Resolution is about one degree. Resolution above 10 deg. is 5 deg. - too much. The wind may shift 4.5 deg. Far too large, see left. Allowed in all classes.
Some classes prohibits electronic compasses.
No battery required. No risk compass stops working because of flat battery. In small boats which normally has no battery it requires a separate installation. Must be charged or compass doesn't function. No electrical circuitry that can get damaged from water seeping in.