing a cold-water dive. The extreme change in tempera ture can cause condensation condensation in the dive watch and ruin ruin the mechanism. mechanism. It is also possib possible to ruin the seals in a watch in this way, which w wililll cause the watch to flood.

 V e r i f y W h a t  Y e n H a v a L e a r n e d Review the following following questions about instrumentation: 13. A calculates your remaining remaining allowable allowable bottom bottom time time while diving. 14. A diving diving watch must be and measure while under water. 15. Proper maintenan maintenance ce of instruments includes and ______________________

________________

____________________

______________________________

B U O Y A N C Y C O M P E N S AT O R  A buoyancy compensa compensator  tor  (BC  (BC), ), enables enables you to to control control whether you floa floatt on the surface of the the water, hover in the water, or sink to the the bottom bottom. You control this by adding adding air to or venting air air from your BC. By

controllin controlling g the amount amount of air in your BC, you can pre cisely control your buoyancy. buoyancy. Buoyancy control is one of the mo most st important skills you will will learn as a diver. diver.

All BCs are made made of durable material material that can hold air air and are designed for rugged rugged use. use. Alternativ Alternatively, ely, a

Chapter 2- Diving Equipment

button before you stop blowing or take your mouth off the mouthpiece mouthpiece,, or air air wil willl flow flow out out of your BC. On some BCs, you can pul pulll down on your your inflator/d inflator/deflat eflator or hose hose or bleed valve activato activatorr to open open the overpressure ressure relief relief valve or dump valve. Some BCs have the dump valve valve located located elsewhere on the BC. Pulli ulling ng on a knob knob attached to a cable that hangs from the valve valve opens ens this valve. Alternatively, Alternatively, to deflate or bleed bleed air from your BC, you can lift your inflator/ inflator/ defla defla tor hose hose over your head and press the deflator/oral infl infla a tor valve button. button. This allows air air in in your BC to flow up up and out the inflator/defl inflator/deflator ator hose. se.

Far Ymirlntormlm Some older BCs were equippe equipped d with carbon dioxide

F IGI G 2 3 2 . T H E L O W P R E S S U R E I N F L A T O R D E V I C E (P( P O W E R III I U FLF L A TOR) IS ATTACHED TO YOUR CYLINDER WITH A LOW PRESSURE HOSE.

m

plastic plastic bladder that is inside the BC BC might hold the air. The amount amount of air the BC can hold determines determines its avai avail l able lift capacity. You use the lift lift capacity capacity to offset offset any weight you and your gear might might develop develop in the water. water. BCs must be equippedwith with an overpressure relief  valve to prevent damage to the BC from from too much interna internall air air pressure. The BC must also have an infla tor/deflator hose that is at least 2 centimeters centimeters (3/4 inch) inch) in diameter. At the end of the inflator/defl inflator/deflator ator hose is a  power-in  power-infl flato atorr mechanis mechanism m  and a deflator/oral deflator/oral infla infla  tor valve. All BCs are also equipped with with a mouthpiece at the end end of the inflator/d inflator/deflat eflator or hose hose that enables you to inflate the BC byblowing air air into it (figure (figure 2-32). 2). The power-inflator mechanism is is attached attached to the reg ulator ulator first first stagewith with a low-pressure inflato inflatorr hose. The power-inflator mechanism enables you to add air air to the BC directly from your cylinder by pushing a butto button. n. If your power-inflato power-inflatorr mechanism fails or you have no ai airr in your cylinder, you can oral orally ly inflat inflate e your BC by press ing the deflator/oral deflator/oral inflato inflatorr valve button and blowing into the mouthpiece at the same time. Stop pressing the

(C02 (C02) cartridge cartridge inflator inflator mechanisms. mechanisms. These These mecha nisms were designed to be used in an emergency only, but the mechanisms mechanisms could corrode easily if they they weren’t maintained properly and they they were were unreliable. You can still till use a BC that is equipped equipped to use a C02cartri C02cartridge dge infla inflator tor mechanism as long as it has been been equipped with a plug to avoid air air loss. Avoid using the mechanism.

Types There are are three general general types of buoyancy buoyancy compen sators sators (BCs) (BCs):: back flotation, flotation, jackets, and horse horse collars. Some BCs have integrated integrated weight system systems. Some BCs combine features features of more than one type.

B a c k F lol o t a tit i o n Back-fl Back-flota otatio tion n systems are designed so that that the entire entire bladder of the BC is behind you. you. This leaves your chest and waist uncluttered. Back-flotati Back-flotation on systems are popular popular for underwater photog photography raphy for this reason. reason. Back-fl Back-flota otatio tion n systems provide goodtrim  as you swim under water becaus because e the air air in in the bladder on your your back counteracts the weights you wear around your waist. Howeve However, r, on the the surface, the the back flotati flotation on can tend to push you face down in in the the water unless you actively kick or recline recline to mainta maintain in a faceface-up up position. position.

NAUI Scuba Diver

Jackets  Ja  Jacket-style BCs are the most popular buoyancy compensators. These BCs are designed designed so that that the blad blad der wraps from your back around to your waist (figur (figure e 2-33). These BCs are comfortable comfortable to wear, provide good trim trim under water, and float float you upright on the surface when your BC is inflated.

Horse Collars The older horse horse colla collarr design encircles your your neck. You can use a horse collar collar for for both skin and scuba div ing. The adjustment adjustment of the harness is critic critical al to keep the BC from from riding riding up when it is inflated. inflated. You must don don and remove remove the horse horse colla collarr separately from y your our cylind cylinder. er. Always remember to detach the low-pressu low-pressure infla inflator tor hose when removing removing your cylinder. cylinder.

I n t e g rar a tet e d W e igi g h t S y s t e m s Some jacket-style and back-flotati back-flotation on BCs enable you to integrate or add your your weights direct directly ly to the BC instead of wearing wearing them on a weight belt. The BC must have a means of allowing allowing you to quickly quickly release release the weights weights in an emergency. Some integratedintegrated-weight weight systems use pockets that you load with with weights and then secure in your BC BC with Velcro Velcro™. ™. In an emerge mergency ncy,, you pull pull the entire entire pocket out of the BC and drop it. Other integratedintegratedweight system systems have pockets that are secured at at the bot tomwith a threaded threaded cable. cable. You load your weig weights hts direct ly into into the pockets in the BC. In an emergency, you pull pull the cable and the weights drop out of the pockets. The advantages to an integrated-weight BC include: include: • The need to wear a weight belt belt is elimin eliminated ated.. • The weights cannot slide around around your body. dy. • The weight is not supported solely solely by your lower back. One disadvantage to an integrated-weight integrated-weight BC is that once it is is assembled, it can can be heavy and awkward to handle. If you need need to carry the system systemfor any distance, you must either either remove the weights or wear wear the system. Apotential potential major major hazard is that iitt is impossible for a dive supervisor supervisor to tell tell at a glance approximately approximately how

F IGI G U R E 2 3 3 . J A C K E T - S T Y L E B C S A R E T H E M O S T P O P U L A R STYLE OF BC.

much weight you are wearing (for (for example, wheth whether er you are obviously obviously overweighted). overweighted).

Selection The best way to select a BC is to try on different different models and see seewhic which h one is the most most comfortable comfortable for you. Also, the features and design of the BC should match the type type of diving you will will be doing. For exam ple, if if you are going wreck diving, rugged materia materiall is more mo re critical. critical. If possible, try on tthe he BC with a cylinder cylinder attached to the backpac backpack k and try the the unit, or a rental like it, it, in the water. Ensure that you inflate inflate the BC to see how how it feels when full full of air. air. The BC BC should not interfere interfere with your body movement ovement when it is full full of of air. The controls must must also be easy to to locate locate and and operate.

maintenance You should rinse your BC intern internall ally y and externally m after each diving day (figure (figure 2-34). 2-34). Salt Salt water, water, dirty

Chapter 2- Diving Equipment

i        v      i        n       g     E        q      u     i         p     m     e     n     t      

F IGI G U R E 2 3 4 . Y U U S H O U L D R I N S E Y O U R B C INI N T E R N A L L Y A N D E X T E R N A L L Y A T T H E E N D O F E A C H D I V INI N G D A Y

water, water, or chlorinated water inside your BC can cause cause damage. Every time you bleed bleed air from your BC under water, some water water gets into the BC. Rinse the inside of your BC using using the following following procedure: 1. Fil Filll the inside of the BC with fresh water through the oral inflator inflator mouthpiece mouthpiece.. 2. Slosh Slosh the water around around inside the BC thoroughly, thoroughly, turning turning the BC upside down and right side up. 3. Drain Drain the water by turning turning the BC so that the inflator/def inflator/deflator lator hose outlet is the lowes lowestt point and pressing the deflator/oral deflator/oral infla inflator tor valve valve but ton to allow the water to drain out of the mouth piece (figur (figure e 2-35). Rinse the exterior of the BC thoroughly, thoroughly, as well as the power-inflator hose. ose. Infla Inflate te the BC to allow allow it to dry completely. completely. Store the the BC in a cool, dry place with air in the bladder. BCs must have their power-inflator mechanism inspected once per year. If it is not serviced, it can mal mal

F IGI G U R E 2 3 5 . B E S U R E T O D R A I N A L L T H E W A T E R O U T O F T H E BLADDER AFTER RINSING.

function. You should should also inflate your BC completely to to check for leaks leaks before each dive trip.

 V e r i t y W h a l  Y o u H a v e L e a r n e i Review the following following questions about buoyancy compensators: 16. The three main main types of BCs are ., and 17. The two essential essential features found on all BCs are are and ___________________________

18. Why should you rinse the the inside of your BC?

N A M S c u b i D ivi v e r

W E IGI G H T S A N D W E IG I G H T B E L TS TS You wear lead weights when when you are diving diving to offset the buoyancy buoyancy of your body, body, your your wetsuit, and other div div ing gear gear you are are wearing. Weights are availa available ble in in many configurations configurations and as you gain diving diving experience, experience, you will will find the configuration that fits you best. st.

T y p e s o f W e igi g h t s Weights come in ma many ny different different shapes and sizes (figure (figure 2-36). Mo Most st commonly, you will ill find find lead mold mold ed into cylinders cylinders or blocks with slits slits to enable a weight belt to be threaded through the weight. The block of lead can be uncoated uncoated or coated coated with a plastic plastic covering. Some of the larger larger blocks of lead are curved to fit fit the hip and are known aship weights. Solid Solid lead weights weights come in sizes from 0.5 to 6.5 kilogr kilograms ams (1 to 14pounds). pounds). Lead can also be be molded into cylin cylindr drica icall shapes shapes with a slit slit in the middle to enable a weight belt to pass through. through. These are calle called d bullet weights.  Bullet weights typica typicalllly y come in sizes from 0.5 to 2.0 kilogra kilograms ms (1 to 4 pounds). pounds). Also, lead shot can be sewn sewn into pouches of various various  soft weig weight ht..  Soft sizes. This This type of weight weight is known as a soft \{J2 weights conform to the shape of your hip hip and are are more comfortable comfortable to wear. Soft weights also cause less dam age to a deck or injur injury y to a person if they are dropped.

W e igi g h t B e l lsl s , H a r n e s s e s , ana n d W e igi g h tit i n g S y s t e m s The simplest and and most common weight bel beltt is a 5.0 centimeter (2-inch) (2-inch) wide nylon web web belt belt with a metal or plastic plastic buckle (figu (figure re 2-37). Weight keepers are used on this type of weight belt to keep keep the weights from shifting shifting on the belt. Some weight belts are composed of a series of of pock ets attached to a nylon web web belt. These pockets will ill hold hold either solid weights weights or soft soft weights. weights. There are also shot belts belts that have one continuous compartment fille filled d with lead shot. shot. The compartm compartments are filled filled with with different different weights weights of shot shot and you simply choose the weight weight you need. Another type type of weight belt is a stretchable/ com

F IGI G U R E 2 -3- 3 6 . W E IGI G H T S C O M E I N M A N Y D I F F E R E N T W E I G H T S  A N D S I Z E S .

F IGI G U R E 2 - 3 7 . W E IGI G H T B E LTL T S C O M E INI N M A N Y S T Y L E S .

pensating belt with a quick release buckle. This type type resists slipping, slipping, compensates for suit suit compression,  spring ngss off your releases releases cleanly, cleanly, and spri your body if you must ditch the weight belt. A weight harness, harness, usua usually lly used with dry suits, uses uses a belt and shoulder shoulder harness systemto support the weights weights on your shoulders rather than around your waist. This helps reduce reduce strain strain on your lower back and helps pre pre vent the belt from sliding sliding around your body. body. A desirable safety feature of many weight belts is the abili ability ty to compen compensate for the compression compression of a wetsuit as you descen descend under water. Without Without a compensating fea ture, weight weight belts become looser at depth. A loose weight belt can slip down belowyour waist waist or can rotate to place the buckle at your side or back instead of in the front where it should be.

Chapter 2- Diving Equipment

The length of your weight belt belt must be be adjustable so there is not an excess of belt to pose a quick-release quick-release hazard. hazard. Your instructor instructor will will showyou several meth methods ods of adjusting adjusting your weight bel beltt so that you do not need need to cut the end end of the the belt. The tail tail of the belt should not be longer than needed to provide provide a tightenin tightening g grip of about 8 to 10centimeters (3 or 4 inch inches es). ). One advantage to the wire cam buckle is is the complete abs absenc ence e of a tai tail.l.

Q u i c k R e l e a s e o f W e i g h tst s No matter what what type of weight weight system you choose, choose, you must have have a means of ditchin ditching g the weights with one hand. This type of system is known as a quick quick release. The plastic or metal buckle buckle on a weight belt must be a quick-release quick-release buckle that open opens s by pullin pulling g on the end of the weight belt or on the buckle. buckle. You can then pull pull the weight belt free from your body by grasping the buckle and pullin pulling g the belt away as as nee neede ded. d. Integrated Integrated weight systems in BCs use either pockets that can can be quickl quickly y pulled out of the BC and dropped or a cable that can be

DIVING SUITS Your normal body body temperature temperature averages about 37°C (98.6 (98.6°F). °F). Your skin will will be cooler, cooler, but but any time time the water water temperature is colder than than your your skin tempera tempera ture, your bodywill ill lose heat to the water. Divers must must wear a thermal-protec thermal-protection tion diving suit in all but the warmest waters (fig (figure ure 2-38 2-38). It is essential to wear the right thermal protection for the conditions where you dive. dive. When you grow cold under water, water, you lose your abi abilit lity y to perform at your best. Heat loss loss under under water water affects your abi abilit lity y to think, and you fatigue rapidly. Cold water is a contributing factor in many diving accidents. The amount of insu insulat lation ion you need to to wear on a dive depends on the water temperature, your your activi activity ty level during during the dive, and other factors such as your build, build, body body fat, and so on. In colder water, water, every diver needs eds to wear more insulatio insulation n than than they would wear in warm water. The harder you work under water, the more heat your body generates, nerates, and the warmer you are, unless you fai faill to wear adequate protection.

pulled pulled to drop weights out of the bottom of the BC.

 V e r i f y W h a t Y o u H a v e L e a r n e d Review the following following questions questions about weight belts: belts: 19. The most importa important nt feature feature of of a weight belt belt is . the _______________________________

20. A compensating weight weight belt belt

21. Divers might might prefer soft weights over molded molded lead weights weights because because

__________________

_______________________________

and

F IGI G U R E 2 3 8 . D I F F E R E N T D I V I N G S U I T S A R E N E E D E D T O A L L O W  Y O U T O D I V E I N W A T E R F R O M F R I G I D T O T H E W A R M E S T T R O P I C A L W A T ER S .

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NAUI Scuba D iver

Different ranges ranges of temperatures temperatures feel comfortable to different divers. divers. You might wear more more or far far less insula insula tion than your dive instructor instructor or bud buddy. dy. It is essential to wear what feels feels right right for for you, rather rather than what what someone

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tells you to wear. In the warmest tropical tropical waters, you might be able to dive in just a skin suit. In colder water, water, you will ill need a wetsuit. In the coldest waters, dry suits suits are the most effective form of thermal insulatio insulation. n. Dive suits also provide protection from cuts, scrapes scrapes,, and stings. stings. Even if the water isn’t cold, you should wear some type of protective protective covering covering to avoid inju injurie ries s and sunburn.

Dive Skins Dive skins are thin thin,, one-piece suits designed to pro tect your skin from cuts, scrapes, scrapes, and stings that can occur when when you you dive in tropical tropical waters. The term dive skins covers covers a wide range of products made made from differ differ ent materials. materials. To determine what you are buying, it is important important to ask what materi material als s were used to make the suit. Two Two comm common on materials materials are Lycra® and Polartec®.

Lycra® By themselves, Lycra® Lycra® dive skins provide provide only min mini i mal thermal thermal protection (figur (figure e 2-39), 2-39), but Lycra® can be combined combined with polypropylene, which is is a plush fabric, fabric, or other insulating materials materials to add som some thermal capabi capabil l ity. Lycra® dive skins, skins, like like wetsuits, provide almost no protection from the wind, especially especially when they are wet. This can can be a problem problem on the surface with many suits, where heat is lost as water outside your suit suit evaporates evaporates and carries heat away from yo your ur body.

Polantec® Polartec® is a combination of Lycra® and a velour fleece fleece thermal lining lining that traps traps air air and water as as insula insula tion. Dive suits made made from Polartec® Polartec® provide the the warmth of a thin thin neoprene neoprene wetsuit without the need to wear as much weight to compensate compensate for the buoyancy buoyancy of the suit.

F IGI G U R E 2 3 9 . S K I N S H E L P P R O T E C T Y O U F R O M C U T S , S C R A P E S ,  A N D S T I N G S .

W e t s u iti t s Wetsuits are made from foam neoprene neoprene,, which which is a synthetic rubber fil fille led d with thousands thousands of tiny tiny gas bub bles. Neopren Neoprene e provides good insulatio insulation n in many diving situations. situations. Wetsuits are the most widely widely used used thermal protection for dive divers rs becau because of their simplicit simplicity y and rela rela tively low initial cost. To work properly, a wetsuit must fit fit your body body quite precisely, and snugly. Once Once you you enter the water, a thin layer layer of water is trapped trapped betwe between your skin and the inner surface of your suit. The water water is then warmed warmed to your skin temperature temperature and the insula insulating ting suit keeps keepsyou, and the water, warm. If you do not dive d dee eep or make multiple multiple dives in very cold water, a wetsuit will will provide provide you you with reason reason able insula insulation tion.. As a wetsuit ages, ages, it loses some of its insulating insulating capabilit capability y because some of the cells (gas bub bles) with within in the wetsuit break down on each dive. Wetsuits come come in a variety variety of colors. The color color is usuall usually y in the nylon coating coating on the outside and inside of the neoprene neoprene materia material.l. Nylon provides provides better durab durabili ility ty and makes the wetsuit easier to put put on and take off, but it makes makes the the wetsuit wetsuit slightly slightly thicker.

Ch apter 2- Diving Diving Equipm Equipm ent

Thicknesses Wetsuits are avail available able in many many thicknessesfrom 2 millimeter millimeters s (mm (mm)) to 7mm and in many many different styles. styles. The thicker the suit, the greater the insulation, insulation, although thick thick suits can bebulky bulky and awkward towear. The most popular thickness of a wetsuit for warm water water to 27°C (80° (80°F) F) is 3mm. In colder waters, most divers prefer a suit thickness of 6 mm or greater.

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Styles Shorty Shorty wetsuits (wetsuits (wetsuits with with short sleeves sleeves and thigh-length legs) legs) and 2 mm or 3 mm full-body suits are popular for wear in tropical tropical temperature temperature water. For colder water diving, diving, some divers prefer to wear a bib overall overall set of pants known as a farm er john  and a combination. They also wear a hood,  step-i  step-in n jacket combination. booties, and gloves. You can adjust the warmth of your wetsuit by layer winter, you might wear a vest ing. For example, in the winter, or a hooded vest underneath your farmer farmer john john to add insulatio insulation. n. In the summer, you might be able to dive without a hood.

F IGI G U R E 2 4 0 . D R Y S U ITI T S K E E P Y U U W A R M E R T H A N W E T S U ITI T S IN COLD WATER.

which you will will be doing mo most st ofyour diving. Their Their rec ommendations will ill help help you select the most appropriate type type of suit. suit.

Options

Dry Suits

If you are tall, thin, very very muscular, or o otherwis therwise e dif fer from standard s sizes izes, you might might want to consider hav hav ing your wetsuit custom custom made made toyour measurements. measurements. If you have a wetsuit wetsuit custom-made, you can choose from a wide range of options. options. Options for wetsuits can include include:: • Zippers Zippers at the wrists and ankles to make the suit easier to put on. Howeve However, r, water can enter and leave the suit through the zipp zippers ers,, chi chilli lling ng you. • Knee pads to protect your your knees and the su suit it from sharp rocks. • A spine pad to cushion cushion the cylin cylinde derr and keep the spine warmer. • Pockets inside the wetsuit to hold keys. keys. • Sheaths built built into into the leg to hold a dive knife. • Attached Attached hood for extra extra warmth. Talk to your NAUI Pro Center Center and dive instructor about the types of suits used used in your your area or the area area in

Dry suits are preferred for colder water. Dry suits are much more expensive expensive than wetsuits, but are well worth the cost for the increased comfort in many many diving diving situations. situations. A dry suit suit is designed designed to keep you dry. The suit keepsyou dry by using a c combin ombinatio ation n of wrist seals, a neck seal, and a waterproof zipper zipper (fig (figur ure e 2-40). 2-40). With With some non-neopren non-neoprene e dry suits, you we wear ar under wear under the sui suitt to add insulat insulation ion and keep keep you warm. The underwear trap traps s air between between your skin and the suit. You can layer layer the underwear to adjust your insulatio insulation n for any water temperature. temperature. The water tem perature, your bo body dy structure, and your activity activity level level during during the dive determine the amount amount and type of underwear underwear that that you wear beneath your dry suit. Dry suits are easier to put on than wetsuits, wetsuits, but it does take specialized specialized or additional additional traini training ng to learn how to use them properly. Most dry suits are bulki bulkier er than

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NAU I Scuba Sc uba D i ver

wetsuits. wetsuits. Dependin Depending g on the fit of your suit suit and the type of insulati insulating ng underwear you use, use, you might need to wear moreweight with a dry dry suit than with with a wetsuit. wetsuit.

Types There are many different types of dry suits. Dry suits can be made from foam neoprene, solid solid neoprene, or a variety variety of of heavy-du heavy-duty nylons with water waterproof proof mate rials laminated to them. The foam neoprene suits are are one-piece suits that that have a waterproof zipper and seals at the wrists and neck. The suit itself provides provides insulati insulation. on. This suit is warmer than a wetsuit made made out of the same same material material because the inside of the suit is dry dry and the air air in the suit as well as the suit itself itself provide insulatio insulation. n. The solid neopren neoprene e suit requires requires that undergar undergar ments beworn under the the suit for additi additional onal insulati insulation. on. The amount of insulation insulation worn can can vary depending on the temperature of the water. This suit suit is less less bulky than the foam neoprene suit. The nylon-shell suit is loose fitting, fitting, whic which h gives you greater greater mobility mobility and comfort. comfort. The nylon shell shell suit also requires that that undergarments undergarments be worn.

Features Most of the options options availab available le for for wetsuits, wetsuits, such as pockets, knife sheaths, and kneepads, are also avail availab able le for dry suits. suits. Other options made especially for dr dry y suits suits include: • Dry hoods • Dry gloves • Attached hard-sol hard-sole e dry boots Because dry suits do not need to fit fit as closely closely as wetsuits, custom fittin fitting g is rarel rarely y necessary necessary. However, ever, the cost cost of dry suits is st still ill greater because cause of the special watertight watertight zipper zipper and and the other materials materials and labor labor needed to make the sui suitt waterproof.

Buoyancy Control While diving, you control the amount of air in your dry suit with an infl inflator ator valve, which allows you you to add

air air to the suit, and an exhaust valve, valve, which allows you to bleed bleed air air from the suit. The inflator inflator valve is similar similar to the power inflat inflator or used on a BC. You add air to the dry suit suit as you dive deeper and then bleed air air as you return to the surface. surface. The most common common location location for the inflator inflator valve is in the middle middle of the the chest chest so it will will not interfere with your BC jacket. The exhaus exhaustt valve is a low-profile va valve lve that usually automa automatic ticall ally y vents vents air air as you ascen ascend. d. A common common loca tion for the exhaust valve is on the outside of your upper left arm. Different Different valve models bleed air air at different rates. A valve valve that vents quickl quickly y is better, better, because it allows you to blee bleed d air air from your suit suit faster. faster. When you dive with a dry suit, you use the dry suit for buoyancy control and and the BC for surface flotation. flotation. You use the BC for backup backup buoyancy control. You must must be very careful careful if adding air air to both your dry suit and the BC under water because it is diffic difficult ult to control both both pieces of equipment at at the same time. You must always wear a BC with a dry suit. suit. If you are taking your NAUI Scuba Diver Diver certifica certifica tion course course in an area of the world that normally normally requires dry suits (for (for example, Alaska or Canada) you will probably be diving in dry suits suits from your very first class. class. If this is the case case, your instructor w will ill presen present sup plemental material material and training training soyou will will understand understand how to use use your dry suit. If your class does does not include traini training ng in dry dry suits and you decide to to buy one, one, you m need need to take a NAUI Dry S Sui uitt Special Specialty ty course to leam how to use use the dry suit suit properly.

Hoods You lose the greatest amount of heat from your m head, hands, chest chest and armpits, and groin. Therefore, thermal protection for your head is critic critical al when you are diving. In cold water, water, you can lose lose a significant significant amount of your body heat through your head alone. For most cold-water cold-water diving, diving, you can use use a simple hood made made from wetsuit material material (figure (figure 2-41). The  that tucks under the hood can have an attached bib that colla collarr of your wet suit to kee keep p your neck warm and help keepwater from circu circula latin ting g in and out down down the back of your neck. neck. The warmest arrangement is to have have

Ch apter 2- Diving Diving Equipm Equipm ent

F IGI G U R E 2 - 4 2 . W E T S U I T S C A N B E D R IEI E D A N D S A F E L Y S T O R E D O N W I D E H A N G E R S M A D E F O R W E T S U ITI T S . F IGI G U R E 2 4 1 . W E A R I N G A H O OD OD H E L P S Y O U C O N S E R V E B O D Y H E A T.T .

your hood attached to your suit. If you are diving in colder water, you might want to use use a dry hood attached directly directly to a dry suit. The dry hood keeps your head completely completely dry. Most hoods are fair fairly ly uncomfortable out of the water. However, once you are under water they are almost almost unnoticeable. unnoticeable. Pressure Pressure equalization in your ears when you you wear a hood hood may require special special attention. Your instructor instructor will will address ress any special techniques needed for the the type of gear you are wearing. wearing.

your resistance resistance to cold might be less. less. For example, if you live in a dese desert rt climate, you might have to wear more insula insulatio tion n because your body is accustomed to high temperat temperatures ures.. If you live in a cold climate, you might be wearing wearing less insulati insulation on in the water because your your body is accustomed to colder temperatures. temperatures. Use the following general  guidelines  guidelines when when deciding what type of diving suit to wear: • 27°C (80°F) and warmer water.

A skin skin suit suit is is recommended. • 24°C to 27°C (75°F to 80°F) waters.

A 2 mm to 3 mm full full wetsuit or shorty shorty is recommended. • 13°C to 24°C (55°F to 75°F) waters.

C h o o s i n g t h e C o r r e c t S u i t t o r t h e C o n d i tit i o n s Some insulation is required for most diving activi ties and having the correct suit for the conditions conditions is one one of the the keys to enjoying a dive. The correct suit fo forr you might not be the correct suit suit for for your buddy because ecause your reaction reaction to cold might be be quite different. Also, Also, depending depending on the area of the the world in in which which you live, live,

A 5mm 5mm to 7 mm full fu ll wetsui wetsuitt is suggested. As the water gets colder, colder, you also need to wear a hood and gloves. • 2°C to 13°C (35°F to 55°F) waters.

