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Old 13-08-2015, 00:02   #1
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Sailing backwards

Recently I bought a boat with a Raymarine C90 W chart plotter. I worked flawlessly for 1500 miles. Then, shortly after leaving an anchorage I noticed that it was showing me sailing backwards and the autopilot was showing a heading that was the reciprocal of what I was on. Additionally the tide current vector (blue arrow) was at it's largest size even though we were at slack tide. I reset the display to factory settings hoping for a miracle to no avail. The COG is giving the correct information. Does anyone know what the heck happened and how to fix it??

Thank you in advance for any productive ideas about how to resolve this without spending lots of boat bucks.
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Old 13-08-2015, 23:41   #2
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Re: Sailing backwards

Try and reset your autopilot and sail the three circles to recalibrate the flux gate compass as well. Check to make sure you have not put anything magnetic or metal around the flux gate if you recently cleaned your speed log did you reinstall it correctly?
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Old 14-08-2015, 00:00   #3
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Re: Sailing backwards

Thank you Truemettle. I'm going to dig into the manuals on that and see how to reset the autopilot. Nothing has been changed on the boat around the flux gate compass. We were on the last 20 miles from Drift Wood Bay into Seward Alaska after coming from Anacortes. The only thing that had changed was our growing anticipation of a celebratory steak in Seward. Is there anything I need to do for the compass other than drive around in circles three times?

Thanks again for weighing in on this. It's a huge help.

John
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Old 14-08-2015, 17:14   #4
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Re: Sailing backwards

By "showed me sailing backwards" it sounds like you mean just the boat image is backwards...since the COG is correct...right? If so, I vote for swinging the fluxgate too.
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Old 14-08-2015, 17:26   #5
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Re: Sailing backwards

That is correct. Just the boat image is backward (facing the direction of the course on the autopilot). The COG on the plotter is accurate and in reasonable agreement with the magnetic compass. The heading on the autopilot is nearly an exact reciprocal of the COG show on the plotter. When the autopilot is engaged it tracks just fine (maintaining reciprocal of the course it is showing). When I attempt to have it track to a waypoint on the plotter, it vigorously attempts to turn to the reciprocal heading to the waypoint. I'll be back on the boat in two weeks and am looking forward to recalibrating the flux gate compass. I'll post my progress and the outcome of my efforts. It's been suggested that something metallic has been put close to the compass. With my wife cleaning up the boat and putting things away that is a distinct possibility, but I'm very new to the boat and don't even know where it's been mounted.
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Old 14-08-2015, 19:18   #6
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Re: Sailing backwards

"...don't even know where it's been mounted."

Be aware, audio speakers have strong magnets in them, if you do have something in the wrong place, it could be affecting things. Also, those of us who use Milwaukee right angle drill motors as poor man's "electric winches"--those batteries confuse compasses, too.

If you go through the re-set process, and it doesn't work, really get into the manual. Then onto the manufacturer. Be forceful.

Ann
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Old 15-08-2015, 04:22   #7
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Re: Sailing backwards

Quote:
Originally Posted by Alaska JD View Post
... It's been suggested that something metallic has been put close to the compass. With my wife cleaning up the boat and putting things away that is a distinct possibility, but I'm very new to the boat and don't even know where it's been mounted.
Yes, anything with electromagnetic properties can effect the fluxgate. It should be mounted well clear of any such influences and nothing with potential to interfere stowed near it.

I would inspect the area around the fluxgate first before swinging. Would be frustrating to swing it, have it compensate for a nearby influence...and then have your wife rearrange things. ;-)
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Old 19-08-2015, 14:43   #8
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Re: Sailing backwards

This happened to me, when I had to replaced my fluxgate compass. When I installed the new compass, I corrected the original install by oriented the compass facing forward as described in the manual. Yep, I started sailing backwards...


To correct:
- Enter Dealer Calibration, go to Aligning the compass (ALIGN HDG)

This process will attempt to align the heading from the fluxgate compass/auto pilot, with the heading received from the GPS. This corrected the issue for me.
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Old 19-08-2015, 14:53   #9
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Re: Sailing backwards

Thank you Diesel45mpg. That's really helpful and reassuring. Seems like an easy fix. What has me confused and I can't check it until next week, is that the problem didn't occur until the last 20 miles of a 1550 mile trip. While I can't prove it sitting at my desk, I'm very suspicious that the problem occurred as my wife was "putting things away" preparing to dock the boat and head north for a month. I'm very anxious to see what got stored next to the compass. Because I'm new to the boat and to the system, I didn't know to check that possibility. If there is nothing there, it brings up a different problem as in "How did the system get so far off so quickly?" I will definitely post how the problem gets solved when I get back after Labor Day.

Thanks for your input,
John

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