Do make sure that the steering compass, particularly those on a binnacle with wheel steering, are protected as much as possible from the weather. There are often four small holes in the binnacle which are there so a compass adjuster can remove or lessen the compass’s deviation by playing with some magnets. These magnets allow the compass to be adjusted without taking the device off the binnacle; the holes are normally protected by plugs which may deteriorate over time and with salt water ingress rusting the magnets, errors can creep in. If you have a bulkhead mounted compass, you can have the same problem. If you ever have to remove any steering compass and find there is electrical wiring nearby, do ensure that the positive and negative wires are twisted together. A single DC wire creates a magnetic field which will cause deviation.
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Sticky's Tips 
November 2, 2011 at 2:29 pm |
With the amount of electronic equipment on board yachts these days, compass deviation can be a major problem. On a recent yachting holiday in Turkey, sailing a Dufour 405, I found the loudspeakers in the cockpit sited only a few inches below the steering compasses. (2 steering wheels therefore 2 compasses). The large deviation caused was extremely abnormal resulting in a ridiculous deviation curve. Beware yacht owners where you place your electronics in relation to the compass position. If in doubt, use the services of a compass adjuster.
November 4, 2011 at 10:43 am |
I have just delivered another Dufour to Malta which had stereophonic speakers in the cockpit, but well away from the steering compasses. This boat had been coded and fortunately the compasses had been swung. We had a maximum of 2 degrees deviation, which, with a maximum leg distance of 700 M was not too much to worry about. Maybe soon someone will find an economic way of producing fluxgate compasses. I am always happier with equipment which does not rely on an electric current.
November 4, 2011 at 1:54 pm |
Dear Sticky, Thanks for your recent reply. As a retired Master Mariner I have delivered numerous yachts and motor cruisers and many’s the tale I could tell about compass deviation and its’ causes, even discovering on one occasion that as the consumption of tinned food progressed so the deviation altered! The compass was sited directly over a deckhead locker in the galley. Fluxgate compasses can be badly effected if they are installed low down in the fore part of the vessel near to the anchor chain locker. One needs to be a detective! Cheers for now and bon voyages!
G.P.GRAHAM