Understanding your magnetic compass
As a seafarer The magnetic compass has been the main directional tool in the seafarer’s toolbox to try and determine true north and then use that information for steering a course or take a bearing to fix position. The problem is that it has errors [1] . Let us take a closer look at a ships magnetic compass. Today it is likely to be found on the monkey island as a backup to satnav systems but is still a requirement on ships. The compass card is a magnet overlaid with a card holding the points of the compass. The card has a pivot and is mounted in a bowl filled with alcohol and water to dampen the movement of the card. The bowl is then mounted in a set of gimbals so that the compass remain as horizontal as possible with the ships motion and the complete magnetic compass is installed in a wooden stand called a binnacle. The binnacle provides housing also for important tools to minimise compass errors. ...