The key issue here is the nature of your relationship with the other person:
- Ask your buddy out on the boat for the day and he happens to pay when you top at the fuel dock
, no problem. It's not a commercial venture, so you are allowed to take friends out and they can share in some of the costs.
- Go online and offer to take random people you don't know out on boat rides but it's mandatory for them to cover the fuel
bill, it's a commercial operation. At that point insurance, marina rules, captains license requirement all must be addressed.
You're playing in a bit of a gray area. You could claim it's a buddy staying with you. In theory, you are covered right? Let's say he accidentally breaks off a thru hull
and sinks the boat. No problem your insurance covers such an accident
... but you ask him to cover the $1000 deductible. He's not the standup guy you thought things turn a bit ugly and when the insurance company asks, he tells them that you are subletting space on your boat as a commercial venture...a couple weeks later you get a nice letter from the insurance company notifying you that they aren't covering the incident because it was part of a commercial venture and you didn't buy commercial insurance. (we can make if far worse if your room mate invites a date over while you are gone and she trips cracking her skull open.)