I've got an Autohelm
st4000+ hooked up to a Standard Horizon CP180 chartplotter
(via the NMEA
input of the Autohelm).
When I try to have the Autohelm
follow a route
set by the chartplotter
, the boat tends to wander off course after about 10 minutes (generally steering
just slightly to port every time).
The data pages on the Autohelm are accurately indicating XTE and BTW - it doesn't look like a communication problem.
Also, the auto steers fine to the wind
- just not to a route
(so I don't think I have motor
polarity wrong or anything like that).
Here are my guesses, none of which I'm sure about
1. I've damaged the autopilot
- the previous owner mixed up colors on the power wires, and at one point I reversed the polarity to the Autohelm and tripped the 15A breaker. As mentioned, everything else seems to work, and the NMEA
sentences are being read properly, so this seems somewhat unlikely, but 15A+ to the auto can't be a good thing...
2. I'm sending the wrong NMEA sentences - I've tried turning all NMEA sentences on at once (I don't really understand why I'd ever want to turn them off... is there something wrong with outputting more information than less? Does the receiving device get confused?), and also tried just turing on the ones that I think I need, with no change in results. But some seem redundant (e.g., RMB contains BTW and XTE data, so far as I can glean) and I guess I'm not 100% positive that I'm outputting exactly and only the info that I need.
3. The SeaTalk
inputs (which I'm using for other devices on the boat such as the windvane) are somehow stepping on or overriding the NMEA data.
Any thoughts or advice?