Roger gives you excellent information. I would add to your post, that the wires are hot, black, neutral, white and ground is green.
I prefer a double pole breaker on the boat, but with your setup, you can use a fuse and a single pole breaker. What is did is go to Home Depot and for about $10, there is a metal box, with a 30 amp switch, which has a screw in fuse up to 30 amps inside the box. This is made as an "on off" switch for heavy duty motor. But it is a safe and effective single pole switch and fuse for a boat. In my case, since I run only a single 15 amp circuit (GFI protected) and battery charger, I have this one breaker. The inlet is placed on the aft bulkhead, of the cabin, where the controls and wires go thru on the starboard side under the gunnel. I cut a hole sized for the battery charger inlet (this is a plug rated for 15 amps, and not to be left attached when the boat is not attended, as the marine plug is. This plug does have a "stopper" in it to avoid corrosion, and I spray with corrosion block when not using. The plug is male, and you plug the female end of a # 12 extension cord into it. Most of the time (95%) we are running power to the boat from the 1000 watt Honda generator. Most of the rest of the time is at home where we use a 15 amp circuit.
Theoretically there could be an objection to running this off a 30 amp breaker in a marina. Some marinas do have 15 amp circuits, as do must RV parks. However, the only risk would be a dead sort in the cord, and we test the cord before use (there is a neon light at the end of the cord built into the plug).
In your setup, I would just run the green wire to the ground of the plug, and not ground the boat--that is leave the ground "floating". Again, this could be controversial--but in our small boats we don't leave in the water this is acceptable.
If you are gong to leave the boat in the water, hooked up to a 30 amp plug--then definitely put in a true marine panel, with double breaker on the inlet, breaker for each circuit, and consider a galvanic isolator as is installed by the factory currently. The new "smart plug" would be advisable in this case.