A full full dry suit is recommended. • 2°C (35°F) and colder water.

Special Special traini training ng and equipment are neede needed to dive in water this cold.

NAUI Scuba Diver

 V e r i l y W h a t V o n H a v e L e a r n e d Review the following following questions questions about diving diving suits: 22. A is suitable for only warm, tropical diving. __________________________

23. A is made only only from foam neoprene. 24. A uses under under garments for insulation. 25. True or False. You do not need special trai trainin ning g to use a dry suit. __________________________

__________________________

 A C C E S S O R Y E Q U I P M E N T F IGI G U R E 2 -4- 4 3 . Y O U S H O U L D A T T A C H Y O U R D IVI V INI N G I N S T R U M E N T S T O  Y O U R R C S O T H E Y D O N O T D R A G A L O N G T H E B O T T O M .

Maintenance You should should rinse a diving suit suit with fresh water after every diving diving day. Rinse dive skins and wetsuits inside and out. out. There are commercial commercial products products you can use at the end end of a dive trip to clean clean your dive suits completely before storage. You should store your wetsuits on wide hangers designed especially especially for wetsuits (figur (figure e 2-42), or unfolded, lying flat. If you get a hole in your wetsuit, wetsuit, you you can repair it with with wetsuit cement cement and neopren neoprene patch material material.. If the inside of a dry suit is completely dry, and it is worn with under clothing, you only need to rinse the the out side of the dry suit. You need to elimin eliminate ate sweat, dead skin, and soon, from neoprene dry suits by rinsin rinsing g the suit inside and out. out. All dry suits should should be occasionall occasionally y rinsed inside inside and out. You should should lubricate lubricate dry suit zip pers with only only paraffi paraffin n wax, beesw beeswax, ax, or preparations pro vided by the manufacturer manufacturer.. Your dry suit can be stored stored rolled rolled up in a bag away from heat and ozone-produ ozone-producing machine machinery ry such as hot-water heaters and electric electric motors. Your dry suit, with with its valves, zippers, and seals, seals, should beinspected ected annually annually by a qualified qualified repair technician. technician. Dry-suitvalves can malfuncti malfunction on if if they are not regularly regularly serviced. Your dry suit owner’s manual should be your pri pri mary guide guide and will list any special special care instruction instructions. s.

Accessorie Accessories s are availa available ble that can can make diving diving more enjoyable. There are also accessorie accessories s for specialized activiti activities. es. Some Some of of the availa available ble accessories accessories are described as follows. follows.

 A t t a c h m e n t D e v i c e s Clips enable you to attach your instruments instruments to your BC. Withou Withoutt clips, clips, your gauges and octopus regulator regulator will natur naturall ally y hang at your side, side, and a foot or more more below your waist, as you swim horizontal horizontally ly through the water. If you are swimming close to the bottom bottom, your instruments can can strike and damage damage marine life life,, or be damaged thems themselves. elves. When corals and other delicate organisms are broken, they do not grow back. They die. Remember Remember to clip your your instruments instruments to your BC on every dive to avoi avoid d damage to them or the underwater environment. environment. The clips clips you use must must be be fastened fastened so you can remove remove your BC easily easily and quickly in an emergen emergency (figur (figure e 2-43). Accessory clips clips and other holders holders are availa available ble at most most dive store stores.

Knives A dive knife is a working tool used used for many pur pur poses. Its most important important function function might might be to cut fish fish ing line line or nets nets if you get get tangled in them under water. water. Knives are not used asweapons to figh fightt sharks, as you might might have seen seen on on television. television.

Ch apter 2- Divi Div ing Equipm Equipm ent

F IGI G U R E 2 4 4 . S E L E C T T H E K N IFI F E M O S T A P P R O P R I A T E FO FO R T H E D IVI V INI N G Y O U U S O A L L Y D O .

There are many diff different erent styles and s sizes izes of diving diving knives and you should select the knife mo most st appropriate for the diving diving you do (figure (figure 2-44). For example, an underwate underwaterr hunter might want a knife with with a thin, sharp sharp blade, blade, while while a wreck diver might want a heavy knife with a blunt tip for for prying and pounding. pounding. All dive knives should be be kept sharp and have their their blades blades coate coated d with a thin thin layer of oil when they are not not in use. use. Even stainless-stee stainless-steell knives can rust rust if they are not properly maintained. Keepyour dive knife knife in its sheath when it is not in use. use. Sheaths are usual usually ly made made from plastic plastic and can be mounted mounted in different places including: including: • On the the inside of your cal calf. f. • On the back of your instrument instrument console. • On your your BC pocket or shoulder shoulder strap. How and where you mount mount your your knife knife depends on the design design of the sheath, sheath, the size of the knife, and your individual individual prefere preference nce..

bag as a gear bag. Nylon is is usually usually better because because it does not rot or mildew as easily easily as canvas. Mesh bags or panels help any any wet gear in the bag to dry. dry. You should mark all all your gear with som some personal personal mark, and your bag with your your name, address, and telephone number number so it can easily easily be be identified in case case you you accidentally accidentally leave it on a dive boat. Special Special gear bags are availab available le at dive shops. ops. These These bags bags are the easiest to to use for diving diving because they usual usual ly have special compartments for fins, regulators, regulators, and instruments. Many Many of the bags are padded for air airliline ne travel and even have wheels so they roll roll through airports airports or on wharves. wharves. Some of the the bags bags have have special special dry com partments for your logbook, logbook, clothing clothing,, and other items items you do not want want to get wet.

D i v e F l a g s and Floats When you you are diving, it is almost impossible impossible for a boat or jet jet ski moving moving at at high high speeds to see your your bubbles or for their operators to know you are in in the area. To avoid an accident, accident, you should use a special diver down  flag  to let others know you are under water. The United States States dive flag is a red flag flag with a white diagonal stripe running running from the upper-inner upper-inner corner to the lower lower-ou -outer ter (fly (fly)) corner of the flag (figure (figure 2-45) 2-45).. This flag must be flown from your surface support sta tion or boat any time you have scuba scuba divers in the area. Many states states require, by law, that this this flag flag be flown when divers divers are in the water. It is your obligation to stay stay within within a set set distance distance of the the flag (no more than 30

U.S. Dive Flag

Internationa l Diver  Code "Alpha"

Gear Bags You need a gear bag to transpor transportt your gear to and from the dive site and keep keep it safe, clean, clean, and out of the way at the site. Without a gear gear bag, bag, it is diffic difficult ult to han dle your equipment equipment and easy easy to drop delicate delicate gear. On a charter dive boat, boat, it it is easy to lose lose your gear or have your gear accidental accidentally ly picked up by by other divers unless you have a bag to keep it in. in. You can use almost any heavy-duty heavy-duty nylon or canvas

FIGURE 2-45. ALWAYS HAV E A DIVE FLAG FLYING W HEN DIVERS  A R E I N T H E W A T E R .

I\IAUI Scuba Diver

F IGI G U R E 2 - 4 6 . A S U R F A C E F LOL O A T G I V E S Y O U A P L A C E T O R E S T O N THE SURFACE.

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meters [100 feet], but local laws might require less). It is also your obligat obligation ion to take the flag down when all all divers are are out of the water. When appropriate, dive boats boats must fly the intern interna a alpha flag  fla g  when tional blue and white alpha  when divers are in the water (figure 2-45). This signal flag indicates that the the boat’s maneuverabi maneuverability lity is limited limited becaus because of diving diving activ activ fla g  in ities. This This flag is also used used as the diver down flag   in many countrie countries. s. Your instructor wil willl let you know know what the local regulations are for dive dive flags. If you are shore diving, diving, your surface surface support support station can be anything anything from an inflata inflatable ble inner inner tube tube to an inflatable inflatable surf mat or kayak (figure (figure 2-46). 2-46). It does not matter what what you use as long as some type of object appropriate for the conditions and area area that can can support support you is nearby in in case you need need it.

Logbooks E 3

A logbook logbook is your record of experience experience in the water (figur (figure e 2-47). You should record the informatio information n from every dive you you make in your personal logbook soon after you leave the water. In some parts of the world, world, there are laws requiring requiring that you log log your dives. dives. You will will be required to use use a logbook logbook during your NAUI diver-training diver-training course courses. In addition, addition, some dive operators operators will will want to review your logbook before before they

F IGI G U R E 2 4 7 . Y O U R L O G B O O K R E C O R D S Y O U R E X P E R I E N C E INI N T H E W A T ER ER .

make diving diving services availab available le to you. you. If you decide to continue continue your education education on to diving leadership, your logbook shows: • That you have var varied ied divin diving g experience experiences. • You have documented documented performing performing advanced div ing skills skills under the the supervision supervision of an instructor. • How many hours you have have spent under water. • How many dives you have have made. Your training, training, diving, and hours hours will have to to be documented before before you can be accepted for leadership leadership training.

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F i r s t A i d Kits It is is a good idea to have a first aid kit kit on any dive trip. trip. All All you need to do is add a few items to a standard first aid kit kit to meet meet the particula particularr needs of diving and you are ready to deal with typical typical minor minor diving-related diving-related inju injuri ries es.. See Appendix C for the recommended recommended items for a diving first aid kit.

O t h e r A c c e s s o r iei e s Some other useful accessories accessories are: slate so you can • An underwater slate can record data data and communicate with with your buddy buddy (figu (figure re 2-48).  ,goodi diee bag  bag  to • A ,goo  to hold game, specimens, artifacts, artifacts,

E D

Chapter 2- Diving Equipment

 V e r i t y W h a t Y o u H a v e L e a r n e d Review the followin following g questions about accessory accessory equipment: 26. What is the mo most st likely likely use for a dive knife under water?

27. When you fly fly a dive flag, flag, you must ______________________________

and

28. You should record all all dives in your logbook because

___________________________

and and

______________________________

.

additional accessories accessories that wil willl be useful to 2 9 . Two additional you when when you dive dive are are __________________

and and

________________________________

F I G U R E 2 4 8 . W R ITIT I N G O N A S LAL A TE T E I S A G O O D W A Y T O C O M N I U NIN I C A T E U N D E R W A T ER ER .

trash, and other treasures. • An underwater light, light, which which is is necessary necessary for night diving, but is also good to have during the day to bring out colors colors and to peer into holes and crevices. • A marker marker buoy to mark the locat location ion of a dropped item or a specific area. • Aspare spare parts kit that that includes includes the items that can can save a dive. dive. The items items can include include a mask strap, a snorkel keeper, keeper, a fin fin strap, assorted O-rings, and a regulator mouthpiece with attachment attachment strip. • Achecklist checklist is a great way to remember all all of the gear you you need need for diving diving as well well as personal personal items. See Appendix C for samples of checklists. checklists.

_

_

_

_

.

_

CONCLUSION Diving is an equipment-intensive activity. Remember Remember that all all this equipment helps you adapt to the underwater underwater environment and function function there as com com fortably fortably and safely as p possible. ossible. The more more you work with your your gear, the easier easier it becomes to use. Once the gear is easy to use, you wil willl be able to devote more of your attention to your surroundings surroundings and activities.

CHAPTER

NAU I Scuba D i ver

LE A R N I N G G O A L S In this chapter chapter you you will: will: • Be Be introduced to the snorkeling snorkeling skills skills you will will learn during your course. • Learn the steps for assembling assembling and testing your scuba equipment. • Learn Learn the steps for donnin donning g your scuba scuba gear. • Read about some of the methods methods for enteri entering ng and exiting the water. • Be introduced to tthe he mask and regulator regulator skills skills you will learn during during your cours course. e. • Learn Learn about buoyancy control and buoyancy skills. • Be introduced to the safety skills skills you will will learn during your course. It is one thing to use use your diving diving gear in a swim ming pool or other confined water setting, but exploring open open water is the purpose purpose of scuba diving. To enjoy div div ing, you you must be able to combine your your knowledge of the underwate underwaterr environment with the abili ability ty to handle your equipment equipment under a variety variety of conditions. You must must have the confidence confidence and abi abilit lity y to operate your gear by feel, becau because se your mask mask will will restrict much of your vision. In your NAUI Scuba Diver certificatio certification n course, course, you learn the basics of divin diving, g, but you become become a knowledgeable diver only through through additional additional experien experience ce and further training. If your training is occurring during the the winter months months in an area where the the weather is cold, you still still have the option option of completing your open-w open-water training training immediately. You can complete complete your class through NAUI’s Universal Referral Referral Program by training training at a trop trop ical ical resort under the direction direction of another instructor. Ask your NAUI instructor instructor for details about this program.

SNORKELING SKILLS Developing good snorkeling skills skills is fundamental fundamental to being a good diver. diver. You must know the proper use use of your mask, snorkel, and fins.

P r e p a r ini n g Y o u r G e a r l o r U s e You need to prepare almost all all of your new diving diving gear before you can use it. This is is especially especially true with a new mask. New mask lenses are covered with with a thin thin film film of of lubricant. lubricant. You can use use toothpaste thpaste to to re remov move e this lubrican lubricantt by using the following following procedu procedure: 1. Put Put a dab of toothpaste toothpaste on the inside of each lens of the mask. 2. Rub the toothpaste over the entire entire lens. lens. 3. Rinse Rinse the mask well with fresh water. water. Washi Washing ng the lens with with toothpaste helps keep keep the lens from fogging, which which occurs when condensation condensation forms on on the inside of the lens. Each Each time you don don your mask for diving, you will will need to to prepa prepare re it sothat it will not fog because because of the temperature temperature difference difference inside inside the mask compared compared to the surrounding surrounding water. The most most common way to prevent fogging is to use the following following procedure: 1. Apply a few few drop drops s of antifog antifog solution solution 2. Rub the solution solution on the inside of the lens. lens. 3. Rinse Rinse the mask thoroughly. An alternative alternative is is to use use saliva, saliva, but many prefer prefer commercial commercial products. products. The commerci commerciall ally y prepared prod ucts ucts usually usually work mo more re effectively than saliva. To pre pare your mask properly, be sure to to read the instructi instructions ons enclosed enclosed with with the product. product. The snorkel is usu usuall ally y attached to the the left side of your mask strap if your regulator regulator comes comes around your right right side (figure (figure 3-1). 3-1). Some snorkels are design designed to be worn only on the left side. Some snorkels snorkels use a sili sili cone snorkel keeper, keeper, while while others have plastic clips. The snorkel should hang so that the mouthpiece com com fortably fortably reaches your mouth and the top is properly positioned behind your head when in use. Your instruc instruc tor wil willl show you the best best way to attach your your snorkel to your mask. To prepare your fins for use, make sure you you take any storage inserts out of the foot pocke pockets and, if you are wearing wearing heel-strap fins, adjust the straps straps around your heels for a snug, snug, comfortable fit (figure (figure 3-2). 3-2). Have your booties on when you adjust the straps. straps. Making Making the straps too too tight can can cause your feet to cramp. If the straps are too loose, loose, your kick kick will ill be

Chapter 3- Diving Skills

F IGI G U R E 3 - 1 . T H E S N O R K E L ISI S U S U A L L Y A T T A C H E D T O T H E L E F T SIDE OF YOUR M ASK STRAP.

F IGI G U R E 3 - 2 . B E S U R E T H A T Y O U R F I N S T R A P S A R E A D J U S T E D S O T H A T T H E Y A R E S N U G B U T N O T T IGIG H T .

awkward awkward and ineffici inefficient, ent, your your foot might cramp, cramp, and you might lose a fin. If your fin straps are oily oily or slippery from a lubri lubri cant used in manufactur manufacturing, ing, wash the straps straps in mild soap and water to remove the oil. oil. Leavin Leaving g the straps oily oily can cause the straps to slip in in the water and loosen your fins.

D o n n i n g  Y o u r G e a r When you are ready to go diving diving,, and you have complete completed d your site survey and dive plan, plan, you don or put on most or all all of your gear at th the e dive site. site. Depending on your gear, your w wet et suit is usual usually ly the first piece of gear to put on. Sit Sit down when you don your your booties to avoid falling falling,, especially if if you are on a rocking boat. boat. Your feet and your booties must be be either completely dry or completely wet wet for the booties booties to slip on easily. Your fins must be be donned donned at the the water’s edge. If it is possible to to put your fins fins on while sitting sitting,, you wil willl be less likely likely to fall. fall. However, most most of the the time, you will ill  fig  have to to don don your fins while standing. Always use a fig urefou r positi position on  when donning your fins as follows: 1. Steady yourself by putting one hand on your buddy’s shoulder. 2. Cross the ankle of the leg leg closest to your buddy over the knee knee of your your other leg (fig (figur ure e 3-3)-

F IGI G U R E 3 - 3 . U S E Y O U R B U D D Y F O R S U P P O R T A N D T H E F IGI G U R E F O U R P O S I T IOI O N T O D O N Y O U R F I N S .

3. Hold your your fin fin by the side side where where the blade and foot pocket meet, meet, or by the strap with with the bottom facing facing away from you. 4. Put Put your your foot in the foot pocket of the fin. 5. Slide Slide the heel strap up and over your heel. 6. Turn Turn around and and repeat the proce process for your other leg. Avoid walkin walking g more than a short distance while while you are wearing your ffins ins because you can easily easily lose your

NAUI Scuba Diver

F IGI G U R E 3 -4- 4 . I F Y O U M U S T M O V E W H E N W E A R I N G F I N S , B E S U R E T O W A LK B A C K W A R D .

m

balance and fall. If you must must mo move ve when wearing your fins out of the water, water, be sure to move by by shuffling shuffling your your feet backward or by side steppin stepping g (figu (figure re 3-4). Never try to walk forward in your fins. You might need to don your mask and snorkel snorkel last last so that you will will not restrict your vi vision sion when you are out of the water. One procedure to don your your mask is: 1. Positi Position on the mask on your face. 2. Slide Slide the strap down over the back or your head(figure (figure 3-5). 3-5). 3. Check the skirt skirt of the mask to be sure that no hair hair or part part of any suit hood hood are caught under the skirt skirt (figur (figure e 3-6). 3-6). Be sure sure that your mask strap is not too too tight. If the mask and strap are too too tight, it wil w illl not be comfortable. comfortable. If you are going in the water to snorkel, place the snorkel in your your mouth and adj adjust ust it along the strap so the snorkel fits easily in into to your mouth (figure (figure 3-7).

F IGI G U R E 3 - 5 . B E S U R E T H A T Y O U R M A S K I S P O S I T IOI O N E D COM FORTABLY ON YOUR FACE AND HEAD.

U s i n g Y o u r Fins Your fins provide provide you you with thrust and stability stability in the water. When you are fully fully equipped equipped for diving, you must must use the large muscles muscles in your legs for propulsion. Using your legs frees frees your hands to carry carry a camera and take pictures, a ligh lightt for night diving, diving, or use other items items.. You can move your fins fins in in a number of ways to cre-

F IGI G U R E 3 - 6 . B E S U R E T H A T Y O U G E T A L L Y O U R H A I R O U T O F  Y O U R M A S K .

ate propulsion. The most common common kick is the flutter kick (figu (figure re 3-8). 3-8). This kick differs in many ways from a swimmer’sflutter kick. When you kick with fins, think of 

Chapter 3- Diving Skills

F IGI G U R E 3 -8- 8 . Y O U R K I C K S H O U L D B E S L O W A N D W I D E A N D U S E T H E F IGI G U R E 3 7 . T H E S N O R K E L S H O U L D R E P O S I T IOI O N E D C O M F O R T A B L Y

M U S C L ES E S O F Y O U R U P P ER E R L EG EG S A N D L O W ® T O R S O .

W H E N T H E M O U T H P I E C E ISI S I N Y O U R M O U T H .

your legs as broomsticks and your fins fins as the bristles of the broom. You sweep up and down from from the hip, hip, keep ing your knees almost straight straight and your toes pointed. When kicking kicking in fins, your kick kick must be slow, deliberdeliber_ _ ate, ate, and andwide wide. If you bendyour knees toomuch much and pull I L L J your upper legs legs up towardsyour stomach, kicki kicking ng as if you are pedaling pedaling a bicycle, bicycle, your fins w will ill slip back and forth in thewater andproduce very littl little e thrust. If you kick kick too fast, you will will tire quickl quickly y and your up and down strokes will will be small andwill will not give give you much much propulsion propulsion. If youwant to move faster in the water, simply simply kick kick harder, and longer with emphasis on your your downward stroke. On the surface, modify your kick kick so that that you keep your fins in the water. water. Shorten the up stroke so so that your fin fin does not come out of the water. You can also also swimvery efficiently on your back or your side while using the the flutter flutter kick on the the surface. Swimming Swimming on on your back (figu (figure re 3-9) or side (figur (figure e 3-10) keeps your fins in the water and is is a good change change of pace from swimming face face dow down. Periodic Periodically ally check in the direc tion of travel, travel, asyou cannot cannot see ahead while while swimming swimming on your back. When you are kicki kicking ng on the surface, make sure you have just enough enough air in your your BC to make you buoy buoy ant or float. float. If you get get tired, you can stop stop kicking kicking and rest. As long as you are buoyant, you can rest without without effort for for as long as necessary.

F IGI G U R E 3 -9- 9 . M A N Y D IVI V E R S P R E F E R T O S W I M O N T H E I R B A C K S O N THE SURFACE.

RG URE 3-10. YOU CAN ALSO SW IM ON YOUR SIDE ON THE SURFACE.

NAU I Scuba Sc uba D i ver

at the surface, be sure to establish buoyancy by inflat inflating ing your vest or buoyancy compensator compensator (BC (BC)) soyour need to kick is eliminated. When replaci replacing ng a fin in the water, use the the same same fig fig ure four position you used used to don your fins. fins. This posi tion elimina eliminates tes muscle strain on the large muscles muscles in the back of your leg leg and might brin bring g your foot into position where you can see what you are doing, though this is not essential. essential. You should learn to don don and and remove gear by feel alone. alone. F IGI G U R E 3 1 1 . W H E N Y G U D U T H E D O L P H I N K ICI C K , Y O U S T A R T B Y

B r e a ttt t i i n g t h r o u g h Y o u r S n o r k e l

BENDING FORW ARD AT THE HIPS.

:

•/ :•*

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 V 4

Breathing Breathing through your snorkel snorkel while face down in the water will will help you conserve conserve energy, energy, as well as the the air air in your cylinder. cylinder. You breathe slowly and deeply deeply when using a snorkel so you get good air transfer through through the snorkel tube. Be sure that that the end of the snorkel snorkel is positioned positioned at the back of your head to keep keep the open end out of the water. Also, remember to keep your body body in a horizon horizontal tal position when swimming at the surface.

S u r faf a c e D i v ini n g F IGI G U R E 3 1 2 . W H E N Y O U A R C H Y O U R B A C K , Y O U R L E G S R ISI S E I N T H E W A T ER ER .

You can also use the dolphin kick when diving. When doing the dolphi dolphin n kick, kick, keep your your legs together and knees relaxed relaxed and alternate alternately ly bend forward from your your hips and then a arch rch your your back back (figu (figures res 3-11 and 312). This This movement causes your body to move through the water just like a dolphin. You will ill learn learn these these and other other ways to kick kick with fins fins soyou can change kicks if if your legs get get tired. Also, Also, you will learn how to kick with one fin in case a fin strap breaks or you lose a fin. fin. If a strap on your fin works loose during a dive or pulls pulls free, free, you must be able to remove the fin, fin, correct correct the problem problem, replace replace the fin, fin, and continue with your dive. dive. It is usually usually easier to to correct correct a fin proble problem m under under water than at the surface. If you need to fix a problem

There are a number number of dives you can can use to get  surface div dives es.. To under water. These These dives are called surface perform perform a good surface dive, dive, you must be weighted so you are neutra neutrally lly buoyant at the surface. The key to a successful surface surface dive is is to get as much of your body out of the water as possible. possible. The weight of your body body out of the water wi willll help push you ben beneath eath the surface of the water.

Head First There are two common headfir headfirst st dives: the pike dive and the tuck dive. The tuck dive causes less splash, and is less likel likely y to scare fish. With either either dive, you want to get your leg legs as far out of the water as possible possible in a straight, vertical vertical line. line. The weight of your legs legs carries you well well below the surface. The steps for the pike pike dive are: I. Lie horizontal at the surface. surface.

Chapter 3- Diving Skills

F IGI G U R E 3 1 3 . T H E K E Y T O A S U C C E S S F U L P IKI K E D IVI V E ISIS T O G E T A S M U C H O F Y O U R B O D Y O U T O F T H E W A T E R A S P O S S I B L E .

2. Poin Pointt your hands, palms together, together, and anns straight, at the bottom bottom or your target for the dive. 3. Bend forward at the hips hips until until the trunk of your body body is vertical vertical in the water. water. 4. Snap your legs legs up in the air until until they are in a straight line line with the rest of your body body.. 5. Kick Kick to continue continue your your descent assoon as your down ward momentum begins to decrease (f (fig igure ure 3-13). The steps for the the tuck tuck dive are: 1. Position Position yourself yourself upright upright in the water. 2. Tuck your legs to your chest in a tuck position and, at the same time, use your your hands and fins fins to rotate your body to a head down position. position. 3. Quic Quickly kly and smoothly, smoothly, extend your your arms down as you extend your legs up into the air air so your body body is in a straight vertical vertical line. line. 4. Kick Kick to continue continue your descent as soon soon as your your downward momentum begins to decrease (figure 3-14). Both dives should be carried carried out in in one smooth, continuous motion.

F IGI G U R E 3 1 4 . A T U C K D I VE V E ISIS A G O O D D IVI V E T O U S E F R O M A S T A T I O N A R Y P O S I T IOIO N .

F e e t Fipst Feet-fi Feet-first rst dive dives s are partic particula ularly rly useful for skin divers. divers. On scuba you usually usually settle gently below the sur face and continue your descent descent feet first. first. The steps for a feet-first dive are: 1. Position Position yourself yourself upright in in the water. water. 2. Hold your head upright upright and breathe through your snorkel or regulator.

F I G U R E 3 - 1 5 . A F E E T - FIF I R S T D I V E ISIS A G O O D D I V E T O U S E T O C O N  T R O L Y O U R D E S C E N T A N D C L E A R YO U R E A R S .

3. Stretch your your arms out to your sides. sides. 4. Spread your legs forward and back into a split position.

NA UI Scuba Sc uba D i ver

5. Kick Kick your legs together and bring yo your ur arms forceful forcefully ly down to your sides at the same time. time. 6. Stroke your your arms up over your head as your head goes under water. 7. After you have cleared cleared your ears, tuck tuck your knees knees to your chest chest and turn turn your body soyou are are fac fac ing down. 8. Continue Continue your descent tothe bottom (figur (figure e 3-15). A feet-first dive is also called called a kelp dive. dive. There are variations to this dive dive that your instructor will w ill show show you. you.

S h a l lol o w W a t e r B l a c ko ko u t If you are free diving, before you do a surface dive, dive, you want to breathe in in and out deeply a few times before before you take in a deep breath of air air and hold your your breath to doyour dive. If you take in more than three or four breaths, you are hyperventilating  excessively  excessively and this this can be a problem. If you breathe in and out out deeply deeply and rapidly for more than three breaths, you lower the level of carbon dioxide (C0 (C02 2) in your your body. However, ever, the deep deep,, rapid rapid breathing cannot raise the the level of oxygen oxygen (02 (0 2) in your body body.. Mo Most st people do not realize that that it is higher levels of carbon dioxide that that gives the stimulus to breathe. breathe. When you you do your dive, you use u up p the 02in 02 in your your lungs, but do do not build up enough C02in C02 in your body to the point that that you you feel the need to breathe. breathe. This can can cause you to lose consciousn consciousness ess or black black out under water. Because you you are most most likely likely to black out at, o orr as you you near, the surface on your ascent, the problem is called called  shal  shallo low w water water black blackout out.. Shallow Shallow water blackout is easy to prevent. vent. Just Just breathe in and out deeply twice, and on your third third breath, do do your dive. dive. This breathing technique technique will will work without excess excessively ively lowering the the level of C02in C02in your body.

