How fast can a 20 hp reach?

Question

How fast can a 20 hp reach?

Answer 1

Depends what it's fitted to, whether it's inboard, outboard or jet drive, what load is being carried and whether the hull is designed to plane or not so more detail is needed.

An old 9' Fletcher Arrowsport GRP-hulled speedboat fitted with a Mercury 20 outboard  I owned could touch around 25kts in ideal conditions whilst carrying two small adults.

Answer 2

It all depends on the size of the boat and its running surface.

Answer 3

In space, it could cause you to approach the speed of light.

In a median such as air or water, the speed is greatly limited. With size and weight greatly reduced, the speed of sound is probably achievable. For a given boat, there is a complex partial differential equation that can be used at great cost and effort to test.

For an arbitrary boat, there is only guessing and testing. More weight, a larger cross sectional area, smoothness of the surface of the boat and many other factors will contribute. Results will vary even from salt to fresh water, calm or windy, and other factors.

Answer 4

8ft hydroplane, 40mph.

26 foot pontoon, 6mph

Answer 5

K.O has the right answer- I would only add that the pitch in the prop is also a factor in the equation- most people don't realize that it is the boat the motor is on that determines the speed , plus prop pitch.

Answer 6

My dad raced a B utility back in the seventies, With a slightly modified  Merc 20 H.  His top speed in the measured mile was 46 mph.  Not to shabby for a 9' boat.

Answer 7

10 mph