Autopilot drive pushes rudder hard over

[Derek - Raymarine - Moderator]

Question
I have a Raymarine Autopilot with a Type 1 Rotary drive motor. When the autopilot is engaged the motor is engages like normal but after about 10 seconds, and WITHOUT pressing any other buttons on control head, the motor drives the rudder hardover to starboard and continues to drive until I press "standby."
The rudder reference bar indicator is correct and corresponds with the direction helm is turned.

Answer

First check the Rudder feedback unit is correctly connected - in STANDBY turn the steering to STARBOARD - does the rudder angle display show STARBOARD rudder? Repeat test to PORT. If both tests are correct, the connections are correct. If the display is reversed, the swap the Green and the red wires from the Rudder reference unit where it connects to the Computer/ ACU. click here for details .

next check the Drive unit connection polarity, click here for details

Once the above tests have been carried out, select AUTO and select 2 x +10 course change buttons on the control unit, does the drive still move toSTARBOARD, pause and then nudge over to STARBOARD?

If this symptom happens when the boat is stationary, then it is likely that the Autopilot is operating correctly, with the boat tied up stationary, if you engage AUTO and select +10, then the Autopilot will initially drive the rudder to Starboard a few degrees - then stop. After about 10-20 seconds, the drive will then 'nudge' all the way over to STARBOARD until the Autopilot is returned to STANDBY. This is Normal, the boat is not turning and so the Autopilot keeps trying to turn the boat until the boat turns and the compass shows some heading change.

If however, the drive moves constantly and at full speed to STARBOARD, this is incorrect and suggests a malfunction.

If this happens whilst the boat is underway, then this also suggests a malfunction.

The next thing to check is the compass operation, click here for test details . If the test is fine, then check for local deviation, , click here for further information , and click here too.

If you can identify the compass is at fault, this will need to be replaced, otherwise the Autopilot is defective and either Local Raymarine approved Service Dealer must be called to the boat, or the Computer returned to a Raymarine workshop for further investigation.

RAYFAQ#