The system works simply, with a single right-angle HRP upper gearbox with silent mesh spiral bevel gears transmitting the power to a vertical, oil-lubricated propeller shaft.

The bronze propeller takes its water from the top and accelerates it downward.

The water is then deflected by means of an outlet nozzle and comes out under the keel of the ship, providing omnidirectional thrust. The outlet nozzle is suspended from a slew bearing, designed to lead the thrust forces into the ship. A hydraulic or an electric motor controls the steering.

Because of a relatively low intake speed of water there is virtually no chance of sucking in foreign objects, including divers, which makes the system well suited to diving support vessel applications. The compact, low noise system is maintenance friendly, the propeller can be withdrawn afloat separate from the steering gear/nozzle.

General performance is greater than 70% of what can be achieved by a normal propeller.

The new units are available in a power range of from 100 to 2,200kW and are delivered as an integrated package with either diesel, hydraulic or electric prime movers. HRP's in-house Controls Division supplies PCB based control systems, enhancing the microprocessorbased functions for self-thinking adjustments to achieve automatic fine tuning of steering characteristics. The systems can be interfaced with autopilot, joystick, and DP functions.

Possible applications include main propulsion units on shallow water ferries, auxiliary thrusters for research vessels and inland cargo ships, as a steerable bow thruster alternative to tunnel thrusters on work pontoons, sheerlegs or dredgers, and as a replacement of retractable azimuth type bow thrusters due to depth restrictions.

MJ Information No: 17233