Autopilot steers to port when engaged in AUTO mode

[feickenberg]

I own a 1999 Jeanneau Sun Odyssey 34.2. She’s equipped with a ST4000 PLUS that was installed in 2012. The autopilot is connected to a wheel drive with lever to steer the boat when the autopilot is engaged. She is not equipped with a rudder reference transducer.

Until 3 weeks ago the autopilot worked perfectly fine. Without that I made any changes to the system or the boat the autopilot now always steers to port in several small steps once it gets engaged (AUTO mode).

Wheel Drive:
When I engage the wheel drive with the lever and leave the autopilot in STANDBY I can turn the wheel to port by pushing the -1 and to starboard by pushing +1 buttons which indicates that the wheel drive is working properly.

Fluxgate Compass:
When I press the disp button the heading that is shown is always very similar to the angle that is shown by the ‚regular‘ compass that’s mounted on the pedestal. The displayed angle doesn’t jump and is quite stable (not changing more that what you’d expect because of the movement of the boat). The fluxgate compass is mounted in the main cabin. I checked the resistance between the different wires as described in the „Fluxgate Compass Test“ instruction here in the forum. Resistances are in the range as they are described in the article. Thereby I conclude that the fluxgate compass and wiring are also ok.

The problem:
When I engage the wheel drive with the lever and push AUTO the wheel gets always turned in small steps to port until the end. When I change the course by pressing -1; -10; +1 or +10 the bars below the course indicate correctly the difference between course and heading, but independent if the course needs to be changed to port or starboard the wheel drive turns the wheel always to port until the end.

https://drive.google.com/file/d/1V2N4CRt...sp=sharing

Any idea what’s wrong with the ST4000 PLUS?

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum Frank,

Please accept our apologies for the delay in moderating this thread. Upon reviewing your thread and watching the video, we had a couple of questions:
1) To access the maximum deviation detected by your autopilot during calibration, hold the STANDBY button pressed for approximately 2 seconds until the autopilot enters Setup mode. Then DISP button to scroll through autopilot's settings until Deviation is listed. What was the value of the maximum deviation detected by your autopilot during calibration?

2) In watching the video, the autopilot was commanded into Standby after it had deviated only a couple of degrees from the initial heading. When operating in an area which would permit the boat to safely execute a greater amount of heading change, does the autopilot continue to add port rudder until reaching the rudder limit or does it eventually add starboard rudder to correct steering to the autopilot?

[feickenberg]

Chuck,

Thank you for your reply to my thread.

1) I had the chance to check the deviation as you described and the value shown is "1 degree".

2) I took the video only to show the effect but was restricted as I was by myself. When I engage the autopilot and keep it engaged the autopilot steers to port in small steps until the wheel can't turn any further. Then it the keeps pushing against the mechanical rudder limit. In AUTO mode the autopilot never steers to starboard to correct the course (even when the boat makes full turns). When I leave the autopilot engaged the boat makes full turns as long as the autopilot remains in AUTO mode.

Thanks
Frank

[Chuck - Raymarine - Moderator]

Frank,

Our Repair Technician has recommended that the autopilot be reset and that a full dockside and sea trial calibration then be performed as the next step in correcting the reported issue. The manual for the ST4000+ may be found here. Resetting the autopilot would be accomplished by configuring the autopilot's settings to their default values via the autopilot's Dealer Calibration Mode (see Section 5.2 of the ST4000+ manual). Dockside procedures and sea trial are covered in Chapter 7 - Post Installation Procedures of the ST4000+ manual.

[feickenberg]

Chuck,

Thank you very much for your support which I appreciate a lot. As my boat is now in winter storage I'll need to wait until spring before I can perform the sea trial procedure. I'll let you know the outcome next spring.

Thanks again for your support
Frank

[Chuck - Raymarine - Moderator]

You're welcome.

[feickenberg]

Chuck,

last weekend I got my boat back into the water and followed your instructions.
The autopilot now works better than ever before and keeps the boat on course even during rough conditions when I sailed her in 25+ knots and waves back to the marine where I keep her during the summer.

Thank you again for your great support.
Frank

[Chuck - Raymarine - Moderator]

You're welcome.