As Scott said a 4 or 5 amp should work, but I'd want to know what gauge wire you're using. You want the fuse to blow before the wire melts. If you have a digital voltmeter they usally have a 10 amp dc current scale. You can put it in series with the gauges and see exactly how much current they draw.
Just a guess but maybe the meter is showing there's 120v shore power and is wired before the master panel switch. Is the master panel switch on your boat?
I'm just throwing this thought out there to think about. Won't the zinc coating eventually dissolve, chip or deteriorate and start corroding the exposed metal of the bolts especially if in saltwater?
I should have been more specific, I meant pictures of the end of the plug, the male part. the part that fits into the socket. I wanted to see if there's a tab or threaded end that's suppose to keep the plug in the socket.
Someone would need to know what kind of weather and sea conditions you have in your area to help you decide on what type of boat to buy. Since this is your first go around with boats I suggest you take a look here.
https://www.uscgboating.org/recreational-boaters/boating-safety-courses.php...
I just did a search to see what the boat looks like and saw several for thousands cheaper. I didn't compare the details that may explain the difference in price. Hopefully someone is familiar with this make and model boat that can answer your questions. You may want to post pictures of the...