I've had the chance to be on the course many times with skiffs over the years. Up to about 15 knots or so, it is quite easy to outpace them up and down the course. But I've noticed that downwind, the skiffs seem to have a faster top end (and sail deeper) when the breeze really get up. The limiting factor for me seems to be the friction on the hulls--my rig is outpacing my hull(s). At times, I've felt the lee hull semi planing; but it still isn't totally planing like a sailboard.

I've seen flatter and flatter aft hull sections, but has anyone taken modern cat design in this direction?

http://www.youtube.com/watch?v=JbOr46fV4n0&NR=1

Isn't it just a matter of how much wind? When it gets too windy to sail the 5.7 I take an Arrow out to blast around and that has dead flat hulls with a single centreboard. You can feel when it lets go because it takes off and goes all over the place overreacting to every tiller movement with a 3ft water spout off the front of the centreboard.

I hear a hard chine catamaran hull is in the works..

how about a 60' planing hull catamaran designed and built by Yves Parlier. It even had steps near the stern like old-school hydro racers.



http://www.bowmansunion.com/portal/news/anmviewer.asp?a=501

He's also working on a strange and interesting kite powered cat now.
http://www.parlier.org/beyond_the_sea/eng/index.php

On the first site, there is a picture of a model or prototype that is intriguing. Do you suppose A cats and F16s could be built in this manner? And still have similar performance.

My knees, back and hips don't like to trapeze all that much. The biplane looks like it might be a little more user friendly.

For that matter, it might make a great Tybee boat!

Jake,
I've seen that Parlier cat--the hulls look like they're off a seaplane. The guy's a genius; too bad that cat broke up so soon.

Pete,
Any cat type that flies a hull downwind (F16/18, A-class, etc) would really benefit from a hull that truly breaks free (and I don't mean via pitchpole). I've seen the chines, the trip turbulators, the flattened sterns, etc. But have we seen any of these truly break free so the lee hull is skipping on top of the water like a wake board?

It sounds like with enough wind Jeff gets planing on his Arrow--totally flat bottom from front to back:
http://www.seabreeze.com.au/News/Sa...nglehold-in-Arrow-cat-class_2251396.aspx

Go back and read the article in Jake's initial citation. The hulls are directly the result of sea plane design and permit speeds in the 250 kph range!

Randy Smyth won the Worrell with a planing hull designed by Richard Rouch (sp?) A smaller version of the design was made and attempted to put into production, but it sucked in light air and was only decent in heavy air. Guess it needed the 20' of length to get it on a plane and stay there.
Rick

Any pictures? What are your thoughts on the biplane thingey?

It looks good to me, but I'm totally ignorant of design theory.

I took lots of pix, but have no idea where they are now.
Rick

There were also two scaled down production versions, the Hurricane 500 and the Hardcore 16. I had a 500 for a while and whilst planing it was truly a fast boat and didn't feel like a traditional cat. I can remember having to slow down for a club rescue boat to catch up and I knew the rib could do 26mph as I had gps clocked it previously. When production ceased John Pierce tried to buy the moulds but was turned down. This then led to the Stealth 16 which was slightly more traditional in having less volume in the hulls. As everything in sailing is a compromise the 500 had its failings and was not a particularly good allrounder. With current developments in foils I think you are much more likely to see cats move in that direction rather than a planing cat. Regarding the itzacat, can you imagine that in any swell?

Cheshirecatman

Eric-
Good to hear from you! Their was a Lindahl designed "A" cat in the '80's that was almost literally an "upside down hull" design w/ intention to plane and there was a production planing cat- I believe it was a 16 footer even- not very popular- sold here in the US. I of course can't remember the name right now. I also recall I think it was Wouter posted about a new cat in Europe that had planing steps in the hull and was supposed to plane, I believe he saw it at one of the European boat shows.
Here's an interesting link from the designer of the cat video you posted-
http://www.mckeewildthings.com/Wet%20and%20Wild%20Fluid%20Dynamics.htm
You could always build your own too- seehttp://www.maelabs.ucsd.edu/mae_guides/presentations/examples/Catamaran.pdf
Or get an inflatable that one that claims it easily enters the "planing state"-http://www.maelabs.ucsd.edu/mae_guides/presentations/examples/Catamaran.pdf
Even the venerable AquaCat is claimed to be "planing"- "Featuring wide, flat bottom hulls with turned up bows and a small keel skeg, the pontoon design is unequaled in weight carrying capacity and planing speed." !!

Kirt

Hull shape for the Roake21(Smyth Worrall boat)/Hurricane 6.5/Hurricane 500.

http://www.TheBeachcats.com/NewFiles/Hurricane%206.5.html

Cheshirecatman

hm, if it is really blowing hard, I think nose diving is the limit. Have a cat with a low aspect ratio rig and lots of sail area (low on the mast) and you are on the same level as a skiff.

Cheers,

Klaus

a year or 2 ago, warbird, on this site was working on an 18' tigercat to make it a planning cat

he felt that as it had the required flat rear he could make it work. the tigercat being a 2 man boat was over powered and threatening to trip over it's bows so he was shortening the mast and mainsail to get the power lower

he's gone quiet of late but a search would find his posts on the matter