Ladies and Gentlemen: I asked my local guru, Rick Dinon the following question. He was stumped. So, on to the next level of expertise: I have noticed that my R/M 7000+ series auto pilot has not agreed with the compass heading or COG. I calibrated it today and found a 7 degree deviation. I then manually changed the reading, per the manual, to match that of the compass. I later found that on different headings, it would agree on some headings but not agree (up to 5 degrees off) on others. I removed all metal objects from the vicinity of the compass. My fluxgate is located inches from the water heater and was placed there by Hunter. What, if anything do I do about the seven degree deviation? The manual said that if the deviation is over 15 degrees to relocate the fluxgate. John Richard s/v Jack's Place
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John,
I, too, have an ST-7000 on my 420; and I, too, have had almost exactly the same problem that you describe. I've recalabrated a couple of times (by slowly driving the boat in a large circle a few times as the manuel describes) with some success. I was out Sun. motorsailing and (once things settled down) the autopilot was holding the boat within 2-3 degreees of GPS course. If you've recalabrated by motoring the boat around in a circle till the computer says "I'm good"...without much success; then you may have to relocate the fluxgate compass... a few inches from the water heater may be too close.
I, too, have an ST-7000 on my 420; and I, too, have had almost exactly the same problem that you describe. I've recalabrated a couple of times (by slowly driving the boat in a large circle a few times as the manuel describes) with some success. I was out Sun. motorsailing and (once things settled down) the autopilot was holding the boat within 2-3 degreees of GPS course. If you've recalabrated by motoring the boat around in a circle till the computer says "I'm good"...without much success; then you may have to relocate the fluxgate compass... a few inches from the water heater may be too close.
My Experience
Is your main steering compass okay as the differences may be due to that. Also the calorifier might not contain any magnetic materials so it might not be affecting the fluxgate. On my 376 the dealer installed a Raymarine autopilot which has a magnetic steel sprocket on the wheel shaft directly under the main steering compass. The chain is magnetic and the steering console has two loudspeakers within two feet. No way can I get the main compass deviation free so the autopilot's fluxgate has become the main steering compass and the binnacle is only used as a vague cross check.
Is your main steering compass okay as the differences may be due to that. Also the calorifier might not contain any magnetic materials so it might not be affecting the fluxgate. On my 376 the dealer installed a Raymarine autopilot which has a magnetic steel sprocket on the wheel shaft directly under the main steering compass. The chain is magnetic and the steering console has two loudspeakers within two feet. No way can I get the main compass deviation free so the autopilot's fluxgate has become the main steering compass and the binnacle is only used as a vague cross check.
My thoughts
As Donalex says, I use the compass more as a reference/checkpoint. I find it 5-10 degrees off aff the time. I would be more apt to believe the fluxgate and GPS. Take a second GPS on board and set your AP to those readings assuming your main GPS and handheld are calibrated the same. Make sure you are not comparing magnetic vs. true and/or have the variance correctly set. Good Luck. Bob.
As Donalex says, I use the compass more as a reference/checkpoint. I find it 5-10 degrees off aff the time. I would be more apt to believe the fluxgate and GPS. Take a second GPS on board and set your AP to those readings assuming your main GPS and handheld are calibrated the same. Make sure you are not comparing magnetic vs. true and/or have the variance correctly set. Good Luck. Bob.
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