|
|
|
||||||||||||||||||||||||||||||||||||||
Swinging the CompassDeviation is the problem of compass error due to structure of the vessel, proximity of metal objects, magnetic fields or electrical equipment. It may be influenced by loading cargo (e.g. canned fruit) or having repair work done (new metal parts or electronics). Deviation also varies with the ship's head (way it is pointing) as this changes the position of the magnetic fields in the boat relative to the earth's magnetic field as well as it's relationship with interfering objects onboard. Individual vessels have individual deviation cards that show the adjustment required for changes in position of the vessel's head. The process used to produce a deviation card is called 'swinging the compass'. There are several methods for doing this but in general terms the procedure is as follows:
Below is a sample table of deviation values:
This can be plotted as a deviation curve and intermediary values read off the graph if required. Total compass error is the combination of both deviation and variation (declination) and the rule is:
For example, a variation of 15° east and a deviation of 5° west, gives a total compass error of 10° east. Whereas a variation of 11° west and deviation of 3° west, gives a total compass error of 14° west. |
Coastal Boating (Reg. in Ireland No. 443222) is a division of Knowledge Clinic Ltd.
Europe: Port Aleria, Rosnakilly, Kilmeena, Westport, Co. Mayo, Ireland - USA: PO Box 726, Mahwah, NJ 07430 All content on this site is subject to Copyright© - All rights reserved. Contact us - Advertising - Privacy - Terms & Conditions - Copyright & Trademark - Webmaster |