anchor

NAME 429: Marine Engineering

Anchoring: Windlass, Winch, Anchor and Chains

Prepared by: Dr. Md. Mashiur Rahaman Assistant Professor Department of Naval Architecture  Marine !ngineering "angladesh #niversity of !ngineering  $echnology Dha%a&'(((, "angladesh !&mail: mashiurrahaman)name.buet.ac.bd

Prepared by: Dr. Md. Mashiur Rahaman, Rahaman, Assistant Professor, Dept. of NAME, BUET

NAME 429: Marine Engineering '. *ntroduction

+igure: Forecaste of a ship showing the anchor and anchor handling equipment The anchor gear (or ground tackle) is located on the forecastle and consists of all the equipment used in anchoring. This includes the anchors, the anchor windlass, anchor cables or chain, chain stoppers and the connecting devices (shackles, swivels), etc. When the ship is underway, the anchor is stowed in the hawse-pipe. t is attached to the anchor chain or cable by means of an anchor shackle (type !) and a swivel shackle. The chain then goes through the hawse-pipe onto the windlass (anchor winch) fitted on the forecastle deck. " ship is normally fitted with ten shackles (shots in #$) of cable, each shackle about %& metres in length, and connected to another shackle (length of chain) by an accessory fitting called kenter 'oining- shackle. The cable is lifted and lowered by the cable lifter (gipsy or wildcat) from where it falls down through the spurling gate and spurling pipe into the chain locker. The cable is secured on the forecastle deck by stoppers, devil-claws and anchor lashings. The chain is held by the windlass brake. The windlass also consists of one or two drums on the sides of it for warping and heaving on the mooring lines. "n anchor windlass is a machine that restrains and manipulates the anchor chain, allowing the anchor to be raised and lowered. The cable lifter (a notched wheel) engages the links of the chain. " brake is provided for control and the windlass is usually powered by an electric or hydraulic motor operating via a gear train.

Figure* +ombination "nchor Windlass  +apstan Prepared by: Dr. Md. Mashiur Rahaman, Assistant Professor, Dept. of NAME, BUET

NAME 429: Marine Engineering Technically speaking, the term windlass refers only to horiontal winches. /ertical designs are correctly called capstans. 0oriontal windlasses make use of an integral gearbo1 and motor assembly, all typically located above-deck, with a horiontal shaft through the unit and wheels for chain andor rope on either side. /ertical capstans use a vertical shaft, with the motor and gearbo1 situated below the winch unit (us ually below decks). Wildcats (gipsies, technically referred to as cable lifters) are used in windlasses to haul in and pay out anchor chain on board ships. "n associated chain stopper is used to secure the chain while the ship is anchored, or the anchor is housed. The wheels on either a vertical or horiontal windlass provide for either chain or rope to be engaged. The wh eel for rope is termed a warping head, while the chain handling wheel is variously referred to as the gypsy (in the #2) or wildcat (in #$), though due to the influence of the offshore oil industry the latter usage is now more common. For clarity in communication the generic term chain wheel is often used. 3owadays, especially on large tankers and cruise ships, the windlass may be split into independent 4ort 5 $tarboard units. n these cases they are frequently coupled with Warping !rums (as distinct from Warping 0eads). n some of these the warping drums are of the self tensioning or constant tension type.

