Andy.
Not an electrical genius but surely the windlass is either 12 or 24 volts so would normally just be wired through an inline fuse.
The problem you will have is that the windlass is not standard spec so could have been wired in any manner of ways. From memory the main switch panel has a spare switch on it to wire the windlass to. If you start looking here you may be able to trace it back and find what you are looking for.
