New power cat - help please!

foxfish - thanks for PM. i really can't analyze performance without more info on proposed design, weights, etc. I'm sure that you'll have plenty of fun building and testing and modifying your boat. Let me know if i can help.

 

The pic shows half the transom on a hardboard template, I think the hull angle is 17 degrees, what would be the effect if I changed the angle to say 14 degrees?
This would give me more buoyancy but what is the trade off?
(650 = total height)

 

Lesser deadrise generates more Lift, but is slightly less forgiving in heavier seas. Actual benefit in Lift depends on your velocity and width of pad, and angle of attack (trim).

 

evolution

any evolution?

 

Yes some, I have been doing a lot of sanding with the 9'' grinder, in fact the the boat must be half of its the original weight!
Of course I will be replacing all the material with fresh glass but at the moment its just more sanding!

 

Hello foxfish,
we built about 23 power catamarans from 8.2m to 13m under the brand Silver Tiger. Each one was a development of the previous boat. The most efficient was 9.75 loa with a flybridge. With two 250hp outboards it used 1L petrol/motor/NM at 20 knots
The same fuel consumption at 35knots that our previous cats got at 25knots.
3.5L/NM/motor at it's top speed of 48 knots.
With 50hp motors on a 5m boat, you need a planing bottom.
One of our cats was hit by a heavy boat on it's mooring and went ashore on rocks in a 100knot storm. My son pushed it off the next day in a 50knot wind and drove it for an hour and onto a boat ramp.
We were considering selling plans and have CAD sketches of rather stylish 6m and 7m boats. We could easly draw a 5m if you are interested.
If you supply your e-mail address, I will send some photos of some of the cats and the rescue off the rocks.