Hamilton Jet.pdf

March 7, 2019 | Author: David.Quijano | Category: Jet Engine, Hull (Watercraft), Water Transport, Mechanical Engineering, Ships
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Product Line and Selection Guide

General Information

The Waterjet Difference In the modern world, waterjets have rapidly gained acceptance as the leading means of propulsion for all types of high speed craft -ferries, workboats, patrol craft, yachts etc. Recent advances in waterjet technology put them ahead of conventional pro peller systems in both performance and reliability. Ride in a modern water jet powered craft and the difference is obvious -rapid acceleration, higher speed, shallow draft capabilit y, unrivaled maneuverability and smooth, quiet operation. Add to these lower maintenance, longer engine life and easy installation and the advantages over propellers with their inherent shortcomings of  vibration, engine overloading and susceptibility to damage are obvious.

Hamilton Jet Overview Hamilton Jet pioneered commercial development of the modern waterjet in the early 1950’s and today, have over 30,000 jets installed worldwide. With a complete range of models for power inputs ranging up to 4700hp per unit, Hamilton waterjets are ideally suited for the efficient propulsion of a wide variety of high speed work and patrol  boats, fast passenger ferries and pleasure cruisers, typically in the 20 to 200 feet size range. Hamilton Jet is dedicated to the production of the highest quality jets and all models are designed and manufactured to meet the requirements of the world’s leading certifying authorities. Full logistic support for all projects is provided by the Hamilton organization and its extensive network of factory trained distributors who can be found in over 50 locations worldwide.

Today’s Waterjet Unit Mounted partly inboard at the stern of the vessel, the Hamilton waterjet consists of a totally integrated package with steering, reverse and hydraulic control system included. Water is drawn through an inlet screen at the  base of the intake or transition which is mounted flush with the hull bottom. The pumping unit accelerates the water rearwards where it is discharged through the outlet nozzle, creating a powerful forward thrust. A single piece balanced steering deflector directs the flow to port or starboard as commanded at the helm giving maximum turning force. The separate split-duct reverse deflector, usually hydraulically driven, redirects the water forward and underneath the boat giving powerful astern thrust. The follow-up control system allows intermediate positioning of the reverse deflector for “zero speed” while maintaining full steering capacity.

Typical Applications With over 30,000 installations worldwide, Hamilton Jet propulsion systems are well proven for providing efficiency, reliability and flexibility in a wide range of hull forms. With models available to suit speeds in excess of 60 knots and power inputs ranging from 200 to 4700hp, Hamilton waterjets can be used in single or multiple configurations in vessels typically up to 200 feet long as main propulsion system, or as boost or loiter propulsion. Fast Passenger Ferries, Work Boats, Patrol Craft, Rescue Craft, Military Support Craft, Pilot Boats, Recreational Cruisers and Fishing Boats are just a few of the typical applications of the Hamilton Waterjet.

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 Advantages Waterjet propulsion has many advantages over other forms of marine propulsion, such as stern drives, outboard motors, shafted propellers and surface drives. These advantages include...

Excellent Maneuverability  • Precise steering control at all speeds • "Zero Speed" steering provides 360° thrusting ability for docking and holding stationary. • Sideways movement possible with multiple jet installations. • High efficiency astern thrust with "power-braking" ability at speed High efficiency  • Propulsive coefficients as good or higher than the best propeller systems achievable at medium to high planing speeds • Low drag and shallow draft • Absence of underwater appendages reduces hull resistance. Jet intake is flush with hull bottom to afford minimum draft Total safety  • No exposed propeller for complete safety around people in the water • Low maintenance • No protruding propulsion gear eliminates impact damage or snags • Minimum downtime and simple maintenance routines Smooth and quiet • No hull vibration, no torque effect and no high speed cavitation gives maximum comfort levels on board • Low underwater acoustic signature Maximum engine life • Jet unit impeller is finely matched to engine power • Power absorption is the same regardless of boat speed • No possibility of engine overload under any conditions Simplicity  • Single packaged module • No heavy and expensive gearbox required for many installations. Simple driveline from engine to jet coupling Easy installation • Complete factory tested package, ready to bolt in • No difficult engine alignment problems Hamilton waterjets have several advantages over other waterjet makes. These include...

Superior cavitation resistance • Pump design offers up to 25% more thrust than other waterjets between 0 and 20 knots. Maneuverability at low speeds & acceleration to high speeds are superior. Precise steering control • The unique JT steering nozzle minimizes thrust loss when steering. No central dead  band provides higher course-keeping efficiency and higher overall boat speeds.

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Hamilton Waterjet Features Complete Integrated Design

Optimized Controls Package

Each Hamilton waterjet is a single packaged propulsion module providing thrusting, steering and ahead/astern functions. All functions are optimized then integrated into the single package for maximum effectiveness. On models which offer hydraulically actuated astern function, the hydraulic power system in an integrated part of  the jet, incorporating hydraulic pump driven by the mainshaft, oil cooler cast into the intake, hydraulic piping and control valves. The system is setup to be fully proportional so the astern deflector movement follows that of the control lever and is fully factory adjusted and tested.

To interface between the control station(s) and the jets, a number of control system options are available. Depending on the jet model, these range from simple push/pull cables to sophisticated microprocessor driven electronic systems.

Proven Practicality  The intake is an integral part of the Hamilton Jet design. This section is of robust cast construction capable of  transmitting the full force of the generated thrust to the hull bottom, not the transom or engine via the driveshaft. The main thrust bearing is incorporated in this rigid structure and is unaffected by hull movement. All Hamilton waterjets include an intake protection screen and this feature is engineered into the design so that operational parameters such as cavitation resistance are unaffected by its presence.

