[MHml] Horsepower

[Alan Christoffersen]

How about 2 sets of foils for Afterburner? One usual for sailing, and
another with T-foils for motoring. Would need a diver to install, but if
made with a rotating “angle of attack” adjuster, you could dial in the right
angles for the speed and sea state. Once up on the plane the energy required
will drop. See the Moth pages for rotator adjuster

 

Alan

 

  _____  

Fra: multihulls-bounces at steamradio.com
[mailto:multihulls-bounces at steamradio.com] På vegne af TLam45387 at aol.com
Sendt: 6. februar 2007 00:35
Til: multihulls at steamradio.com
Emne: Re: [MHml] Horsepower

 

There is room for innovation here and the idea of getting the Burner on
plane has merit.  The long thin hulls are solely to get the boat through its
hull speed hump. Either above or below about 10 knots the extra wetted
surface is just creating unwanted friction drag. 

Because Bill's need is for speeds well above hull speed then the objective
should be getting the existing hulls as much out of the water as possible at
cruise  while keeping the long waterline during acceleration.  Power tilt on
outboards can be used for this purpose but it does not seem there will be
enough force available to use this to much effect.  One device used on semi
displacement powerboats is to add chine strakes or chine extensions along
the hull sides.  The extensions provide a clean lateral flow break and add
lifting surface to help raise the hull and help get the bow up.  Many a
underpowered or overwieght power boat design has been saved this way.  

Hydrofoils between the hulls are even more effective and efficient.  The
Prout Panther power cat used this device and the Corsair power cat also had
a midships foil between the hulls.  Unclear if these function as true foils
or switch between being foils and being planing surfaces like a stepped
seaplane hull. Should not be too difficult to strap on such a foil just for
delivery.  might take the power requirement out of the 300-400 hp. range and
into the 150-200 area.  

I would guess Malcolm has studied these possibilities in his many power cat
designs.

Tom




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