Page 113 - Electronic Navigation Cyber Book

CHAPTER 10 AUTOPILOT

An autopilot (autohelm ) is a mechanical, electrical or hydraulic system
which can maintain a vessel on a predetermined course without the need
for human intervention. Using a direct or indirect connection with a
vessel’s steering mechanism, the autopilot relieves the crew from the
task of manually steering the yacht. On sailing boats certain types of
autopilot can be programmed to maintain a course defined at a pre-set
angle to the wind.

An autopilot can improve the profit margin of a vessel in two ways. First,
it enables a reduction to be made in the number of ships' personnel, and
second, a considerable saving in fuel can be achieved if the vessel
makes good its course with little deviation.

The most basic autopilots are simply linked to an electronic compass and
are set to maintain a fixed compass course.
More sophisticated units incorporate processors which contain advanced
software algorithms as well as an integral compass to combine position
and navigation data from the GPS chart-plotter with wind, speed and
depth data from the instrument system. The result is smooth control of
the boat’s rudder providing accurate steering performance in all sea
conditions.

The basis on which autopilot functions is the optimum adaption of its
control behavior to the dynamic characteristics of the ship with, however,
only manual input of sea and weather conditions as assessed by the
operator. That is to say, the adaptive autopilot, after the operator has
selected a steering strategy suitable to the prevailing sea and weather
conditions (confined waters, open sea, rough seas), will adapt itself to an
optimum to the behavior of the ship.

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