Sounds like there is a possibility that this is something specific to the boat/engine but in general I would rule
everything else out first. A tripping breaker is trying to tell you something. It may only be the breaker is going bad. I would replace the breaker first. If the new one still trips then you now have a good spare, which is a good thing if you have some electrical
gremlin running around.
You absolutely need to find out why it is tripping. I had to replace half of an AC circuit board once because the owner kept turning back on a tripping breaker. It overheated and fried several breakers and many wires around it. They only called me in once they smelled burning wire insulation
. You never forget that smell.
It could be just a loose wire too. Check all the wire terminations, starting with the circuit board. If you haven't ever done that it is a good use of a few minutes in any case.
If it is engine related, and this is common for this engine, I would seriously worry about the design of a system that trips the main breaker before it trips a circuit breaker or fuse.