. Anchor Windlass Windlasses are installed on board ships primarily for handling and securing the anchor and chain used for anchoring the ship and for handling anchor chain used for towing the ship. 6ost windlasses have capstans or gypsy heads for handling line in mooring and warping operations. Windlasses can be located on the stern of the ship for stern anchoring, b ut are usually located in the bow of the ship for handling bower anchors. Windlasses also handle bottom-mounted braided fluke anchors (keel anchors) used on submarines (stern) and some surface ships (bow). Two general types of windlasses are installed on naval ships. They are the vertical shaft and the horiontal shaft types (see figures). These two types are subdivided into classes, depending on the power source. These classes are electro-hydraulic drive and electric drive. The essential parts of a typical windlass, regardless of its type and class, are the drive motor, wildcat, locking head, hand brake, capstan or gypsy head, and control. 0oriontal shaft windlasses are usually made as a selfcontained unit with the windlass and drive motor mounted on the same bedplate. /ertical shaft windlasses have their power source located below deck with only the wildcats and capstans mounted above deck. The windlass wildcat is a special type of drum or sprocket constructed to handle the anchor chain links. The outer surface has flats (or pockets) which engage chain links. "t each end of the pockets, lugs (known as whelps) are provided, which contact the end of the flat link. " central groove in the outer surface accommodates the vertical links which are not in contact with the wildcat at any point. Windlass wildcats have a locking head for disengaging the wildcat from its power source. The locking head permits free rotation of the wildcat when you are 7paying out8 the chain. 9ocking heads usually consist of two sliding block keys that may be shifted to key together a drive spider and the wildcat. The drive spider is keyed to the windlass:s shaft, while the wildcat is carried on bearings and is free to rotate, e1cept when the locking head keys are engaged or when the wildcats brake is set. ;ach wildcat has an e1ternally contracting flat hand brake operated by a hand wheel. This brake may be used to hold the anchor and chain and to control the speed of descent when the anchor and chain are payed out. +apstan and gypsy heads fitted on windlasses are keyed to the drive shaft and rotate when the windlass power source is turning. When using the heads, apply the wildcat hand brake, then disengage the wildcat locking head. The heads will now operate independently of the wildcats. When the wildcats are used, however, the capstan heads will always rotate.

Prepared by: Dr. Md. Mashiur Rahaman, Assistant Professor, Dept. of NAME, BUET

NAME 429: Marine Engineering

Figure* "nchor windlass

Figure* /ertical shaft anchor windlass

Figure* 0oriontal shaft anchor windlass

Prepared by: Dr. Md. Mashiur Rahaman, Assistant Professor, Dept. of NAME, BUET

NAME 429: Marine Engineering 3.

Winch

" winch is a mechanical device that is used to pull in (wind up) or let out (wind out) or otherwise ad'ust the tension of a rope or wire rope (also called cable or wire cable). n its simplest form it consists of a spool and attached hand crank. n larg er forms, winches stand at the heart of machines as diverse as tow trucks, steam shovels and elevators. The spool can also be called the winch drum. 6ore elaborate designs have gear assemblies and can be powered by electric, hydraulic, pneumatic or internal combustion drives. $ome may include a solenoid brake andor a mechanical brake or ratchet and pawl device that prevents it fr om unwinding unless the pawl is retracted.

Figure* Winch 3.'

Applications

The rope is usually stored on the winch, but a similar machine that does not store the rope is called a capstan. When trimming a line on a sailboat, the crew member turns the winch handle with one hand, while tailing (pulling on the loose tail end) with the other to maintain tension on the turns. $ome winches have a stripper or cleat to maintain tension. These are known as self-tailing winches. Winches are frequently used as elements of backstage mechanics to move scenery in large theatrical productions. They are often embedded in the stage floor and used to move large set pieces on and off. Winches have recently been fabricated specifically for water and snow sports (e.g. wakeboarding, wake skating, snowboarding, etc.). This new generation of winches is designed to pull riders swiftly across a body of water or snow, simulating a riding e1perience that is normally supplied by a boat, wave runner, or snow mobile. 3.

$ypes of -inches 3..'

nubbing -inch

This is a vertical spool with a ratchet mechanism similar to a conventional winch, but with no crank handle or other form of drive. The line is wrapped around the spool and can b e tightened and reeled in by pulling the tail line, the winch takes the load once the pull is stopped with little operator tension needed to hold it. They also allow controlled release of the tension by the operator using the friction of the line around the ratcheted spool. They are used on small sailing boats and dinghies to control sheets and other lines, and in larger applications to supplement and relieve tension on the primary winch mechanisms.

Prepared by: Dr. Md. Mashiur Rahaman, Assistant Professor, Dept. of NAME, BUET

NAME 429: Marine Engineering 3..

Wa%es%ate -inch

Wake skate winching, which is the popular term today, is a growing hobby for many water sports enthusiasts. t consists of an engine, spool, rope, handle, frame, and some sort of simple transmission. The person being towed walks (or swims) away from the winch and pulls out all of the rope. When the winch is engaged, it pulls the boarder usually between kmh). Winches are popular for people wanting to board on ponds and lakes, or 'ust don:t have a boat. "lso, the winch can either be mounted on the trailer hitch of a vehicle, set into the ground by stakes, or tied to a tree. These winches have also been modified for use by skiers and snowboarders in cities. 3..3

