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Old 07-07-2010, 15:05   #1
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Autohelm ST4000+ - Won't Track to a Route

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 or compass - 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?
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Old 07-07-2010, 15:25   #2
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I don't think it's any damage beyond the inherent 'damaged' design of Raymarine equipment. 15v is not a big deal. The ST will complain directly if there is some NEMA problem.

The few times I've tried the track feature on my ST it has bahaved oddly. I attributed it to some parameter not being set correctly or just Raymarine weirdness. So I never use it.

It's more salty, and safer, to set a heading. Just like the navigators of old would tell the helmsman. That way you can notice currents and other effects, in my opinion.
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Old 07-07-2010, 15:51   #3
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I have the same setup as you although my autohelm is a slightly older model. I dont recall if it wandered in any particular way, but I recall that it was off course but corrected as I got closer to the mark. I So it steered off course part of the way, but got better as it got closer. I gave up on it. (I dont use any seatalk units)
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Old 07-07-2010, 22:14   #4
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When on the route does it ever get to the next waypoint? Mine always gets there.

I have noticed the farther away from a route waypoint the boat is heading as much as 30 degrees off from the waypoint. The track is usually right on the route.

I think the computer in the Autohelm is correcting for currents and wind drift. So the heading of the boat is off to one side.

Do you have a manual?

It took me over a year to figure out all of the settings on the Autohelm. Once I got them set it has worked for the last three years. I found the unit is very complicated. Dealer Setup, User Setup and other things. I couldn't set it up with out the manual. I even created a spread sheet to record the recommended setting, default settings, current setting and changed settings for the Dealer and User Setup parameters.

I had to follow the manual for setup step by step. Don't skip any steps and make sure you understand each setting.
Started with Compass Deviation Correction and Heading alignment.

Gordon
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Old 09-07-2010, 00:11   #5
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As far as I can recall, my ST4000+ (Raymarine) uses the APB sentence to follow a route.

Hope this helps,

Cheers.
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Old 09-07-2010, 02:18   #6
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Tracks to wind and compass - wanders to course.

My guess is the XTE has a range before correcting setting. Could be a half mile or more. Probably adjustable. In the plotter software not the autopilot.

This may not be apparent when tracking compass or wind because you have set a specific heading in each case. One derived from compass and one derived from wind angle.
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Old 15-08-2010, 11:38   #7
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for anyone else who might run across this: i figured it out.

there's a setting on the chartplotter for "magnetic heading" vs. "true heading". when i changed true to magnetic, she works like a charm. i guess whatever declination error there is was between the autohelm fluxgate compass and the true heading on the chartplotter made the auto confused...
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Old 15-08-2010, 12:29   #8
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have you checked your rudder sensor placement??
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