My auto pilot is psychotic

[BayMan]

I have autohelm autopilot. Periodically it will just turn 90 or so degrees and wander off on a new course. Not so much lose its couse and flounder around but change all on its own to a different course. This happened twice in a 2 hr sail yesterday and has happened before. Recently New to me Hunter 450. Ideas? I was going to recalibrate the compass but don't think that is the issue.

 

[weinie]

Do you have any large metal items near your flux gate compass such as an emergency tiller, etc.?

 

[Anonymous 121765]

Bay,

I ran into similar problems awhile back. So, I checked my wiring for any loose connections etc.
I also checked the runs for any damage to the wiring itself & found none.

The solution for me, was opening the controller. My flux gate compass had come loose from the mounting. I also found the other screw had loosened. I fixed this by applying Loctite to the screws. Another problem I found is that because of vibration harmonics while under power, the connector plug receptacle had some loose wire connections. I have the screw pinch wire type from Bowdeck Dry-Plug & receptacle.

I find I need re-tighten these at least once a year. Hope this helps pal.

CR

 

[Don S/V ILLusion]

There are only a few reasons why autopilots go crazy. As stated above:
1. Magnetic field disruption
2. Loose, corroded or bad connections, or
3. Low voltage or intermittent voltage variations (usually caused by #2 above).

 

[mz4wheeler]

Recently New to me Hunter 450. Ideas?

Yes. The possibility of connections, but also highly likely the PO didn't install a rudder reference unit. Odds are this issue has always been happening. Sure, the autopilot will "technically" work w/o it, but it will eventually wack out at the worst times, causing a safety issue. Nothing like full right rudder at 6 knots.

 

[Ken Cross]

Cell Phone. You guys are going to think I'm bonkers, but;
I found interference just as you describe from my cell phone and naturally not all the time because it depended on where the phone was located at the time. This however was a tiller pilot, so possibly not the answer for your issue. Just engage the autopilot and move the phone around different components and see what it does. You don't need to be talking, just connected to a cell tower.

Ken

 

[jssailem]

The autopilot compass relies on the magnetic lines of forces generated by the earth to steer a course much like a heat seeking missile. As you drift away from the intended magnetic field it senses the change and corrects. Usually crossing the magnetic line you asked it to follow then correcting back again. If you introduce an elector-magnetic generator (i.e cell phone, bluetooth transmitter, Multi Functional Display, Engine magneto, etc.) you mess with the earths lines of magnetic force and you get an auto pilot wondering which way to go. In BayMan's words psychotic in it's behavior. Find the source of confusion and you will get the autopilot to start behaving as you wish.

 

[BayMan]

I will check all of these things. Silly question: Where will I likely find the fluxgate compass (is that like the fluxgate capacitor from Back to The Future?). Something the size of a hockey puck in my transom storage area that could be it.

 

[BayMan]

highly likely the PO didn't install a rudder reference unit.

The Autohelm does show the position of the rudder and I believe it to be accurate. Does this answer the question about a rudder reference unit?

 

[JohnVTX]

I will check all of these things. Silly question: Where will I likely find the fluxgate compass (is that like the fluxgate capacitor from Back to The Future?). Something the size of a hockey puck in my transom storage area that could be it.

Yes to the hockey puck

 

[woodster]

you say it is changing 90 degrees when this happens ...could it be programed for a tack and at random times trying to tack ....this suggestion may be worth a look see.......

 

[kloudie1]

Yes on rudder reference. It can show rudder position only if a position sensor is installed

 

[mz4wheeler]

The Autohelm does show the position of the rudder and I believe it to be accurate. Does this answer the question about a rudder reference unit?

Since we have new information:

1) Could be the compass. Try to re-calibrate again. If the compass has flat spots, it won't pass calibration. Deviation should be less than 15.

2) Could be the rudder reference sensor. In standby mode, move the helm back and forth. If the resistor inside is getting worn, especially close to center-line, the rudder indicator may jitter. A better way to test this is to disconnect the leads to the autohelm and put an ohm meter on the wire. Move the helm back/forth. Resistance changes should be smooth.

3) Most likely the connections. Re-seat all of them.