Two types of wheel-steering rigs are commonly used in a sailing yachts over 30 feet - the chain-and-sprocket system (left) and the worm steering gear (below). Both types provide the helmsman with some basic advantages over a tiller. Because of the mechanical advantage inherent in its design, a wheel with, say, a two-foot diameter gives the helmsman four times more turning force on the rudder than would a typical four-foot-long tiller. Moreover, a wheel can be mounted practically anywhere in a vessel, affording the helmsman better visibility and shelter than does a tiller.

The chain-and-sprocket steerer is the more sensitive of the two predominant wheel rigs. The worm-gear rig is a plow horse by comparison - less responsive than its rival but also more hardy.

Hydraulic boost on a motor yacht

Hydraulic steering, designed for motor cruisers over 30 feet, differs significantly from both the drum-and-cable and rack-and-pinion systems in that it utilizes a basic power source other than human muscle.

The heart of the system is a pump powered by the engine and mounted at the steering wheel. Depending on which way the wheel is turned, the pump forces hydraulic fluid-stored in a central reservoir - through one or the other of a pair of metal tubes leading toward the rudders. There, a cylinder manipulates the rudders by extending or retracting its piston arm in response to the varying fluid pressure. A relief valve helps control the pressure of the fluid.

Hydraulic steering permits multiple steering stations - and has some additional advantages all its own. The system is designed so that the fluid exerts pressure only on the rudder, never the helm. Hence the wheel always moves easily - a factor that is as desirable on a large motor yacht as sensitivity is in a sailing yacht. Moreover, the system is capable of enormous power - the only limit being the space available for larger pumps and cylinders.