Bank of Scotland also offer a calculator for marine mortgages, but they offer two types, the first calculates how much you can borrow based on how much you can afford to pay for your boat each month, and the second how much a specific amount will cost to borrow.
The Marine Mortgage calculators can be found here: Bank of Scotland Marine
Bank of scotland have been providing marine finance for over 30 years. Their main website for boat loans can be found at : bank of scotland boat loans