It wasn't crimped properly. The crimp was loose, that's why the terminal looks perfect where it screwed on the panel, but fried aft of the terminal.
In the U.S. we never have breakers on the Neutral. Only the line(s). All neutrals go to a shared terminal strip.
Yes, the tiny vent could be the problem. I would put an elbow on it so it isn't open to the sky and the opening ponts downward. Or even just...
With the electricity here, you HAVE to use a single pole breaker for 120 volts. The way our electricity works is you have 1 line (hot wire) and 1...
They're great boats, everything Pascal said I'd agree with. You're going to want to run it 20 knots or above to stay on plane........why not just...