Horse power is not an indication of speed.
The speed of any vehicle depends on a variety of factors.
What medium through which it is moving. (Air, water, land, space)
The power of the engine.
The weight of the vehicle.
The streamlining.
The gear ratios. (If any)
The efficiency of the system.
50 to 60
8-15
15
about 40mph
165 hp
Answer now.
A 6 hp outboard will go about fast enough to plane a 10 ft. aluminum boat, with one passenger aboard.
about 10 to 15 miles per hour depending on pitch of prop i believe but don't quote me
59 hp
Depends on gearing
274 HP
50 mph