Nomad Willy
Guru
Art I don't ever think of MPG. Only GPH. Willy burns 1GPH and goes 6.15 knots so I guess it's 6 MPG. That's over twice as bad as my 73 Buick.
And a FD boat requires 3 or 4 hp per ton of displacement. My Willard has 5. Four hp per ton is about as close as one can get not considering the specific boat in question. The Clipper has an extremely fine entry fwd and an easy exit aft. I suspect the wetted surface is not high. Displacement for a 34' X 10.5' FD is rather light. Could be that 24hp should push her close to hull speed and cruise her at 3/4 of a knot below hull speed. But I'd put 30 to 32hp in her if I was repowering.
Bob,
One what ... Clipper?
Predictions of power and speed for a FD boat is far simpler than faster craft. And it helps to have similar boats to compare. 40hp for this boat would be almost overpowered. 60hp certainly is. Why have 60hp when 16 is all that's necessary. It's not that I have extreme ideas. It's just that FD boats require so much (or little) power w a little for headwinds (like 15%) and that's it. They say the Willard 30' boats take 18hp to run about 6 knots ... a knot below hull speed. And that is just about exactly where you want to be. My highest cruising speed is 6.4 knots at 2500rpm. That's 500 down from max of 3000rpm. Nobody in their right mind cruises a FD boat over 1/2 a knot below hull speed. I'd say from 1/2 a knot below and up is overdriven and if one wants to get into those speeds a SD hull or extreme length to beam ratios as in a catamaran would be appropriate or/and necessary.
And a FD boat requires 3 or 4 hp per ton of displacement. My Willard has 5. Four hp per ton is about as close as one can get not considering the specific boat in question. The Clipper has an extremely fine entry fwd and an easy exit aft. I suspect the wetted surface is not high. Displacement for a 34' X 10.5' FD is rather light. Could be that 24hp should push her close to hull speed and cruise her at 3/4 of a knot below hull speed. But I'd put 30 to 32hp in her if I was repowering.
Bob,
One what ... Clipper?
Predictions of power and speed for a FD boat is far simpler than faster craft. And it helps to have similar boats to compare. 40hp for this boat would be almost overpowered. 60hp certainly is. Why have 60hp when 16 is all that's necessary. It's not that I have extreme ideas. It's just that FD boats require so much (or little) power w a little for headwinds (like 15%) and that's it. They say the Willard 30' boats take 18hp to run about 6 knots ... a knot below hull speed. And that is just about exactly where you want to be. My highest cruising speed is 6.4 knots at 2500rpm. That's 500 down from max of 3000rpm. Nobody in their right mind cruises a FD boat over 1/2 a knot below hull speed. I'd say from 1/2 a knot below and up is overdriven and if one wants to get into those speeds a SD hull or extreme length to beam ratios as in a catamaran would be appropriate or/and necessary.