F IGI G U R E 3 - 1 6 . E X H A L I N G T H E A IRI R I N Y O U R L U N G S F O R C E F U L LYL Y C L EA R S T H E W A T E R O U T O F Y O U R S N O R K E L

and with minim minimal al effort. They are the blast clear  and  and displacem ent clear. clear. the displacement You can also obviously clear your snorkel at at the surface by lifting lifting your head completely out of the the water, water, removing the snorkel snorkel mouthpiece, and allow allowing ing the water to drain drain out of the snorkel. This technique technique uses uses a lot of your energy energy,, is a signal of a novice (new) (new) diver or a problem, and is not recommended.

Blast C l e a r i n g You perform perform the the blast clear by exhaling air air from your m lungs forcefull forcefully y as as you surface surface from a dive. dive. The air will will blow the the water out ofyour snorkel (figure (figure 3-16). 3-16). Take in your next breath breath cautiously cautiously in in case any water is left in the snorkel. You can breathe past water left left in the bottom bottom of your your snorkel as long as you breathe slowly. Then you blast clear again again to get rid of the the remaining water. water. Each time you take a breath following a blast clear clear you should be cautious to avoid inhali inhaling ng water. water.

D i s p l a c e m e n t Clearing Clearing Water Irom Your Snorkel Water can can enter your snorkel through through the open end from waves, waves, from accident accidentall ally y dipping the end of the snorkel in the water, and from doing a dive. dive. There are two ways ways to clear your snorkel quickly and efficiently

The displacement displacement clear clear is an alternative technique. It uses uses the least amount amount of energy and removes removes the water from your snorkel snorkel by the expansion of a very small amount of air you exhale into the snorkel as you surface(figur (figure e 3-17).

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Chapter 3- Diving Skills

 A S S E M B L I N G S C U B A E Q U I P M E N T You must know how to assemble assemble your own gear for diving. Your gear gear includes your cylinder, buoyancy compens compensator ator (BC (BC), and regulator as well as your weight weight belt. Remember Remember that as a respons responsible ible diver, no one is responsible responsible for the proper assembly and operation operation of your equipment except except you.

I.

 A s s e m b l i n g Y o u r S c u b a U n i t F IGI G U R E 3 1 7 . T H E D ISI S P L A C E M E N T C L E A R R E P LAL A C E S T H E W A T E R IN THE SNORKEL WITH AIR, IN PART, BECAUSE THE  A I R E X P A N D S A S Y O U A S C E N D .

You perform the displacement clear clear by using the following following step steps: 1. Til Tiltt your head back s so o you you are looking looking straight straight up when you are ready ready to ascend from your your dive. 2. Swim to the surface, keeping your head tilted tilted back. 3. Exhale Exhale slowly slowly into your snorkel as you approach the surface. The air air displaces the water as you ascend. 4. Til Tiltt your head forward to look face down into the water as your head breaks the surface. 5. Inhale. Inhale. You should should not have any water left in your snorkel.

 V e r i f y What tfeu H a v e Learned Review the followin following g questions questions about using your mask, mask, snorkel, and fins: 1. If you must must walk in fins, you mu must st walk 2. To prevent losing losing your balance when donning fins, you can or _______________________

3. Two recommended methods of clear clearin ing g your snorkel are and and 4. The clear of your snorkel requires the least amount of energy. energy. _________________________

_______________________________

____________________

Your scuba scuba unit unit consists consists of your your cylinder, BC, and regulator. regulator. By using the follow following ing steps, ps, you will will soon be able to set up up your scuba unit correctly and efficiently. An instructor or divemaster divemaster can easily easily tell tell whether some some one is an an experienced diver just from the way they set set up their gear. To assemb assemble le your scuba unit unit,, use the followi following ng steps: 1. Place Place your cylinder cylinder in front of you with the on/off knob knob to your right, right, and the opening where the the air air comes out of the valve fa facing cing away from you. 2. Pu P ull the dust dust cap cap off of the scuba scuba cylinder cylinder valve and check check for the presence of the O-ring O-ring on the cylinder valve. valve. 3. Wet the tank strap of your BC if water is is easily accessible. 4. Pick Pick up your BC with the shoulder straps straps in your hands and the tank strap facing facing you. 5. Slip Slip the tank strap over the the cylinder cylinder and move it down the cylinder cylinder until until it is at the correct height. Your instructor wi willll showyou the cor rect placement placement for your BC’s tank strap (figure 3-18). If the strap is too too low, your first first stage will hit your head head during your dive. If the the stra strap p is too high, the cylinder will will be too low on on your back. This position might throw throw you off bal ance, ance, and it will will be difficu difficult lt for you to to reach your your second stage hose at the first first stage to recover a lost regulator. 6. Tighten the tank strap strap and secure it. Your instructor will will show show you the correct operation of your tank tank strap fastener. fastener.

NAU I Scuba D i ver

F IGI G U R E 3 - 1 8 . Y O U R R C M U S T B E P O S I T IOI O N E D A T T H E C O R R E C T H E IGI G H T I N R E L A T I O N T O T H E C Y L I N D E R .

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7. Pic Pick k your BC up by the shoulder straps straps to see see if the cylinder cylinder slips in the tank strap strap (figu (figure re 319). If the cylinde cylinderr moves, oves, you must tighten the strap strap around the cylind cylinder. er. 8. Pick Pick your regulator up and turn it so that the the second stage hose extends toyour your righ rightt and, for most regulators, regulators, the gauges and low-pressure low-pressure infla inflator tor hose to your left. Make sure sure that the knurled (ridged) (ridged) knob of the yoke screw is fac ing your stomach. 9. Loosen the yoke screw and remove remove the dust cap from the first first stage. 10. Attach the regula regulator tor to the cylind cylinder er using using one of the following methods: • For a United States-made regulator, regulator, slip slip the yoke down over the cylinde cylinderr valve (figu (figure re 320). The inlet for the first stage stage will ill match up with the outlet from the cylinder valve. The inlet for for the first stag stage of the regulator regulator will will fit right into into the indentation on the cylinder cylinder valve and against th the e cylinder’s cylinder’s O-ring. -ring. Only tighten the knob knob until until it is finger tight. • For a DIN valve valve regulator, regulator, screw the the first stage stage into the the DIN valve only unt untilil it it is finger tight. 11. Tighten the yoke screw only unt untilil it is finger tight (figure (figure 3-21). Do not use force. The 0ring will will form an airtight airtight seal when when you turn on the cylinder.

F IGI G U R E 3 1 9 . B E S U R E T H A T Y O U R C Y L INI N D E R D O E S N O T S L IPI P INI N THE TANK STRAP.

F IGI G U R E 3 - 2 0 . T H E O U T L E T F R O M T H E C Y L I N D E R V A L V E M A T C H E S U P W I T H T H E I N L E T F R O M T H E F IRI R S T S T A G E W H E N  Y O U H A V E T H E R E G U L A T O R P O S I T I O N E D C O R R E C T L Y .

12. Connect the low-pressure low-pressure infl infla ator tor hose from your first first stage to the the power-inflator hose hose on your BC (figure (figure 3-22). 13. Hold Hold your console so that your submersible submersible pressu pressure re gaug gauge e (SPG (SPG)) is facing away from you, you, anyone else, else, or other gear. It is is best best to point the face down down when you turn turn on your cylinder. cylinder. There is a very sligh slightt chance that the glass face of the SPG could could pop pop off, off, should the inner inner workings workings and the pressu pressure re relief relief fail. fail.

Chapter 3- Diving Skills

F IGI G U R E 3 - 2 1 . T H E Y O K E S C R E W S H O U L D O N L Y B E T IGI G H T E N E D U N T I L I T ISIS S N U G . D O N O T U S E A N Y F O R C E .

F IGI G U R E 3 - 2 3 . C H E C K T H E S U B M E R S I B L E P R E S S U R E G A U G E T O B E SURE THE CYLINDER IS FULL.

15. Open the cylind cylinder er valve completely completely by turning turning the on/off on/off knob knob counterclockwise counterclockwise unti untill it it stops. Then turn the knob back about one-quarter turn. This completes the assembly assembly of your scuba un unit. it. However, before you can use the unit, unit, you must test it to be sure it is operating operating properly.

T e s t i n g  Y o u r S c u b a U n iti t F IGI G U R E 3 - 2 2 . B E S U R E T O C O N N E C T T H E L O W - P R E S S U R E ININ F L A T O R H O S E T O T H E P O W E R -I- I N F L AT AT O R H O S E O N Y O U R B C .

14. Slowly Slowly turn on the cylinder cylinder by turning turning the on/off on/off knob knob counte counterclockwis rclockwise. e. You will ill hear air pressurizing the hoses oses of the the regulator. If you hear a loud hissing hissing sound from the cylinder cylinder valve, you may have a problem with with the seal betwe between en the the cylinder cylinder valve and the first first stage. This indicates that the valve valve O-ring needs eeds to be be replaced. replaced. Air leaks elsewhe elsewhere indicate indicate other problems that must be be corrected before diving. diving.

Testing Testing your scuba unit includes making sure that your prim primary ary and back-up back-up second second stages work and that m your BC is infla inflating ting and deflating properly. The steps to test your scuba unit are: 1. Look at your SPG to see how much air air you have in your cylinder cylinder (figure (figure 3-23). If you are using using a 200 bar (3000 (3000 psi) cylinder, your your SPG should reflect reflect about 200bar (3000 psi). If your gauge reads less than about 165 bar (2500 psi), psi), you should switch your equipment equipment to another cylinder, if you are planning a normal full-length dive. 2. Put Put your primary regulator regulator in your mouth, breathe out, and then breathe in to be be sure sure that

NAU I Scuba D i ver

F IGI G U R E 3 2 5 . O N E W A Y T O S E C U R E Y O U R E Q U I P M E N T I S T O L A Y T H E C Y L ININ D E R O N I T S S IDI D E IFIF YO YO U W O N T B E U S I N G I T I M M E D I A T E LYL Y . F IGI G U R E 3 2 4 . C H E C K Y O U R P R I M A R Y A N D B A C K - U P R E G U L A T O R S T O B E S U R E T H E Y A R E D E L I V E R INI N G A I R O N D E M A N D .

the regulator is delivering air air on demand demand (figure (figure 3-24). Do not forget and breathe breathe out first, first, as you might inhal inhale e debris, sand, or small pebbles. pebbles. Even insects have have been found in regulator regulator second stages after after storage. 3. Repeat the process in step 2 with with your your back-up or alternate air air source regulator. regulator. 4. Press your power-inflator power-inflator button to be sure that air is flowing into yo your ur BC on dema demand nd.. 5. Press your deflator/oral deflator/oral infl inflat ator or valve button to be sure that air air flows out of your BC on demand. When you have finishe finished d assembling your gear, you must make sure that the unit unit is is secured and not in da dan n ger of fallin falling g over and injur injuring ing you or someone else else or damaging the cylinder cylinder valve or regulator. If you are on a boat, place the unit unit back in the cylinder cylinder rack rack and secure the cylinder cylinder with the supplied elastic elastic or other tie cord. If you are beside a pool, place your second stages and gauges inside the BC and lay lay the cylind cylinder er down on the tank strap strap (figure (figure 3-25). If you are on a sandy beach, push the tank bottom deeply into into the sand to make a secure base and wrap your hoses around the valve.

Howyou set up your weight belt is is important important because because it affects your comfort and safety. safety. You want to have the correct correct amount of weight, and you want the weights to be balanced balanced on the belt. With With train training ing and experience, you w wililll know how how much weight you need need to wear based based on the diving diving suit suit you are wearing. wearing. As a new diver, diver, your instructor will will help you determine determine how much weight you should wear. A rule of thumb for the the amount of weight an average size person person needs eds in salt water with a full full 7 mm (1/4 inch) inch) wetsuit is 10% 10% of your body weight plus 2 kg (5 lbs). lbs). The length of your belt is also important. important. The excess cess tail tail of the belt that hangs out of the buckle must be long enough for you to grab it with your your entire entire hand, and only that long. If you are are using using a flat 5 cm (2 inch) inch) wide nylon nylon web belt, with no elas elastic, tic, and blockweights, blockweights, string string the weights on your belt using using the following following procedure: 1. Lay Lay the weight belt out straight on a flat flat surface with the buckle facing up. 2. Brin Bring g the end of the the weight belt up through a slit slit in the first weight and down down through the other slit. 3. Position Position the weight so so it will will be over over or slightly slightly

Chapter 3- Diving Skills

forward of your hip. 4. Repeat the process in steps 2 and 3 unti untill you have all all the weights strung on the the belt. 5. Try Try the belt on to see the position position of the weights. Be sure that you distribute distribute the weights evenly on IL jL J each side and leave the area of the belt that spans spans your middle back cl clear ear of weight weights. s. To keep the weights weights from shifting shifting,, you can put weight keepers, which which are metal or or plastic clips, clips, between the slits in in the weight to keep the weights weights from sliding. sliding. You can also put a twist in the belt as you thread it through your last last weight to keep keep the the weights from slid slid ing off the belt. belt. Ask Ask your instruct instructor or for tips to keep keep your weights securely positioned on the weight belt. If you are using soft weight weights s in a weight belt with pocke pockets, distribute distribute the weights evenly throughout the belt. If you have too mu much ch weight on one side and not not enough on the other, other, you wil willl not be able to easily easily stay in control in the water. water. The weights weights will keep pulling pulling you to one side.

on a moving boat. boat. You usually usually don the bottom bottom of your m suit first, first, followed by your booties. oties. The bottom bottoms of the legs ofyour diving diving suit suit should then go over over the outside outside of your your booties. You don the hood and then the jacket. The hood hood tucks tucks into the jacket of your diving diving suit. If the weather is warm, you you want to be sure to set up your scuba un unit it and weight weight belt before donning your diving suit. If the weather weather is cold, you might want to don the diving suit first first before you set up your scuba. If you get get too warm with your suit suit on, be sure to cool yourself yourself down by getting in the water or pouring cool water over your head and suit.

CB C O ■

So"

D o n n i n g  Y o u r S c u b a U n i t A buddy pair pair must don don scuba units as a team (fig (fig ure 3-26 3-26). ). It is easier to don scuba gear when you work IT ^ l together together beacause beacause of the extra hands that that are availa available ble to position position hoses and straps.

DONNING SCUBA GEAR There is a specific order to donning all all of your scuba gear beforeyou get in the water. Your instruc instructor tor will ill show you the way they want you to don your gear. gear. One order order is as follows. For obvious reasons, reasons, your diving diving suit must beput on first. first. Your scuba unit unit is next, fol fol lowed lowed by by your weight belt. belt. And And final finally ly your mask and and fins. Putting Putting your gear on on in this order makes the proces process easy and fast, and ensures ensures that that your your weight belt belt can be readily ditched, if if necessary. necessary.

D o n n i n g Y o u r D i v ini n g S u i t Depending Depending on where you learn learn to dive, you might might use anything anything from a dive skin to a dry suit. There are different specific specific procedures procedures for donning ea each ch type of diving suit. Your instructor wi willll show show you the prope proper techniques techniques for the suit you w wililll be using. No matter which which type of suit you are wearin wearing, g, be sure you sit down down when donning the b bottom ottomportion. portion. This This is especially important if you are donning your diving diving suit

F IGI G U R E 3 2 6 . Y O U A N D Y O U R R U D D Y A LW LW A Y S D O N Y O U R S C U B A U N IT S A S A T E A M .

59

MAUI Scuba Diver

F IGI G U R E 3 2 7 . B E S U R E T H A T YO YO U R B A C K - U P R E G U L A T O R A N O GAUGES ARE CLIPPEO TO YOUR BC.

To donyour scuba unit unit while while standing, standing, use the following procedure: 1. Stand your cylinder cylinder upright upright and face your BC towards you. 2. Grasp your BC by the shoulders as your your buddy grasps the scuba unit unit by the first first stage and the bottom bottom of the cylinder. cylinder. 3. Lift Lift the cylinder cylinder together with one smooth smooth motion and help your buddy buddy steady steady the cylinder cylinder on his/her thigh. 4. Put your arms through the armholes. 5. Fasten your waistband and clips. 6. Let your your buddy know you are are ready ready to support the weight of the cylinder cylinder so they can llet et go. 7. Secure your back-up regulato regulatorr and gauges gauges to the front of your BC (f (figur igure e 3-27). 8. Repeat the the process so your your buddy can don their BC. After you have both donned your gear, check check to be sure that your shoulder straps are comfortably posi tioned. The cylinder cylinder should feel secure on your back. Also, Also, if if your weight belt is already already in place, place, be sure sure that the buckle of your weight belt and the free end end of your weight belt can be easily reached without without obstructions.

 A N D T H E N S T E P O V E R IT .

Donning Your Weight Bel! One way to don your weight belt belt is to use the foll follow ow ing procedure procedure if your dominant hand is your right hand: hand: 1. Hold the buckle of the weight belt in your left hand hand and the free en end d of the belt in your your right hand. 2. Step over the belt with with both legs (figu (figure re 3-28). 3. Slid Slide e the belt up your legs and over over your hips. 4. Bend over and let y your our back back support the weight of your belt. 5. Slid Slide e the free end of the belt through the buckle buckle and fasten the belt securely around your waist. If your left hand is your dominant hand, you can use use the previous procedure procedure with your left hand hand holding holding the free end end of the weight belt so that your dominant dominant hand will ill open the quick release release buckle. Always be sure to pick pick up a weight weight belt by the free end, end, which which is the end end without the buckl buckle, e, to prevent prevent the weights from sliding sliding off the belt. It is best to to secure ly fasten your weights on your own belt to further further pre vent this possibility.

Ch apter 3- Divi Di ving ng Sk ills ills

 V e r i l y W h a t  Y o u H a v e L e a r n e d Review the following following questions questions about assembling your scuba gear: 5. Howshould your regulator be oriented when when you mount it on your cylinder?

6. A scuba cylinder valve valve is turned on when you rotate it in in a direction. 7. How should you and your your buddy don your scuba units? ___________________

8. To ensure that it is clear to beditched if necessary, you should put the weight bel beltt on

F IGI G U R E 3 2 9 . 0 0 A G O O D E Q U I P M E N T I N S P E C T I O N B E F O R E Y O U  A - l

G E T I N T H E W A T E R . Y O U M U S T B E F A M I L I A R W IT H

- J

Y O U R B U D D Y ' S G EA EA R .

_____________________________

ENTERING AND EXITING THE WATER Because you will will be diving diving at many different different sites, you must know know different ways of getting in and out of the water. There are general general rules that apply apply to all all entries and some rules that that are specific specific to each type of entry. You You will will beco becom me famili familiar ar with with a number number of entries entries during your confined-water and openwater openwater trainin training. g. Your instructor wi willll also teach you you specific techniques techniques for your local divin diving g area. This section of of the book introduces introduces some of the common entries entries and exits that divers use. It would take an entire entire book book to to describe all all of the entry and exit tech niques used used worldwide. You will ill learn learn local local methods thods from your instructor. instructor. Never Never assume that you know ho how w to enter and exit the water water everywhere. Always get an orientation from a NAUI diving professional to the diving diving procedures for every new site and region.

C h e c k i n s  Y o u r E q u i p m e n t Onceyou and your your buddy have your equipment equipment on, you must check one another’s another’s equipment equipment one last time

before before getting in the water (figure (figure 3-29). 3-29). You must know how your buddy’s equipment works works and they must know how to operate yours in case of an emergency. The acronym, SEABAG, is an an easy way to remember remember the series series of step steps that you follo follow w to plan a dive and check each other’s equipment. SEABAG stands stands for: • Site surv survey ey • Emergen Emergency cy planning • Activity planning planning • Buoyan Buoyancy cy • Air

• Gear and and go See Chapter 6 for the steps for site site survey, emer gency planning, planning, and activity planning. planning. The steps teps for buoyancy, air, air, and gear and go are covered covered in this sec tion. tion. A checklist checklist for the steps is included included in Append Appendix ix C. To check for buoyancy, use the follo followi wing ng steps: 1. Check your your own and your your buddy’s buddy’s weight weight system to be sure that you can easily easily release the weights, weights, if necessary. Note the type of system they are wearing wearing and the type and direction of release. 2. Check Check your own and and your buddy’s BC to be sure that you know how how to power inflate, inflate, orally orally inflate inflate,, and deflate the BCs. Also note the num ber and types of releases on the BC.

NAU I Scuba D i ver

G O

To check for air, use the follo followin wing g steps: 1. Check to be be sure that your your buddy’s buddy’s and your cylinder valve is almost fully fully open open and only back 1/4 turn turn.. 2. Check that your buddy’s and your primary primary regu lator and back back-up -up regular regular are delivering delivering air air on demand. demand. Remember Remember to exhale before before inhali inhaling. ng. 3. Check that your buddy’s and your SPG reflect that the cylinder is full while breathing from the second stage. 4. Check that all all cylinder cylinders s are secure secure in their tank straps. go, use the follo To check for gear and go, followin wing g steps: 1. Check that you both have your mask, mask, snorkel, and fins ready ready to don. 2. Check that your hoses hoses are free, not tangled, and properly secured. 3. Check to be sure that that you both have have any any necessary necessary accessory accessory equipment such as lights lights or cameras. 4. Proceed Proceed to your entry entry point. No matter how experienced experienced and skilled a diver diver you become, you always always want to have your buddy inspect your equipment and be sure sure that you inspect your buddy’s equipmen equipment in addition addition to self-checks. cks. It is much easier to correct a problembefore you get in the water.

B o a t a nd nd Platform E n t r i e s There are general rules that apply apply to most most boat and platform entries: • Your BC should be part partia ialllly y inflate inflated d to provide buoyancy. • You You should hold your mask mask firmly firmly in in place to avoid flooding it or having it come off. • You should breath breathe e from your regulator regulator during during the entry. • You You should make sure that the entry area area below you is clear clear and sufficie sufficiently ntly deep deep for the type type of entry you are using. The only objective for an entry is to get into the water with with minim minimal al effort effort and effect effect on both you and your equipment. equipment. Any entry that accomplishes this objective objective is a good entry.

82

F IGI G U R E 3 3 0 . Y O U U S U A L L Y D O A G IAI A N T S T R I D E E N T R Y F R O M A LARGE BOAT.

S i a n t S t r idi d e E n t r y You can use the giant stride entry entry from a boat or dock where where the distance to the water is is no more than about 2 meters meters (6 feet) (figure (figure 3-30). This entry entry keeps you near the surface. It is appropriate whe when n the water is deeper than than 2 meters (6 feet) feet),, there are no objects under water that you might strike strike while entering, and you want want to stay on the su surface. rface. The steps steps to a giant giant stride entry entry are: 1. Have your fins on and your mask and regulator in place. place. 2. Place Place your fin fin blades blades and the balls of your feet off the edge of the platform. platform. 3. Look Look at the water below you to ensure that there are no divers below you. you. 4. Hold your mask and regulator regulator with one hand and any loo loose se items with your other hand and arm. 5. Step out from the platform platform with with one bold stride. As you step out, your trailing leg will follow behind you. 6. Bri Bring ng your your legs together together once you are under water to propel you back back to the surface. 7. Quickly check that all all your gear is still in place once you resurface.

Ch apter 3- Diving Diving Sk ills ills

C O

F IGI G U R E 3 - 3 1 . Y O U D O A B A C K R O L L E N T R Y F R O M A S M A L L B O A T.T .

8. Turn back to the boat or platform platform and signal signal to the divemaster that you are okay. Do not signal that you are okay until until you know that you are. 9. Swim clear clear of the entry are area a so the next diver can enter the water. The key to doing a good giant-stride entry entry is to be in the steppin stepping position (one leg leg behind you and the trunk of your body upright) upright) as you enter the water. Then, as you go under water, water, bring bring your your legs together to propel yourself back to the surface. Avariation variation to this entry involves putting your feet together together before you hit hit the water. This wil willl take you deeper, and can be used in speci special al cases where you do not wish to to resurface resurface immediately. immediately. This variation variation can also place less less strain on the legs legs if you enter from a height greater than about 2 meters meters (6 feet). feet).

Back Roll En try m

You use the back roll  entry  entry when a boat is so small that if if you stood to enter the water water you could could injur injure e yourself by fallin falling g or fall fall out of the the boat boat (figure (figure 3-31). This entry entry is also used used if you are entering the water from the side of a boat with high gunwales. gunwales. The steps to a back roll roll entry entry are: 1. Have your fins on and your mask and regulator regulator in place. 2. Seat yourself yourself with your your back facing facing the water and your rear rear end parti partial ally ly over the the edge. 3. Look behind you at the water below to ensure that that there are no obstacles or divers below you.

F IGI G U R E 3 -3- 3 2 . T H E S E A T ED E D S IDI D E E N T R Y I S E A S Y A N D C O N T R O L L E D .

4. Hold your mask and regulator regulator with one hand hand and your weight belt and any any loose items with your other hand and arm. 5. Lift Lift your your legs and let the weight of your cylinder roll roll you into the water. Your body should be in an “L” shap shape e with your legs straight. Maintain Maintain an “L” shape as you you are going into the water, or tuck your your legs to your chest. chest. 6. As you go under water, water, swim swim away away from the boat or platform platform and back back to the the surface. 7. Be sure to turn back to the boat or platform and signal signal to the divemaster that you are okay, okay, if appropriate. 8. Swim clear clear of the entry area so the the next diver can enter the water, if if appropriate. You might experience some some dizziness as you rol rolll into into the water. This results from upending upending or agitating agitating the fluids in your inner ears as as you you turn. turn. You will will reorient reorient in a few seconds. Also, be sure to recheck yo your ur mask strap, becaus because e it has a tendency tendency to slip off your head during this type of entry.

S e a l e d S i d e E n t ry You can can use the seated seated side entry entry from the side of a swimming pool, a ledge at water level in in a quarry, or from a boat dock (figure (figure 3-32 3-32). ). This is a good good entry whenever whenever you you can sit at the water’s edg edge, make your final final preparations, and then lower yourself into the water. water. The steps for a seated side entry are: 1. Sit Sit at the edge of thewater with your your legs in the water.

NAUI Scuba D i ver

2. Don your fins fins and mask and put your regulator regulator in your mouth. 3. Place Place both of your hands on the same side of the entry edge and turn and and lower yourself yourself into the water. You should perform this step step in one continuous movement. The seated seated side entry is simple, simple, easy, and effect effective. ive. You are close to the water so the the impact impact of your entry is mini minima mal.l. Also, because you are seated, you are not as as likely likely to lose your balance as you are when standing.

B e a c h E n t r iei e s Beach or shore entries can be very different different depend depend ing on your location. They can range range from wading into calm water to climbin climbing g down rocks to get to the water’s edge. Each Each type of entry entry takes some precautions precautions..

C a lml m W a tet e r

m

When you you can walk walk into shallow, calm calm water to begin your dive (figu (figure re 3-33), it is usu usuall ally y an easy entry, but some precautions precautions are necessary: • Shuffle Shuffle your feet along sandy bottom bottoms, rather rather than stepping. This This detects holes and rocks or obstructions, obstructions, helps prevent loss loss of balance, balance, and chases chases bottom-dwelling animals animals from from your path. • Step Step carefully carefully along rocky bottom bottoms. s. Rocks can be covered with algae, whic which h makes them them slippery. Be sure to have solid footing and maintain your balanc balance e as you take each step. step. • Don your fins fins when you get to waist-deep water. If necessa necessary, ry, inflate inflate your BC and float on your back while while donning your fins. Lie down and begin swimming swimming as soon as possible. • If you lose lose your balance during the entry, entry, do not not try to stand up again. Crawl forward on your hands and knees and begin swimming rather rather than using using your energy to try and stand again.

