What horsepower do you need for a 14 foot boat?

The USCG, ABYC, Canadian and ISO rules all use the same formulas for horsepower for outboard powered boats under 20 feet (6 meter) based on center line length, transom width and transom height.

see chart below

Taken from Title 33 Code of Federal Regulations Subpart 183.53

Outboard Horsepower Capacity

Compute the Factor = Boat Length x Transom width If Factor is (to the nearest integer)

0-35

36-39

40-42

43-45

46-52

Horsepower is

3

5

7.5

10

15

Note: For flat bottom hard chine boats, with a factor of 52 or less reduce HP one capacity increment If the Factor is over 52.5 and the boat has

Remote Steering and at least 20" Transom Height

HP =

(2 x Factor) -90

No remote steering or less than 20" transom Height

For flat bottom hard chine boats

HP =

(0.5 x Factor) -15

For other boats

HP =

(0.8 x Factor) -25

So if your 14 foot boat is actually 13.83 (13 ft 10in) and has a 4.5 ft transom width the factor will be 62.23. If it has a 20 inch transom height and remote steering then 62.23 X 2 -90 = hp = 34.47 round that to 35.

If it has a 15 inch transom and/or tiller steering (the tiller on the motor) then it would be 62.23 x 0.8 -25 = hp = 24.78 round to 25 hp.

You have to measure the actual centerline length and transom width. Transom width includes rub rails. (in other Words use the widest part of the transom)

For more info see the link provided below.

in Canada or Europe this would be in meters and kilowatts.