4-5 mph depending on wind, tides etc..
8-15
50 mph
Depends on how it is geared.
70
25 or so I would guess. My tri cruiser with 90hp Honda goes 23.
25-40
A 3HP motor can reach speeds up to at least 30 mph depending on what you are using it for.
about 25-30 mph
25 HP is 25 HP, no matter how you slice it and dice it.
About 10 to 12 on plane
This all depends on the boat in which it goes. A 25 HP outboard motor, on a 14' aluminum runabout can cruise at 20-25 mph. Now, if you were to install hydrofoils (do a Google search) to the bow and transom area of the same boat, you could go upwards of 45 MPH +. Although not very common today, hydrofoils are currently used on Italian, and American navy battleships...crazy fast
Put a 12 hp motor on it.