Surl Entries through through surf require special training. If your train training ing does not include entries through surf, you

F IGI G U R E 3 3 3 . W A D INI N G E N T R I E S A R E E A S Y W R E N T H E C O N D I T IOI O N S  A R E C A L M .

should receive receive additional additional traini training ng before you dive in an area with surf. Some precautions for surf entries include: • All of your equipment must must be securely in in place. • You You must watch the waves waves continu continuall ally. y. • You must time your entry to coincide with with a low low point point in the wave action. • As a wave approaches, iiff you are not yet in water water deep enough to swim, swim, keep your knees bent and duck duck under the wave as it passes. • Avoid stopping in the surf surf zone. As you approach thigh-d thigh-deep eep water, water, or if if a wave is going to break over you, have your regu regulator lator in in your mouth and and go underwater underwater into into the base of the wave. Your BC BC must be deflated when when doing a surf entry entry so you can easily get under water. water. If you are using a float, it must be traile trailed d behind you.

Rock Jetties or Breakwaters Steep rock entries entries from jetties jetties or breakwaters also require some special traini training ng and considerations. Depending Depending on your comfort level moving about in full full gear, gear, you might use a procedu procedure re simila similarr to the following to get in the water water only if if it it is calm calm without without surge or surf: 1. Find Find a rock at the water’s edg edge e that will will be good to sit on to don your mask and then push off into into the water.

Chapter 3- Diving Skills

2. You and your bud buddy dy carry carry your scuba units units and weight belts down close to the entry rock rock near the water’ water’s s edge. 3. One buddy dons their their mask and and pushes off off into the water. They then then roll roll onto their back and don don their fins. Donning your fins after leaving the rocks avoids avoids the the possibility possibility of having having a fin get stuck in the rocks and twisting or breaking breaking an ankle. 4. The other other buddy passes the first first buddy their their scuba unit unit to don and then the weight belt belt to don. 5. The buddy on land land then passes passes their their scuba uni unitt and weight belt belt to the buddy in the water to hold while while they get in the water. 6. Once the second buddy is in in the water, they don their gear and start the dive. dive. If both both buddies prefer, or if if surge is washing over the jetty, they can don their gear at their their set-up point and then climb down the rocks and into the water. Howe However, ver, you you must be careful careful to maintai maintain n your balance balance and move slowly.

Boat and Platform Exits Procedures Procedures for getting out of the water and back onto a boat boat or platform vary, vary, depending on the situa tion. You might climb climb up a ladder into a boat or onto a platform or have to take take your gear off in the water and then push yourself yourself up onto a platfo platform. rm. Some general rules apply to all all boat and platform platform exits: • Evaluate Evaluate the exit area before getting out of the the water. Conditions can change during during a dive. dive. • Make sure sure all all of your equipment is in place place and is secure as you approach approach the exit. • Think Think out the steps of your exit in in advance. advance. • Keep your fins fins in in place place as long as you are in in the water.

Ladder If a dive boat has a ladder, ladder, you might might be asked asked to climb the ladder with your scuba un unit it and weight belt in place. Use the followi following ng steps when using a ladde ladderr to exit from the water:

1. Stay Stay to one one side of the the ladder or the other unt untilil it is your turn to exit. Never get under another diver trying to exit. 2. Swim to the ladder when it is your your turn. 3. Hold on to the ladder and and use the figure four position to remo move ve your fins. If possible, possible, climb out of the water before removing the fins. fins. 4. Slip Slip your your fin straps straps over over your wrists wrists or hand your fins up to the divemaster. divemaster. 5. Plac Place e your your feet on the the bottom rung of the ladder and stand up. 6. Climb Climb the ladder ladder one step at a time, time, being being sure to maintain maintain your balance and suppo support rt the weight weight of your scuba unit. 7. Take your fins fins from the divemast divemaster er and move away from the exit area. Always remember to stay away from from the ladder ladder when someone is using the ladder. If theyfall fall,, you could be seri ously injured, especially if if they are wearing their cylinder. cylinder. It might also be possible possible in some situations situations to also remove your weight belt and scuba unit unit at at the exit point. Observe, listen, listen, and ask the divemaster for the procedure they want you to use.

B o a t T r a n s o m P l a tft f o r m You must must coordinate your approach to a swim plat plat form with the wave action. The water movement will ill help lift lift you onto the swim swim platform. platform. Sometimes Sometimes you can use the the followin following g stepswhen exiting exiting the water onto a swim platform: 1. Hand any items you are carr carryin ying g up to the the divemaster (figure (figure 3-34). 3-34). 2. Remove your weight belt and hand hand it it up to the divemaster. 3. Remove your scuba unit unit and let the divemaster pull pull it out of the water. water. 4. Place Place your hands, shoulder-w shoulder-width idth apart, on the swim platform. 5. Kick Kick your legs together together and push push up with your arms at the same time to bring bring your your body out of the water. 6. Swivel Swivel around and sit on the swim platform. 7. Remove your fins using the figure ffour our position.

NAU I Scuba Sc uba D i ver

Surf When you are exi exiting ting through surf, you must concen trate on your exit procedures. Keepyour regulator in in your mouth. Hold your mask on. Never stop in the surf zone. If the surf is rough, swim until until you can crawl crawl out of thewater on your your hands and knees (figure (figure 3-35). Once you are are clea clearr of the water, you can rol rolll over and removeyour fins.

Rock Jetties or Breakwaters F IGI G U R E 3 -3- 3 4 . W H E N Y O U E X I T O N T O A S W I M P L A T F O R M , I T I S EASIER TO HAND YOUR GEAR UP FIRST.

With With rock rock exits, exits, you reverse reverse your entry pro procedure cedure.. If If you put your gear on in the water, water, you need to to take it off in the water and hand it out to your buddy. buddy. When approa approaching ching the rock rock you are are going to use use to exit, use the wave wave action action so that the water moveme movement nt will will help you get onto the exit area.

 V e r i f y W h a t Y o u H a v e L e a r n e d Review the followi following ng questions about entries entries and exits: 9. Which Which pieces of equipment equipment must you check check beforeyou get in the water? F IGI G U R E 3 3 5 . I T I S S O M E T I M E S N E C E S S A R Y T O C R A W L O U T O F T H E W A T ER E R T H R O U G H S U R F.F .

8. Leave the swim platfo platform rm area. An alternativ alternative e method is to leave all of your gear in place, remove your fins, fins, and climb up a ladder and onto the deck.

Beach Exits Procedures for beach exits vary greatly depending depending on the situation and the the conditions. You must evaluate evaluate the condition condition of the exit area and the step steps of your exit before you proceed with with your your exit.

C a iri r n W a t e r When you do do a beach exit in calm water, water, swim towards shore until until you are about waist waist deep. Stand Stand up and useyour buddy’s shoulder and the figure four posi tion to remove remove your fins. Walk Walk out of the water.

10. Three general rules that apply to entries are:

11. The objective of an entry entry is to

12. State State one example of when it is appropriate appropriate to use each of the following following entries: a. Giant Giant stride b. Back roll c. Seated

Ch apter 3- Diving Diving Sk ills ills

M A S K S K I L LS LS There are a number of ways that water can get in your mask mask during your dive. dive. For example: example: • Your mask fogs whil while e under water. The easiest way to remove the fog is to let water into your your mask and swish it around. • You You laugh laugh or smile under water, whic which h causes the muscles muscles of your face to create channels that that will will let water into your your mask. • Your mask gets knocked to the side by the careless careless movement of another another diver. In any of thesesituations, situations, you need to know how to get thewater out ofyour mask and feel comfortable doing doing it. If you are skin divi diving ng and water get gets into your mask, you can wa wait it to get back to the surface to pour the water out. out. You can also easily easily clear clear your mask under water while skin or scuba diving. diving.

co F IGI G U R E 3 - 3 6 . T H E A IRIR Y O U B R E A T H E O U T Y O U R N O S E R E P L A C E S T H E W A T ER I N Y O U R M A S K .

C l e a r ini n g W a t e r frf r o m Y o u r M a s k

m

m

To clear water from your mask or replace your mask underwate underwater, you must replace the water in the maskwith air. air. When you exhale air air into into the mask, mask, the air rises to the top and the water flows out the bottom bottom (figure (figure 3-36). Replac Replacing ing the mask underwater is the the same process as on land. land. The steps to cleari clearing ng water from your mask are: 1. Poin Pointt your chin chin toward the bottom bottom whenever you have water in your mask to prevent water water from getting up your your nose. 2. Inhale Inhale a breath of air air if if your lungs are empty and you are on scuba. 3. Put Put your finger finger tips on top ofthe maskframe and push in to mainta maintain in the seal at the top of the the mask. 4. Start exhaling exhaling through your nose. nose. As you exhale, tip your head head back slowly slowly.. The air will w ill force the water out out of the bottom of the mask. 5. If If you have a purge valve in your your mask, do not tip your head back, look toward the bottom, and simply exhale into the mask. mask. When you you are breathing breathing from scuba, you must per form the ste steps to clearing clearing your your mask deliberately deliberately and slowly (figure (figure 3-37). You must consciously think think about

F IGI G U R E 3 3 7 . C L E A R I N G W A T E R F R O M A M A S K I S S O M E T H I N G E V E R Y D I V ER ER M U S T B E A B L E T O 0 0 .

what you are doing and you must concentrate concentrate on inhal inhal ing through your mouth and exhaling through your your nose. nose. This pattern is different different from normal breathing breathing

GO

NAU I Scuba S cuba D i ver

and is different fro from m the normal normal pattern of breathing on scuba. scuba. If you do not concentrate on what you are doing, you might forget and inhale inhale water through your nose, nose, which which wil willl cause you you to choke and cough. cough. A single, single, sustained exhalat exhalation ion is more effective than than short or strong bursts of air. It does not take much air air to clear clear a mask completely. When you becom become profi cient at mask clearing, you will will be able able to clear clear your mask mask several times on a single breath of air. air. Removing water from your mask is an important diving skill. You must must repeat repeat this skill until until you are are completely comfortable with iitt and can do do it automat automati i cally. Initia Initially, lly, your instruct instructor or will will have have you you practi practice ce this skill skill in in shallow water and then will will have you you repeat repeat the skill skill in deeperwater.

R e m o v i n g a n d R e p l a c i n g  Y o u p M a s k You might wonder why you would want to take your mask off under water. Generally, Generally, you don’t, but some some one else might inadvert inadvertently ently remove remove it for you. Your mask can be bumped and dislodged, or it can catch catch on something and be pulled pulled free. In these cases, you must be able able to calmly calmly locate your mask and put it back on. Your vision without without a mask mask will will not be be good good, but you will ill be able to see. Leam to open your eyes without without a mask on, because because they are more useful than you might think. When you are wearing contact contact lenses, lenses, you run the risk of of losing the the lenses if your your mask floods floods or comes comes off your face under water. In this situatio situation, n, keepyour your eyes closed unless you you need to see to locate your mask. If your mask is lost, you will ill have to rely rely on your buddy to find it it or help you surface, to avoid losing your lenses. lenses. One way to replace your your mask under wate waterr is to use use the following steps: 1. Orient Orient your mask so that the inside of the mask is facing facing you and your snorkel is on the side side on which you wear it. 2. Positio Position n the mask over your eyes and nose and place the mask strap on the back of your head. 3. Run Run a finger around around the mask mask seal and make make sure that all all of your hair hair or your hoo hood d (if (if you are wearing wearing one) is out of the mask. mask.

4. Clear Clear the water from your mask as described described in  on page 67. Clearing Water Waterfrom. Your Mask  on

 V e r i f y W h a t Y o u H a v e L e a r n e d Review the following following question questions s about about mask skills: 13. What What are the recommended steps to replac replacing ing your mask under water?

14. Which Which way should you tilt your head when clearing clearing water from a mask with a purge purge valve?

REGULATOR SKILLS Learning Learning to scuba scuba dive dive includes more than  ju  just learning how to breathe from a regulator. You can do that already! Some Some of the regulator skills you will will master master during your NAU NAUII Scuba Diver certification course include: • Breathing undeiwater undeiwater if your mask mask com comes off your face. face. • Finding Finding your regulator if it comes comes out ofyour mouth while you are swimming under water. • Sharing air air with another another diver diver.. • Breathing Breathing from a free-flowing free-flowing regulator.

B r e a tht h ini n g U n d e r W a t e r When you breathe on scuba, you do all of your breathin breathing g through your mouth. However, you must exhale small amounts amounts of air into your mask as you descend to prevent mask squeezes. You must always always remember remember to kee keep p breathing breathing so that you w wililll not trap expanding expanding air air in your lungs during an ascent.

Chapter 3 Diving Shills

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a H o o d e d Mask o r w ith o u t o M a s k

If you lose lose your mask mask under water, water, or if your mask floods, you must concentrate on your breathing breathing and maintain maintain air air pressu pressure in your nose nose to avoid avoid inhalin inhaling g water through your nose until until you correct the problem. You must must be able to do this without without needing to hold your nose closed closed, because because in many many situations, situations, you will will needto use both your your hands for other purposes. purposes.

C l e a r i n g  Y o u r R e g u l a t o r □

Whenever the mouthpiece mouthpiece of your regu regulator lator is out of your mouth, mouth, you must must continua continually lly exhale a small stream stream of bubbles (figur (figure e 3-38). This helps keep your airwa airway y open. You do not want to lock off yow  yow throat.  throat. If you do rise in the water, water, the air in your lungs will will expand, and the air air must be able to escape escape through your mouth instead of over expanding your lungs and causing causing damage. Your regulator sh should ould remain in your mouth as much as possible, ossible, but there are a few situations situations in which which you must remove it. If the mouthpiece of your regulator regulator comes out of your mouth for any reason, the reg regulato ulatorr second second stage stage will automatically automatically fill fill with water. water. When you put the the reg ulator ulator back in your mouth, you must must be be able to clear the water from the second stage before you can can breathe. There are two primary primary ways to clear your your regulator regulator sec ond stage of water: the blast clear clear and the purge purge clear.

F IGI G U R E 3 3 8 . Y O U M U S T E X H A L E A S M A L L S T R E A M O F B U B B LEL E S W H E N E V E R T H E R EG E G U L A T O R ISI S O U T O F Y O U R M O U T H .

P u r g e Clear If you do not not have enough enough air air in in your lungs to per clear  to form the blast clea clear, r, you can use the purge clear   to get the water out of your second stage stage. To perform the purge clear, clear, use the followin following g steps: 1. Put Put your your tongue up to the roof of your mouth and against against your teeth to prevent water from from the sec ond stage from going into into your mouth and throat. 2. Lig Lightl htly y press the purge purge button located on the front front or side of the second stage to replace the water in your second second stage stage with with air air from your cylinder.

R e c o v e r i n g  Y o u r R e g u l a t o r B l a s t Clear The quickest and easiest way to removewater from the secondstage ofyour your regul regulator ator is to do theblast clear. The blast clear is not tru truly ly a blast of air, air, just a simple exhalation. exhalation. To perform the blast clear, you put the regula tor mouthpiece outhpiece in your mouth and exhale the air remain remain ing in your lungs out ofyour mouth. mouth. The air air from your lungs forces the water out of the one-way exhaust valve located on the bottom or side of your your second stage. Most regulators regulators require that you be in an upright position or facing slightly slightly down to clear all all thewater out of the sec ond stage. Some regulators requi require re you to tilt tilt to the side side oppositetire hose to full fully y clear clear the the regulator.

There will will be times when your second second stage will ill be out of your mouth during a dive. For example, if you are diving diving in kelp, the kelp might wrap around your hose hose and it might be convenient convenient to take take the regula regula tor out of your mouth to untangle untangle it. Also, Also, you might get get so relaxed that you forget to bite on yo your ur mouthpiece to hold the regulator iin n your mouth. There are two ways to recover your regula regulator tor:: the sweep method and the reach reach method.

Sweep Method Use the following following steps steps to find your regulat regulator or using  sweep p meth method od'. '. the swee

NA UI Scuba Sc uba D i ver

1. Get into a vertica verticall position, right right side down or lean to the right. 2. Bring Bring your your right right elbow into your side. 3. Touch your right right hand to your thi thigh gh and then move it back to touch your cylinder cylinder.. 4. Sweep eep your right right arm out from your cylinder cylinder in a big circle circle around around to the front front of your body. Your primary primary regulator regulator should be in the bend bend of your arm (fi (figu gure re 3-39)5. Put Put your primary regulator in your mouth mouth and either blast or purge clear clear the second second stage. Always remember remember to blow a steady stream of small small bubbles whenever the regulator regulator is is out of your mouth.

Reach Method Use the following following steps to find your your regulator regulator using the reach method : 1. Reach over your right shoulder with your right right hand and grasp the first stage of your regulator. It might be necess necessary ary to lift your cylinder cylinder by its boot from the bottom with your left hand. 2. Feel for the primary primary regulator regulator hose on the upper or front right right side of your first stage (figure (figure 3-40). 3. Follow Follow the hose hose down to the end. Your prima primary ry regulator regulator will will be at the end end of the hose. 4. Put Put your regulator in your mouth and either blast blast or purge clear clear the the second stage. Remember, if if you happen to recover your back-up second second stage or cannot immedi immediately ately locate your your primary primary second stage, you can can always use your own back-up reg ulator or redundant scuba system for breathing until you find your prim primary ary second second stage. Use Use the alternate air air source source only until until you can find your primary regula regula tor or you can get your buddy’s attention and assistance to locate your primary regulator. regulator.

B r e a t h ini n g f ror o m a F r e e - F l o w i n g R e g u l a t o r When a regulator begins begins delivering air air continuously, flowing  (fig it is freeflowing   (figure ure 3-41). To stop the freeflow, turn turn the regulato regulatorr so the mouthpiece opening opening is down. Fortunately, this this is about the only problemyou will will ever have with a regulator, and it is is usually usually not serious serious..

F IGI G U R E 3 - 4 0 . F E E L INI N G O V E R Y O U R R I G H T S H O U L D E R W I T H Y O U R R IGI G H T H A N D F O R Y O U R R E G U L A T O R H O S E I S O N E WAY TO FIND YOUR REGULATOR.

However, you should should not dive with with a free-flowing regulator. If the regulator starts to flow continuously during your dive, you can continue continue to breathe breathe from the the regula regula tor by using the following following procedure: 1. Using your hand, hold hold the mouthpiece mouthpiece loosley in your mouth. 2. Breathe Breathe the air air you need from the stream of air air escaping escaping from the mouthpiece. 3. Perfor Perform m a safe ascent. ascent. 4. It It is is a good good idea to turn off, or have your buddy

Chapter 3- Diving Skills

F IGI G U R E 3 4 1 . M O S T R E G U L A T O R S W I LLL L FR F R E E FLF L O W I F T H E Y A R E TURNED UPRIGHT UNDER WATER.

turn off your cylinder cylinder when you reach the surface soyou do not drain drain all all the air from from your cylinder. Be sure to allow allow the excess air air to escape through the sides of your mouth. Most Most will will purge through the exhaust port and prevent the pressure pressure of the air escaping to force too too much air air into into your lungs.

F IGI G U R E 3 - 4 2 . Y O U M U S T B E A B L E T O U S E T H E O R A L I N F LAL A T O R O F  Y O U R B C U N D E R W A T E R O R A T T H E S U R F A C E IF Y O U R P O W E R INI N F L A T O R F A I L S .

Orally Inflating Your Buoyancy Compensator If your BC’s pow ower er inflator fails, fails, you must must orally inflate your BC during your dive to maintain maintain proper buoy ancy. To orall orally y inflate inflate your BC, use the followi following ng steps: 1. Inhal Inhale e a breath breath of air. 2. Remove Remove your regulat regulator or mouthpiece. 3. Put Put the BC’s oral infla inflator tor mouthpiece mouthpiece in your mouth. 4. Press the deflator/oral deflator/oral infla inflator tor valve valve button as you blow into the mouthpiece mouthpiece (figur (figure e 3-42). 5. Release the the deflator/ora deflator/orall infla inflator tor valve valve button. button. 6. Stop blowing into the mouthpiece. mouthpiece. 7. Remove Remove the oral oral inf infla lator tor mouthpiece and put your regulator in your mouth. 8. Clear the regulator regulator and take a breath. 9. Repeat step steps 1to 1 to 8 until until you have achieved achieved your desired state of buoyancy.

When you surface, you will usually take your regu lator lator out of your mouth and switch to to snorkel (fig (figure ure 3-

F IGI G U R E 3 -4- 4 3 . S W I TC TC H I N G F R O M R E G U L A T O R T O S N O R K E L S H O U L D B E S M O O T H A N D E A SY SY .

43). When you get ready to to descen descend, you must take your snorkel out of your mouth and replace it with with your reg reg ulator. You will practice practice regulator/snorkel regulator/snorkel exchan exchanges ges at at the surface unti untill they are simple and easy for you to per form. You must must remember remember to inhale inhale before the switch and to exhale before you inhal inhale e after after the switch to clear clear any water out of either the regulator regulator or the snorkel. snorkel.

NA UI Scuba Sc uba D i ver

 V e r i l y W h a t V o u D m L e a r n e d

C O

E D

You must monitor your air consumption during your dive by frequently checking checking your submersible pres pres sure gaug gauge e (SPG (SPG). ). At a minimum, you should should check check your SPG every every 5minute 5 minutes s when you are in shallow water (less (less than 9 meters meters [30 feet feet]) ]) and more frequently when you you are in deeper deeper water (figur (figure e 3-44). You must must also begin checking your SPG SPG more frequently frequently when when your cylind cylinder er pressure drops drops below 70 bar (1000 psi). psi). When you begin diving, your air consumption will be high and you w wililll be surprised at the shortness shortness of your dives. As you you gain gain experience experience and your comfort level in the the water water increases increases,, your air will w ill last longer. When you are cold, diving diving deep, deep, or breathing ra rapid pidly ly on a dive, dive, your air consumption consumption will will increase. increase. When you are diving in in these these conditions, you must monitor your air supply more frequently. On dives to 18meters (60 feet) feet) or less, begin begin your your ascent ascent when your cylind cylinder er reaches a minimum minimum pressure of 50 bar bar (800 (800 psi) psi) or more. On deeper dives, begin your ascent when your cylinder cylinder pressure pressure reaches reaches a mini mini mum pressure of 70 bar (1000 (1000 psi) psi) or more, depending on the conditions.

F IGI G U R E 3 -4- 4 4 . Y O U M U S T C H E C K Y O U R S P G F R E Q U E N T L Y D U R INI N G  Y O U R D I V E .

Review the following questio questions about regulator skills: skills: 15. You shou should ld when ever your regulator regulator is is out of your mouth. 16. Two methods to clear clear water from from your regulator regulator are the method and the method. 17. What What should you avoid when breathing breathing from a free-flowing regulator? ______________________

__________________

__________________

BUOYANCY SKILLS If there is one one skill skill that determines a person’s person’sdiving ability, ability, it it is buoyancy buoyancy control. Buoyancy control c con onsists sists of numero numerous us skills skills that you can leam leam quickly quickly by under standing and applying some basic principles. Proper buoyancy control control makes diving diving easier, adds to your enjoy enjoy ment, and helps protect the underwater environment. Many factors affect your buoyancy in the water. water. You must be aware of all a ll of them and you must know the the various means that are available available to you you for remaining in control of your buoyancy buoyancy at all all times. times. The four major major ways you affect your buoyancy are through: • The type of protective suit suit you wear. • The amount of weight you wear. • The amount of air air in in your BC or dry suit. suit. • The The amount of air in your your lungs. lungs. You must begin your dive properly properly weighted weighted if if you want to easily adjust your buoyancy buoyancy under under water. water. You fine-tune your buoyancy by the amount of air you have in your your lungs. You must must always kee keep p breathing, but you can take shallower shallower breaths to be less less buoyant or deeper breaths to be more buoyant. If you are learning learning to dive dive using a dry suit, you will will use the dry suit instead of your BC to control control your buoy ancy at depth. depth. You use the BC for surface flotation flotation and as a backup for buoyancy under water. When you pick up objects under water and carry carry them with you, you, it it wil willl probably probably be necessary for you to increase your buoyancy to offset their their weight.

Chapter 3- Diving Skills

C h e c l i l i y  V o u p   B u o y a n c y a l D i e S u r f a c e

ED

If you are properly weigh weighted, ted, you should be able to hover at 4 meters (15 feet) feet) with with 34 bar (500 psi) psi) or less of air in your cylinder. You must must test your buoyancy at the surface before before you begin your dive. To test test your buoyancy for scuba diving, use the followi following ng steps: 1. Make sure that your your BC is completely completely deflated. 2. Assum Assume an upright upright position position in in the water. 3. Take in a deep breath and hold iitt while while you hang hang in the water water motionle motionless. ss. If you are properly properly weighted, weighted, you will ill float float at eye eye level. 4. Exhale completely. completely. If you sink, you are properly weighted. 5. As soon as you sink, sink, kick kick back back to the surface surface and inflate your BC. This procedure gives gives you an approxima approximation tion of cor rect buoyancy adjustment. You will ill fine-tune your buoyancy adjustment adjustment as you gain gain experience in using different types of equipment (f (for or example, exposure exposure suit worn, type of cylinder cylinder used, and and size size of cylinder cylinder used) and diving in salt and fresh water. water. Your buoyancy buoyancy will will change change during your dive because because of the compression of your di diving ving suit, the amount amount of air in your BC, the items items you collect during your dive, dive, and the the use of air in in your cylinder. You will control your buoyancy during during your dive by adding to or removing removing air air from your dry suit or BC.

Descending Being Being able to descen descend easily easily in the water is is one of the important skills of diving. Diving is not much much fun if you have to struggle to get to the bottom. Some of the general steps for descending descending are: 1. Have your regulator regulator in in your your mouth. 2. Note Note the exact exact time that you leave the surface. If you are using a dive dive compu computer, ter, it will will automati cally cally start timing your dive when you leave the surface. However, a dive computer does not always record the time of day you leave the sur face. face. Having a slate or your dive dive table in your BC pocket is a good good place to record record the time. 3. Deflate your BC. If you are weighted correctly, correctly,

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F IGI G U R E 3 -4- 4 5 . R E M E M B E R T O E Q U A L I ZEZ E E A R L Y A N D O F T E N D U R I N G  Y O U R D E S C E N T .

you will will slowly slowly sink when all the air is removed oved from your BC and you exhale. Remember to hold the power power infla inflator tor hose hose over your head and watch its mouthpiece to see the air air coming coming out as you go under water. Stop pressing the deflator/oral inflator valve button when you do not see any more air air to prevent large large amounts of water from entering entering the BC. BC. 4. Equal Equalize ize your your ears as you start your descent descent and continuously throughout your desce descent nt (fig (fig ure 3-45 3-45). ). Never Never continue descending if you feel pressure in your your ears and you cannot cannot equalize them. You will not feel feel discomfort discomfort if you are equalizing properly. 5. Exhale Exhale and begin your feet-first descent (figure (figure 346). Remember tobreathe out completel completely y and then take take in a small small breath of air. The less air you have have in your lungs during during the first first few feet ofdescent, the easier your descentwill ill be. If you descendfeetfirst, you can maint maintain ain better better contact contact with your buddy and it will will be easier easier to equalize equalize pressu pressure in your ears, mask, and sinuses. 6. Stay Stay with your your buddy buddy as you descen descend. Remain Remain close enough to touch each other and maintain maintain eye contact contact throughout the descent descent.. If one buddy buddy is having having trouble equalizing, equalizing, the other bud buddy dy must must be be patient and wait w with ith them until the the problem is corrected.

NAU I Scuba D i ver

Controlled Descents Because so many things things are happening happening at once dur ing a descent, descent, your first one will be acontrolled  descent. This means means you you will will descen descend d on on a line or along the contour of the bottom. bottom. Doing a controlled controlled descen descentt will will allow you to concentrate concentrate on equalizing equalizing pres pres sure, sure, mainta maintainin ining g buddy buddy contact, and controlling controlling your buoyancy.

