You don't have to own a 100 foot schooner to use our services, most of our clients' yachts are less than 40 feet long. It is not unusual for some owners, when they acquire a new yacht to assume that the compasses aboard will be accurate. Until the yacht has been 'Swung' and the compasses properly adjusted, deviations are normally present which can be considerable and need adjustment.
Ideally, a magnetic compass will align itself with the earth's magnetic polarity. However, items such as music speakers, VHF sets, electric winches, plotters, tachometers etc, will deflect the compass needle varying amounts on different headings creating errors. Deviation is the name given to the disparity between the compass heading and the actual magnetic course.
A Compass Adjuster establishes the extent of these errors and subsequently removes them using either the compass' own internal compensators, and / or, additional magnets. In certain cases, it is not possible to remove all errors due to unsymmetrical deviation caused by electro-magnetic fields or the proximity of the compass to strong magnetic influences. However, we strive to work to a residual error of one degree.
On a boat where there are no serious complications, i.e. a steel hull, or considerable deviations requiring more time to remove, one hour usually covers the procedure. The Adjuster will meet the client on the boat and is happy to help with leaving and returning to the berth. The owner or helmsman will need to take the vessel out to an agreed location in order to manoeuvre it onto a series of headings. This is known as 'swinging the compass' and subsequently why Adjusters have traditionally known as 'compass swingers'! After the job, a Compass Deviation Card showing Residual Errors will be issued.
Whatever the vessel's dimensions, or indeed purpose, all magnetic compasses potentially have errors. Being aware of these errors and subsequently having them removed by a Compass Adjuster results in accuracy, and, of course, the peace of mind that heading shown on the compass is the actual course steered.