Loiter mode - Boat goes crazy after 5 sec

Hello all,
I’ve just built my first boat based on a bodyboard with skid steering. Very similar to this: https://ardupilot.org/rover/docs/reference-frames-boogieboard-boat.html

In manual it works as expected but when I switch to Loiter mode it behaves ok the first 5-10 seconds and after that it goes crazy and heads out of position at high throttle. I have noticed that when I switch to Loiter the current heading (red line) and Direct to current WP (orange line) lines up in Mission Planner and the boat tries to hold position as expected. But after 5-10 seconds the Direct to current WP shifts 90 degrees and the boat goes crazy.

Since I’m a NOOB regarding this I don’t really know how to troubleshoot this.

Thank you for any help or advice

1 Like

Hi Jonas - did you find a solution to this problem ?

Hi Andrew,

I have made some progress (I think)… Regarding the compass I did follow this article: https://ardupilot.org/copter/docs/common-compass-setup-advanced.html

At first I could not figure out why the external compass was automatically set to yaw270 although the arrow on the module was pointing straight ahead. After some searching on this forum I found this thread: Compass Orientation automatically set wrong

So I disassembled the external module and I could confirm that the compass is actually rotated 270 degrees off the white arrow.

After this finding I recalibrated the compass and accepted the yaw 270.

The current situation is that I can Loiter in a stable manner for maybe 15-20 secs, after that the orange line shifts 45 degrees (before it was 90) and the boat isn’t stable any more…

I’m now learning how to review tlogs but I could need some help in finding the right parameters to focus on.

Regards ///Jonas

Hi Jonas, I’m attempting the same sort of project - there is some discussion here: BuoyBots - self position holding buoys for RC sail boat racing. I’m very new to this, so there are no doubt others who are far more qualified to help. But if you get no other offers, I’ll happily have a look at your log. There is very extensive detail there and the Mission Planner investigative tools aren’t too bad. I’ve learnt quite a lot from my first analysis. Good luck.