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F r e e D e s c e n ts F IGI G U R E 3 - 4 6 . D E S C E N D I N G F E E T F I R S T G IVI V E S Y O U B E T T E R ^ C O N T R O L O F Y O U R S P E E D , B U O Y A N C Y,Y , A N D A B ILI L I T Y - J

T O C LEL E A R Y O U R E A R S .

Your rate of descen descent should not be rapid. The rec ommended rate of descent is no faster faster than than 23 meters (75 feet) per minute. When you are wea wearing ring a wetsuit and make desce descents nts in open water, you will will lose buoyancy as th the e pressure pressure of the water com compresses your wetsuit. You wil willl need to add small small amounts of air air to your BC to compens compensate ate for the compression compression of the wetsuit. wetsuit. You must never sink out of control control.. You should be able to stop your descent at any time time just by inhaling inhaling a full full breath of of air. If you are wearing a dry suit, you will add air to the dry suit instead of your BC to control your your buoyancy. As your your wetsuit compresses, it it can can also loosen your weight belt if if the weight belt iis s not a compensating type. type. Your wetsuit wetsuit loses thickness as it it compresses and causes your weight belt belt to become loose around your your waist. When this happens, happens, the buckle can shift shift position, position, mak mak ing it diffi difficul cultt to locate. locate. The weight weight belt could could even even slide slide down around your legs or fall fall off. Remember Remember to check your belt as you descend descend and and then check it it again again as you reach the bottom bottom. Tighten the weight belt if if necessary. necessary. Useyour fins fins as little little as possible possible during during your descent. You should control your descent descent by your buoy ancy, not not by kickin kicking. g. As you get close to the bottom, kicking can stir up clouds clouds of silt, silt, ruin ruin the visib visibilit ility y and harm the environment. If you take in a deep breath of air air and continue to descend scend,, you are too heavy and you need to add air air to your your BC to help help slow your your descent.

Once you are comfortable with with control controlled led descents descents, descents ts..  Free your instructor instructor will will introduce you to free descen descen descents ts are vertica verticall descents descents in open water without without a line. line. When you can exe execute cute free descents in a controlled manner, you wil willl be well on your way to becom becoming ing a capable diver.

During the Dive During your dive, your goal is to maintain what divers call call neutral neutral buoyancy (figure (figure 3-4 3-47). 7). Neutral buoyancy is a state state in which you neither sink nor float float

F IGI G U R E 3 - 4 7 . M A I N T A I N INI N G N E U T R A L B U O Y A N C Y W H I L E U N D E R W A T ER E R ISI S T H E K E Y T O E N J O Y A B L E D I V ININ G .

Chapter 3- Diving Skills

when at rest. As you go deeper in the water, water, you wil willl add small amounts amounts of air air to your BC to offset wetsuit com com pression or to your dry suit to achieve neutr neutral al buoyancy. You add just a small amount amount of air air to your BC (or dry suit) suit) and then then check check to see if you are still still sinking by slowing your activity and breathing normally. If you are still still sinking, add add another another small amount of air air to your your BC (o (orr dry suit). suit). As you ascend ascend or you feel yourself risi rising ng in in the water because because of the expansion of air, you wil willl need to r y ] vent vent small amo amoun unts ts of of air from from your your BC (or dry dry suit) to maintain maintain neutral buoyancy. buoyancy. Howmuch air air you need need to vent and how often you need to vent it it depends on your situation situation and your depth. pth. To vent vent air air from your BC (or dry suit suit), ), you must get get into the necessary necessary position first. first. Dump valves are usual ly located on the upper left shoulder of your BC and on the upper upper left arm of a dry suit. Some BCs have extra dump valves on either the lower back or top right right side of the BC. If you have have an extra dump dump valve, ask your instructor instructor how to operate operate it. Slow your activity activity and your kicking kicking from time to time to to test your buoyancy. buoyancy. If you float up without kick kick ing, you are too buoyant and need need to vent some air. air. If you sink, you need need to add a little little air. air. You should strive to control your buoyancy so well well that that you can stop at any depth any time and remain remain suspended there without using your fins or hands. This technique technique is how you evaluate your buo buoyancy yancy control and will will be a part of your open-wat open-water er training training..

 A s c e n d i n g For every descent you make, you must also make an ascent. Some of the general procedures for doing an ascent are: 1. Stop a minute minute and and secure any accessories you are are carrying. For example, if you you are carrying carrying a goody bag, close it and clip it to your BC. 2. Make sure your automati automatic c exhaust valve will will open if you are wearing a dry suit. 3. Find your your power-inflator hose hose and your deflator/oral deflator/oral inflat inflator or valve button button and hold the the hose up over your head. If you are wearing wearing a dry

F IGI G U R E 3 4 8 . I F Y O U A R E W E A R I N G A D R Y S U ITI T , Y O U M U S T V E N T  A I R F R O M T H E S U I T A S Y O U A S C E N D .

suit, raise the exh exhaust aust valve until until it is level with or above above your shoulder (figur (figure e 3-48). Holding the hose hose over your head al also so ensures ensures that your hand will will run into an overhead overhead object object befor before e your head head will. will. 4. Give your buddy the up up signal. signal. 5. Star Startt swimming slowly slowly towards the the surface with with your buddy. Remember Remember to look up and around as you are surfacing surfacing and breathe nor mally (figure 3-49). 6. Control your b buoyancy uoyancy and your ascent by vent ing air from your BC (or dry suit). suit). Your rate of ascent must not not exceed a speed of 9 meters (30 feet) per minute if you are using dive tab tables. les. This is only 15 centimeters (6 (6 inches) inches) per second cond and is much slower slower than you natur naturall ally y want to proceed. proceed. If you are using a computer, computer, following following it will will control your rate of ascent, ascent, and it might be be slower than 9 meters meters (30 feet) per minute. 7. Slow Slow your your ascent when you get to 9meters (30 feet). feet). 8. Stop at a depth of 4 meters (15 feet) feet) for 3 min-

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NAU I Scuba S cuba D i ver

9. Proceed to the surface, infla inflate te your BC, switch from your regulator to your snorkel if if desired, and record the time you surfaced. When you you first start diving, iitt will will help if you you time your ascents and compare the ascent time with your depth depth gauge so so you you can can determine your rate of ascent. ascent. You must deve develop lop a feel for the correct rate. Your instructo instructorr will will help you do this. A slow ascent ascent rate is import important ant because the dive tables are are based on a slow ascent ascent rate. If you rise too too quickly, quickly, decompression sickness sickness can result.

 V e r i f y W h a t  Y o u H a v e L e a r n e d F IGI G U R E 3 4 9 . Y O U R N O R M A L A S C E N T S H O U L D A LW LW A Y S B E S L O W  A N D C O N T R O L L E D .

Review the followi following ng questions about buoyancy: 18. What What are are three steps you should should take to prepare for a descent? descent?

19. What What three actions do you perform on every every descent?

20. What What three actions do you perform on on a normal ascent?

21. Four major major factors factors that affect your buoyancy are F IGI G U R E 3 5 0 . I F Y O U A R E P R O P E R L Y W E IGI G H T E D , Y O U S H O U L U B E  A B L E T O H O V E R A T 4 M E T E R S ( 1 5 F E E T ] W I T H 3 4 BAR (500 PSD OR LESS OF AIR IN YOUR CYLINDER FOR A PRECAUTIONARY DECOMPRESSION STOP.

utes to do a prec precaut aution ionary ary decompression stop (figure (figure 3-50). If you can perform the stop stop while while hanging onto a line or by following the contour contour of the bottom, it makes the stop stop easier.

and and . 22. On ascent, ascent, as the air in in your BC or dry suit starts to expand, you must ________________________________

Chapter 3- Diving Skills

SAFETY SKILLS There are som some important important safety skills skills you you must master to be a responsible diver. Your goal goal is to never have to use these skill skills, s, but you must always be prepared in case you you or your buddy buddy have a problem. problem. The impor impor tant safety skills skills are: ^  • Sharing air with another another diver. diver. • Being able able to perform independent controlled controlled emergency ascents.

S h a r i n g  A i r  w i t h A n o t h e r Diver If your buddy forgets forgets to check their their pressure gauge at depth and runs out of a air ir,, you must know how to share share air air with your buddy. dy. If you have a conting contingency ency air bottlee, that supply, such as a pony bottl that is the best method method of sharing air air with your buddy buddy.. If you do not have a contingency air air supply, there are two two major ways to share your air air supply supply with your buddy: the alternate air air source or octopu octopus method method and the buddy breathing breathing method. These methods are called called dependent ascents because your buddy is dependent on your air supply.

m

Octopus Method _ _

J

The The pref prefer erre red d metho ethod d of sharing sharing air with anoth another er diver is is for your buddy to breathe from two separate regulator regulator which which you supply. This might might be a secondary regulator attached to to your air air supply (an (an octopus octopus regu lator or other other alternate air sourc source e regulator). regulator). This tech octopus method  metho d of breathing nique is the octopus breathing (figur (figure e 3-51). 3-51). The exact exact procedure procedure you use for sharing sharing air air with with an alternate air air source depends on your equipment configu ration ration and personal preference preference.. You must must work out how how you will will share air in an emergency emergency before beforeyou start your dive. Your buddy must knowwhich which regulat regulator or to use, where where to find it, it, and how it is attached to your BC or your equipment. If they don’t, and they they run out of air during during the dive, they might grab for the first regulator they see - usually usually the one that is in your mouth! Although this regulator regulator might be the the one one you plan plan to pass, pass, you want want to pass it in a controlled controlled manner.

F IGI G U R E 3 5 2 . A S C E N D I N G INI N A N E M E R G E N C Y R E Q U I R ES E S C O O R D II  N A T I N G . S IGI G N A L Y O O R B U D D Y W H E N R E A D Y

Your buddy will find that breathing from your extra regulator regulator is is just as easy easy as breathing breathing from their their own reg ulator. ulator. However, ascending will ill take some coordination coordination (figur (figure e 3-52). You and your buddy buddy must must ascend at the same same speed by maint maintain aining ing physical physical and eye eye contact. The general general steps to the octopus method of sharin sharing g air are: 1. Give your buddy buddy the appropriate regulato regulatorr for your equipment equipment configuration configuration when they signal that they are out of air.

NA UI Scuba Sc uba D i ver

3. Ask Ask your buddy buddy if they are okay and wait wait for a reply. 4. Give your buddy buddy the the up signal and wait for their their reply before before starting starting your ascent. ascent. Once your buddy buddy is breathing breathing and is okay, you should carry carry out your normal normal ascent procedure. procedure. The normal normal ascent rate is 9 meters (30 feet) per minute if if you are using using dive tables. If you are using a redundant redundant contingency scuba scuba system system, you should sti stillll perform the steps steps of ascending together after after you pass the system system to your your buddy.

Buddy Breathing Method

F IGI G U R E 3 5 3 . M A I N T A INI N P H Y S I C A L C O N T A C T T H R O U G H O U T Y O U R ENTIRE OCTOPUS ASCENT.

2. Hold on to them with one hand and position your buddy in front of you. This position position allows your your buddy to keep keep the mouthpiece of the sec ondary regulator easily in their mouth mouth and allows you both to to maintai maintain n physical physical and eye contact (figu (figure re 3-53).

The other method method of sharing air air with with your buddy is the buddy breathing method. If you do not have a sec ondary regulator regulator or redundant redundant contingency contingency scuba scuba sys sys tem, you share air air by passing passing your primary primary regulator regulator back and forth. This procedure is simple, but requ requires ires a higher level of ski skillll from you and your buddy buddy. Buddy breathing breathing and ascending at the same time can be done done successfully successfully with trainin training g and practice in confinedwater. water. However, you must freque frequently ntly review the steps if buddy breathing breathing is to be successful successful when it it might be neede needed. If your scuba is not set set up with a secondary secondary regula tor, you should rehearse buddy-breathing buddy-breathing techniques before entering entering the water. You should practice practice again again in shallow shallow water at the beginning of every dive to renew your skill skills s and coordinate procedures. Use the followin following g steps for buddy breathing: 1. Take a deep breath of air air and start exhalin exhaling g when your buddy gives givesyou the out of air air signal. 2. Grasp your buddy’s right shoulder strap with your your left hand. 3. Hold your regulator regulator by the hose hose and near the mouthpiece and remove it from your your mouth, using your right hand. Turn the mouthpiece mouthpiece down so the regula regulator tor does not freeflow. freeflow. Keep exhaling exhaling a small small stream of bubb bubbles. 4. Pass the regulator regulator to your your buddy bythe hose and let them guide th the e regulator into their their mouth. Always give them access to the purge button so they can clear clear the second stage of water. 5. Continue Continue to use your left hand hand to hold your

Chapter 3- Diving Skills

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buddy by the right shoulder shoulder of their their BC. 6. Allow your buddy buddy to take two two breaths of air air from the regulator and then pass the the regulator regulator back to you. Never let go of the hose. You must main main tain contact and control control of your air supply at all all times. 7. Take two breaths of air from the regulator regulator and then pass the regulato regulatorr back to your buddy. 8. Give your buddy buddy the the up signal and wait for their their up signal back and begin your ascent when the situation is stabilized. stabilized. 9. Repeat the exchange process while while doing doing a slow, controlled controlled ascent ascent to the surface. Once Once you start buddy breathing breathing and ascending, ascending, do not try to change rhythm or techniques during during the ascent. ascent. During buddy buddy breathing, you must must remember remember to exhale small small bubbles bubbles whenever whenever the regulator regulator is out of your mouth. You and your buddy must control your buoyancy and and you must maintain maintain physic physical al contact. Unless you practice buddy breathing breathing on a regular regular basis, it is unrea unrealist listic ic to expect that you could pe perform rform it in an emerge emergency. ncy. Divers who are not skilled skilled in in buddy buddy breathing breathing but attempt to do it anyway during an emer gency gency risk serious injur injury. y.

Independent Emergency Ascents If you run out of air and you cannot obtain air air from your your buddy, you must make an independent independent ascent to the surface. surface. There are are two types of emergency ascents: swimming swimming and buoyant. buoyant. The one you do depends prim primar arily ily on your your status at the time you realize you are out of air.

Swimming emergency swimm ing ascent  when You do an emergency  when you run out of air air at at shallower shallower depths (about (about 18 meters or 60 feet). feet). They can be done from greater depths but con tingency air air supply is superior and recommended ended for deepe deeper water diving. You simply look up to mainta maintain in an open airway airway and swim to the surface while exhaling exhaling a continuous stream of bubbles from your regulator regulator (figure (figure 3-54). You always keep the regulator regulator in your your mouth dur ing an emergency swimming ascent, because as the water pressure decreases, you will will get another another small breath breath of air air from your cylinder cylinder.. You must also remember tobe ready to vent air from your BC to control your your buoyancy during during the ascent. During your NAUI Scuba Diver certificatio certification n course, course, you will will practice emergency emergency swimming swimming ascents ascents (ESAs) (ESAs) during during your confined-water confined-water traini training ng sessio sessions. ns. During thes these e sessions, ns, your instructor instructor will will tell you to inhale and then start your ascent. You must remember ember that in a real emerge emergency ncy,, you will will exhale and then try to take a breath but little or no air w will ill be available. available. You will ill also discover that the expanding air flows out from your lungs almost almost natural naturally ly with very little little effort on your part.

Buoyant

F IGI G U R E 3 5 4 . K E E P T H E R EG E G U L A T O R INI N Y O U R M O U T H W H E N D O I N G  A N E M E R G E N C Y A S C E N T .

buoy ant emergency emergency ascent  whe You do a buoyant  when you run out of air air at greater depths. You drop your weight belt and gently exhale all all the way tothe surface. surface. If you are wearing wearing a wetsuit and drop your weight belt, you must get get yourself yourself horizontal horizontal in the water and be facing facing up to create as much surface area as possible possible to slowyour ascent as as you approach the surface. surface. You

NAU I Scuba S cuba D i ver

must also remember to vent air air from your BC to slow your ascent. ascent. Your ascent ascent rate will ill increase increase due to the buoyancy of your wetsuit and its expansion. If you are in warm water and d drop rop your weight b belt, elt, you will will have to swim swim to the surface. surface. However, ever, not hav ing the extra weight will will help make your ascent easier.

 V e r i l y W h a t Y u n H a v e l e a n e d Review the following following questions about safety safety skills: skills: 23. Each Each diver diver should should take take breaths when sharing air air with one regulator. regulator. 24. How do you know which which of your your buddy’s two regulators to use during during an assisted assisted ascent? ascent? ____________

G e n e r a l G u i d e l ini n e s If you find yourself without air, air, you might wonder wonder which which method of ascent you should should use. The method method you should use d dep epen ends on the situation, situation, but the follow follow ing general guidelines guidelines should help you decide decide which method to use: • Discuss and agree on emergency procedures with with your buddybefore your dive. This discussion should should include include the signals you will ill use in an an emergency and your respective equipment equipment configurations. configurations. • The optimal method of knowing that you have ILL] air air in in an emerge emergency ncy is to to carry a contingency contingency air air supply like a pon pony y bottle. This is the easiest easiest and safest safest method method for reaching reaching the surface if you find that your prima primary ry scuba unit is not provid provid ing air. Simply place the the backu backup p regulator in your mouth, mouth, clear clear it, and continue breathing as as you ascend. • Adependent ascent, breath breathing ing from from your buddy’s buddy’s air air supply, is better than an independent independent swim ming or buoyant ascent becaus because e you have a sup ply of air during th the e ascent ascent.. Breathing Breathing from your buddy’s back-up regulat regulator or is better than trying to perform buddy breathing. Remember ember that buddy breathing breathing takes practice and you and your buddy must both be comfortable comfortable with with buddy breathing. • You should consider consider doing an independent independent ascent only if your buddy buddy is not available. available. It should should be obvious obvious that not running out of air in the first first place is the bes best course of action. action. Monitor Monitor your submersible submersible pressure pressure gauge gauge frequently frequently during during your your dive to avoid avoid running out of air. Making this one one of your diving habits will ensure that all of your ascents will be normal ascents ascents and you wil willl not need to worry about decisions regar regarding ding emergency ascents.

25. If you are plann planning ing to use buddy breathing breathing in an emergency, you should

26. When is it appropriate to choose choose a buoyant emergency ascent?

BUDDY SYSTEM It is easy to kee keep p track of your buddy in controlled controlled conditions conditions where the visibi visibilit lity y is good and the the area is limited. Maintai Maintaining ning contact with your budd buddy y in open open water is not as easy. easy. Diving Diving is fun, but it is not as fun if if you spend most most of your time looking looking for your your buddy. buddy. If you use the the following following points to ke keep ep track of your buddy buddy,, diving diving will w ill bevery enjoyable: enjoyable: • Agree ree on a leader for each dive. IL L • Discuss the dive before you get in the water and agree agree on the location, location, purpos purpose, e, activity, activity, and general general course course you will will follow under water. water. • Mainta Maintain in your same position relativ relative e to one another for your entire dive dive.. If you start out on on the right right side of your buddy, stay on the right right side for the entire entire dive. dive. It is more more enjoyable to dive side by side than for for one of you to be in front and the other buddy buddy following following behind. • Establish your direction of travel under under water and then then follow that heading until until you or your buddy suggest gest a change or stop stop with a clear clear signa signal.l. Make sure your your buddy acknowledges the signal signal before you change direction. direction. If you you do get separated separated from your buddy, you wil willl

Chapter 3- Diving Skills

G 2

have a general idea idea of where to locate your buddy. • Use the lost buddy procedure if if you do lose your buddy. The common procedure is: 1. Get yourself vertica verticall in the water and look in all directions for for your buddy buddy or their their bubbles (figure 3-55 3-55). If you are are in low visibi visibility lity water (3 meters or 10 feet or less) less),, retur return n to where you last last saw your buddy and start start your search there. 2. Rise Rise about 3 meters (10 feet) feet) in the water water and look again for your buddy or their their bub bles if you did not find them the first time. 3. Ascend slowly slowly to the surface surface after after a minute minute if you do not seeyour your buddy. Keep turnin turning g as you ascend and look look for your your buddy or their bubbles. 4. Surface, Surface, note your position relative relative to two points on the sho shore, re, and wait for for your buddy. When your buddy surfaces, get back together and continue your dive. 5. Use one of the followi following ng options, depending on your circumstances: • If you are diving where where help help is readily availabl available e to assist assist you in a search for a lost buddy, signal for help if if yo your ur buddy does not

surface surface within within 5minu 5 minutes. tes. It is your role in the emergency to contact and guide the help. • If you are diving in a remo remote te location, you might be your buddy’s only source of help if your buddy is in ttrouble rouble under water and minutes minutes are critic critical. al. You will have to search search for your lost buddy buddy within within your capability capability to do so, and be prepared to render aid as need ed. Before you put yourself in th this is type of situation situation,, prepare by taking the NAU NAUII Advanced Advanced Scuba Diver Diver course and the NAUI Scuba Rescue Diver course. As you and your your buddy gain exper experience ience together and get get to know know one another, it it wil willl become easier to stay toge together. You will becom become famili familiar ar with with each other’s other’s diving diving styles and you will ill be able to to function function as a true team team with minim minimal al effort. Developing Developing this harmo ny should be your goal, because diving diving with a good buddy is diving diving at its best. best. Your buddy also makesworking working with equipment easier. For example, if if your cylinder cylinder slips out of its tank strap under under water, it is easier for your buddy to to refasten the cylinder than for you to take offyour BC and fix the cylinder cylinder yourself (fig (fig ure 3-56). A goodbuddyis more likel likely y to notice developing problems, such as a loos loose tank strap, before you do.

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F IGI G U R E 3 5 5 . B E U P R I G H T INI N T H E W A T ER E R A N U L O O K I N A L L D I R EC EC T I U N S E U R Y O U R L O S T B U O D Y .

81

NAUI Scuba Diver

COMMUNICATION There are are standard signa signals ls you need to know to communicate unde underr water as well as on the the surface. The NAUI NAUI Diving Diving Hand Signals Signals are standard in the United States States diving diving community and are usuall usually y recog recog nized in other countries as well well (fig (figure ure 3-57). As a certi fied diver, you must be able to correctly correctly identify identify and use each signal. signal. Once you start using them, they are easy to remember. Remember, Remember, for a signal signal to be effective, effective, all all con cerned must discuss discuss it and agree upon it before you start the dive. dive. Proper use of signals signals is necessary for every dive. Be sure to discuss the signal signals s you are accustomed to using with with any new buddy.

F I G U R E 3 5 6 . I T 18 M U C H E A S I E R T O S O L V E P R O B L E M S U N D E R W A T ER E R I E Y O U W O R K W I TH TH Y O U R B U D D Y .

 V e r i f y W h a t Y o u H a v e L e a r n e d Review Review the followi following ng questions about the buddy system: 27. Three recommended techniques that help maintain maintain budd buddy y contact while diving are and 28. The steps to the recommended lost buddy plan plan are: _______________________________

H I

Underwater Communication You probably realize realize by now that communicat communication ion is not easy easy under water. When you give a hand signal, signal, you must must display it distinctly distinctly and you must must wait for a response from your buddy. Your buddy acknowledges the signal by either repeating the signal or giving giving you the okay signal signal (figure (figure 3-58). Along with the standard standard hand signals, signals, divers create their own hand signals. Some divers even learn learn American Sign Language to expand expand their vocabulary vocabulary for underwater underwater communica tion. Always remember to review your hand signals signals with your buddy before each dive. You can write write messages to your your buddy on an under water slate slate (figu (figure re 3-59)- This This is a handy way to give detailed detailed messages. You can also use the sen sense of touch to communicate. You can touch your buddy to gain their attention or or to let another diver know you are nearby. nearby. Try to avoid touching touching another another diver when when you are behind them, especially iiff they are not not aware of your presence. It is easy to frighten frighten someone in this situation. situation. You can use and and hear audible audible signals signals under water although although you cannot cannot determine sound sound sources by direc tion under water. You or a boat can produce produce sound sound sig nals. Diver-produced audible audible signals signals include include rapping on your cylinder cylinder with a knife or other hard object, object, or using special full-face full-face masks or devices that allow allow you to speak to your buddy under the water.

HI

Chapter 3- Diving Skills

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Down

I'm out of air

Share air 

Dang er

Low on air

Help! (surface)

Ok (surface)

Ok (surface)

Pick me up (surface)

F IGI G U R E 3 5 7 . E V E R Y D IVI V E R S H O U L D U S E T H E S E S T A N D A R D S I G N A L S .

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NAU I Scuba Sc uba D i ver

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F IGI G U R E 3 -5- 5 8 . T H E O K A Y S I G N A L I S B O T H A Q U E S T I O N A N D A N A N S W E R .  Y O U W I L L U S E T H I S S I G N A L R E P E A T E D L Y

Most Most charter charter boats have an underwater reca recallll device that soun sounds ds like a siren. siren. If you hear the recall recall signal while while you are under water, you must surface and look to the boat for instructions. instructions. They might need to reposition the anchor and just want to see seewhere all all their their divers are, or they might might need to have everyone return to the boat because of an emergency.

S u r f a c e C o m m u n ici c a tit i o n At the the surface, you can can use use different different types of audible audible and visual visual signals signals to communicate. communicate. You use use some of the standard hand signals at the surface. For example, l y \ l if you wave wave to som someone eone from the the surfa surface, ce, it is a sign of distress, NOT a way to say say hello. hello.

F IGI G U R E 3 -5- 5 9 . U N D E R W A T E R S LA LA T E S A R E A N E A S Y W A Y T O S H O W  Y O U R B U D D Y A D E T A I L E D M E S S A G E .

Dive boats have a blue and white flag that they fly when they want divers to return to the boat (figu (figure re 360). When you surface surface and see this flag, return return imme diately to the boat. Audible communicat communication ion is possible at the surface, but yelling yelling is not effective at a long distance distance over the water. A whistle whistle produces produces a loud sound sound that you can hear at a considerable distance. Also, Also, using a whistle whistle does not take a lot of energy. energy. A repeated series of four short blasts on a whistle whistle is a standard distress signal.

 V e r i l y W h a t y o n H a v e L e a r n e d Review the following following questions about communication: 29. The four ways ways of communicating communicating under water water are . , and 30. The two ways ways of communicat communicating ing at the surface are are and and . 31. When you are given a hand hand signal signal under water, you must . 32. What What is is the most most important important point point to remember regarding diving communication? ______________

_____________

_________________

________________

_______________________

F I G U R E 3 -6-6 0 . I F Y U U S E E T H E R E C A L L F L A G F L Y I N G U N Y O U R C H A R T E R B O A T , Y O U M U S T R E T U R N I M M E D I A T E LYL Y T O T H E B O ATA T .

1

8 4

H A N D L IN IN G Y O U R S C U B A E Q U I P M E N T I N T H E W A T ER ER Usually Usually you don your scuba equipment out of the water, go diving, diving, and then remove your your equipment after you getout of thewater. There will will betimes when you needto don or remove your your equipment in the water. For example, the boat you are using might might be too small to permit much equipment handlin handling g while you are on board. You might also need to adjust an item of gear in in the water and and will need to rem remove it to adjust it. If your scuba unit is caught in fi fishing shing line or kelp, kelp, you can remove the unit soyou can see the problem and correct correct it.

