ONLY REQUIRED UNDER CERTAIN CONDITIONS: A magnetic compass is not required if the boat is 8m or less and operated within sight of navigation markers.
A proper magnetic compass is a good tool to have onboard. It will help you determine a heading when you are out of sight of visual references and help verify your course when the visual references are in sight. If the conditions or weather gets bad, a compass will help you to verify that you making an ‘accurate 180’ and returning back the way you have come.
Look for a good quality compass. It will feature large numbers and proper lighting of the compass for night reading. When you permanently install the compass, be aware that the presence of metallic objects nearby will affect the accuracy of the compass. A classic example is having speakers close to the compass position at the helm! Also, placing loose metal objects close to the compass will affect its accuracy.