Your boat loan payment comes from three inputs: the amount you borrow, the rate and the term. The term moves the total cost most, because boat loans can run for many years. Navy Federal Credit Union, for one, lends for up to 180 months, or 15 years.
The calculator prices the loan alone, so insurance, storage and upkeep come on top. Financing a motorhome instead? The RV loan calculator does the same math.
Longer terms can come with a higher rate
The rate can depend on the term, not just your credit. On September 26, 2026, Navy Federal's lowest new-boat APR was 6.95% for up to 36 months. For 37 months or more, it was 8.95%. Used boats cost more: 7.45%, then 9.00% up to 72 months and 9.90% beyond. Those "as low as" rates assume excellent credit.
Here's $40,000 borrowed for a new boat at those rates:
| $40,000 borrowed | APR | Monthly payment | Total interest | Total paid |
|---|---|---|---|---|
| 3 years | 6.95% | $1,234.17 | $4,430 | $44,430 |
| 5 years | 8.95% | $829.36 | $9,762 | $49,762 |
| 10 years | 8.95% | $505.62 | $20,675 | $60,675 |
| 15 years | 8.95% | $404.52 | $32,813 | $72,813 |
Stretching to 15 years cuts the payment to about a third. But the interest climbs to $32,813, more than seven times the 3-year cost. Even 60 months more than doubles it, partly because the rate jumps two points.
To weigh two real offers, the loan comparison calculator shows both totals side by side.
Where the $404.52 goes at first
P is the amount borrowed, i the APR divided by 12, and n the number of monthly payments. For the 15-year loan, that's $40,000, 8.95% ÷ 12 and 180 payments.
Interest is charged each month on the balance left. The first month's interest is $40,000 × 8.95% ÷ 12 = $298.33. So only $106.19 of the first payment pays down the loan. On a long loan, the balance falls slowly for years.
Pay a long loan like a short one
There's a middle route. Take the 15-year loan at 8.95%, then use the extra-payment field to add a fixed sum each month:
| Extra each month | Monthly outlay | Paid off in | Total interest |
|---|---|---|---|
| $0 | $404.52 | 15 yr | $32,813 |
| $100 | $504.52 | 10 yr 1 mo | $20,757 |
| $200 | $604.52 | 7 yr 8 mo | $15,341 |
| $400 | $804.52 | 5 yr 3 mo | $10,167 |
An extra $100 clears the loan in 10 years and 1 month, with $20,757 of interest. That's within $82 of the 10-year loan above, for almost the same monthly outlay.
The difference is control. In a tight month, you can drop back to the required $404.52. It works only when both terms carry the same rate and the contract has no prepayment penalty. At Navy Federal's new-boat rates, 10 and 15 years both cost 8.95%.
How much should you put down?
Navy Federal lists a no-down-payment option, but borrowing less shrinks everything. The payment and the interest scale with the amount you borrow. Put $5,000 down on a $40,000 boat, and the first table's payments and interest drop by an eighth.
A deposit also cushions you if the boat loses value faster than you repay the loan. The depreciation calculator projects a value at any yearly rate you expect. Compare that with the balance chart in the result panel.
Can boat loan interest be tax-deductible?
Sometimes. Under IRS rules for 2025 returns, a home includes a boat with sleeping, cooking and toilet facilities. A loan secured by such a boat can then qualify for the home mortgage interest deduction.
At least three limits apply. You must itemize deductions on Schedule A. Only one second home counts in any year. And the debt must be secured by the boat, so an unsecured personal loan won't qualify. Treat this as general information, not tax advice.
APR or interest rate: which one goes in the box?
Lenders such as Navy Federal quote boat loans as an APR, and the rate box is labeled that way. The Consumer Financial Protection Bureau (CFPB) explains that an APR adds origination charges and other fees to the interest rate.
With no fees, the two are the same, and the payment here should match your quote closely. With fees, compare offers by APR, but expect the calculated payment to run slightly high.