Raymarine P70 not holding course

[Scrabble]

I recently updated the firmware on my P70 and now everytime I engage AP it slowly veers off course. It still states the requested bearing though. It seems to be veering to Stb by 40º. Worst still, when I go back to standby the rudder indicator shows around 20º port when steering straight. This affects how much steering I have to port so not good. I have done the dockside setup and also the compass recalibration (figure 8s etc) and everything seems fine until I engage AP.

I have a suspicion that it may be linked to waypoints. I think the first time it went wayward was just after entering a waypoint in the MFD (Raymarine E75) but I am not certain. I reset and redid the dockside etc. Next day everything seemed to be ok initially and again (but I’m not 100% sure) I inputted a waypoint and it then went off course again. It was so bad that I had to do a dockside reset at sea to get steering back. Manually steered for the rest of the cruise. I am now anchored and have again reset so will test the autopilot without waypoints next sail.


Any thoughts would be appreciated.

[Hartleyg]

It sounds like either your rudder position sensor (most likely) or autopilot controller (the box that the rudder position sensor talks to) is in trouble.
Does the rudder position showing on the P70 work correctly when you are in standby? From the above, it doesn't, and that may be your issue. I doubt it is the P70, as that is just a readout and control input device - the real suspect is the autopilot controller and/or the rudder position sensor..


Hartley
S/V Atsa

[PippaB]

+1

It won't work as well, but disconnect the rudder angle sensor and see if it will steer 'straight'. If it does then you know it is the rudder angle sensor.

The Ray systems (at least the one I have) turns the rudder until the rudder angle reads zero when the AP is first engaged. This can cause problems if you have weather helm, or otherwise need to engage when rudder angle is not zero. If this is happening, if you give it long enough it will sort out the steering, but it takes a fair amount of time off course. Ours was always a 30° turn. I had some correspondence with Ray about this, they were not helpful

So, as said, just disconnect the rudder sensor and see if it happens. If not then you at least know where to look.

[Edit] if you think the rudder angle sensor is working, but just off, there is an offset setting you can set to tell it where zero is located. I do not rememberLooks like 9° is the largest offset you can enter. But basically if you are at anchor, check that the rudder is pointed straight ahead and then adjust either the sensor itself, or the offset, or both until the rudder angle reads zero.