It is the negative rail that causes problems--there should be NO
electrical connections of any kind on a self-steering system. The usual culprit if fitted would be the
electric rudder position indicator switch. Another trap for young players is having the negative of the
battery supply permanently connected to the
Anchor windlass--for the same reason--the
anchor chain being galvanised then becomes an electrode via the
windlass drum. In some areas the loss of zinc from anchor and chain is rapid and blamed on the chain manufacturer--and of course thicker galvanising will endure electrolytic
corrosion for longer.