What is Deviation?
Deviation is the difference between Compass North and Magnetic North. Good seamanship recommends that all vessels should have a deviation table for the magnetic compass. What causes deviation? Deviation is caused by the vessels magnetic pull. Steel or electrical sources can affect the pull on the magnetic compass. Common sources include electronics, audio speakers, batteries and wire cables. How long does it take to swing a compass? The time to accurately assess and compensate a compass varies. However, the time should not exceed two hours. The vessel must leave the quay to manoeuvre around the compass headings (swinging the compass). During this swing, distant bearings or other appropriate methods determine the vessel’s magnetic heading. Can I check the compass myself? Yes, you can check for error in your compass by aligning the vessel on known headings and noting the compass reading. How much does it cost to have my compass adjusted? The cost to have a compass adjusted varies, depend