R E M O V IN I N G A N D R E P LA LA C I N G Y O U R S C U B A U N I T O N T H E S U R F A C E A N D U N D E R W A TE TE R Removing your scuba unit in the water is as easy as as removing a jacket (f (figur igure e 3-61). Use the followin following g steps to get out of your scuba unit: unit: 1. Uncli Unclip p any any buckles you have on the front of the BC. 2. Undo the waistband. waistband. 3. Pu Pull your left arm out of the left armhole of the BC and use your right right arm to pull pull the scuba unit around to your right. There are many ways ways to don your scuba unit (fig (fig ure 3-62). Your instructor instructor will will showyou the way they want you to don don your your unit. unit. One method you might might be shown is to don the un unit it over over your head. head. To donyour scuba unit unit by passing passing it over your head, use the followi following ng steps: 1. Position your BC in front of you you with the cylinder under under the BC. The first stage stage of the the regulator regulator is toward you and the second second stage is in your mouth. 2. Keep the hose for for your your second stage between your arms. If you do not have the hose hose between your arms, the hose will ill be trapped under under your shoul shoul der strap when you lower the cylinder cylinder in in place. place. 3. Slip Slip your arms into the armholes armholes of the BC BC until until the unit unit is above above your elbows. ows. It wil willl seem seem like

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F IGI G U R E 3 8 1 . R E M O V I N G Y O U R S C U R A U N I T I N T H E W A T E R ISIS A S EASY AS REMOVING A JACKET.

you are putting putting the unit unit on upside down. 4. Grasp either side of the the tank with with each hand. 5. Slide Slide the unit over your head and down down your back as you arch yo your ur back. 6. Feel around your waist waist for the two two ends of your waistband or strap. 7. Fasten your your waistband or strap snugly snugly and re-clip any buckles at the front of your BC. 8. Straighten Straighten out your second s stag tage e regulator regulator hose and reposition the mouthpiece mouthpiece comfortably in your mouth. If you are on the surface, you want your scuba scuba unit to be buoyant so it wil willl float. float. If you are on the bottom bottom,, you want the scuba unit unit to be negative while donning it.

NAU I Scuba S cuba D i ver

F IGI G U R E 3 -6- 6 2 . R E M E M B E R T O W O R K A T A S L O W A N D S T E A D Y P A C E W H E N D O N N I N G Y O U R S C U B A U N I T I N T H E W A T E R .

Always breathe from your regulato regulatorr when you are donning the scuba scuba unit. When you are at the surface, you will will slip under water as you pass pass the the cylinder cylinder over your head and the regulator will will give you a source source of air. You must learn to refasten your waistband and buckles by feel. Before you refasten your waistband and clips, feel to be sure that your your straps are not twisted and your hoses are not trapped. Work at a slow and steady steady pace pace when removing removing and replacing replacing your scuba scuba unit. unit. You should be able you han dle your equipment independently, independently, but there is nothing nothing wrong with asking asking your buddy for assistance if you have difficul difficulty. ty. An extra set of hands and eyes is useful and saves time.

R E M O V I N G A N D R E P L A C IN I N G Y O U R W E IGIG H T G E LT L T O N T H E S U R FA F A C E A N D U N D E R W A T ER ER Handling a weight belt in the water can be awk awk ward, but with practice, practice, working with a weight belt is not as difficu difficult lt as it seems. There are a few important points to remember remember when working with weight belts: belts: • Always Always handle a belt by the free end to prevent the weights from slipping off off the belt. • Gravity will will pull pull the belt towards towards the the bottom bottom

unless you support the belt with with your your body. • Keep Keep your body body in a horizontal horizontal position at |T ^ | all times when removing and replacing the weight belt. • Work at a slow and steady pace when removing and replacing the weight belt. belt. To remove remove the weight belt to discard it or to hand it out of the water, use the following following steps: 1. Undo the buckle and pull pull the tai taill of the weight belt free of the buckle. 2. Hold the free end of the weight weight belt in one hand and pull pull the belt completely completely away from from your iL L j body body.. The weights will hang in a direct line towards towards the bottom (figur (figure e 3-63). 3-63). 3. Release the weight belt. If you are handing the weight belt belt out of the water, be sure that the per son you are handing handing it it to has a firm grip on the weight belt belt before you let let go. go. You use the same procedure to remove and replace your weight weight belt belt on the bottom as you you do on the surface. Your instructor instructor will will showyou the procedur procedure e they want you to use. If you use use a right-hand release release to your weight belt, one method method to remove and replace you yourr weight belt belt in in the water is is as follows: follows: 1. Assum Assume a facedown position in the water. 2. Undo the buckle and pull the tail tail of the weight weight belt free of the the buckle.

Chapter 3- Diving Skills

 V e r i t y W h a t t t o n H a v e L e a r n e d Review the following question questions s about handling handling your scuba equipment in the water: 33- The prima primary ry differenc difference e between donning donning your cylinder cylinder at the surface and donning your cylinder under water is

34. You can keep your regulator regulator hose hose from becoming trappedwhen you don your your cylinder over your your head by by

35. Handling Handling your weight belt belt is easier if you remember to and and _____________________

____________________________

F IGI G U R E 3 6 3.3 . A I M S P U L L T H E W E IGIG H T B ELE L T C O M P L ETE T E LYL Y C L EA EA R O F  Y O U R B O D Y B E F O R E D R O P P I N G IT .

3. Hold the free end of the the weight belt in your right hand and pull the weight weight belt around your right right side to your front as you are rotating rotating in in the water to your left. Remember Remember that you want to keep your body between the weight belt belt and the bottom. 4. Make your modification modifications s to your weight belt. 5. Hold the weight belt with the buckle in your left left hand, the free end end in your righ rightt hand, and be sure that there are no twists in the belt. 6. Transfer Transfer the buckle to your righ rightt hand and move the entire entire weight belt belt down so that your your right thigh thigh supports it. 7. Drop the buckle and rotate your body to the left. The weight belt wi willll drape across across your thighs. 8. Reach down your left side with with your left left hand and feel for the buckle. 9. Slide Slide the weight belt up your back and position it underyour cylinder cylinder and BC at your waist. 10. Re-buckle the weight weight belt securely. securely. If you use a left-hand release to your weight weight belt, you can use the previous procedure with with the opposite hand and rotating in the opposite direction.

N A V I G A T I O N S K I L LS LS When you are out of the water, you are constantly constantly using navigation navigation skills. Maps, Maps, street street signs signs,, and land marks help you locate a destination and return return you to your starting starting point. There are no street signs under water, but you you can use a combination of natural natural and compass pass navigat navigation ion to keep track of your loca location tion and travel during a dive. dive. This section section will will introduce introduce you you to some of the fundamentals fundamentals of underwater navigation. navigation. You can learn mo more re about this necess necessary ary skill skill in a NAUI Underwater Underwater Navigation Specialty Specialty course. course.

Natural Navigation You can avoid avoid long surface swims by by ending your dives at predetermined locations. To know where you you are and be able to get where you want want to go and back, is the objective objective of of underwater underwater navigation. navigation. By recognizing and using natural natural aids to navigation, navigation, you can achieve this objective. Natura Naturall aids under water w wililll soon become as use ful ful to you as street signs. Ripple Ripple marks in the sand on the bottom bottom form paralle parallell to the shore. As you get

NAU I Scuba S cuba D i ver

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closer to shore, the ripple ripple marks get closer together. together. This fact gives you you one one useful reference. The positions of the sun and shadows dows at the start of your dive are another another useful reference. The back-and-forth movement of water close close to shore is known as surge. usually  surge. The movement is usually toward and away from shore, so this this gives you anothe anotherr clue to your location. The water water gets deeper as you go furth further er away away from shore and shallower as you return return to shore or approach reefs. You will ill see underwater landmarks, such as rock formations, large and unique plants, crevices, crevices, and wrecks wrecks (figur (figure e 3-64). You and your buddy can keep track of your position position under water and be able able to return return to your startin starting g point without surfacing by paying attention to all all of these nat ural aids.

F IGI G U R E 3 - 6 4 . R E E F F O R M A T I O N S A R E E X C E L L E N T N A T U R A L A IDID S FOR NAVIGATION.

C o m p a s s N a v igi g a t ioi o n When you you dive at night or in water with limited vis vis ibility ibility,, natura naturall aids are not as helpful to you. you. You must rely rely more on a compass and your your depth gauge. Using a reckoning, compass allows allows you to navigate navigate by dead reckoning, which which can be very accurate. accurate. The compass shows you directions and your depth gauge tells you your ver vertic tical al position in the water. water. A diving comp compass must be filled filled with liquid liquid to with with stand pressure underwater, have have a reference line line called called a lubber line, and have a means, such as a rotating bezel, bezel, to showthat that you are on a selected bearing bearing or directio direction n (figur (figure e 3-65). Because a compass is magnetic, ferrous  ferrous  (iron or steel) objects objects close close to it wil willl affect it. metal  (iron When you use a compass, you keep keep the lubber lin line e aligned with the centerline centerline of your body. dy. You can wear r ^ | your com compass on on your your wrist or or mount mount it on your con conso sole le LS^J with the rest rest of your diving instruments (figure (figure 3-66) 3-66).. Where Where you carry the c com ompass pass is not critical; critical; having it aligned aligned with your body is. When you reference your compass, pass, always be sure sure that that you are lined lined up with with the lubber line line and that the the compass pass is level. The compass needle always always points to magnet magnetic ic north. If you point the lubber line line towards shore, the the compass needle points to one point. point. Rotate Rotate the index

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F IGI G U R E 3 - 6 5 . T H E U N D E R W A T E R C O M P A S S M A K E S N A V I G A TIT I O N  A C C U R A T E D U R I N G A D I V E .

F IGI G U R E 3 6 6 . Y O U M U S T A L W A Y S A L IGI G N T H E C O M P A S S W I TH TH T H E C E N T E R O F Y O U R 6 0 D Y.Y .

Chapter 3- Diving Skills

F IGI G U R E 3 -6- 6 7 . Y O U M U S T A I M S A L IGI G N T H E L UB U B B E R LIL I N E W ITI T H YO YO U R

Simple navigational techniques make diving more enjoyable. Knowing where you are underwater underwater will help you avoid long surface swims and help you to relocate interestin interesting g areas. areas. You will ill save time, air, air, and be able to spend more time enjoyi enjoying ng the objective objective of your dive. You must be be able to perform the basics basics of navig naviga a tion that you will learn in your NAUI NAUI Scuba Diver certifi cation course. course. To learn more about underwater underwater naviga tion, enroll enroll in a NAUI continuing continuing education course, urse, such as the NAUI Advanc Advanced ed Scuba Diver cert certific ificati ation on course, or a special specialty ty course such as Search and Recovery Diving.

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B O D Y A N D W I T H T H E D I R EC E C T I O N YO YO U W A N T T O S W I M .

 V e r i f y W M Y o n H a v e L e a r n e d marks on the bezel bezel to mark the position of the needle, and you will ill know that whenever the compass pass needle is pointing pointing in in between the marks, you are swimming towards shore. If the compass needle points opposite the marks, you know you are headin heading g away from shore. When you decide decide to begin your dive in a certain certain direction, direction, you sight sight over the level level compass compass and set the index marks marks on the rotating rotating bezel bezel so that they line line up with with the compass needle. needle. Then, by keeping yourself yourself aligned with with the lubber line line,, and the compass pass needle aligned with the index ma marks, rks, you can mainta maintain in your course very accurately accurately (figur (figure e 3-67). Usually, Usually, you only need to reference the compass occasio occasional nally ly to make sure you are on course. course. If you need need to to navigate precise precisely, ly, you must reference the compass frequently. frequently. A reciprocal course is made when your outbound course is a straight lin line e and halfway through your dive, you make make a 180° turn, which which the compass enables you you to do precisely. To make a 180° turn, turn, you swivel ar around ound until until your your compass pass needle needle is directly directly opposite opposite your origi origi nal reference reference marker. Even if if you do do not follow a specific pattern during your dive, the compass pass can still still be helpful. helpful. You and your buddy can surface near the end ofyour dive, line line up the the lubber line with with your body body and the direction direction of your exit point, set your bearing with the index marks on the bezel, subme submerge, rge, and follow follow that that heading heading to your destination. destination. Swimming under water is usually usually easier than swimming on the surface.

Review the following following questions questions about navigation: 36. Three natural natural aids to navigation navigation are and 37. When you are usi using ng a compass compass for naviga navigation, tion, you should and and . 38. A reciprocal reciprocal course is a _________________________

______________________________

D I S A S S E M B L IN IN G Y O U R S C U B A G E A R After diving, diving, you must disassemb disassemble le your scuba gear and rinse it with with fresh water. To disassemble ssemble your scuba unit, unit, use use the following following steps steps: 1. Turn off your air. The cylinder valve turns off in a clockwise direction. 2. Push Push and hold the purge button on one of your secondstages or powerinflat inflator or to relieve all the air air pressure in the hoses of your regulator regulator (figure (figure 3-68). 3. Unscrew the yoke screw screw from the cylinde cylinderr valve (figure (figure 3-69) or unscrew the DIN regulator from the DIN valve. 4. Dry Dry the dust cap attached to the first first stage of your regulator (figure (figure 3-70). 3-70). 5. Replace Replace the the dust cap over the inlet inlet to to the first stage of your regulator regulator and tighten the yoke yoke screw screw until

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F IGI G U R E 3 6 8 . P U R G E T H E A I R F R O M Y O U R R E G U L A T O R A F T E R Y O U

F IGI G U R E 3 6 9 . T H E Y O K E S C R E W O N S C R E W S E A S ILI L Y O N C E Y O U

HAVE TURNED OFF YOUR CYLINDER.

HAVE PURGED YOUR REGULATOR.

F IGI G U R E 3 - 7 1 . R E P L A C E Y O U R D U S T C A P O V E R T H E F I R S T S T A G E  A N D T I G H T E N T H E Y O K E S C R E W F I N G E R T I G H T .

it is finger tight (figure 3-71). If you have have a DIN regulator, regulator, screw in the dust cap. cap. 6. Remove your BC from the cylinder. cylinder. 7. Turn Turn the BC upside down down so that the the power-infla tor hose attachment attachment point is the lowest point. This will will allow any water in the BC to drain down down into the power-inflator hose. hose.

8. Press Press the deflator/oral inflator inflator valve button button to allow allow the water to drain drain out of the power-infla tor hose. 9. Rinse Rinse your equipment with fresh water and allow it to dry completel completely y before storing it.

CONCLUSION Breathing under water is not not difficult. difficult. The hardes hardestt part of scuba scuba diving physical physically ly is putting the gear gear on, and even that that becomes easy with with experience. experience. You need to deve develop certain certain breathing breathing habits for for some circum circum stances, but other than that, there isn’t isn’t much to learn about about breathing breathing on scuba. You will will soon find yourself feeling confident about about handling handling your equipmen equipmentt in the water. The more prac prac tice and experien experience ce you have, the easier it wil w illl become. Your goal is is to make make working with with your equipment equipment as easy as your instructor instructor makes it look. If you find yourself struggling with your gear, this indicates that that you do not understand something about howyour gear works. Learn to work slowly and deliber ately. ately. Think of the ste steps involved in performing a skill skill with an item of gear and then execute execute them one one at a time. Practice Practice wil willl help make the the steps teps blend together together into a natural natural motion for you. you. Learning Learning the other skills skills of diving, diving, such as buoyan buoyan cy control, entries, entries, and emergency procedures requires training g and practice. You will ill start to develo develop p more trainin these skills during your NAUI Scuba Diver certifi certificatio cation n course and and will will polish them them with additional additional NAUI con tinuing tinuing education cours courses es (figur (figure e 3-72).

F IGI G U R E 3 7 2 . D IVI V INI N G I N O P E N W A T E R R E Q U IRI R E S Y O U T O U S E A L L O F T H E S K I L LSL S Y O U W I LLL L L E A R N D U R I N G Y O U R N A U I SCUBA DIVER CERTIFICATION COURSE.

CHAPTER

NAU I Scuba S cuba D i ver

L EA R N IN G G O A L S In this chapter you will: • Learn Learn about som some of the characteris characteristics tics of air air and water. • Be introduced to the concept concept of buoyancy and how if affects you under water. water. • Understand the concept of pressure and how it affects the volume and density of air air in a closed container. • Learn how the pressure of the water affects the air air spaces in your your body and how to prevent problems occurring occurring from the pressure change changes. s. • Be introduced to different different types of lung overex pansion injurie injuries s and how to prevent them. them. • Learn about the indirect indirect effects of pressure pressure on your your body by means of the gasesyou breathe breathe while diving. • Understand Understand the thermal effects effects of the air air and water temperature and your your body. The underwater world presents presents a new and tota totally lly different environment from the the air air world in which which you live. live. As you descend below the surface, surface, the increased increased pressure pressure will ill have direct direct and indirect indirect effects on your body. dy. However, ever, most of your time underwater, you will will not be aware of o orr feel these effects. This chapter chapter addres addresses physica physicall properties of air air and water and ways specific parts of your body are affected affected while while diving. diving. The better you understand these differ differ ences, the easier it wil willl be for you to function as a diver.

heavier heavier than than the first. first. This This is because the compressed air air is more dense. Density is the mass of an element per unit unit of volume. The density of a gas depends on its pres sure and tempe temperature. The density density of a liquid, like water, is constant constant over a wide rrange ange of temperature and pressure. Asyou can can see from the the above example, air has weight. One One liter liter of air weighs 1.25 grams. grams. In the Imperial Measurement System this is usually expressed as 0.08 pounds pounds per one cubic foot of air. One liter liter of fresh water weighs weighs 1.0 kilogram kilogram and one liter liter of salt water, because because of it dissolv dissolved ed salts and minerals, weighs weighs IT ^ l 1.02 1.025 kilograms. kilograms. Again in the Impe Imperia riall System these are commonly expre expresse ssed d as pounds pounds per cubic foot, that is, 62.4 pounds per cubic cubic foot for fresh fresh water and 64 pounds pounds per cubic foot for salt salt water.

Outlie Air You Breathe Most of the the time, we do not think think about air, air, because breathing is an automatic activity activity and we cannot see or feel the air air around us.

Composition Air is is a mixture of differ different ent gases. The gase gases in air air are colorless, odorless, odorless, and tasteless. Air is composed ITT IT T"! of approximately approximately 20.9% oxygen oxygen, 78% nitrogen, nitrogen, and 1.1% miscellaneous miscellaneous gase gases, s, such as argon and carbon carbon dioxide (figure 4-1).

Oxygen (20.9%)

DIRECT EFFECTS OF PRESSURE When you descend in water, the force from the com binedweight of air and water will ill increase. This force is  pressure ure.. In this chapte called press chapter, r, you will learn how pres pres sure increases under water and how it affects your body. body.

Density anil Its Effects If you pick up up one one scuba scuba cylinder with air air in in it at at 1 ILL] bar (1 atmosphere atmosphere)) and another just like it fille filled d with air to its rated rated pressure, the second is about 2-4 kg (4-8 lb.) lb.)

Nitrogen (78%

F IGI G U R E 4 1 . A IRI R ISI S A M I X T U R E O F G A S E S .

Chapter 4- Diving Science

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The most important component of air to us is oxyge oxygen. We cannot survive survive without oxygen. You can breathe pure pure oxygen for limited limited periods, periods, but pure oxy gen can be extremely hazardous above and underwater. underwater. Nitrogen is a metabolically inert  g  gas. It does not react in our bodies when we breathe it under normal conditions. conditions. However, dissolved nitrogen nitrogen is present present in your body, and additional additional nitrogen is absorb absorbed ed in your body when you are under increased pressure underwater. Some divers use special mixtures mixtures of gases, such as nitrox, for diving. These mixtures contain contain different per centage centages of oxygen oxygen and nitrogen than air. air. Diving Diving with special gas mixtures requires additional training and specialized equipment. equipment. The NAUI NAUI Enriched Enriched Air Nitrox (EAN) (EAN) Diver Specialty Specialty course provides provides the additional additional training training you will will need need to to dive with nitrox.

colors, our hearing, our ability ability to retain heat, and our abili ability ty to move move through it, compared to to air.

Characteristics

 V i s i o n

Air can can be easily easily compressed. When pressure is applied to a volume of air, air, it can beforced to occupy occupy a much much smaller smaller area. With a compressor, pressor, we can squeeze a large amount of air air into a smaller smaller space, making it denser denser than normal normal and therefore therefore heavier than normal. For example, the com compressed air air in a scuba cylinder, cylinder, when released, released, would fill fill a space equiva lent to a small closet closet at atmospheric atmospheric pressure. This is why a full full scuba cylinder weighs more more than an empty scuba cylinder cylinder (figure (figure 4-2). 4-2). The air surrounding surrounding the earth at sea level is com pressed by the weight of the air air above it. In other words, the air at sea level is denser denser than the air air at higher higher levels.

The human eye is designed designed to to focus light light rays in air. air. This is is why objects objects appear appear blurry blurry when you open open your eyes under water. The mask allows you to put an air air space in front of your eyes to see see without without the blur. blur. As light light rays pass pass from air air to water, water, they slow down and bend. This bending is called called refraction  and it changes the way you see objects under water. Objects appear 1/3 closer and larger larger than they they do in air. air. Objects are actually further further away away and smaller than the they y appe appear ar L L k J to be under water. Remember this when you are report ing the sighting of an anima animall or an object. As a new diver, you will find that you reach in front of an object object until until you learn to comp compen ensate sate for refraction.

I n tht h e W a t e r

Colors

Water cannot be significa significantly ntly compresse pressed. d. When pressure is applied applied to water, the pressure is transmi transmitted tted throughout the the water. water. The density of water at any depth depth is the same as the density of water at the surface, surface, though the pressure ressure it is under wil willl be greater because because of the weight of thewater above it. But But water is about 800 times times denser nser than air. air. This and other factors have several effects on us as divers. Water affect affects s our vision, our ability ability to distinguish

Colors also look much different underwater. underwater. Sunlig Sunlight ht is compos composed of a spectrum spectrum or a rainbow rainbow of visi visi ble and invisible invisible colors ranging fro from m infrared to ultrav ultravi i olet. As light light passes through through the water, the water absorbs the colors of the spectrum spectrum of the sunlight. The first visi visi ble color color to be absorbed is red, red, followed followed by orange, tthen hen yellow, then green, green, then then blue, then indigo, and final finally ly violet. violet. At greater greater depths, the only colors colors you can see see without without a dive ligh lightt are blues and purples.

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F IGI G U R E 4 - 2 . A I R H A S W E I G H T A S Y O U C A N S E E B Y T H E D I F F ER ER  E N C E I N W E IGI G H T B E T W E E N A N E M P T Y A N D F U L L SCUBA CYLINDER.

NAU I Scuba Sc uba D i ver

F IGI G U R E 4 - 5 . S U U N D T R A V E L S F A S T E R I N W A T E R T H A N I N A I R . F IGI G U R E 4 -3- 3 . T H E C O L O R S S E E N W I TH T H N A T U R A L LIL I G H T  A R E M U T E O .

F IGI G U R E 4 - 4 . A R T I F ICI C I A L LIL I G H T A L L O W S Y O U T O S E E T H E T R U E COLOR OF OBJECTS UNDER WATER.

If you take a dive light light with you on your dive, and shine it on objects at depth, you will will be amazed at the colors colors you will ill see. Most underwater underwater photographs are made with artifi artificia ciall light light (an electronic flash or strobe strobe)) to bring out the magnificent, true colors of the underwa ter world (figure (figures s 4-3 and 4-4).

Hearing Noises Noises sound different underwater than than they do in air. In air, you can tell where a sound sound is coming from because the sound waves hit hit one ear sli sligh ghtly tly before the other. Although the the time difference is very very short, short, it is

enough for your mind to tell and be able to locate the source of the sound. Because of of the greater density of water compared to air, air, sound waves travel travel about four times faster in water than they they do in air. air. The sound sound waves move so quickly that it it is diff difficu icult lt to determine th the e source source of a soun sound. You can hear the sound getting louder or softer, but you cannot tell its direction. When you you hear a noise, noise, you you must look all all around around you to see where the noise is com ing from (figure (figure 4-5). 4-5). Boat motors, propellers, propellers, and jet skis skis have distinctive sounds underwater. underwater. If you want to surface, but hear a boat or jet ski, stay stay under as long as safely possible or until until you hear the boat or jet ski ski leaving leaving the area. fla g  and stay Remember to always fly a diver down flag  within within its perimeter to to avoid surfacing surfacing in the same area as a boat or jet ski.

Heat Loss When When the the air is 27°C (80 (80°F), °F), you you think it is warm and comfortable. comfortable. When you jump into 27°C (80 (80°F) °F) water, the water also feels comfortable at first, first, but you will notice you start to feel chilled if you remain motionless for a short time. Because water is much denser than air, air, water can absorb a great deal of heat without changing changing its temper ature. Also, heat can be conducted out of your body by direct direct contact with water at a rate nearly nearly 25 times faster than by air.

Chapter 4- Diving Science

Your body is transferring transferring heat to the water touching touching your your body to try to get the water as warm as you are. When your body body is drained of enough heat, you will will be chilled chilled and start to shiver. Shivering Shivering is your body’s body’s sig nal nal to tell you that it can can no longer genera generate te enough enough heat to keep your intern internal al organs warm. When you start to shiver on a dive, you must end your dive and get out of the water to rewarm.

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Have you you ever tried to run iin n water even up to your waist? If so, you know how diffic difficult ult it is compared compared to running running in air. air. The water resists your movem movement. This resistance to movement is called called drag. Drag is some thing that that you must must deal with when diving. The total frontal frontal area of your body body and equipment equipment and its surface configuration configuration also affect your resistance resistance to movement in the water. water. If your equipment is sleek and compact, compact, it wil willl be easier for you to swim than if if your gear has dangli dangling ng hoses and loose straps. The more mo re you can streamline streamline yourself yourself and your equipment, equipment, the easier it wil willl be for you to move through the water. water. If you are in a horizontal horizontal position, position, you have much much less resistance resistance to forward movement ovement than if if you are in in a semi-upright semi-upright position (figur (figure e 4-6). 4-6).

F IGI G U R E 4 -6-6 . S T R E A M L INI N I N G Y O U R E Q U I P M E N T A N D Y O U R S E L F M A K E S IT MUCH EASIBI TO MOV E THROUGH THE WATER.

I lel e r l lyl y W l i a t Y o u H a v e L e a r n e d Review the followi following ng questions about density density and its effects: 1. Air is approximately oxygen and 78% . 2. True or false: Air is denser denser in the mountains (at altitude) than at sea sea level. 3. True or false: Water is denser at 30 meters (99 feet) than than it it is at 3 meters meters (10 feet). 4. One way you can reduce drag unde underr water is is by ____________

5. When you look at objects under water, water, they appear and than they really are. are. 6. True or false: Sound travels slower under under water. ________________________

__________________

BUOYANCY When different different objects are placed in water, some float float,, some sink, sink, and some remain remain suspended between the surface and the bottom bottom. These objects objects all all have vary vary ing densities and this affects their their buoyancy. By under standing buoyancy, you can control it to your advantage for diving.

 A r c h i m e d e s P r i n c i p l e Archimedes, a Greekphilosopher, noticed that that the level of water in a tub ros rose e when he sat in it. From that observation and other experiments, experiments, he found found that an objec objectt in a flu id is buoyed up (lifted) (lifted) by b y a force equal to the weight of theflu fl u id it displac displaces. es.

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NAUI Scuba Diver

F IGI G U R E 4 -8- 8 . Y O U W A N T T O F L O A T,T , O R B E B U O Y A N T W H E N Y O U  A R E A T T H E S U R F A C E .

F IGI G U R E 4 - 7 . B U O Y A N C Y I S AL AL W A Y S A N U P W A R D F O R C E T E N D I N G TO CA USE YOU TO FLOAT, RISE, HOVER, OR SINK LESS QUICKLY.

If you weigh the water that overflow overflows s and the ping-pong ball, ball, you find find that that the water weighs more more than the ping-po ping-pong ball. ball. If an object displaces an amount of water weighing more than it does, it floats. If an object displaces displaces an amount of water weighing less less than it it does does,, it sinks. sinks. If an object object displaces displaces an amount amount of water weighing weighing the same as it does, it it hovers.

S t a tet e s o f B u o y a n c y Buoyancy Buoyancy is always always an upward force tending to cause you to float, float, rise, hover, or sink less quickly quickly (figure (figure 4-7). As a diver, you control your buoyancy prima primaril rily y by the the amount of weight you wear and the amount amount of air you you |L n have in your your buoyancy compensator pensator (BC (BC)) or dry suit.