/lider -inch

?liders are often launched using a winch mounted on a heavy vehicle. This method is widely used at ;uropean gliding clubs, as a cheaper alternative to aero-towing. The engine is usually a large 4etrol, 94? or diesel, though hydraulic fluid engines and electrical motors are also used. The winch pulls in a >> to >-metre (A,>>> to &,&>> ft.) cable, made of high-tensile steel wire or a synthetic fibre, attached to the glider. The cable is released at a height of about =>> to B>> metres (> to %,%>> ft.) after a short, steep climb. 3..0

Air Winch

"n air winch, sometimes known as an air hoist or air tugger, is an air-powered version of a winch. t is commonly used for the lifting and the suspension of materials. n the oil and gas, construction, and maritime industries, air winches are frequently preferred to electric, diesel, and hydraulic winches because of their durability, versatility, and safety.

=. Types of anchor 0.'

toc% anchor

+igure: $tock anchor

This type, with its two flukes and its stock at right angles, remained the basic anchor for many centuries. t is known as a stock anchor in the #nited $tates and as a fishermans anchor in the #nited 2ingdom. Prepared by: Dr. Md. Mashiur Rahaman, Assistant Professor, Dept. of NAME, BUET

NAME 429: Marine Engineering 0.

toc%less anchor

3ow almost all ships have a stockless anchor which equipped at bow on both 4ort and $tarboard side. $tockless anchors consist of a set of heavy flukes connected by a pivot or ball and socket 'oint to a shank. +ast into the crown of the anchor is a set of tripping palms, pro'ections that drag on the bottom, forcing the main flukes to dig in.

Figure: Stockless anchor

+igure: Terminology of stockless

anchor parts

Prepared by: Dr. Md. Mashiur Rahaman, Assistant Professor, Dept. of NAME, BUET

NAME 429: Marine Engineering 5.

Po-er

4owered solutions include steam (antiquated), hydraulics, and electrics. ;lectrics are convenient and relatively cheap, but hydraulics prove more efficient and powerful on all but small boats. n general, windlasses and their power system should be capable of lifting the anchor and all its rode (chain and rope) if deployed so that it hangs suspended in deep water. This task should be within the windlass: rated working pull, not i ts ma1imum pull. " super high holding po-er anchor is an anchor with a holding power of at least four times that of an ordinary stockless anchor of th e same mass. " super high holding power anchor is suitable for restricted service vessels use and does not require prior ad'ustment or special placement on the sea bed.

+igure: $tockless (0all:s) "nchor 9ayout (cross-section) of the anchor gear

1. Anchor chains and accessories

There are basically two types of ship anchors* the stockless anchor and stock anchors. +hains consist of chain links which can be either stud-links or studless links. The chain accessories include shackles (anchor shackle, 'oining shackle, kenter 'oining shackle, swivel shackle, Camfor connector, pear shackle, mooring shackle, swivel-forerunner, etc.) "n anchor cable is an assembly of a number of individual units properly secured together. These units are connected to the anchor by means of a swivel piece made up of shackles, swivels, and special link. ;ach shot or shackle (D%& m) of chain is 'oined together with a detachable link.

Prepared by: Dr. Md. Mashiur Rahaman, Assistant Professor, Dept. of NAME, BUET

NAME 429: Marine Engineering

+igure: +onnecting "nchor to "nchor +able

2. $ypes of chains 2.' tudlin% anchor&chain  is used for permanent and emergency anchoring of ships and other floating installation. The studs secure that every link comes into the gypsy (cable lifter), in correct position.

2.

tudless anchor chain

$tudless anchor chain is made to be used in permanent moorings when the chain wil l not go over a gypsy. The advantages are* less weight, fit bigger shackles without end-links and avoid problems with loose studs. $tudless anchor-chains are available in the same steel qualities as studlink anchor-chains. $tudless anchor-chains in every sie are supplied both for fish-farm mooring and off shore installations.

Prepared by: Dr. Md. Mashiur Rahaman, Assistant Professor, Dept. of NAME, BUET

NAME 429: Marine Engineering 8.

