Deviation Meaning in Sailing

Deviation refers to the error in a magnetic compass caused by local metal objects. Every boat contains iron, electronics, and wires that pull the compass needle away from north. This local interference changes depending on the direction the boat is currently pointing in water. Sailors create a table to track these specific errors for every major heading on compass. One specific example involves a compass pointing two degrees east because of the heavy boat engine. The sailor must subtract those two degrees to find the correct magnetic direction for travel. Proper calibration of the compass helps minimize these errors but some deviation always remains present. Keeping large metal tools away from the steering station helps maintain the accuracy of the reading. Understanding this error ensures the navigator follows a precise path toward a distant island or buoy. It is a critical factor for safe travel when land is not visible to crew.