ACU200 Eventually Starts Steering Wildly

[eddschillay]

I have an ACU200 Autopilot, ST4000-II wheel drive and a P70 control head. When I first engage the autopilot, it works beautifully -- a small red bar, the boat turns slightly, then a small green bar, it turns back. And on and on...

After about 45 seconds, the turns get wider and wider. Hard to port, hard to starboard. No green bar on the display will show. In no time, the turns get so wide, the alarm goes off and goes back in to standby.

I shut it down, reset and it works great again for about 45 seconds, then the S-turns get wider and wider again.

Any ideas?

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum Ed,

Please click here to view a FAQ addressing this subject. Should the autopilot's components not have been updated with the latest available Raymarine product software updates, then it is recommended they be updated accordingly. Please click here to view a FAQ addressing the actions to be taken after updating the autopilot's software. Care should be taken to ensure that following execution of the Dockside Wizard, that the rudder bar responds correctly to rotation of the vessel's wheel. If not, then the transducer leads are reversed for the orientation of the rudder reference transducer.

To correct this condition, the autopilot calibration lock may be configured OFF to then permit commanding Reverse Rudder Ref. (MENU->SET-UP->AUTOPILOT CALIBRATION->DRIVE SETTINGS->REVERSE RUDDER REF.). Alternatively and better yet, the red and green rudder reference transducer lead connections to the ACU may be swapped. Of these two options, the latter is recommended to eliminate any future confusion with the rudder. Afterwards, a cruise to permit the autopilot to determine the deviation sensed within the area of the EV-1 CCU. If greater than 10 degrees, then it is recommended that the EV-1 CCU be relocated. Please click here to view a FAQ addressing this subject and including tools to aid in locating the EV-1 CCU.

As indicated within the initial FAQ referenced within this response, the Evolution autopilots are quite dependent on accurate speed through water or SOG data to correctly operate. Inaccurate speed through water or SOG data can cause the autopilot to act in an erratic / oscillating manner as you have described. Also as indicated within the initial FAQ referenced within this response, should there be an issue with the speed through water source, then the autopilot's Speed Input configuration should be configured to SOG until such time as the issue wit the speed through water source has been addressed.