Autopilots have developed rapidly in the past 20 years. Mechanical and hydraulic actuator arms evolved quickly to their present state of power and reliability, electronic fluxgate compasses became more sensitive, and the control units were offered with remote hand-held controllers. Now, however, the advances in autopilots are not as easy to see, because the focus of development is control software, even using artificial intelligence techniques. The drive is on to make smarter autopilots that can “learn.”
Autopilot use has grown enormously in recent decades. The U.S. Navy has used them for years and merchant fleet ships are on autopilot most of the time. Long-distance ocean racers also are big users of autopilots. Many solo circumnavigating racers have dual autopilots installed to ensure that they always have one system available. It has been said that self-steering is a cornerstone of bluewater voyaging, and that if manual steering were the only option, there would be a lot fewer long-distance sailors.
For the Navy and the commercial vessels, the reasons for autopilot use are primarily time and fuel savings. For ocean racers, it’s time saved by optimizing the route. But what about long-distance voyagers? They’re not, as a rule, in a great hurry to reach their destination. But if you’ve ever spent long tedious hours, day after day, standing at the helm, making continual, never-ending small adjustments to the wheel to keep the boat on track, you understand that the autopilot reduces boredom and fatigue.
Another excellent reason is safety. A prudent sailor must be prepared to single-hand his or her boat. Seasickness, illness or an accident could incapacitate you or your partner, leaving one person to handle everything on the boat. Fatigue is the number-one cause of short-handed or single-handed boats going aground or being involved in collisions while making landfall. Ideally, a serious offshore voyaging boat will have – as a start – manageable sails, appropriately rigged; a dependable wind-vane self-steering system; and because wind vanes are vulnerable to damage and capable of steering only at preset angles relative to the apparent wind, a powerful autopilot.
Autopilots consist of three principle elements: heading sensor(s), control unit and actuator. Early autopilots simply zigzagged the boat across a set course. A compass card bearing electrical contacts (the heading sensor) detected an off-course condition by closing the contacts and sending an electric current to a junction box (the controller), which energized a motor-driven gearing system (the actuator), which moved the rudder to compensate for the course error. The boat would swing back, through its set course, reach the limit contacts on the other side and repeat the process. These systems were popularly known as “hunters.” They were predominantly electro-mechanical and not very accurate or reliable. Parts wore, contacts corroded and failures occurred. Accuracy was somewhere between 5° and 15°. The advent of solid-state electronics brought with it great strides in reliability, accuracy and size reduction, primarily in the area of heading sensing and control.
Most autopilots offer essentially the same basic keypad functions – course selection, operations mode, rudder gain, yaw and dodge – and feature the same alarm and emergency options: Off Course, Man Overboard, and others. Many current autopilots are capable of adjusting the compass automatically so it provides accurate readings and headings. However, the focus now is on the development of new and innovative algorithms; software programs for executing various boat-handling and sailing maneuvers automatically; and integrating these so they all work together, each as the occasion demands or the need arises.
Unfortunately, there has been no industry standardization of terminology and little common use of terms. Raymarine’s SmartPilot Series, advanced steering technology (AST) is a case in point. AST will automatically and continually monitor the pitch and roll of the vessel, anticipate course changes, and execute crisp and timely course changes with no vessel overshoot or instability. This is especially useful when sailing downwind in a following sea. AST also incorporates a software algorithm Raymarine calls AutoLearn, which actually learns the vessel’s steering characteristics, enabling the autopilot to continuously adapt to changing sea conditions and automatically set up the autopilot for optimum performance. ComNav has a similar feature it calls IST, or intelligent steering technology.