My first suspicion would be that you have developed a bad electrical
connection over the years - a very common thing on boats, especially in salt water
. I'm not familiar with the Lewmar
AP drive, but it must have an electric motor
in it, and likely one that draws a fair amount of current
. If you lower the voltage to a motor
, which will happen if you have a failing electrical
connection, the motor
will in turn draw more current
than normal. More current through a bad connection creates more voltage drop which in turn creates more current draw, and the cycle so continues. Eventually your fuse does it's job and breaks the circuit before a fire starts.
Check connections, and to the extend you have access, take voltage readings at point progressively closer to the AP drive. Ideally you would not see more than a 5% drop (about 0.5V) out at the drive when the drive motor is actually running. By probing along the way you should be able to narrow down where the problem is.