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High Propulsive Efficiency  The impeller design employed in Hamilton waterjets is a highly refined inducer style, capable of pumping large volumes of water at relatively low pressures, permitting very high propulsive coefficients to be achieved at fast boat speeds with outstanding resistance to cavitation. The impeller runs within a removable stainless steel wearing, with the whole design permitting easy routine maintenance to be carried out insitu. Water flow exiting the impeller passes through stator vanes where the rotational elements are removed so a straight uniform flow pattern is presented to the discharge nozzle.

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Hamilton Waterjet Features International Design Standards

Maximum Astern Thrust

All Hamilton waterjets are designed and manufactured to meet the requirements of the world’s leading certifying authorities. Materials renowned for strength and resistance to corrosion, such as LM6 aluminum, SAF2205 and CF8M stainless steel are used extensively and in models suitable for use in permanently moored craft, an integral cathodic protection system using pure zinc anodes is incorporated.

Ahead/astern function is an integral part of the Hamilton Jet package. The split duct astern deflector is designed to provide maximum astern thrust under all conditions of boat speed, water depth and throttle opening. A splitter is incorporated in the deflector to divide the flow and angle the astern jet stream down to clear the transom, and to the sides to retain a steering thrust component. This arrangement vectors the astern jet stream away from the jet intake, avoiding recycling and producing a powerful astern thrust which can be maintained up to high throttle settings.

Balanced Powerful Steering The balanced steering deflector is a separate but integral part of the Hamilton Jet design. Deflecting the jet stream to port or starboard in response to helm commands, the deflector is designed to maximize lateral thrust with minimal loss of forward thrust, whilst maintaining lightest operating loads for highly responsive steering control.

Precise Vessel Control

Large Range – Optimum Sizing

Like propeller diameter in conventional drive systems, nozzle diameter is the key to achieving the best propulsive efficiency. Because of the size of the Hamilton Jet range, the large number of effective nozzle sizes available enables the most effective propulsion option to be selected for all applications. Computerized selection, taking into account factors such as speed, power input, fuel load, lifetime propulsion costs etc, are possible.

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The separation of steering and ahead/astern functions permits the independent effects to be used in conjunction with each other to achieve complex vessel maneuver. With the astern deflector fully raised, full ahead thrust is available. In the fully lowered position, full astern thrust is generated. In all positions full independent steering effect is available for rotating the craft. By setting the astern deflector in the intermediate “zero-speed” position, thrusts are equalized for holding the vessel on station but with full steering effect still available. Infinitely variable adjustment of the astern deflector either side of “zerospeed” enables the craft to be crept ahead or astern resulting in unparalleled vessel control and maneuverability.

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 Applications Suitable Hull Forms In general the hull shape, whether monohull or multihull, should be that which best suits the size, displacement and cruising speed of the craft but, with the following prerequisites: • hull shape and appendages must avoid entraining air into the waterjet inlet. • if no keeling is proposed, the hull shape must be directionally stable without such appendages. • there should be no appendages such as keels, rudders, planing strakes, water-pickups etc. for at least 6.5 feet in front of the waterjet intake. These appendages can however generally be placed to the outside of the projected area in front of the waterjet inlet(s) without affecting their performance. • in order to prime (pump water when driven) the water level must be at least up to the waterjet mainshaft when the craft is at rest. • Hamilton Jet should be consulted in all cases before construction starts.

High (“Planing”) Speed Craft (over 30 knots) For best directional stability and speed, a hull with monohedron lines (constant deadrise over the aft planing area) is recommended. Deep and fine bow stems should be avoided as, without additional keeling, these can cause directional instability at speeds over 25 knots. Also for directional stability and to avoid air being entrained into the waterjet from bow waves, deadrise angles of between 10° and 25° are generally recommended.

Medium Speed Craft (10 to 30 knots but increasing with length) Low trim angles, particularly in conjunction with slender hulls of high length to beam ratio are best suited.

Semi-Displacement Hulls with beam narrowing and bottom lines rising towards the transom are suitable provided there is sufficient immersion for the waterjet(s) to prime when the craft is at rest. For best speed, take care to maintain the LCG well forward, especially with round bilge hulls. Warped Hulls with reducing deadrise angles going aft can reduce trim angles and thus hull resistance in the semi-planing speed range, improving load carrying ability. Catamarans, of both semi-planing and semi-displacement types, can perform well in this speed range provided they obtain low running trim angles. Keeling – due to moderate dead rise and immersion aft and deeper vee forward sections, some keeling aft may  be required to maintain directional stability.

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 Applications Slow Speed Craft (0 to 10 knots but increasing with length) Slow (or ‘Displacement’) speed craft operate at speeds where the water is displaced around and underneath their hull and no significant lift or planing effect is generated. Craft speed is limited by the Water Line Length (LWL) and efficient speed hull shape rather than shaft power. Natural Displacement Speed (NDS), a function of the craft’s Water Line Length (LWL), is the speed at which dynamic lift, and thus planing effects, commence. At speeds up to NDS, very modest shaft power is required and acceptable propulsive efficiencies can thus be obtained with relatively small waterjets. Slender hulls, having higher length to beam ratios, are recommended as they are more easily driven. True efficient ‘displacement’ speed craft, refer “Low Resistance” below, are designed to generate minimal bow and stern waves with narrowing beam and rising bottom lines towards the transom. Any less efficient slow speed hull forms can however be operated at their inherently reduced NDS’s, refer “High Resistance” below.

High Resistance Low length to beam ratio (>3:1) Large area of submerged transom Heavy displacement Flat, non-vee’d bow shape (such as scow type  bow commonly used on landing craft/barges)

Low Resistance High length to beam ration (3:1) • Large area of submerged transom • Heavy displacement • Flat, non-vee’d bow shape (such as scow type bow commonly used on landing craft/barges).

Low Resistance • High length to beam ratio (
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