$ypes of anchor shac%les

Anchor hac%les & $ype D are used to connect the anchor to the anchorchain. The shackle requires a studless endlink at the chain-side, and fits the anchors crownshackle. "nchor-shackles Type ! ready in stock in most sies from dia yards of the center of the anchorage. ''. Anchor  Cable Wor%

"fter being instructed from the bridge by the officer, the ships Ioatswain releases the brake on the windlass and, with a clanging roar, the port anchor drops and the cable chain runs out through the hawse pipe. $i1 shackles of cable, attaching the anchor to the ship, have been run out. The vessel, drifting astern with the tide, pulls on the cable. The +hief Hfficer is leaning over the bows, directing a torch on the part of the cable that he can see. $lowly, it is lifting ahead, becomes taut, and is slackening again. The vessel is being brought up. When the 6aster orders 7!ead slow ahead8, the vessel is inching towards the lying ground of her port anchor. Then the +hief Hfficer on the forecastlehead says 7$lack away starboard cable, heave in port cable easy8. Three shackles of the starboard cable are being paid out and three of the port cable hove in, and the vessel, her engines stopped, comes to rest mid-way between her two anchors. This manoeuvre is known as making a standing moor. t means that the ship is put in a position between two anchors. To be moored indicates that a ship has been put in position by two or more anchors and cables. To be moored also implies that a vessel is attached to a buoy or two buoys. " vessel is also moored when she is made fast alongside (i.e. port or starboard side to) or bowstem on. " ship may be moored to a single buoy ($I6) or to a number of buoys (6ultiple-Iuoy 6ooring). When the ship is under way, the anchors are stowed in the hawse pipes, on either side of the ships bow (bower anchors). The cable runs through th e hawse pipe and is stored in the cable locker below the forecastlehead. "n anchor is also carried on the afterdeck and is called the spare anchor. The anchor is carried out by boat some distance from the ship and the vessel is then pulled up to it by means of the windlass or a winch. Iuoys and beacons are fi1ed into place by means of mooring anchors. +able is supplied in lengths of ninety feet, fifteen fathoms, and these lengths are called shackles of cable. Hur ship has ten shackles of cable attached to each bower anchor. n order to distinguish one shackle from another, the lugless shackle is painted white. (;ach length of cable is 'oined to the ne1t by a link which can be dismantled, and is called a lugless Prepared by: Dr. Md. Mashiur Rahaman, Assistant Professor, Dept. of NAME, BUET

NAME 429: Marine Engineering shackle.) 3eighbouring links are also painted white. The windlass is used to heave in or veer out the cable. t has two drums called gypsies. t is driven by electricity and equipped with powerful brakes. From the gyp sies the cable drops vertically through openings called th e spiralling gates into the chain lockers. /arious stoppers are used so that the pull of the anchor will not come on to the winch alone and that the anchor can be firmly secured when not in use. They are devices fi1ed on to the inboard end of the hawse pipes and are known as compressors.

7"nchor clear of the hawse pipe8 means that the anchor has been eased out of the hawse pipe and is hinging by its ring. The cable 7grows8 in the direction it leads outside the hawse pipe. 7Wind-rode8 means that a ship, when she is at anchor, is with her head to the windM 7tide-rode8 means that her head is to the tideM 7riding weather tide8 is when a ship is at anchor and the wind is against the tideM 7riding lee tide8 means that the wind and tide are in the same direction. When a cable is at short stay, it is taut and leads down to the anchor vertically and when it is at long stay it reaches out and makes an acute angle with the level of the water. To veer cable is to let it run out under controlM To surge cable is to let it run out under its own weightM To snub or check cable is to stop it running out by putting on the brake. When the anchor is weighed-broken from the ground and hove up clear of the water the officer in charge will report whether it is clear or foul. +lear means that it is free from obstructions such as a chain picked up from the bottom, and foul means that the cable has its own cable twisted around it. f a ship is moored in a good holding ground and the weather is fair, there is little to worry about. There are, however, a number of rules to bear in mind about anchor work generally, and managinghandling vessels at anchor in bad weather in particular. "n anchor is dragging when through stress of wind or tide it does not hold well, and is drawn along the bottom. '. chematics of various anchors

+igure: Types of "nchors

Prepared by: Dr. Md. Mashiur Rahaman, Assistant Professor, Dept. of NAME, BUET

NAME 429: Marine Engineering '3. chematic of se9uence of -eighing anchor

Prepared by: Dr. Md. Mashiur Rahaman, Assistant Professor, Dept. of NAME, BUET

NAME 429: Marine Engineering

Prepared by: Dr. Md. Mashiur Rahaman, Assistant Professor, Dept. of NAME, BUET