Boating is more affordable than you think. In some instances, you can buy a brand new boat for around $250 a month while a new PWC may be purchased for around $125 a month. Interest on a boat loan may be deductible if the boat has a galley, berth and head. If you know your monthly budget amount, enter it in the total loan amount window and work backwards to determine what size loan you can afford. Or, if you know the cost of the boat or PWC you want, put that amount in the monthly payment window to determine your monthly payment.