General Description

The 241 waterjet is normally directly driven by a high r.p.m. diesel or 'big block' gasoline marine engines and can be used in planing and displacement craft or in a dual speed role as both loiter and high speed boost propulsion. With it's computer aided impeller designs the 241 waterjet can give high propulsive efficiencies, at least equivalent to the best propeller systems at planing speeds. Any number of jets can be employed without loss of propulsive efficiency. 

The waterjet mounts inboard at the stern, drawing water through an intake fixed to the hull bottom. The intake is protected by a highly developed screen which, at planing speeds, is largely self cleaning. An intake screen rake is optional. 

The pumping unit carries through the transom, where it is sealed with a rubber 'O'-ring seal, and discharges water directly aft through the outlet nozzle. The reaction of the water being thrust rearwards generates a powerful forward thrust which is fully transmitted through the intake base to the hull (no thrust is transmitted to the engine via the driveshaft).

Steering A steerable nozzle deflects the water to port and starboard, giving powerful steering. Steering is actuated via an inboard mounted tiller. Preferred control is by a manual hydraulic  system however, less effcient rotary cable steering is optional. 

Reverse A split duct thrust reversing deflector cuts the jetstream aft of the steering deflector, providing an infinite range of ahead, zero or astern manoeuvring speeds. Control is by a cable operated Hydraulic Servo Reverse Control (HSRX) system - a follow up system where the reverse deflector "follows" control lever movement. The HSRX system comes complete with hydraulic powerpack (JHPU) and oil cooler integral with the jet. 

Full steerage is always available regardless of reversing duct position i.e. regardless of of speed or direction. By working reverse and steering in unison a resultant thrust can be obtained in any direction giving 360 degrees manoeuvring. 

Designed and manufactured in corrosion resistant materials to international standards, 241 waterjets are further protected by fitting of sacraficial anodes. The units are supplied factory tested as a complete package including  integral steering and revese systems with controls and powerpack. 

Installation is simplified as an aluminium intake base is supplied which is fixed into the hull and forms the correct jet inlet shape and mounting for the builder. This block welds into aluminium hull or is molded into G.R.P. or wooden hulls. The GRP version eliminates the need for builders to mould a thick GRP block. This system saves boat builders both time and money. 

A gearbox is not necessary as the waterjet matches a large range of common marine engines directly driven off the engine's flywheel. The engine should be left hand rotation (anti-clockwise when looking on the engine flywheel).

Extensively tested in both HamiltonJet's water tunnel and test craft, the 241 waterjet is an ideal propulsion unit for high speed work and patrol boats, and pleasure carft where operators require proven performance and reliability.

241

Because engine overload does not occur and appendage drag is eliminated, model 241 waterjets are a simple solution ot multiple speed capability such as loiter and/or boost functions, whether mixed with other size waterjets or other types of propulsion systems.