For all your rentals you have to use a contract and have it signed by both the boat owner and the tenant, regardless of the type of rental (with or without a captain).
If you are a private owner, and you rent your boat "with a captain", Click&Boat automatically creates a contract to be filled out and signed by both parties.
On this contract, you will find all the relevant information about your rental, but also the check-in and check-out documents, as well as a damage report that you can use in case any damage occurs during your rental.