Division is angle contained between north-south line of ships magnetic compass and Earth’s magnetic pole.
Compass deviation is caused by magnetism in ship structure.
- We know that Earth’s magnetic effect is least at the equator and increases as we proceed towards the pole so ideally ship should be at the equator.
- Ship is then steered to every 10° interval starting from 000° to 360°
- Corresponding magnetic course was noted for that every 10° interval.
- We get variation from chart of that place in which we are sailing
- DAVIATION calculated from it is tabulated . This is how we used to obtain daviation table.