Positive F IGI G U R E 4 -9- 9 . Y O U W A N T T O B E N E U T R A L L Y B U O Y A N T D U R INI N G  Y O U R D I V E .

You can observe observe displacement by fill fillin ing g a glass to its brim with water. water. If you push push a pingping-pon pong g ball into the glass, glass, the water runs over the side. The volume  or  or amount of water that overflows the glass is the volume that has been displaced displaced..

If an object floats, it means means the object object displaces displaces an amount of of water that weighs more than the object does. In other words, words, the object is less dense than the water. You want to have enough buoyancy to float when you are at the surface before before and after you dive (fig (figure ure 4-8). 4-8).

Neutral If an object is neutral, neutral, it it hovers. hovers. This means means the object displaces displaces an amount of water th that at weighs the the

Ch apter 4- Diving Diving S cienc e

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same as it does. You want to be neutra neutrally lly buoyant throughout throughout your dive (figure (figure 4-9). 4-9).

Negative i        v      i        n       g    

If an object object displaces displaces an amount of water that weighs less than the the object does, it sinks. Because the object is denser denser than the water, the water does does not pro vide sufficient sufficient buoyancy to to make it hover or or float. You want to overcome any buoyancy you have when you begin your dive to be able to get beneath beneath the surface.

 S        c      i         e     n      c       e    

Factors Affecting Buoyancy Your weight and your volume affect your buoyancy. Your weight includes includes the weight of your body and the weight of your gear (divin (diving g suit, weight belt, and scuba unit) nit).. Your volume depends on your body size, size, the thickness of your diving diving suit, and your gea gear. r. Remember, Remember, density is mass mass per unit unit volume. Wetsuits are muc much h less dense than water water because of the thousands of nitrogen nitrogen gas bubbles trapped in the neoprene material. If youwear a full full 6 mm thick wetsuit wetsuit andjump in the waterwithout without any other gear, it wil willl be impossible for you tosink belowthe surface. You cannot dive with a heavy wetsuit and a standard 12-liter 12-liter or 80 cubic foot aluminu aluminum m cylinderwithoutwearing additional weigh weights. If you can imagine making a dive in a wetsuit, wetsuit, you can begin to understand how your buoyancy changes over the course of a dive. Asyou descend, the pressure of the water increases increases and compresses the gas bubbles in your your wetsuit. As the bubbles compres compress, the wetsuit wetsuit dis17^1 places less water and therefore, therefore, loses some of its buoyancy (figure (figure 4-10). 10). You will notice that you you are sinking faster and faster the deeper you go. To compensate for the loss of buoyancy, buoyancy, you must add air to your BC, which which increases increases your volume to rregain egain the lost buoyancy. buoyancy. As you ascend at the end of of your dive, the bubbles in your wetsuit wetsuit and the the air air in your BC will will expand expand because because the pressure pressure of the water is reduced. You will will notice that you are rising faster and faster. To compen compen sate sate for the additional buoyancy, buoyancy, you must vent ai airr from your BC to control control your ascent. Uncontrolled Uncontrolled X  ascents are extremely extremely dangerous.

F IGI G U R E 4 - 1 0 . A S Y O U D I V E , T H E P R E S S U R E C O M P R E S S E S Y O U R W E T S U ITI T A N D M A K E S Y O U L E S S B U O Y A N T .

The density of the the water in which you dive also affects your buoyancy. Salt Salt water is about 2.5% denser than fresh water becaus because of the weight of the minerals minerals dissolved in it. it. Therefore, you displace more weight in salt water water than in fresh water, soyou have greater greater buoy buoy ancy in salt water. If you are weighted to be neutral neutral in salt water and you dive in fresh fresh water with the same amount of weight, you will ill sink. You must must recheck recheck your buoyancy if you change from from diving diving in salt water to fresh water and vice versa. As a diver, you you usually usually want to avoid having so little buoyancy that you mustwork to mainta maintain in your your depth depth or to keep eep from sinking (figure (figure 4-11). 4-11). Neutral buoyancy beneath the surface is your constant constant goal, and it is is important to help help protect protect marine life. Divers who land,

m

19I

F IGI G U R E 4 1 2 . T H E A V ER ER A G E P E R S O N C A N F L O A T M O T I O N L E S S A T T H E S U R F A C E W I TH TH T H E I R L U N G S F U L L O F A I R .

F IGI G U R E 4 1 1 . I T I S A C C E P T A B L E T O K N E E L I N S A N D , B U T I T ISIS N O T A C C E P T A B L E TO T O K N E E L O N C O R A L , O R O T H ER ER UNDERWATER CREATURES.

sit, or stand on on coral reefs or other marine life can dam age or kill ill these creatures. Diving Diving without buoyancy control is tiring, tiring, hazardou hazardous, s, and a sign of an unskilled, unthinking, unthinking, and uncaring uncaring diver. diver.

Buoyancy Checks Different people have different different amounts of personal buoyancy. Some people people float higher, higher, some float lower, lower, and some peop people actuall actually y sink, even with th their eir lungs full full of air (figure (figure 4-12). You must must check to determine your buoyancy in the water. water. To check your personal buoyancy, use the following following steps, wearing wearing a bathing bathing suit in fresh water: water: 1. Assum sume a vertica verticall position in in the water. You must must remain motionless. 2. Inhal Inhale e a deep breath of air and hold hold it. If you can hang motionless motionless at any level, level, tota totally lly submerged, you are neutral. If any part part of your your head head is out out of thewater, you are buoyant. buoyant. If you sink, you are not.

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10 0

3. Exhale Exhale the air air in your lungs. Your chest chest deflates deflates and you displace less water so you will ill start start to sink, unless you are very buoyant. 4. Kick back back to the surface. You can also also try this experiment in in salt salt water to see see the difference. difference. Your instructor instructor wil willl recommend mend how much lead weight you should should put on a weight belt based based onyour personal buoyancy and gear. The lead weights divers wear to adjust buoyancy buoyancy are many many times more dens dense than water. By selecting the right amount of weight, weight, you can adjust your buoyanc buoyancy y to be neutral neutral at depth. Before you begin a dive, you you must check to see how buoyant you are with your your gear on. on. To check your buoyancy for diving, diving, use the followin following g steps: 1. Assume a vertica verticall position in the water. You must must remain motionless. 2. Inha Inhale le a normal breath of air air and hold it. 3. Vent Vent or dump dump all of the the air air from your BC. BC. If you float at eye eye level, you are are properly properly weighted. weighted. If your head is higher higher out of the water, you are too too buoyant. buoyant. If your head is is in the water, you you are too heavy. 4. Exhale Exhale the air in your lungs. Your ches chestt deflates and you displace less water so you will will start to sink. 5. Kick Kick back to the surface and infl inflate ate your BC. 6. Change the weight weight on your your weight belt, if neces-

Chapter 4- Diving Science

sary. If you were too buoyant, buoyant, you need to add weight. If you were too heavy, you need need to take weight off your wei weight ght belt. If you change equipment equipment or if if you lose or gain weight (more than 2.4 2.4 kilograms or 5pounds), 5pounds), you must recheck your buoyancy before you start start your next dive.

Decreases

 Atmosphere  Atmos phere

 Air Pressure

Increases

Water pressure is consistent

 V e r i t y W h a t Y o u H a v e L e a r n e d Review the following following questions questions about buoyan buoyancy: cy: 7. The The three factors affecting buoyancy are

F IGI G U R E 4 1 3 . O N E A T M O S P H E R E O F P R E S S U R E I S A 6 U U T 1 B A R ( 1 4 . 7 P S I)I ) .

and 8. You can change change your buoyancy by or 9. An ocean diver needs needs to. weight to dive in fresh water. water. 10. During During descent, a diver diver’s ’s buoyancy buoyancy tends to

posed of mostly fluid fluids, s, which which cannot be compressed. Second, most air air spaces in your your body, such as your lungs and sinuses, are open to the surround surrounding ing atmosphere and its pressure. As long as the pressure in a body’s air air spaces matches the surrou surroundin nding g atmospheric atmospheric pressure, the pressure is equalized equalized and you do not feel any any effects from your surroundi surrounding ng atmospheric pressure.

F r e s h W a tet e r

WHAT IS PRESSURE

3

When you descend in water, the force from the weight of the air and water above you affects affects you. you. This force is called called pressure pressure and is measured measured in bar or  pounds per square square inch inch (psi (psi). ).

flip If you weighe weighed d a column of air air that was 1centime 1centime ter by 1centimet 1centimeter er and extended all all the way to the edge of the atmosph atmosphere, you would fin find d that that it it weighed about 1kilogra kilogram. m. If it were ere 1inch 1 inch by by 1inch, 1inch, it would would weigh weigh about 14.7 pounds. In other words, this colum column n exerts a pressure of about 1bar 1bar or 14.7 pounds per square inch inch (psi (psi). ). This constant pressure pressure is called 1atmosphere of pressure (figur (figure e 4-13). This atmosphere osphere of pressure ssure is constantly constantly pushing on your body from all all directions. However, ever, you usually usually do not notice it it for two reasons. First, First, your your body is com-

If you took a column of fresh water that was 10.3 meters (34 feet) tall tall and weighed weighed it, you would also see see that it it exerted a pressure pressure of about about 1bar 1bar (14.7 psi). This This equals equals the pressure exerted by the atmosphere atmosphere at sea level. Therefore Therefore,, 10.3 meters ters (34 feet) of fresh water i & i i is also equivalen equivalentt to 1atmosphere of pressur pressure. e. Because water is not compressible and transmits pressur pressure e freely, pressure pressure in water increases at a constant rate, and pressure pressure is cumulativ cumulative. e. In other words, 10.3 meters (34 feet) feet) of of fresh water is is 1atmosphe 1 atmosphere, 20.7 meters (68 (68 feet) of fresh water water is 2 atmosphere, 31 meters (102 feet) of fresh water is 3 atmosphere, and so on.

Sail Water If you took a column of of salt water that that was 10 meters (33 feet) tall tall and weighed it, you would also also see that that it exerted a pressure of about 1 1bar bar (14.7 pounds per square inch inch). This This equals the pressure exerted by the atmosphere at sea sea level. Therefore, 10 meters (33 feet) of [T ^ l seawater seawater is also equivalent equivalent to 1atmosph atmosphere ere of pressu pressure. re. LbUJ

NAUI Scuba Diver

         i        c        n        e          i        c          S

Because atmospheric pressure pressure is nearly nearly constant at sea level, most div diving ing depth gauges (pressure (pressure gauges) are adjusted or calibrated to read zero at at sea level. When a depth gauge indicate indicates s 10meters (33 feet) in salt salt water, it is saying that that the pressu pressure re is 1atmosphere greater than it it was at the surface. The pressu pressure re on such pressuree because it ignores the a gauge is called gauge pressur 1atmosphe atmosphere from the air air above above the the water (fig (figure ure 4-14). You always use absolute pressure when determining determining the total total pressure being exerted on your body at any any depth. For For example, if if you descend from the surface to 10 meters meters (33 feet) of salt water, you are doubling doubling the m pressure on your your body. If you continue continue to 20 meters (66 feet), feet), you are are triplin tripling g the pressu pressure re on your body. As a diver, diver, you must be concerned with with pressure and how it can affect the volume of your air air spaces under under water. water.

= 3 CO CO

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 V e r i f y W h a t Y o u H a v e L e a r n e d

* *

F IGI G U R E 4 1 4 . W A T E R P R E S S U R E A L O N E I S C A L L ED ED G A U G E P R E S  S U R E . W A T ER ER P R E S S U R E A N D A T M O S P H E R I C P R E S  S U R E C O M B I N ED ED A R E C A L L E D A B S O L U T E P R E S S U R E .

Because water is not compressible and transmits transmits pres surefreely, pressure pressure in water increases at a constant rate, and pressure is cumulative. cumulative. In other words, 10meters (33 feet) of salt water equals 1atmosphere, 20 meters (66 feet) of salt salt water equals 2 atmosphe atmosphere, 30 meters (99 feet) feet) of salt salt water equals 3 atmosphere, and so on.

Units of Pressure You can refer to pressure pressure in two different ways ways:: absolute and gauge.  gauge. When you dive, the pressure pressure of the water as well well as the pressure of the atmosphere push on you. At sea level, you are already under 1atmosphere of pressure absolute (a (ata). ta). At a depth of 10 meters (33 feet), feet), you are under under 2 atmosphere of pressure absolute: 1atmosphere sphere from the the air air plus plus 1 atmosph atmosphere ere from the salt salt water. At 20meters (66 feet), feet), you are under under 3 atmosphere sphere of pressure absolute absolute (ata (ata): ): 1atmosphere sphere from the air air plus 2 atmosphere atmosphere from the salt water.

10 2

Review the follo following wing questions questions about pressur pressure: e: 11. One atmosphere of pressure is equal equal to about meters ( feet) of fresh water or meters meters ( feet) of seawater. seawater. .times greater greater at 12. The pressure pressure is is . 40 meters (132 feet) in salt salt water than it it is at the surface. 13. The absolute pressure pressure is ata at 20.7 meters (68 feet) in fresh water.

H o w P r e s s u r e A t i e c t s V o lul u m e To understand the direct direct effects of pressure, you must consider consider the effects of of pressure on an open system and on a closed closed system.

Open System If you invert invert a bucket, bucket, force it below the surface of the ocean, and and take it to depth, the pressure sur rounding rounding the bucket increases and compre compresses sses the air air in the bucket. bucket. The water level rises into the bucket. bucket. As the air air compresses, its volume decreases. decreases. No air is is lost from the bucket. When you take the bucket back to the

Chapter 4- Diving Science

VOLUME 1 0'-1 ata

VOLUME x 1 0'-1 ata Buck et is still still full full of air, air, although exce ss ■ air volume has vented off,

VOLUME REDUCED TO Va 33-2 ata

VOLUME x 1 33'-2 ata Compressed air expands and overflows bucket as pressure is reduced.

VOLU VO LUME ME x 1 66'-3 ata

VOLUME REDUCED TO Vz 66‘-3 ata

Compressed air expands and overflows bucket as pressure is reduced.

VOLUME REDUCED TO 'U  99'-4 ata

VOLUME x 1 99'-4 ata Compressed air is added to open system at depth.

—

OPEN SYSTEM DESCENT F IGI G U R E 4 1 5 . A S T H E P R E S S U R E O N A IRI R I N C R E A S E S , T H E  V O L U M E D E C R E A S E S .

OPEN SYSTEM  ASCEN  A SCENT T F IGI G U R E 4 - 1 6 . I F Y O U F I L L A N O P E N B U C K E T W I TH T H A I R W H I LEL E A T D E P T H , T H E A IRI R E X P A N D S A N D B U B B L E S O U T O F THE BUCK ET AS YOU BRING THE BUCKET BACK

surface, the pressure decreases, and the a air ir expands to its original volume. When the bucket bucket gets to 10 meters (33 (33 feet) feet) of sea water or 2 ata, the pressure has doubled on the bucket. The volume of air air in the bucket bucket has decrea decreased sed to half half of the original original surface volume. When the bucket desce descends to 20 meters (66 feet) feet),, whic which h is 3 ata, the pressure has has tripled tripled on the the bucket bucket and the volume of air in the buck et will have have decrea decrease sed d to a third of the original original surface surface volume (figure (figure 4-15). This inverse relationsh relationship ip between pressure and vol  Boyle’s Law, which is named for the ume is known as Boyle’ scientist who first first recognized the relations relationship. hip. Knowing the name of the law is not as importan importantt as understanding the concept concept of the relati relationship onship between pressure and vol vol ume. When one increases, the other decre decreases, if it it can. Now Now conside consider a situation situation where you you have the abilit ability y to maintain the volume of air in the bucket bucket during its descent. Asyou take the bucket to depth, you add air air to the bucket through a hose. You keep the volume volume constant by adding adding enough air to match the origi original nal volume. volume. You take the bucket to 10 meters (33 feet), feet), fi fill it it with air, air, and raise it to the surface. surface. As the pressu pressure decreasesfrom 2 ata to 1ata, the volume of air air

TO THE SURFACE.

doubles. The bucket cannot cannot hold this increased volume, volume, so the excess air bubbles out around around the rim of the bucket. If you took the bucket to 30 meters (99 feet), feet), filled filled it with air, air, and then then raised raised it to the the surface, surface, a vol ume of air air equal equal to 3 buckets buckets would escape and the vol vol ume equal to one one bucket bucket would remain remain (figur (figure e 4-16). 4-16).

C lo s e d S y s t e m The effects of pressure on a closed closed system can be much more dramatic. If you take a sealed sealed plastic plastic bag filled filled with air air down to depth, depth, the bag becom becomes smaller smaller and smalle smallerr as the air air compress compresses and the the volume decreases. When you return return the bag to the sur face, the air air expands expands and the volume increases back back to its origina originall size size (figure (figure 4-17). 4-17). Now imagine imagine that that you you take the same bag down down to depth depth, open open it, fil filll it with air air back to its its origina originall volume, volume, and close it again. again. When you bring the bag back to the surface, the air air expands, ands, but it cannot escape because because the bag is sealed sealed.. The bag bag will ill expand expand slightly, but will will final finally ly burst to releas release e the expanding expanding air (figure (figure 4-18). 8).

NAU I Scuba Sc uba D i ver

VOLUME 1 0'-1 ata

VOLU VO LUME ME x 3 0'-1 ata Bag ruptures! ruptures!

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m heal

F IGI G U R E 4 3 7 . W H E N T H E T EM E M P E R A T U R E O F A S C U B A C Y L INI N O E R R I S E S , T H E G A S M O L E C U L E S I N S I D E T H E C Y L INI N D E R  A L S O B E C O M E M O R E A C T I V E . T H I S C A U S E S T H E P R E S S U R E I N S IDI D E T H E C Y L INI N D E R T O R I S E .

You must drink drink plenty of fluids fluids before, between between,, and after dives dives to replace the lost fluids. Dehydration decre decrease ases your abil ability ity to exercise ercise at full full capacity and makes you more susceptible susceptible to decompression sickness. Anything Anything you drink before diving diving must be non-alco non-alco holic and should not contain caffeine. Caffeine is a diuretic, which means it will cause you to urinate and lose lose additional additional fluids. You should should drink decaffeina decaffeinated ted coffee, caffeine-free soft or sport sport drinks, decaffeinated tea, juices, juices, and and water.

Scuba Cylinders and Temperature

F IGI G U R E 4 3 6 . Y O U R M A S K F O G S W H E N T H E W A T E R V A P O R I N T H E  A I R I N Y O U R M A S K C O N D E N S E S .

When a container container fill filled ed with with a gas is heated heated, the gas molecules inside the container becom become more active. If the container is flexible, the container will expa expand nd.. If the container is not flexible (for (for example, example, a scuba scuba cylinder), cylinder), the pressure ressure inside the the container container will will rise (figur (figure e 4-37). Cylinders should be kept from extreme extreme heat after after they are filled. filled. If the cylinder cylinder is subjected subjected to changes changes in temperature temperature once it is full full,, the pressure pressure inside can vary by several bar (several hundred psi). psi). The pressure pressure will ill increase or decrease decrease by approximately approximately 0.6 bar for each change of 1°C 1°C (5 psi psi for each change of 1°F 1°F)) even though no air air has been added or lost. This change occurs beca because use the the molecules of air air speed or slow their activit activity y as the temperature rises or

Chapter 4- Diving Science

falls, falls, respectively. Because of this change, it is not a good idea to store store scuba cylinders in car trunks, which which can reach reach temp temperatu eratures of over 50°C (122 (122°F °F). ). There is littl little e danger from the pressure pressure increase becaus because e of heat, but if a cylinder becom becomes hot enough, it will rupture the burst disk in the valve. valve. Also, Also, if the cylinder cylinder repeatedly expands and contracts ffrom rom the changes iin n temperature, it wil willl stress the metal and shorten the useful life life of the scuba cylinder. cylinder. It is better better to store cylinders cylinders with only only 7 to 14 14 bar (100 to 200psi) psi) of air air and fil filll them just before use than to store store them full. full. The metal metal alloys from which aluminum aluminum cylinders are made will crystallize if subjecte subjected d to relatively relatively low heat. They should not be placed near fires. If smoke smoke stains are are found found during the annual visual visual cylinder inspection, the cylinde cylinderr cannot be approved proved for use.

 V e r i f y W h a t  Y o u H a v e L e a p n e d Review the followin following g questions questions about the thermal thermal effects of diving: diving: 34. You lose lose most heat under water prim primar arily ily from water and some from warming . 35. Water vapor in air air condenses enses to a liquid liquid when ____________________________

___________________

36. You can prevent a mask from fogging under water by by lowering the the of  the water. 37. You must drink plenty of fluids when diving to __________________

38. True or or False. If the temperatur temperature e surrounding a rigid rigid container container fu full of gas increases, the pressure ressure of the gas increases.

i        v      i        n       g      S        c      i         e     n      c       e    

NAUI Scuba D i ver

LEARNING GOALS In this chapter chapter you you will: • Learn about ingassing ingassing and offgassing nitrogen and how it affects the amount of time you can spend underwater. underwater. • Understand Understand the conce concept pt of residual nitrogen. • Learn about dive table terms and rules. • Learn how to use the NAUI Dive Tables to plan your dives and find your your Letter Group designation after each dive. • Be introduced tothe NAUI Dive Pla Plann nnin ing g Worksheet and howto use it to keep track of the inf informat ormation ion from your dives and the NAUI Dive Tables. • Leam about precautionary and mandato mandatory ry decompression stops and how import important ant they are in minimiz minimizing ing the risk risk of decompression ression sickness sickness.. • Be introduced to the NAUI Dive Time Ca Calcul lculato atorr and how to use it. • Be introduced to dive computers computers and their their benefits. Your depth, and tthe he number and depth of dives dives you have made made in a series are two major major factors that determine the length of time you can stay under water. water. This This chapter explains the use use of the NAUI Dive Tables, the NAUI Dive Dive Time Calcula Calculator tor,, and dive computers. computers. You plan your dives with with the correct time and depth depth lim lim its by using either either version of the NAUI Dive Tables or a dive computer.

N I T R O G E N A N D D IVI V IN IN G The gase gases s in the air air you breathe disso dissolve lve into into your body’s body’s tissues tissues according to the part partia iall pressure of each gas in the air. air. Air is 78% nitrogen, 20.9% oxygen, oxygen, and 1.1% other gases. Your Your bodyuses part part of the oxygen you inhale inhale with with each breath. Your tissues tissues use the oxygen oxygen for the chemical chemical processes that keep keep you alive, alive, convert converting ing it to carbon carbon dioxide and other waste products. However, the nitrogen that that dissolves dissolves in your tissue tissues during your dive is is the gas you must be concerned concerned about when you plan your dives.

124

ingassing Nitrogen When you breathe in and out, out, the air air you breathe is 78% nitrogen. nitrogen. Nitrogen is a metabolically metabolically inert gas, gas, which means that your your bodydoes not use it. However, nitrogen nitrogen does absorb into into your your bloodstream bloodstream and tissues tissues as oxygen does. The pressure of nitrogen nitrogen is balanced balanced between the air air and your body. This state is called equilibrium.  par tial pressure of Under increased increased pressure, pressure, the partial  of nitrogen you inhale with each breath is increased. Therefore, the pressure pressure of nitrogen nitrogen in the air air you are breathing is greater than the pres pressur sure e of nitrogen in in your body. body. Your body body ingasses nitrogen until the pres sure of nitrogen in your your body body equals the pressure pressure of nitrogen in in the air air you breathe breathe.. If the new pressure ressure is constant, ingassing occurs rapidly rapidly at first and then slows unti untill your body reaches reaches equili equilibriu brium m many hours later. later. You do not experience experience any negative negative effects when ingassing occurs at moderate depths. The different different tissues of your body (fat, (fat, muscle, bone, bone, and so on) absorb absorb nitrogen at different different rates when you are under water. Your muscle absorbs nitrogen quickly, quickly, but fat absorbs nitrogen slowly. There are differ differ ent ingassing rates for each type of tissue. tissue. Calculat Calculating ing the cumulative cumulative effects effects of the ingassing rates for each type of tissue requires complex mathematics. mathematics. Dive tables, dive computers, computers, and dive time calculat calculators ors consid er all all these these varying rates and and eliminate eliminate the need need for you to make complex calculations.

Offgassing Nitrogen After you you spend spend time under water, the increased par tial tial pressure of nitrogen nitrogen has caused your body body to absorb a quantity quantity of nitrogen from the air air you breathe on on scuba. This quant quantity ity has been added added to the quantity quantity found in your your body body at sea level. level. When you ascend, ascend, and the ambient ambient pressure pressure decreas decreases, es, the part partia iall pressure of nitrogen nitrogen decreas decreases. The pressure pressure of nitrogen in your your body is now greater than than the partia partiall pressure of nitrogen in the air you are breathing. Your bodywill offgas offgas nitro nitro gen unti untill the nitrogen nitrogen is balanced balanced between your body body and the air.

Chap ter 5-5- Decom pression, pression, D ive Tables, and Dive Com puters puters

F IGI G U R E 5 - 1 . T H ISI S B O T T L E O F S O D A W A S S E A L E D U N D E R P R E S  S U R E . W H E N T H E B O T T L E ISIS O P E N E D , B U B B L E S FORM B ECAUSE OF THE SUDDEN DROP IN PRESSURE INSIDE THE BOTTLE.

The excess nitrogen nitrogen passes from your your body tissues into your blood. blood. The nitrogen then passe passes from your blood to your lungs, where you exhale the nitrogen. This process occurs rapidly rapidly during during the first few minutes after your ascent, but it takes takes many hours for your body’s nitrogen level to return to normal. If you reduce the pr pressu essure re on your body gradually, gradually, and the reduction in pressure from the depth of your dive to the the surface is not too rapid for the amount of nitrogen you have absorb absorbed, ed, offgassing occurs without without a problem. However, if the change in pressure is sudden, r y j the the nitrog nitrogen en in your tiss tissues ues can com come out of solution solution so so rapidly rapidly that that bubble bubbles s form in your your body. These These bubbles can damage tissues and cause a painf painful ul condition condition known as decompression sickness (DCS) or classically, as the bends. A bottle of soda can illu illustr strate ate the princ principl iple e of DCS. Carbon dioxide is dissolved dissolved in the soda under pressure and it remains in solution solution until until opening opening the the bottle bottle reduces the pressure. The rapid rapid drop in pressure causes the carbon dioxide to form bubbles bubbles in the liq liquid uid and the

soda foams (figure (figure 5-1). 5-1). If you open the bottle bottle slowly, reduced bubbling occurs. You must control control the two factors that that affect affect in-and offgassing: time and pressure. pressure. You do this by control control ling ling your dive time and depth. depth. To do this, you rely on the informatio information n provided by dive tables, dive time calculat calculators, ors, and dive compute computers. rs. You must also consider factors that can can increase increase your chance of suffering DCS DCS in situations where where it might not normal normally ly occur. These factors include dehydration, dehydration, fatigue, injuries, injuries, hard work during or shortly after a dive, effects effects of of drugs or alcohol, alcohol, obesity, or advanced advanced age. In any case, you mustbe fit fit for diving diving and dive conservatively. Bubbles form in the human body if pressure pressure is reduced beyond a specific point. point. If you dive deeper deeper than approximately approximately 6 meters meters (20 feet) and then ascend, the pressure pressure change might might be sufficient sufficient for for bubbles to form if you have absorbed absorbedenough nitrogen. If you dive to to depths of 6meters meters (20 feet) feet) or less, DCS is not lilike kely ly to occur unless you go to to altitude after diving, which reduces the pressure outside your your body and can create create a sufficient pressu pressure re differentia differentiall to cause cause bubbling. For For depths of 6.4 meters (21 feet) feet) or deeper, time time limits called dive time limits  or  or no-decompression limits have been established. established. The time spent at a given depth is not to exceed ceed these these limits, limits, or you could could experi ence DCS during during or after your ascent from the dive. If you take take special precaution precautions, s, involv involving ing offgassing offgassing in a series of planned planned decompression stops during during ascent; you lesse lessen your risk of of DCS. DCS. The United States Navy has established time limits limits for for various various depths based on research and field field experience experience of milita military ry divers. divers. Recreational Recreational diving diving use uses shorter time time limits than those those in the US Navy ta tables bles (fig (fig ure 5-2). Research and analy analysis sis by many experts experts deter mined that shorter dive time limits limits would would reduce the the risk of DCS DCS during recreational recreational diving. Reduced Reduced time limits limits have have been incorporated incorporated into the NAUI Dive Tables and NAUI Dive Time Calculato Calculator. r. Most Most dive computers also use use shorter time limits limits than than the US Navy tables for a single dive at a constant constant depth. Any dive you make puts you at at risk risk for DCS. However, diving with within in the limi limits ts set by the dive tables

 e      c       o     m     p     r       e      s       s      i         o     n       ,  D       i        v       e     T        a      b       l         e      s        ,   a     n      d       D       i        v       e      C        o     m     p      u     t        e     r       s     

NAU I Scuba D i ver

DIVE LIMITS

       r        e         t        u        p        m        o          C        e        v          i          D          d        n        a   ,         s        e          l          b        a          T        e        v          i          D   ,         n        o          i        s        s        e        r        p        m        o        c        e          D

i

D E P TH

N A U I L I M IT

U.S.N. LIMIT

0-20’ (0-6m)

No Limit

No Limit

21-40’ (6.4-12m)

130 mi ns.

