Guessing that your boat weighs 40,000 lbs and is a semi displacement hull. My experience is that it takes 2 hp per thousand pounds to push a semi displacement hull to its hull speed. This is a little higher than FF's rule above because yours is a semi displacement hull and they are less efficient than displacement hulls.
For your boat that is 80 hp to reach almost 9 knots hull speed and at 7 kts it will take about half of that. Twin Lehman 80s will be fine for those speeds.
So go for it.
David
|