An autopilot is almost a necessity for either a cruiser or a single hand sailor.  I do a fair amount of both.   The installation is fairly straight forward though a little more complicated for the wheel pilot compared to a tiller pilot.  The price is also considerably different.

I chose the Raytheon which is now Ray Marine.  It has a stand alone control head that mounts on the bulkhead or in a pedestal pod.  I chose to add the full feature remote.   The pilot uses a fluxgate compass which must be mounted in a free from magnetic influence environment.

The pilot is connected electrically to a Seatalk or NMEA bus for communication with the GPS and other NMEA devices on the boat such as wind, sounder, or speed instruments.

Connected to the GPS, the autopilot is able to perform track functions and will move from one waypoint to another of a gps route which is activated.  It does require user input once a turn is needed so it doesn't turn unexpectedly throwing someone overboard.

A wheel pilot eliminates the need for a wheel brake as engaging the clutch serves the same purpose.

A couple of quirks of the installation are that the actuator motor on the c250 pedestal has to be mounted on the port side at 10 o'clock to the wheel rather than the usual position at 5 o'clock considerably farther from the compass.  The result is that the compass has a tremendous amount of deviation, far too much to set a course with and probably too much to swing (adjust the compass). 

A wet compass is far easier and more desirable to helm to than an electronic set of numbers on the gps or auto pilot head and one might think that significant deviation eliminates use of the wet compass.  It actually doesn't present much of a problem because a course is taken  using the gps and then the compass noted and steered to regardless of deviation.  If its off 30 degrees... it doesn't matter.  The fluxgate compass heading is available on the autopilot head as well. 

The other quirk is that the Garmin 125 gps / sounder combo doesn't interface sounder data as NMEA and therefore the sounder data is not read on the remote.

In this picture, the full feature remote unit is shown to the left of the gps.  It will show all information conforming to SeaTalk or NMEA.  The round black object between the gps and the vhf radio is the back cover for the autopilot control head.  On it is mounted a buzzer(siren) from radio shack.  It is driven by the gps and will announce both sounder and proximity to waypoint alarms and do so very loudly.  A very neat feature is the the flexibility of the control head screen selections.  A favorite of mine is to monitor the XTE (cross track error) which allows staying very near the rhumb line between two waypoints.  Also note the gps/sounder unit mounted inside on a stud.  To mount outside, it simply connects around to the outside with no need to disconnect any of its three wires.  This is a cheap take off of a swing mount and it stays more out of the way.  Last, a DB-9 pigtail & connector can be seen hanging from the wire harness of the gps.  It interfaces the lap top to the gps for moving map display or loading waypoints/routes into the gps from the computer charting software.