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Boat depreciation calculator: value by age from a published method

UPDATED 10 NOVEMBER 2026 · 3 SOURCES · FREE, NO SIGN-UP

Estimate what a powerboat, sailboat or personal watercraft is worth by age, using the California Board of Equalization's vessel depreciation factors, with BoatUS's depreciation curve for comparison and where the numbers stop being a valuation.

DEPRECIATED VALUE
$142,665
57% of the price new after 8 years, a loss of 43%. 12% in the first year, then 6% a year.
BoatUS's figures for dayboats: about 20% lost by year five, 30% to 50% by year ten, bottoming out at 10% to 30% of the original price.
A tax assessor's mass-appraisal guide. Condition, engine hours and comparable sales decide a survey valuation.

Pick the boat type, enter the price new and the age, and the calculator applies the California Board of Equalization's vessel depreciation factors year by year.

Where the factors come from

The Board developed its factors for county assessors to value boats for property tax. It built its database from the BUC Used Boat Price Guide, the N.A.D.A. Marine Appraisal Guide and the ABOS Marine Blue Book, using several years of values from each. Its table:

Boat type First year, bought new from a dealer Each year after
Powerboat to 42 ft 12% 6%
Powerboat over 42 ft 12% 4%
Sailboat 3% 3% to year ten, then 1%
Personal watercraft 22% 8%

The powerboat factors cover inboard, outboard and sterndrive boats, from bass boats and center consoles to trawlers and yachts. The Board left out houseboats, since most are custom built and the value guides don't list them.

The calculator applies each year's decline to the previous year's value, the way the Board's later letters apply their factors to a prior year's value.

How it compares with the market

The Board later replaced this table with yearly valuation factors, to follow swings in the market. In one of those years the factor for powerboats under 38 ft was 1.05, a rise in value. So treat this table as the shape of a typical decline, and the market as the judge of any one year.

BoatUS describes that shape as an S-curve: a 10% to 15% drop in the first year, around 20% lost by year five for the average dayboat, and 30% to 50% by year ten. Depreciation then speeds up again with age and the boat bottoms out at 10% to 30% of its original value. It names brand, build quality, size, regional demand and the boat's maintenance history, engine hours included, as what slows the decline.

In a valuation

The Board says its table is a guide for mass appraisal and that data on the specific boat should always be considered. A condition and valuation survey works from that data: the boat's condition, its equipment and engine hours, and what comparable boats have sold for. Use the calculator to sanity-check an asking price or a client's expectations, and the copy button to note the figure as a reference.

Frequently asked

How fast do boats depreciate?

The California Board of Equalization's factors give powerboats 12% in the first year when bought new from a dealer, then 6% a year up to 42 ft or 4% a year above it. Sailboats lose 3% a year for ten years, then 1%. BoatUS says there's no single rate and most boats follow an S-curve.

Do sailboats hold their value better than powerboats?

In the Board's study, yes. It found every class lost more in the first year when bought new from a dealer, except sailboats, which declined a steady 3% a year to year ten.

Can I use this for a condition and valuation survey?

As a cross-check only. The Board built its factors for mass appraisal for property tax, and says data on the specific boat should always be considered. A survey valuation comes from the boat's condition and comparable sales.

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