Question 633Navigation General

The correct answer is A) deviation. The difference between magnetic heading and compass heading is called deviation. Deviation is the difference between the compass reading and the true, or magnetic, heading caused by the magnetic fields of the ship's metal components. This causes the compass to deviate from the actual magnetic north. The other options are incorrect - drift refers to the effect of wind and current on a vessel's course, variation is the difference between true north and magnetic north, and compass error encompasses both deviation and variation.