Swing Compass

Seven Spades

Seven Spades

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I need to have my compass swung, it is at least 10 degrees out in a n/s direction. The problem is that it is attached to the binical and I can't see how one can access the base without dismanteling half the tridata and chartplotter equipment, it is this equipment that is undoubtdly the cause of the deviation.

So where can I find someone to fix the impossible? Recomendations please.
 
As far as I can see you have several options:
1) Employ a compass adjuster at great expense to come out to your boat and swing the compass for you.
2) Buy a book and try adjusting it in-situ yourself
3) Separate the compass from the objects causing the deviation by resiting one or the other.
4) Spend half a day making up your own deviation card by taking bearings and headings on a transit.

Personally I'd opt for (3)

Dave
 
number 3 is not so easy...

Compass.jpg
 
I don't think swinging the compass is going to help. The instruments will produce a different magnetic field when powered up than when off. You may even find that adjusting the brightness on the chart plotter affects the compass.

Just a thought. Are the power cables to the instruments as far away from the compass as possible? Also, is 0V and 12V (black and red) twisted together?
 
I agree with the others, I don't think you're going to get a conventional magnetic compass to work that close. The conventional wisdom is 2 feet or more from any iron, much more if it's actually magnetic. Even a deviation card might not help, if you get different deviations with different devices running.

Accepting that no solution is going to be cheap and easy, have you considered adding a fluxgate compass (remote sensor up the mast or wherever) with an electronic display at the binnacle? It would be more accurate than trying to use gps COG as your heading.
You'd still want an analogue compass as backup, maybe sited somewhere less convenient as you will only use it in an emergency? On my boat the standard mounting point is on a removable board that sits across the cockpit foot well in front of the helmsman. Depending on the layout, something similar, e.g. a mounting point lower down the binnacle, might be acceptable.
Good luck.
 
Robinsons' of Hamble will give you a definitive answer but you may not like it and they will require paying.

http://www.compassadjuster.co.uk/

They are one of the few outlets I have parted with money to with a song in my heart but only because I've bought "object's d'art (the art of navigation)".

They sorted my boat compasses and serviced my handbearing compass and I thought they were good VFM for those services too.
 
The bottom instrument on the right is the auto-pilot and that gives a heading, but I am not sure how it is getting it, I presume that there is a remote sensor, does that sound right? Obviously my concern is in the event of a power failure, my compass is misleading. For the rest of the time it is less of a problem because I can use the reading on the auto-pilot.
 
An autopilot will have its own compass, as you surmise, but it will be magnetic again, and you will need to ensure that it is free from interference. That being the case, you have no need to buy another electronic compass, but I think the advice to re-site the main compass is still your simplest option.
 
Re: Get yer compass swung

I've a worrying amount of kit almost as near my steering compass and Robinsons took it in their stride. Highly recommended, £70 I didn't begrudge.
 
Tosca,

First you should confirm that it's the electric stuff that's throwing the compass off. If the problem is on a n/s heading then tie up at a n/s dock and check the effects of switching the gear off and on, individually and in groups. If it is indeed the cause of the problem, then I wouldn't bother adjusting the compass as you won't be able to minimize deviation for all situations - if needed swing it with the electrics turned off. If your autopilot has a compass (I would suspect it's a remote flux-gate type) then you should locate it and ensure it is properly sited; if you're satisfied with its deviation, then I would use it as your primary source, and only use the analog compass when the power is off (whether you're conserving battery or have a malfunction). Good luck.

Kevin
 
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