Barclays Marine finance have a handy and quick calculator that enables you to work out the repayments on a marine mortgage that you may be considering to purchase your new boat.
You can simply select the amount of the boat loan and the number of years and it calculates the monthly repayments for you. See the calculator here: Barclays Marine Calculator
Barclays Marine Finance section also has some useful information about boat loans and an online application form. The main marine mortgage pages can be found here: Barclays Marine