Yacht autopilot calibration & setup

How commissioning and calibration are carried out

Autolearn tunes rudder response — how much helm the pilot applies and how quickly it takes it off again. It does not correct heading. A pilot holding a steady course that is off the one requested has a compass deviation or sensor alignment fault, which autolearn will not address. The two corrections are separate procedures and are carried out separately; treating them as one is a common reason a pilot is reported as faulty after a calibration that appeared to complete.

Approximately half of commissioning is completed at the dock: drive type, rudder travel limits, hard-over time from lock to lock, the rudder feedback centre and its end stops, and a follow-up test confirming that the drive and the feedback agree on direction. Only the compass swing and the response tuning require sea room. Completing the dockside stage first is what avoids running the sea trial twice.

Scope of work

Dockside commissioning & rudder limits

Drive type, travel limits and hard-over time from lock to lock set at the berth, along with the play in the steering the pilot has to work around.

Rudder feedback alignment & polarity

Feedback unit zeroed at dead ahead and its end stops set, then a follow-up test run to prove drive and feedback agree on direction before anything goes to sea.

Heading sensor alignment

Solid-state sensors aligned to the vessel’s centreline, which decides whether the pilot steers the heading it is asked for or one a few degrees off it.

Compass deviation swing

Run under way in flat water, slowly through rather more than a full circle, and repeated where the automatic routine will not complete — a manual correction is the fallback, not a failure.

Response tuning & sea trial

Rudder gain and counter-rudder tuned under way against how the vessel actually behaves, loaded and trimmed as she is used rather than as she left the yard.

Sensor siting & interference

Heading sensors relocated where they sit near pumps, motors or the engine — a compass that will not swing cleanly is usually mounted somewhere it never should have been.

Diagram of the autopilot steering loop: helm display and heading sensor on the instrument network backbone, autopilot computer, rudder feedback returning rudder angle, and the drive unit pump and ram with its supply measured under load

Attendance sequence

Phase	Stage	Actions and deliverables
01	Symptoms by message	Vessel, berth and what the pilot actually does — wanders, will not engage, holds a steady but wrong heading, or hunts. Each points somewhere different before anyone attends.
02	Dockside setup	Drive and rudder limits set, feedback zeroed and its end stops confirmed, and the follow-up test run so drive and feedback are proven to agree before the lines come off.
03	Sea trial	Compass swung in open water and response tuned against how the vessel handles under way. Weather is chosen for it — a swing attempted in a chop will not complete and gets blamed on the equipment.
04	Work, test, document	Pilot run on a settled heading and through several course changes to prove it holds, with the settings arrived at, the readings and photographs issued.

What is measured

A pilot is proven on the water, on figures rather than on how it feels. Every setting below is recorded, so the next person to touch it knows what it was set to and why.

Rudder feedback against actual helm

Reported angle checked against where the rudder physically is, at centre and both stops — a feedback unit a few degrees out sends the pilot hunting for a centre that does not exist.

Hard-over time, lock to lock

Timed rather than taken from the manual, because it is what the pilot uses to decide how hard to push, and a tired drive no longer matches its own data plate.

Heading against a known bearing

Compared on a settled heading against a transit or known bearing, which separates a sensor that is misaligned from one that is uncorrected for deviation.

Deviation across the swing

Recorded around the full turn rather than at one heading — deviation varies with heading, so a correction checked in one direction proves little about the other three.

Where this work is carried out

Dockside setup at the berth across the North Adriatic, with the sea trial run from the vessel’s own marina in settled weather.

Croatia Pula, Rovinj, Vrsar, Poreč, Umag, Novigrad

Slovenia Izola, Koper, Portorož

Italy Trieste, Muggia

Questions asked most often

The autopilot wanders or refuses to engage — is that the drive unit?

Usually not. A pilot that wanders is more often a rudder feedback or heading sensor fault than a failed drive, and one that will not engage at all is frequently an interlock or supply issue rather than the actuator. Feedback alignment, drive polarity and supply are checked at the dock before the drive unit is considered, because replacing it is the most expensive way to find out it was fine.

Autolearn has been run twice and it still steers off course. What now?

Autolearn tunes rudder response, not heading. If the pilot holds a steady course that is simply the wrong one, the problem is compass deviation or heading sensor alignment, and no amount of autolearn will correct it. Those are separate procedures — the sensor is aligned to the centreline and the compass swung, then response tuning is run last.

Can the autopilot be calibrated at the berth without going out?

Partly. Drive setup, rudder travel limits, feedback alignment and the follow-up polarity test are all done alongside, and that is where most faults are actually found. The compass swing and response tuning need open water and settled conditions, so a full commissioning means a sea trial. Doing the dockside stage first means the trial is one trip rather than two.

The compass calibration will not complete. Is the sensor faulty?

Check the conditions and the mounting before the sensor. A swing needs flat water and a slow, even turn through rather more than a full circle, and it will abort in a chop or if the turn is uneven. Where it still will not complete, the usual cause is where the sensor sits — near a pump, an electric motor or the engine — and the fix is relocating it rather than replacing it. A manual deviation correction is the fallback.

Autopilot calibration