How does autopilot work on a boat

The main options are a hydraulic system, a mechanical linear drive, or a rotary drive. The latter is aim at predominately older vessels with chain and sprocket type wheel steering systems. Hydraulic and linear mechanical drives can be permanently attached to the quadrant, but allow for instant transitions between using the pilot and hand steering without disconnecting any hardware. Advantages of the hydraulic option include fast lock to lock times and incredible power, especially on larger models.

They are well proven in the field, with excellent levels of intrinsic reliability, but tend to be more power hungry than mechanical drives. Tiller steered boats are unlikely to have a quadrant below decks unless the model was also offered with wheel steering, or has twin rudders.

The latter is a mechanical system with a powerful electric motor, mounted in a dry location below deck, driving a Bowden cable connected to the tiller. A clutch releases when the system is switched to standby, allowing hand steering with almost imperceptible additional friction from the drag of the cable.

It can also be used in conjunction with an outboard motor on RIBs and other powered craft, or attached to a conventional quadrant in installations with restricted space. Manufacturers of all types of self steering gear generally quote recommendations by boat size and length. In addition, even boats of a modest size tend to collect a significant weight of additional gear, supplies and crew weight that can easily add a further 20 per cent to the total weight of the boat that must be considered when the pilot is specified.

Pilots are controlled via a keypad and instrument display, which may be combined within a single module, as with the 70 series control heads for Raymarine autopilots, or be provide as two separate items. In addition, an increasing number of MFDs Multifunction displays have the facility to control a networked pilot.

Control pads need to be mounted within easy reach of the helm, when on either tack for sailboats, while flybridge powerboats will need one at each helm station. Many manufacturers also offer remote units that enable users to change course from anywhere on board. In some cases, it also allows you to pre-program helpful directions; some units have dedicated trolling patterns for anglers, or the ability to detect via networking and follow specific bottom contours.

However, those with older systems that output only NMEA data are at a disadvantage as the wiring is significantly more convoluted and the protocol will only support a relatively small number of devices.

Given the reliance on the pilot, power management on a sail boat is an important consideration for any passage of more than around hours.

This can be particularly true for lower specification units that struggle to keep the boat on course, thereby using more power than a system that will steer a better line. For long offshore voyages back-up charging options are also important to consider.

For some crews this will be little more than an inconvenience, however, for weaker, less experienced or short handed sailors it has the potential to create significant problems, especially on long passages.

Installing a second unit that can be engaged at the flick of a switch therefore makes a lot of sense. However, even that is by no means a fail-safe panacea if it relies on the same instrument data stream and charging system as the main unit. There are legions of boats with a second pilot drive that has sat festering in a damp locker for months, or even years, and no longer has any chance of functioning.

For boats travelling very long distances with a small crew a wind pilot is therefore still a popular option that provides a completely independent back up that will work even in the event of total power failure. No pilot will work efficiently on a sailing boat if the sail plan is not well balanced. Paying careful attention to sail trim, including shortening sail in good time as the wind increases, is crucial to the ease of steering the boat and the performance of all types of self-steering systems.

Many electric pilots allow you to tweak a range of settings to enable the unit to maintain an efficient course across a wide range of conditions. The bottom line? There was a time at which any long-distance voyaging boat would sport a windvane self steering gear on the transom. They tend to be robust, often requiring servicing only after tens of thousands of miles, require no electrical input, and can often be easily fixed using locally sourced parts and labour even in remote parts of the world.

These remain undeniable advantages in today's world, and many seasoned skippers swear by their wind vane gear for good reason. On the downside, the upfront cost can be relatively expensive, and windvanes tend not to be effective sailing downwind in light airs, when the apparent wind is low, and are useless for motoring in a calm when the apparent wind is always from ahead, irrespective of your course. For this reason many yachts with a windvane system will also carry an electric pilot, although the latter does not need to be of a high specification as it will only be used in easy conditions.

Here are some of the ways that your autopilot can find out how to steer your boat well:. Operating an autopilot is quite simple and straightforward. It would be quite frustrating if it was difficult to operate. Operating an autopilot is as simple as putting your boat in the direction you want it to go, holding the course, pressing the button to hold the course, and letting go of the helm. The autopilot will remember the course and direct the helm to keep it. Sometimes it can take some experimentation to work out exactly how to set your course properly and make sure the GPS is following it, but with some practice, you are likely to find that it is very simple to set your GPS.

