P70 Autopilot veers off course

[Scrabble]

Note: This is a continuation of another thread as I think I have narrowed the issue down. https://www.cruisersforum.com/forums....html#poststop

My Raymarine AP has started veering off course after a software update. After several days of recalibrating I think it may be due to the boat being ‘knocked’ off course. Yesterday, I had a 4hr run (under motor) in calm seas and the autopilot work fine for about 2 hours when it suddenly turn to Stb (always Stb) and I quickly disengaged. Now the rudder indicator shows about 10deg port when sailing straight. I adjusted the offset to compensate and continued on. When nearing my destination an overpowered gin palace blasted past our port side and knocked us around significantly. The AP immediately started to veer to Stb (about 20deg offset). I have become adept and doing a dockside reset at sea so quickly fixed it before entering the port.

To me, it seems to be very coincidental that the AP failed when hit by a ‘rogue wave’. Has anyone ever experienced this. I’m keen to get this sorted as I have a 18hr crossing coming up this week.

Cheers

PS. No problems under standby

[donradcliffe]

The problem could well be loose rudder indicator.