Compass adjustment

windrose · Post by **windrose** » Mon Jun 13, 2005 8:50 am

I have two bulkhead mounted compasses on each side of the compainonway. They are Aqua Meter Saturn's.... and they read 30* difference. How do I calibrate/adjust them?

Post by **Tim** » Mon Jun 13, 2005 3:09 pm

I have the same compass. They should have some little adjustment screws inside the cowl, I think. One is for east-west correction, and the other for north-south. I don;'t recall immediately where these are located, but if you search you should find them.

And of course, you checked to make sure there was nothing magnetic near one of the compasses.

Invitation · Post by **Invitation** » Mon Jun 13, 2005 3:13 pm

30 degrees is a lot a difference. I would check for interference before trying to adjust them. The problem is most likely not the compass but something else - portable radio nearby ( i.e. magnet as suggested by Tim), anything with a speaker in it will cause this.

Post by **dasein668** » Mon Jun 13, 2005 7:52 pm

You probably have one mounted on the bulkhead with the electrical panel behind? I would expect that all that wiring coming together right there would lead to a ton of electromagnetic interference.

tartan30cirrus · Post by **tartan30cirrus** » Mon Jun 13, 2005 9:20 pm

Twist the pairs of wires together...this helps cancel the electric field a bit and helped me reduce interference in my boat.

Then when you know there is nothing interfering, take you boat out with the GPS and track straight on a N-S line going as fast as you can with little or no tide/wind setting you. It is best to find a range...two landmarks that are dead N-S or E-W. Once under way on the N-S track (I have used autopilot to help steer) adjust the screw that gives you the N-S change and match the GPS heading. Then motor on an E-W track and repeat the process adjusting the E-W screw. We have gotten +/- 5 degrees with this technique and feel comfortable using the compasses now.

Cheers,
Clint

windrose · Post by **windrose** » Tue Jun 14, 2005 5:43 pm

I decided not to adjust anything until I got in the water..... I was thinking of the jack stands etc NOT the rotting metal (40'+) hulk next to me. When they dropped her in the water, yeah baby, each compass was right on target. It has been a very big day..... I am exhausted.

Thanks for heads up. I need to check them with a hand bearing compass now.