Thank you for bringing up the insurance
issue. It is a very important consideration. If someone gets injured or dies on your boat while you are renting
it out, I can't see any insurance
company covering that. If the injury or death was caused in part by a mechanical failure (broken seacock, etc.) your liability exposure could be extreme.
To answer the OP, companies like Airbnb function only as a listing service
. They don't check to make sure the property you rent out is allowed to be rented out. People who have boats on there are either do so in violation of their contract
with the marina, or have worked out a deal with the marina that may or may not be under the table.
However they are doing it, it does not address the insurance and liability issue, so give it some thought before pursuing. Evidently not everyone is concerned about that issue, but it only takes one fluke accident
for it to become apparent that everyone should at least plan how to deal with it.