Autopilot
Autopilot
An autopilot steers for you, either holding a compass heading or following a route from the chartplotter. It needs a heading sensor (compass), usually a rudder position sensor, and a drive unit that turns the wheel, tiller or hydraulic steering.
How it works
In heading-hold (auto) mode the pilot keeps the bow on a chosen heading, so wind and current can push you sideways off your intended track. In route or track mode it uses cross-track error and bearing to the next waypoint from the plotter to stay on the line. A rudder reference sensor tells it where the rudder is. Gain settings decide how hard it steers: too much and it swings back and forth; too little and it wanders.
Using it
- Know how to take control instantly: the standby key hands steering back to you, and some systems also let you override by simply turning the wheel.
- In heading-hold mode, watch the chart: holding a heading isn't the same as holding a track, and current or cross-wind will set you off the line.
- Before a route turn, look ahead. In route mode the pilot needs navigation data from the plotter; one maker's pilot drops back to heading hold and warns you if that data stops.
- Keep a proper lookout at all times, as Rule 5 of the Navigation Rules requires; makers warn never to leave the helm unattended.
- In rough seas, use the sea-state or response setting to cut down constant rudder movement.
- Navigation Rule 5 (Inland and International, USCG): every vessel must keep a proper lookout by sight and hearing at all times. Steering by autopilot doesn't change that.
Looking after it
- Calibrate the pilot's compass after installation or when heading errors appear. One maker's method: slow circles at under 2 knots, each taking at least 2 minutes.
- Keep magnetic things such as speakers, tools and steel away from the pilot's compass; move the compass if deviation is large.
- Check the rudder reference: with the rudder centred, the display should read centre. One maker says reversed readings mean two wires are swapped.
- Inspect the drive unit mounting, linkage, and any hydraulic fittings. An over-busy pilot wears the drive and drains the batteries faster, one maker notes.
- Keep the pilot's software current.
Troubleshooting
Autopilot wanders off heading or snakes back and forth
- Recalibrate the compass and look for anything magnetic newly placed near it.
- Snaking or overshooting points to rudder gain set too high (or counter-gain too low); slow wandering to gain set too low.
- Check the rudder reference sensor reads correctly and its linkage isn't loose.
- Check the drive unit and steering for slack, leaks or loose mounts.
- In a following sea some wandering is normal; try the sea-state or response setting.
Autopilot won't engage or keeps dropping out
- Read the alarm: one maker's list includes low supply voltage, no rudder feedback, rudder near its limit, and lost connection.
- Check battery voltage at the pilot while it's working hard.
- Check the rudder sensor and its calibration.
Autopilot won't follow the route
- Check the plotter is actively navigating a route and sending cross-track error and bearing data.
- Check the network connection between plotter and pilot.
- Watch for a large cross-track error alarm and bring the boat back near the line before re-engaging.
Buying a boat that has one
- Find out what drive is fitted (wheel, tiller or hydraulic) and how old the pilot is, and ask the maker whether parts and support are still available.
- Test it at sea in both heading-hold and route modes; watch for snaking, wandering and a noisy or slipping drive.
- Look at what's mounted near the pilot's compass.
- Check it can take navigation data from the plotter you plan to use.
Sources (5)
static.garmin.com · www8.garmin.com · ycfrejus.fr · navcen.uscg.gov · ritchienavigation.com
General guidance for recreational boaters, researched from the sources listed and written in our own words. Your equipment manuals, local knowledge, the Navigation Rules and a qualified instructor come first.