power to push 40 footer at hull speed

[sjoduvan]

Does anyone know where I can get data on how much power I need to push a 40 foot Cruise-a-Home at hull speed ?
Thanks
marke

[longliner45]

well,,,,,,,, many more smarter than I,,but I (have learned,on these threads) that rule of thumb is 2 hp per ton works well,,I have a 10 hp volvo ,,but if I hade a few bucks extra I would throw in a couple more horses for kicks,longliner

[Jango]

Do you have a no. for Hull Speed (knots or mph) and also approx. weight?

[marshmat]

Is this the boat? http://www.geocities.com/ctenning/index.html , see photo below.

Looks like the thing originally came with more engine choices than you can shake a stick at, anywhere from 200 to 540 hp in single or twins.

I'd guess around 36' on the waterline, specs appear to be 39'11" LOA and 12'0" beam. Weight is given as 14,000 lb (6350 kg).

By the 1.34*sqrt(lwl) approximation, "hull speed" is about eight knots. I suspect you'd see it trying to raise its bow by that point, though, so perhaps seven knots is the speed you're after?

The 2 hp/t guideline longliner mentions would give you 13 hp.... doesn't strike me as enough to be able to handle it on a breezy day, though, so maybe more like 25-30 hp would be appropriate for sedate cruising below seven knots?

[charmc]

Longliner's rule of thumb holds true for boats without a lot of sail area. If the one you are considering is anything like the picture marshmat posted, I'd go with the extra power to have the reserve to be able to hold 7 knots against a brisk wind. You will be able to run at reduced throttle to use less fuel under light wind conditions, but when the wind catches that high cabin, the extra power will be handy.

[Jango]

My calculations show 15.4 HP, but I agree with the two previous people, 20 -25 HP min.

Jango