Compass inclination

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leechips

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Just bought a contest 101 compass. My bulkhead is not vertical but is inclined at 8 degrees and in the instruction manual it says there is a different model for inclined bulkheads. However on the Plastimo website the inlcined compasses are supposed to be for 10deg to 20deg inclination. anyone come across this problem before? Should I stick with a vertical compass?

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Interesting point, but I wonder if it makes any difference when your boat is pitching into waves - how much does the bulkhead move from its steadystate angle?

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The main problem with all compasses is that as the boat heels it introduces an error. The compass card of course stays still, but the lubbers line moves with the heel angle to give an error. This will be compounded by having a compass, designed to be mounted vertically, but mounted inclined to the vertical. hard to say how much the error will be, as this will also depend on the size of the compass.

Since the whole art of navigation is to reduce uncertainty, I would go with the advice of mount the compass vertically or get one that is designed to be inclined.

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mm yeah that might work, as I said the problem is the inclined compasses are meant for 10-20deg so at 8deg inclination Im not quite there. thanks for help

Lee

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G'day Leechips, and welcome to the forums,

I had the same situation some years back, and as a navigation freak it was a concern, however, it took no time at all to make a compass error card to correct the errors.

So all you need to do is mount the thing as normal, get your hands on a gps and a good hand bearing compass and pick a good day the make a card.

I made 3, the first for motoring with the assumption we would not be heeled over, as second for cruising and a third for racing, only to discover the difference in the errors was so small most helmsmen (or should the be persons) would have great difficulty steering to them as the card was in 5 degree increments and most errors were less than 3 degrees.

I hope this helps and Avagoodweekend.



<hr width=100% size=1> Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.
 
The inclination you talk about is in the fore/aft and is not effected by heel for such a small amount of angle fit the compass you have and let the internal built in heel of the compass pivot and sapphire take care of the rest
www.bpsc-marine.co.uk

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