By combining its established interceptor system for waterjets with the Vector Stick control.

Rolls-Royce has produced a joystick system for Kamewa FF waterjets which gives precise five axis control of the boat at both high and low speeds.

Vector Stick-IIC integrates the control of interceptors placed under the external part of each waterjet with the steering nozzles, reversing buckets and engine rpm. By using an advanced algorithm in the control software, the net yawning and rolling forces applied to the boat are independent of each other, giving the operator a high level of control and quick, effective, exact steering.

In practice, if a small steering correction is required, the interceptor of one waterjet unit is moved slightly and there is no movement of the steering nozzles. This provides sensitive control. Average boat speed is simultaneously improved and fuel consumption minimised because all of the jet thrust is applied to pushing the boat forwards. However, in a hard turn the jet nozzles swivel to steer the boat while the interceptors determine how much the boat banks into the turn whilst also improving craft stability.

These functions are provided on the main joystick of the Vector Stick-IIC system, which also has two different operating modes. At speed the joystick controls the boat in the normal way, but for docking it can be switched to the manoeuvre mode. The control logic then works the jets so that the boat goes in the same direction as the joystick is moved.

Vector Stick-IIC has been subjected to intensive trials installed in a 46 knot prototype Response Boat-Medium (RB-M) for the US Coast Guard. This 14.7m long, 14.6 ton craft was built by Kvichak Marine to a Camarc design and is propelled by two Kamewa FF375S waterjets, each powered by a 615kW engine.

Boat handling qualities are reported as excellent, the interceptors playing a major part in reducing rolling. Use of interceptors also gives significant course altering capability without losing speed.

A Vector Stick-IIC system is also installed in a 39 knot ambulance boat owned by Rodne & Sonner and in service on the coast of Norway. The 18m vessel uses carbon fibre sandwich construction for hull and superstructure and is equipped with two Kamewa FF410 waterjets, each rated at 615kW.

MJInformation No: 22006