Power / Sailing Multihulls

[beau]

It's a bit hard to get good photo's in such narrow hulls, and he has bolted down the original access hatch.

We went out again on the weekend, fantastic, we were accompanied by a Mariner 34 which is a typical planning power cruiser.
Both had Steyr motors.
The Mariner had replaced two 130 hp diesels with two 265 hp Steyrs, the Steys were considersbly lighter than the original motors even though they had much more power.

An interesting calclation, the Mariner had a power to weight ratio of 60 Hp/tonne (a planning hull)
The power to weight ratio of the Catamaran was 25hp/tonne.
Both do 20 knots

The catamaran had a far better motion, cutting through the waves not over the top.

Does anyone else out there have experience with fast displacement hulls and the power to weight ratio in use.

Today I will be checking on a fast displacement ferry range (Citycat) to check on there p/w ratio. I am of the opinion with better hull design we can get the P/W down to under twenty. (the grainger cat was designed as a sailing boat)

[drewke07]

I sometimes get the chance to captain a 55' wingmasted motorsailor here in Hawaii. She is set up for daycharter, carrying 50 people at a fully loaded cruising speed of 20 knots. I think she weighs in at around 16 tons and uses 2 medium continuious rated 350hp Cummins diesels. Top speed empty is around 24knots. I've had her up to 16knots reaching under sail freewheeling 26" four blade fixed prop.