It costs a lot of money to maintain a vessel. The cost depends on the size of the vessel, how often it is used, and what kind of maintenance is needed. For example, a small boat that is used infrequently may only need to have its hull cleaned and waxed once a year, which would cost around $100. A large yacht that is used regularly may need to have its hull cleaned and waxed every month, which could cost over $1,000 per month.