The most obvious fee is interest. Depending on the size of your loan, the lender you choose, and your credit history, you could pay as little as 3% or as much as 36% APR. Your boat loan may also come with a one-time origination fee, costs for a marine survey or other paperwork necessary before your loan is approved, and so forth. Be sure to get a fee breakdown before you sign on the dotted line with any provider of boat loans.