Paper 20. Improvement of Control by Special Devices

The paper discusses hydrodynamic devices for improving manoeuvring and control. Two hydrodynamic concepts are shown to be of practical significance for large craft: control of hydrofoil lift independent of incidence, and deflection of the propulsion jet through a large angle by means of a simple hydrofoil. Lift control independent of incidence is illustrated by the jet flap and the trailing edge rotating cylinder. Improved deflection of the propeller slipstream involves extending the rudder stall angle, and it is shown how this may be achieved by fitting the rudder with a leading edge rotating cylinder.