How to use the Boat Loan Calculator
- Enter the amount financed after your deposit and any trade-in.
- Enter the quoted rate — marine loans usually price a point or two above auto loans.
- Set the term; larger vessels commonly qualify for 15 to 20 years.
- Read the total interest line before deciding on the longest available term.
How the calculation works
Boats depreciate quickly while marine loan terms are long, so the negative equity window is wide — often five to eight years on a new vessel. A larger deposit is the only reliable way to shorten it.
Payment alone understates ownership cost. Mooring, winter storage, insurance, haul-out and antifouling commonly add 8–12% of the hull value each year, so budget the loan payment as roughly two-thirds of true monthly cost.
Secured marine loans on newer vessels price meaningfully better than unsecured lending, and many lenders decline hulls beyond a certain age, which is why older boats often end up on personal loan terms.
Payment = P × r ÷ [1 − (1 + r)⁻ⁿ], n = term in monthsSource: National Marine Lenders Association standard marine loan term guidance; NADA marine valuation depreciation curves.
Worked example
$45,000 financed at 8.25% over 12 years.
- 144 payments at a 0.6875% monthly rate.
- Payment is about $489 a month.
- Total repaid comes to roughly $70,400.
Around $25,400 of interest — more than half the original amount financed.
Frequently asked questions
Is boat loan interest deductible?+
Sometimes. A vessel with a berth, galley and head can qualify as a second home in the US, subject to current mortgage interest rules.
How much deposit do lenders want?+
Typically 10–20%, with better rates above 20% because it offsets first-year depreciation.
Can I finance a used boat?+
Yes, though many lenders cap hull age around 20 years and require a marine survey.
Last reviewed September 1, 2026. We review this page whenever the underlying formula, tax year, published rate or standard changes.