200 mins.

41-50’ (12.5-15m)

80 mi ns.

100 mi ns.

51-60' (15.5-18m)

55 mins.

60 mins.

61-70’ (18.6-21 m)

45 mi ns.

50 mins.

71-80’ (21,6-24m)

35 mi ns.

40 mi ns.

81-90'(25-27m)

25 mins.

30 mins.

91-100'(27.6-30m)

22 mi ns.

25 mi ns.

F IGI G U R E 5 - 2 . R E C R E A T I O N A L D I V ININ G U S E S S H O R T E R D I V E T I M E L IM IM I T S T H A N T H E U S N A V Y T A B L E S . ] Represents Residual Residual Nitrogen Nitrogen

lessens the risk. Divers who use time limi limits ts in in excess of the recommended mended limits limits (for (for example, example, technic technical al divers) divers) recognize recognize and accept the increased risk that that is associated with these longer dive times and the need for special special decompression procedures. Deepe Deeperr diving requires experience, plannin planning, g, and training. training. As a certified entry-le entry-level vel NAUI Scuba Diver, you should should not dive dive to depths deeper than than 18 meters (60 feet). feet). As a certified certified NAUI Advanced Advanced Scuba Diver, Diver, you should should not dive dive to depths deeper than than 30meters (100 feet). feet). The maximum recommended recommended depth for all recreationa recreationall divers is 40 meters meters (130 feet). feet). You do not need to memorize the dive time limi limits. ts. They are included in your NAUI Dive Tables Tables or your NAUI Dive Time Calculato Calculator. r. Note that the dive time decreases as the depth depth increases. If you are using using a dive computer, computer, the limits limits wil willl probably be different different from the the limits limits present presented ed in this textbo textbook. ok. Nitrogen offgassing occurs at different rates among your various body tissues. The rate of offgassingfor differ differ ent tissues is the basis for the non-linear variatio variation n in time limits for for different different depths. You should be fami familia liarr with this concept becau because it does form the basis basis for the calc calcul ula a tions performed by dive computers and the time limits limits established by dive tables and dive computers. computers. When you take the the NAUI Master Master Scuba Diver course, you wil willl leam various various principles principles and theories behind dive tables.

F I G U R E 5 -3- 3 . R E S I D U A L N I T R O G E N I S T H E N I T R O G E N T H A T S T A Y S I N Y O U R B O D Y F R O M D IVI V E S M A D E I N T H E P R E VIV I O U S 2 4 H O U R S .

residual nitrogen. nitrogen. In reality, reality, it takes takes hours to fully fully absorb nitrogen into your body or fully eliminate nitro gen from your body body.. If you dive and absorb nitrogen at depth, ascend to the surface, surface, and then make make another another dive within within 24 hours of the first dive, you will will stil stilll have nitrogen in your body body from the first dive (figure (figure 5-3). 3). Your bodywill ill absorb nitrogen from from the second dive in addition to the nitrogen nitrogen remaining remaining from the first dive. dive. You must must always take the nitrogen remaining remaining in in your your sys tem from any previous series of dives into account when planning planning your next dive. dive. This residual nitrogen redu reduces your time time limits limits for any given depth depth on your next dive.

 V e n ify if y W lis li s t  Y o u Have Learned Review the following following questions about ingassing ingassing and outgassing nitrogen: 1. When you go under pressure, y your our body nitrogen until it reaches a state state of  of  . 2. Bubbles form during during offgassing when when you _________________

_________________________ _________________________

3. You can dive to meters meters ( without a dive time limit. 4. Residual nitrogen is the nitrogen

_______

Residual Nitrogen To properly use dive tables, dive time calculators calculators,, and dive computers, you must understand the concept concept of 

126

feet)

m

Chap ter 5 17431727 " :

DIVE TABLE OVERVIEW The NAUI Dive Tables use use a Letter Group designation designation to express the amount of residual residual nitrogen nitrogen in in your your body. The letters range in sequence from Ato L. The letter letter A represents a small small amount amount of nitrogen and the amount of nitrogen increases as the letters progre progress towards L. When you dive, a Letter Group from the tables designates the the amount of nitrogen you have absorbed during during the dive. As you spend time on the surfa surface ce between dives, you are assigned to “lower” “lower” Letter Groups Groups as you offgas nitrogen. When you you start a dive ag again ain to a given depth, depth, your Letter Group at tha thatt time determines the time represent ing the residual nitrogen in your body. The tables show show you how to subtract this time from the normal normal dive time limits, which results in a shorter shorter time limit limit for your repetitive dive. You must add your residual ni nitrogen trogen time to the the time you actua actually lly spent diving to determine your total nitrogen time time at the end of the dive. You use the total time to determine a new end-of-dive Letter Group. The NAUI NAUI dive time calcu calculato latorr is based based on the NAUI dive tables, tables, but it eliminates the calculations calculations required to determi determine ne Letter Groups when you make more than one dive. The dive time calcu calcula lator tor also reduces the errors that that are are often made when readi reading ng dive tables. It is easy easy to learn learn how to use a dive time calcu calcula la tor, but you should should do this only after you you are fam familia iliarr with the the proced procedures ures for planning planning dive time limits limits using the dive tables. tables. A dive time calcula calculator tor might might not always be available, but dive dive tables tables usually are (figure (figure 5-4). 4).

, Dive Tables, Tabl es, aad D ive Com puters puter s

A variety of dive dive tables, dive time calculators, calculators, and dive computers exist. The informati information on they provide varies varies and some some are more conservative than than others. Numbers and Letter Groups Groups are not always intercha interchange nge able between tables. tables. Always use use the the type of table, calcu calcu lator, or comp compute uterr with with which you you are familiar. If your dive buddy is using a different different type, you should should agree to use use the most most conservativ conservative e dive planning planning infonnation. infonnation.

 c       o     m     p     r       e      s       s      i         o     n       , 

Dive Table Terms Different Different dive tables and dive computers computers might use use terms different different from the ones used in the NAUI Dive Tables (figur (figure e 5-5). Also, Also, the same same term might have a different meaning. The following following terms apply to the NAUI Dive Tables:  Dive Sche Schedu dule le.. This is an abbreviated statement • Dive giving giving the depth and time of the dive. It is expressed as depth/time ((fo forr example, example, 21 meters/40 minutes or 70 feet/40 minute minutes) s).. It is also called a dive profile, especially especially when when it is one dive in in a sequence of dives. Dive Tim Timee (MDT). • Maximum Dive  (MDT). This is the time you can spend at a given depth without havi having ng to do a required decompression stop during during ascent. This time is also also known as the Maximum  Allo  Allowa wabl blee Dive Dive Tim Timee or no-decompression limit. lim it.  or no-decompression  Decomp mpre ress ssio ion n Stop Stop.. This is a point in a dive • Deco dive where you stop stop at a specified depth for a specified

D       i        v       e    

m

T        a      b       l         e      s        ,   a     n      d       D       i        v       e      C        o     m     p      u     t        e     r       s     

No Decompression Limit

F I G U R E 5 -5- 5 . T H E D I V E T A B L E T E R M S F D R T H E N A U I D IVIV E T A B L E S M I G H T F IGI G U R E 5 - 4 . D I V E T A B L E S A R E U S E D T D P L A N Y O U R D I V E .

H A V E D I FFF F E R E N T M E A N I N G S W I T H O T H E R D I V E 1 A D L E S .

127

NAU I Scuba S cuba D i ver

m        e         t        u        p        m        o          C        e        v          i          D          d        n        a   ,         s        e          l          b        a          T        e        v          i          D   ,         n        o          i        s        s        e        r        p        m        o        c        e          D

128

□

time during ascent to allow allow nitrogen offgassing before before continui continuing ng your ascent or surfacing. surfacing.  Precautionar onaryy Deco Decomp mpre ress ssio ion n St Stop. - Precauti This is a stop stop at five meters meters (15 feet) for three minutes as a safety precaution precaution when you have not exceeded the Maximum Dive Dive Time. You should should perform such a stop at the end of every dive. It is also known known as as aSafety Stop.  Required Deco Decomp mpre ress ssio ion n St Stop. - Required This is the amount of time specified by the NAUI NAUI Dive Tables, that that you must spend spend at five meters (15 feet) whenever you exceed the Maximum Dive Time. Time. Other tables specify additional additional stop depths for deeper or llonger onger dives.  Actual  Actual Dive Dive Time Time (AD (ADT). T). This is the elapsed 1 time from from the moment you begin your your descent from the surface surface unti untill the time you retur return n to the the surface. Time spent spent at your Safety Stop does does not need to be included in the Actual Dive Ti Time me when determining your Letter Group.  Residual Nitro Nitroge gen. n. This is the excess nitrogen 1 Residual nitrogen remaining remaining in your your body from any dive or dives made before you have complet completely ely offgassed. offgassed.  Letter er Grou Group p Des Desig ignat natio ion. n. This letter symbol * Lett symbol identifies identifies the amount of residual nitrogen you have in your syste system m. The closer the letter is to the beginning of the alphabet, the less residual nitrogen you have in your body. body.  »Sur  »Surfac facee Interv Interval al Time Time (S (SIT). IT). This is the time spent on the surface surface between dives. During During this this time, your body is elimi elimina natin ting g excess cess nitrogen. Your Letter Group will will change and move move closer to the beginning of the alphabet, depending depending on how long you are on the surface.  »Rep  »Repeti etiti tive ve Dive Dive.. This is any dive that you make before you have complet completely ely offgassed from any any previous dive dive or dives.  »Residua  »Residuall Nitrog Nitrogen en Time (RNT (RNT). ). This is the amount of time you must consider as already having having been been spent at a given depth depth for a planned planned repetitive dive. This time is based based on the residual nitrogen remaini remaining ng in your body from a previous dive or dives.

 Adjusted ed Maximum Dive Dive Time Time (AMDT). This is • Adjust the Maximum Dive Time minus the Residual Nitrogen Time for for a repetitive repetitive dive to a given depth. • Total Nitrogen Time (TNT). This is the the sum of your Residual Nitrogen Time and your Actual Actual Dive Time followin following g a repetitive dive. dive. You use use this total total to obtain obtain your new Letter Group Group at the end of the dive.

Dive Table Rules You must understand understand the the following following NAUI Dive Table rules completely. Sim Similar ilar rules will will apply to any new new set of dive tables or di dive ve computer that you might might use to calculate calculate your dive times. • Ascend no faster than than 9 meters (30 feet) feet) per m minute minute.. This This is 0.3 meters (1 foo foot) t) every every two sec onds. You need a timing timing device device and a depth gauge (or (or a dive computer) to measure your rate of ascent. This rate rate will will seem quite slow to to y you. ou. • Use the exact or the next greater number listed listed in the table for your depth depth.. If you excee exceed d a number number in the table, use the next greater number. The depths in the table table range from from 12 meters (40 feet) feet) to 40 meters (130 feet) feet) and increase increase in increments of 3 meters meters (10 feet). For example, you round round a dive to 13meters (43 feet) feet) up to a 15 meter (50 foot) foot) dive. • Use the exact or the next greater number listed listed in the table for your time. If you exceed a number in the the table, use the next next greater number. number. The times range from 5 minutes minutes to 130 minutes. For example, you round a dive to 15 meters (50 feet) for for 41 minutes up to 50 minutes. • Use the deepest depth you reached duri during ng your your dive to determine the dive schedule for your dive. For For example, if you you do a dive to 18 meters (60 feet), feet), but spend most of the time a att 12 meters (40 feet) feet),, you must consider consider the dive to be an 18 meter (60 foot) dive. • Always make your deepe deepest st dive first first when making making a series series of dives. dives. Plan Plan each of your repetitive dives to a shallower depth than your your previous K  dive. This might allow allow you to offgas nitrogen on

Chapter 5- Decompression, Dive Tables, and Dive Computers

□

m

□

progressively shallower dives and prevents prevents you from carrying carrying progressively progressively larger amount of residual nitrogen on deeper repetitive dives. dives. Consider any dive shallow shallower er than than 12 meters (40 feet) feet) to be a 12-meter (40-foot) dive when plan plan ning your dives. Surface Interval Interval Time (SIT (SIT)) must must be at least least 10 10 minutes betw between dives. dives. If your SIT SIT is less than 10 minutes, you must consider your second dive as a continuat continuation ion of the the first first dive. NAUI recommends mends a SIT SIT of at least one hour between dives. ives. 1Use the next next greater dive time if if your dive is par par ticular ticularly ly cold or strenu strenuous ous.. For example, if you do a dive to 18 meters (60 feet) feet) for 22 minutes, minutes, the 22 minutes minutes rounds to 25 minutes. minutes. However, if you become chille chilled d during during the dive, round the time again again to 30minutes. 1Avoid dives that take you right right to the no-decompres sion limi limitt for any given depth andtime combina tion. If you accidentally accidentally overstay overstayyour bottomtime or use an incorre incorrect ct ascent rate on such a dive, you could be in a required required decompression situation situation or suffer DCS. Always allow allow yourself enough time to make a slow, comfortable ascentwith plenty of air. air.

DIVE TABLE ORGANIZATION The NAUI Dive Dive Tables are composed of three tables: • Table 1- End-Of-D -Of-Dive ive Letter Letter Group Group • Table Table 2- Surface Surface Interval Time Time (SIT (SIT)) Table • Table 3- Repetitive Dive Dive Timetable The NAUI Dive Dive Tables are based on on the US Navy Decompression Tables and and have been designed specif specifii cally cally for recreational diving (figure (figure 5-6). The tables tables are designed designed to flow from one to the other in a continuous loop (figure (figure 5-7). When you are are using using the tables, be sure to use a ruler ruler or a straight-edg straight-edged ed object to read the numbers across across and work your way from table to table. table. If you try using a finger finger to trace your path through the tables, you might slide into another row and read the the table incor incor rectly, especially especially if if you are on a rocking boat.

 p     r       e      s       s      i         o     n       ,  D       i        v       e     T        a      b       l         e      s        ,   a     n      d       D       i        v       e      C        o     m     p      u     t        e     r       s     

 V e r i t y W i i a t Y o u H a v e L e a r n e d Review the followi following ng questions about Dive Dive Table Table Rules: 5. When you use the NAUI Dive Tables, you ascend from all dives dives at a maximum rate of  meters (_ (_ feet) per minute. 6. You should allow a minimum of min min utes between dives and NAUI recommends a SIT SIT of  . 7. Arrange the foll followi owing ng dives into the preferred sequence: 9 meters (30 feet)/40 minutes 18meters (60 feet)/30 minutes 15 meters (50 feet)/20 minutes 8. Adive of up to 8 meters (26 feet) feet) for 40minutes minutes should be considered considered as a dive schedule schedule of  when planning a repetitive dive.

 c       o     m   

_______ _______

________________ ________________

___________________

F IGI G U R E 5 -6- 6 . T H E N A U I D I V E T A B L E S H A V E B E E N D E S I G N E D F O R R E C R E A T I O N A L D I V ININ G A N D A R E E A S Y T D U S E .

NAIII Serin Diver

TABLE 1 - END-OF-DIVE LETTER GROUP M

M

M

D IV E T A B L E S

00 I DIVE DIVE TIME TI ME REQUI RING DECOMP RESSIO N NO MINU TES REQUIRED AT 15‘ STO STOP P (5M)

SWBT

i tttt M W M S r o * s r P i £ ' C 0 M « ! A « 5 V Wl Wl t' l i : < s t r t f e f S W H i H O T S U M w n t f MO M  !'J   o f K W B t s w * s j cm cm k s s a t m . i m v

RN T RtS IDUAl NITROGEN TIME +A DT ACTUALDIVETIME ACTUALDIVETIME TN T TOTAL NITROSEN TIME IUSE THISfIGUfif TO , / OtTESMIN OtTESMINEE * / END-OfDIVE . U T T E R G RO RO UP UP ! / -

V

cam

WM »i. iwaitmswoHtHHij' i

‘ft'

12 40 V 15

50v

18

60 v

80:100 110 5 15 25 30 40:50 70 80:1

130a

i10 15 25 30 40 5060 70 80 10 15 20 25(30 40 50 55

n

21 70 v

5

10 15 20:30 35 40 45

24 80 V

5

27

90v

5

10 15 20 25 30 ( 35 n 10 12 15'2 0 ‘ 2 5 1 ^

30 100v

5

7

■ a *

10 15 2 0 (22

33 110v

5 10131 y 15y

36 120v

5

40 130 V

5

8a

C

D

A

B

yn io I? y

a

 _.  _.

A

E

F

irn

EX

H

I

J

K

L

.

TrZS  

* 0-.10(W6 V16

?«

SO O«# IS*

AVOIO - REPETITIVE DIVES OVER 100 FEET TABLE 3 - REPETITIV E DIVE TIMFTABLE

A

B

C

D

E

F

G

H

I

J

K

L

F IGI G U R E 5 - 8 . T A B L E 1 - E N D - O F -D- D I V E L E T T E R G R O U P.P .

03S;0»»6

TABLE 2 - SURFACE INTERVAL TIME (SIT) TABLE

F IGI G U R E 5 - 7 . T H E N A U I D IVI V E T A B L E S A R E D E S I G N E D T O F LO LO W F R O M O N E T A B L E T O T H E N E X T I N A C O N T I N U O U S L O O P.P .

T a b l e 1 - E i f - D i v e L e ttt t e r O rer e o p Table 1- End-OfEnd-Of-Dive Dive Letter Group gives you a Letter Group designation at the end end of your dive (figure (figure 5-8). 5-8). This table table also gives you the Maximum Dive Time (MDT) (MDT) inform informati ation on for for depths from 12 meters to 40 meters (40 (40 feet to 130 feet). feet). The MDTs are the red, circled numbers. The table is arranged arranged with with the depths pths in columns columns on the left side of the table and and the times for eac each h depth in rows across across the table. To find your your Letter Group, use the follo following wing steps: 1. Take the deepest depth you reached reached duri during ng your your dive and round round it to the next greater depth found in Table Table 1. For example, example, if if the dee deepe pest part of your your dive was to 23 meters (75.5 feet), feet), round the number to 24 meters (80 feet). feet). 2. Locate the row corresponding corresponding to yo your ur deepest depth. 3. Follow Follow the row across until until you you find the column containing containing the total time of your dive. dive. You might have to round the total time of your dive to the next greater time found on the table. table. For

example, if if the total time for your dive to 23 meters (75.5 feet) feet) was 26 minutes, minutes, you must round the time time to 30 minutes. 4. Follow the column containing the total total time of of your dive down until until you reach a letter. This is your Letter Group Group designation for your dive. For example, the Letter Group for the dive dive to 23 meters (75.5 feet) for 2 6  minutes, which is round ed to 24meters (80 (80 feet) for for 30minutes, minutes, is G.

 V e r i l y W h a t  Y o u H a v e L e a r n e d Review the followin following g questions questions about Table 1: 9. If you do a dive to 18meters (60 feet) for 42 minutes, your Letter Group is ____ . 10. If If you do a dive to 12 meters (40 feet) feet) for 88 minutes, minutes, your Letter Group Group is is____ . 11. If I f you do a dive to 36 meters (120 feet) feet) for for 9 minutes, your Letter Group is ____ .

Table 2 - Surface interval Time (SIT) Table The longer longer you stay stay on the surface between dives, the more excess ess nitrogen you eliminate. eliminate. Table 2 Surface Interval Interval Time (S (SIT) IT ) Table give gives s you credit for eliminati eliminating ng nitrogen by changing your Lett Letter er Group Group (fig (fig ure 5-9). Table 2 consists of blocks containing containing two num bers. The numbers are expressed expressed as hours and minutes.

Chapter 5- Decompression, Dive Tables, and Dive Computers

 A

Y

B

Y

C

Y

D

Y

E

Y

24:00 24:00 24:00 24:00 24:00 0:10 3:21 4:50 5:49 6:35 3:20 4:49 5:48 6:34 0:10 1:40 2:39 3:25 1:39 2:38 3:24 0:10 1:10 1:58 1:09 1:57 0:55 0:10 0:54 0:10

F

V

G

Y

24:00 7:06 7:05 3:58 3:57 2:29 2:28 1:30 1:29 0:46 0:45 0:10

H

Y

24:00 7:36 7:35 4:26 4:25 2.59

2:58 2:00

1:59 1:16 1:15 0:41 0:40 0:10

I

Y

J

V

K

Y

24:00 24:00 24:00 8:00 8:22 8:51 7:59 8:21 8:50 4:50 5:13 5:41 4:49 5:12 5:40 3:21 3:44 4:03 3:20 3:43 4:02 2:24 2:45 3:05 2:23 2:44 3:04 1:42 2:03 2:21 1:41 2:02 2:20 1:07 1:30 1:48 1:06 1:29 1:47 0:37 1:00 1:20 0:36 0:59 1:19 0:34 0:55 0:10 0:33 0:54 0:32 0:10 0:31 0:10

 V e r i f y I M V i i u H a v e L e a r n e d

L

V

24:00 8:59 8:58 5:49 5:48 4:20 4:19 3:22 3:21 2:39 2:38 2:04 2:03 1:36 1:35 1:12

24:00 9:13 9:12 6:03 6:02

4:36 4:35 3:37 3:36 2:54 2:53

Review the followin following g questions questions about Table 2: 12. If If you have a Letter Group Group of I and your SIT SIT is 2 hours and 36 36 minutes, your your new Letter Grou Group p is . 13. If If you have a Letter Group of C and your SIT SIT is 3 hours, your new Letter Group Group is . 14. If If you have a Letter Group Group of G and your SIT SIT is 42 minutes, your new Letter Group is .

2:20

2:19 1:50 1:49 1:26 1:11 1:25 0:50 1:05 0:49 1:04 0:29 0:46 0.28 0:45 0:27 0:10 0:26 0:10

F IGI G U R E 5 - 9 . T A B L E 2 - S U R F A C E INI N T E R V A L T IM I M E (S(S I T ) T A B L E .

The lower lower number number in the block is the minimum Surface Interval Time (SIT (SIT)) for a particul particular ar group group and and the uppe upper number is maximum maximum SIT for a partic particular ular group. up. To find your new Letter Group based based on your SIT SIT,, use the follow following ing steps: 1. Look across the top row of the table table unt untilil you you come to the Letter Group designati designation on you had at the end of your previous previous dive. For example, you had a Letter Group of G. 2. Go down the column unt untilil you find find the block into which your SIT fits. For example, example, you you were were out of the water for three hours. hours. The block into which which three hours fits is is the one which which starts at 2:59 and ends at at 4:25. 3. Move left across the row containing containing your your corre corre sponding sponding block until until you come to another letter. For example, if you had a Letter Group of G and were out of the water for for three hours, you would have a new Letter Group of C. Note that the maximum time in this table table is 24 hours. hours. All exces excess nitrogen nitrogen is considered eliminat eliminated ed after you have been on the surface surface for 24hours. Therefore, Therefore, a dive after after 24hours on the surface is not considered considered a repetitive dive.

T a b lel e 3 - R e p e t iti t i v e D i v e l i m e t i l e Table 3 - Repetitive Dive Timetable provide provides s your Adjusted Adjusted Maximum Maximum Dive Time (AMDT) for your next dive and your Residual Nitrogen Time (RNT (R NT)) based on your current current Letter Group Group (figur (figure e 5-10). You use this table twice for each repetitive dive. First, First, you use use the table to find your AMDT AMDT when plannin planning g your dive. Next, you use the the table to find your your RNT after you complete complete your dive. You add add the RNT to your Actual Actual Dive Time (ADT) to find your Total Nitrogen Time (TNT (TNT). ). The table table is arranged arranged with with the depths from from 12 meters to 40 meters (40 feet to 130 feet) feet) in columns columns across the table and the Letter Letter Groups in rows down the table. Each Each block block of the table contains contains two numbers. numbers. The upper number is the RNT RNT corresponding to each depth and Letter Group. Group. The lower, red number is the the AMDT AMDT for each each depth and Letter Group. Use Use the follow following ing steps to find your your AMDT when when planning a repetitive dive: 1. Find Find your new Letter Group, based based on your SIT SIT,, in the column column on the right right side of the table. For example, you have a new Letter Group of C. 2. Search along the row corresponding to your Letter Group until you come to the column corresponding to the depth to which you want to dive. For For example, you want to dive to 15 meters meters (50 feet). feet). 3. Look at the the lower number number to find your AMDT. AMDT. For example, with a Letter Group of C, you can dive to 15 15 meters meters (50 feet) for a maximum maximum of 59 minutes. minutes.

 e      c       o     m     p     r       e      s       s      i         o     n       ,  D       i        v       e     T        a      b       l         e      s        ,   a     n      d       D       i        v       e      C        o     m     p      u     t        e     r       s     

NAU I Scuba S cuba D i ver

Use the followi following ng steps to find your your TNT at the end of your repetitive dive: 1. Find Find your new Letter Group, based based on your SIT, SIT, in the column on tthe he right side of the table. For example, you have a new Letter Group of C. 2. Move along the row corresponding corresponding to your your Letter Group Group unt untilil you come to the column correspon ding to your deepest depth depth during during the dive. For example, you went to 14 meters (47 feet), feet), whic which h rounds to 15 meters (50 (50 feet). feet). 3. Read the upper upper number number in the block. This is your RNT. For example, the RNT for a dive to 15 meters (50 feet) for L Letter etter Group C is 21 minutes. 4. Add the RNT to your your ADT to find your your TNT. For example, if your your ADT was 35 minutes, you you must add your your RNT RNT of 21 minutes minutes from step 3to get a TNT of of 56minutes. Notethat the AMDTs and RNTs in in each each block block add up to the circle circled d MDT for each corresponding depth in Table Table 1.

1 2 1 5 1 8 21 4 0 50 60 7 0 7 123 17 113 25 105 37 93 49 81 61 69 73 57 87 43 101 29 116 14 138

6 74 13 67 21 59 29 51 38 42 47 33 56 24 66 14 76 4 87

161

5

2 4 2 7 30 3 3 36 40 NEW 80 90 1 0 0 1 1 0 1 2 0 1 3 0 GROUP

50 11 44 17 38 24 31 30 25 36 19 44 11 52

4 41 9 36 15 30 20 25 26 19 31 14 37 8 43

4 31 8 27 13 22 18 17 23 12 28 7 32

3 22 7

61

3

3 12

3 9

6 9 10 5 13

6 6 9 12

11

16

15

13

20

18

16

< F

26

24

21

19