Heading sensor on alloy boat

Electrical/Electronics discussion
OceanTrvlr
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Location: Boston's South Shore

Heading sensor on alloy boat

#1

Post by OceanTrvlr » Sun Oct 07, 2018 12:18 pm

I have a Garmin GHP Reactor autopilot on my North River RAIV with the course computer (heading sensor) mounted below the deck, under the helm area. It works but I’m not able to get very good compass calibration values. Am I fighting a losing battle with a metal boat or should I be looking for other sources of magnetic interference?

Ethan
NRB Almar 28 RAIV

3f8
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Re: Heading sensor on alloy boat

#2

Post by 3f8 » Sun Oct 07, 2018 9:38 pm

Is it consistent or all over the place? Alloy should not be the culprit. Some thing ferrous or electromagnetic. Not all stainless steel types are non magnetic if there are any near. Also on the center line of the boat is best.
"It was the Law of the Sea, they said. Civilization ends at the waterline.
Beyond that, we all enter the food chain, and not always right at the top."
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OceanTrvlr
Posts: 13
Joined: Thu Nov 13, 2014 2:36 pm
Location: Boston's South Shore

Re: Heading sensor on alloy boat

#3

Post by OceanTrvlr » Sun Oct 14, 2018 6:48 pm

3f8 wrote:
Sun Oct 07, 2018 9:38 pm
Is it consistent or all over the place?
I’m not sure, I’ll have to experiment some more. It’s primarily the Garmin autopilot Calibration Value in the Dealer Setup menu which concerns me. It’s gives a number from 0 to 100, with 100 being a magnetically perfect environment. Mine is somewhere around the mid 50s and I think needs to be much higher.

peterbo3
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Re: Heading sensor on alloy boat

#4

Post by peterbo3 » Tue Oct 16, 2018 2:51 am

Do you have electric wiring near the sensor? This can cause magnetic interference. One reason why the compass light wires should always be twisted to negate any interference which will affect the compass heading.
If there are hot wires in the vicinity a quick test is to turn off the power if this is possible & check the calibration value. If there is wiring & it is house feed you can wire a smaller battery directly to your panel buss & turn off your house feed then check the calibration.
Alloy is not magnetic so my money is on the wiring.
Regards,

Pete in Brisbane
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OceanTrvlr
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Joined: Thu Nov 13, 2014 2:36 pm
Location: Boston's South Shore

Re: Heading sensor on alloy boat

#5

Post by OceanTrvlr » Thu Oct 18, 2018 8:11 am

Here's the installation below the floor of the helm area, looking aft. I guess I have to admit that the course computer being only a few inches away from the bilge pump wires is probably not good.

Ethan

IMG_4016.JPG
IMG_4016.JPG (132.61 KiB) Viewed 20 times

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gandrfab
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Re: Heading sensor on alloy boat

#6

Post by gandrfab » Thu Oct 18, 2018 1:54 pm

Just because I haven't seen the addressed.
Are you calibrating the compass on the water underway?

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