Revised by BoatUS editors in April 2012
Image courtesy of West Marine
An autopilot will immensely add to your boating pleasure. A good autopilot can give you the freedom to read charts and instruments, plot courses, or just enjoy lunch! Once considered a luxury, the autopilot has slowly become a staple of electronic gear. (Of course, the convenience of an autopilot doesn't relieve the skipper of the responsibility for keeping a proper lookout and monitoring the boat’s systems and operation.)
Recent technological advances have made autopilots more practical and more affordable. Plus, with modern circuitry and electronic wizardry, their power drain is much less than earlier models.
Autopilot manufacturers publish tables to help you select the right type and size unit for your boat. Remember, these are general guidelines. Problems arise when a boater purchases a unit that is inadequate for anything but calm, friendly conditions. You'll really appreciate a good autopilot when seas are difficult and you need another pair of hands to steer the boat, at least temporarily. However, a weakness with many autopilots is that they have a difficult time steering well with a following sea. There may be instances when you simply have to do it yourself and you should be prepared to do so. The following questions will help to determine the autopilot for your boat
- What type of vessel do you have? Sail or power? Planing or displacement hull?
- What is the size of your vessel or its displacement?
- What is your hull configuration. Full keel? Flat bottom? Etc.
- What is the speed you usually travel?
- Do you have hydraulic or mechanical steering?
- If hydraulic, what is your RAM size? This is the hydraulic device that actually does the pushing and pulling.
Sometimes more complicated information, such as helm resistance, is needed in order to select an autopilot for mechanical steering. And most autopilots today can be adjusted to perform optimally for different boat characteristics. For example, the speed of rudder response to a course deviation and the rate of rudder turn can often be adjusted to correlate with the characteristics of the boat. But equipped with the above information, you are more than likely to select the correct autopilot for your boat. Autopilot manufacturers are your best source of information for assuring that you get the right unit.
We are primarily referring to electric autopilots, however, many long range sailors use wind vanes which steer the boat relative to the angle of wind. These are seldom used for typical short distance cruising of most sail boaters, because they require attention anytime the wind shifts. But for long ocean trips many sailors love them.
Interfaces can connect the autopilot to a GPS or GPS chart plotter so it can follow a course to a waypoint, or correct for set and drift. Also, typically, with the correct interface, you can set up a trip on the chart plotter, with course changes at different points, and the chart plotter will control the autopilot so that it stays on the course, including making the course changes at the proper location. Compatibility of equipment and the proper interfaces are, of course, critical here, and you should consult the manufacturers or qualified marine electronics professionals before you buy. Qualified professional help is often needed in the installations, but this will soon pay for itself in the pleasure and assistance you get from a well working system.
A handheld remote control allows you to control the helm and make course changes from anywhere in the cockpit (but always keep watch around and of your systems). Dodge capability allows you to make quick, temporary course changes to avoid a floating object or another boat. A man overboard function (usually found on the GPS) lets you push a button for a hopefully accurate range and bearing back to the victim. An off-course alarm can signal you if, for some reason, (such as malfunction or extreme current or sea changes) you go off course to a significant extent. An alarm may also warn you if an extreme course change is required, for example, by input from the chart plotter or a sudden veering of the boat caused by extreme current change or sea state. This is important for several reasons, including, for example, that said extreme course change may put you in harm’s way with another boat or with the bottom. A watch alarm can prevent dozing by making you push a button every few minutes to prevent the alarm from sounding. And models usually have a manual override so that you can turn a dial or other component for power-assisted manual steering control.