Modern high speed craft, propelled by waterjets with flush inlets, often show unsatisfactory directional stability due to insufficient aft underwater lateral area, when compared with propeller driven hulls having appendages such as rudders, shaft brackets and skegs. In beam and quartering winds, it is the rule rather than the exception that waterjet-propelled vessels, despite frequent corrective steering by means of large jet deflections, have difficulty in keeping straight course while maintaining high speed. Humphree’s steering systems offer the perfect solution to overcome this major shortcoming of today’s marine waterjet propulsion systems.

Whether applied to a large semi-planing vessel or a planing craft, Humphree’s steering systems provide alternative steering control.

A steering interceptor generates an increase in pressure on the side of the hull or fin directly ahead of the transom or fin’s base by intercepting the flow with a blade. As the blade only has to extend a few millimetres outside the side edge to substantially raise the pressure over a large area, this results in a high hydrodynamic lift while the smallness of the projected blade, despite being subject to high pressure, results in low hydrodynamic drag. This drag, when compared to the loss of thrust associated with waterjet steering is practically negligible.

The benefits with Humphree’s virtually loss-free steering systems are:

• Impressive course keeping and general handling
• Increased speed and vessel range
• Improved fuel economy
• Increased passenger comfort in all seaways
• Reduced structural loadings on hull and waterjets
• Added steering force and increased safety
• Actuator power reduced by a factor of 100