My first experience with an autopilot was in the cockpit of a Piper Archer II fixed gear low wing aircraft. I didn’t really care much for it. Sure. It maintained a course. I felt more comfortable, however, with my hand on the “stick” as I was more prepared to quickly deal with updrafts and downdrafts. I remember one occasion, on autopilot, when the starboard wing dropped more than 60 degrees. It seemed that I may have been subjected to wake turbulence. At any rate, it was rather disturbing to be reaching for the stick and switching off the autopilot to regain control of the aircraft looking starboard and seeing ground and sensing airflow had been disrupted. That was the last time I employed autopilot in an aircraft. I’m sure the autopilot systems on aircraft these days are much more refined. In fact, it’s the autopilot managed by a pilot that does most of the work when you fly commercial aviation.
Employing autopilot on a sailboat is an entirely different experience. I find it quite useful at times and I’m now comfortable giving the steering of the vessel over to the electronic helmsman.
I principally use the autopilot when single-handling. I activate it after selecting a direction into the wind, while motoring, and ensure there is no vessel traffic just prior to going to the forward part of the cockpit to unfurl the main sail. Of course, while cranking the winch, I’m periodically checking for traffic. I then go to the aft part of the cockpit and unfurl the head sail. I turn off the autopilot, bear away to begin sailing, shut off the engine, and enjoy the day. I resume the autopilot, in pretty much the same way, when it’s time to take in the sails.
I have used the autopilot when motoring and must leave the cockpit for some reason. I’m usually tethered to the boat. The “coast is clear” as I would never leave the helm with even the slightest chance of another vessel, shore, dock, buoy or some other potentially dangerous object coming anywhere close to my vessel.
The autopilot is also useful in the ocean, provided the swell is minimal, when motoring along on a course for an extended period of time. A person at the helm is not going to be able to steer a course as accurately as would the autopilot due to many factors including fatigue, distractions, etc.
One thing that must be kept in mind is that the autopilot does not have eyes. It cannot see outside the vessel. That is perhaps less of a problem in the middle of the ocean. There are, however, other boats out there so vigilance is always a good idea.
I wrote, in a previous blog, about a skipper believing his vessel had a steering failure when, in fact, the autopilot had been inadvertently switched on and locked the steering on course. Try to turn the wheel at your helm with the autopilot engaged so you have the feel for this happenstance should you find yourself in a similar situation.
The autopilot system is attached to the steering system by way of a driver that actuates the course changes. The driver is mechanical linear drive by Raymarine that is attached to the starboard side of the quadrant. Of course, given the autopilot steers a course, the system must have an electronic compass. A computer does all of the work in regards to maintenance of course, user input changes, etc. A sensor is attached to the port side of the quadrant so that the computer knows the rudder position. An autopilot controller is located at the helm to permit activation, course changes, and more.
Once the unit components were installed on my vessel, to upgrade to a newer system, it had to be calibrated to ensure accuracy during use. That process was rather interesting and required putting the vessel through different maneuvers to train the system to the rudder and more. My friend Paul McGraw and I delighted in this sea trial and we learned a lot.
The helm. Lovely wheel, compass, and autopilot controller. 
The autopilot controller. 
Steering cables passing under a sheave and then aft through the upper reaches of the engine compartment. 
A sheave guide of the cables located in the aft stateroom. 
The quadrant. The rudder post is located in the middle on top of the “disc” of the quadrant. the emergency tiller attaches to this post. The driver rod is under the quadrant off to the left of the photo. 
The rudder sensor is attached to the quadrant. 
Underneath the quadrant where the rudder post passes through the hull. 
The autopilot computer.
I was prompted to take these photographs and blog about this topic during my inspection of the steering systems. All pieces parts seemed to be in good condition and working order. That’s added security when sailing!
