Anyone tinkered with or have reasons that a stepped hull design would or wouldn't work with our type of cats?
Sea Hunt and Glassmaster are claiming doubling of fuel efficiency and increase in speed with their stepped hull designs.
If that's true, then what would it do for us?
ps patent pending....!

Look for the ORMA cat, Region Aquitaine.

It was not very successful.

Steps would be hugely draggy at less than planing speed = 95% of the time. Those big power boats can do it as they have 7 kazillion horsepower on the back that can quickly get them up on the step.

agreed...that's a high speed planing hull shape. We don't go fast enough to take advantage of that.

you do Jake!

Mattia back in 2003. Lets just say they only built one.





There are two issues stopping it working.
1. As stated above speed.
2. Venting. for the steps to make a difference you have to be able to get air to them. a normal cat (non foiling) would require vent cutouts to go almost up to the gunwales to achieve this. If you can't get air in the step actually sucks you down onto the water and adds drag.

That Tri , l'Hydroptere ; they use stepped hulls.

Here is a good shot of them ; it turtled after a 60K
run.

http://yachtpals.com/hydroptere-4036

Bille

I think Hydroptère is one of those corner-case boats. Huge amount of sail power allows it to work in windy conditions.

You could probably do this on an 18' boat too, but would only be "fast" and up on the step when its blowing over ~20kts. In all lesser conditions I'm quite certain that normal style hulls would be faster.

I Totally agree !
To make a stepped hull work ; you'd need Copious amounts
of power, to drive it.

The thing that impressed me most about Hydroptère ; is
the speed they'd get out of conventional sails !!

Bille