Seiwa SW AP01 - Manual (Page 7)

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CHAPTER 1 SYSTEM DESCRIPTION
1.1 INTRODUCTION TO AUTOPILOTS
The main function of a marine autopilot is to hold the heading of a vessel on a reference
course which is held in the memory of the autopilot. When it is operating, the autopilot
continuously compares the vessel’s heading with a reference course, and if they are
different, it applies helm to bring the vessel back on course. Since there has to be a
compromise between the accuracy of course holding and the activity of the rudder, the
autopilot has controls which let the user set the balance between these two factors.
The four basic components of an autopilot are a compass, an electronic control box, a
rudder angle sensor (transducer) and the steering drive. See Fig 1.1. In a SW AP system,
the electronics are housed in two cases - a Junction Box containing most of the system and
a Controller (Control Head), which is mounted near the steering station.
Figure 1.1 Basic components of a marine autopilot.
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