More advanced autopilots are better at maintaining their course using the more complex sensors discussed above. If you are using a simple autopilot, keep in mind that you will want to check your course frequently to make sure that the autopilot is really maintaining it correctly. This is true even if you are connected to an autopilot and feel confident that the course is being maintained.

Particularly when you are just learning how to use your GPS, be sure that you are constantly checking and reinforcing your course with a variety of different navigation tools. An autopilot can do a number of tasks to assist you in handling your sailboat. A good way to think about an autopilot is as an extra pair of hands for steering that never get tired or complain.

A good autopilot makes it almost as if you had more crew than you do. The simplest autopilots can keep your sailboat on a course you set by compass. More complex autopilots can gather information from other instruments on your boat and use that information to help inform the boats ideal track. When conditions are light or a bit breezy but not too rough or windy, autopilots are most effective.

They require minimal programming and can guide your boat for an indefinite period without getting tired. When you are enjoying a light sail in good conditions, you will very likely find yourself often setting the autopilot and going on about your business of enjoying the boat.

In very rough or heavy conditions, autopilots can fail to control your boat effectively. When changes in wind or waves occur rapidly, autopilots are not as quick to respond as a human pilot would have been.

They may seriously mishandle the boat or fail to maintain the desired track. Any time that it would take you a significant amount of skill and strength to pilot your sailboat, it is probably best not to entrust it to an autopilot. If it is difficult for you to hold a course, your autopilot will struggle. Autopilots need to work harder in rougher seas and stronger winds.

When the strength of the wind and sea outmeasure the strength of your autopilot, you can be knocked off course. Thankfully, there are alternatives to the autopilot that can also work well to hold your course. A wind vane uses the direction of the wind and the pressure of the water to navigate and to power your sailboat. That means that when the wind and waves get stronger, the wind vane has more power to work. This makes the wind vane a nearly ideal tool for rough weather sailing.

If you are using a wind vane, it is a good idea to trim your sails so that your boat will stay under control even in very rough weather. No matter what you used to steer, remember that if conditions are bad enough that you are struggling to maintain a course, your navigation tools will likely struggle as well. The fluxgate provides a stable, long-term directional reference and works with a rate gyro compass. Boaters should know how these compasses function: Fluxgate Compass : Uses electronics to generate course headings and communicates with the rate gyro compass.

Fluxgate compass data can be interfaced with chart plotters, GPS, and radar. Rate Gyro Compass : Indicates angular change relative to a course heading over short periods, not direction. Used to control pitch-and-roll movement, the rate gyro provides fast, accurate data and corrects fluxgate compass errors.

Drive Unit : The workhorse of an autopilot that moves the rudder by electricity or hydraulics. Drive units are one of three types, described below: Linear : The most common type on sailboats which moves the rudder directly from the tiller arm or rudder using electricity. Rotary : Used on chain and cable steering wheeled systems that may use sprockets ranging from 13 to 25 teeth.

Hydraulic : For boats with hydraulic steering systems. The drive unit must match the size of the existing hydraulic ram. Control Unit : The interface between the helmsman and autopilot, usually with an LED display on a control panel with knobs, joysticks, or buttons. Autopilot Advantages Autopilots provide several advantages to sailors and boaters: Save fuel by reducing cruising time, particularly on vessels with a GPS interface. Have an infinite attention span and do not tire.

Helpful when sail or power boating with a short- or single-handed crew. For anglers, pre-programmed trolling patterns can make fishing more productive. Disadvantages of Autopilots There are some disadvantages to autopilots: If autopilot components need repair, recalibration, or replacement during a voyage, getting service, especially in foreign ports, may be difficult.

Heavy weather can affect how quickly an autopilot responds with helm corrections and works harder at maintaining headings in adverse conditions, which can strain the electrical system.

Water intrusion and corrosion in the computer, drive motor components and wired connections can cause an autopilot to fail or generate faulty data. Even for short periods, an unattended helm without an engaged autopilot can put the boat off course and create potentially dangerous or unsafe situations. The electric power needed to operate an autopilot during rough weather and heavy use can be high and sudden energy spikes can cause the unit to fail or generate faulty data.

When an Autopilot Should Not Be Used In some conditions, navigating a vessel with an engaged autopilot can create potentially dangerous conditions. Constant awareness degrees around a vessel is critical, even with an engaged autopilot. Should an autopilot fail or generate suspect data, immediately disengage the unit, check the magnetic compass and adjust as needed.

Most autopilot hardware is waterproof, but should be cleaned after a voyage. Below-deck units should be mounted in a dry, well-ventilated area, as they generate considerable heat. The speed at which an autopilot makes course corrections can be a safety issue.