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.
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