Loan amount: the amount borrowed from a lender or bank.
Down payment: The down payment is an upfront amount of cash paid by the borrower at the time of the purchase of the vehicle. It is usually expressed in terms of a percentage of the total price. It is not a legal requirement when taking out a boat loan, but is almost always required by the lender.
Interest rate: An interest rate is a basic rate charged to the borrower for the money loaned. The interest rate is normally expressed as a percentage for a one-year period and known as the annual percentage rate (APR).
Terms and conditions: All of the other items that comprise a boat loan, including the term of the loan, typically stated in terms, months or years; insurance and registration requirements; loan repayment and resale terms; maintenance requirements; conditions regarding theft or collisions; and conditions of loan default and repossession.

The boat loan calculator helps estimate the monthly payment due for the duration of the repayment period of the loan.

The information you need is the amount of the loan, the interest rate per month and the total number of months that you will make a payment.

Monthly payment = r + r / ( (1+r) ^ n -1) x Present Value
Where:
r = rate per month
n = number of months