boat speed

Question
I'm looking into buying a small 15-ft pontoon party boat to replace an 18 ft with a 75 hp motor.  The max motor that the 15 ft boat will take (according too specs) is 40 hp.  I'm concerned that I will be unhappy with the speed of that combination, as my previous boat went quite fast. What speed can I expect from the 40 hp motor on the small boat?  I use it on a 4 mile lake - trying to figure how long it will take me to travel that distance.
Thank you for your advice!!!

Answer
Hi Elaine...Thank you for selecting the undersigned to reply to your question.

Your maximum speed is primarily determined by the diameter and pitch of the propeller, so check your engine's owners manual to find how far the craft will travel in one revolution of the prop.

Do not exceed the max. recommended hp that appears on the boat's "Capacity" plate, which is regulated by the U.S. & Canadian Coast Guards.

In the event you are involved in an accident, your insurance company may deny coverage because your vessel was over powered, so don't exceed the max. hp for your own safety. Also bear in mind, pontoon boats were not designed for high speed, but rather jonting along to enjoy the scenery, etc. If your desire is to go fast, consider an alternative single hull boat.

Safe Boating
Ron