Hi all, Ive been looking at bonzer’s and other interesting bottom shapes and I was wondering if anyone here has shaped or ridden a catermaran shaped surfboard - something with a twin hull type design…
I know its a ong shot but I thought I’d ask…
this is about as close as youre gonna get
http://www.swaylocks.com/forum/gforum.cgi?post=195914;#195914
This board is not yet finished. It still needs a final sanding (the epoxy is not yet fully cured), hence the bumps on the surface. So it hasn’t yet been in the water, but I expect it to be very, very fast!
The template used was the same Lis Fish template I used for the balsa Fish on the ‘Making Your Own Balsa Blank’ thread, with modifications.
That template was 5’6” in length, but due to the nose cut out on this board it is only 5’3”. It is 20 ½” wide and about 2” thick. Fins are my own design. They are designed to work in conjunction with the channel (which is approximately 6” wide and ¼“ deep) which should add to the directional stability of the board. It weighs about 10 pounds.
The idea is that, just like a catamaran sailboat, the board will get up on one ‘hull’, reducing its wetted surface area thus greatly increasing its speed.
I call it a Cat Fish (combination of catamaran and fish) and it is intended for use as a kneeboard, although I suppose it could be ridden as a standup.
please tell us how she works. looks beautiful.
Wow interesting board…interesting fins too, what is the purpose of the fins, exactly? I’ve never seen anything like that. Jack
looks like a bad copy of the Gemini
fins:looks like the trailing edge is as thick as the fin
Hmmm it does look like it started to be a Gemini…
Howcum so bumpy, unless it’s just the hotcoat, and even then…? I hope your epoxy is realllly sander-friendly.
Does that concave section decrease in width towards the tail? I’d think it would have to.
I used to kneeride the North Shore and a few other places here… at about 160 or 180 pounds, six foot six… I used PU/PE boards 22 inches wide with 14 inch diamond tails… twin symmetric fins, no toe, no cant, up to 9 inches deep… all of them just under 5 feet long, flat bottom and with a more pronounced nose rocker than your balsa. You’ll go fast, but it doesn’t look like a board that will turn too suddenly.
Any thoughts of rail grab handles, or do you just grab the whole rail?
I shaped deep knee wells in my kneelo boards, the better to stay onboard when it got choppy. Three layers of 7.5 ounce in there (lotsa point load forces from my bony knees).
Anyway, rode well enough to get a pic in Surfer, but unidentified… it was at Sandy Beach, I still remember the day.
I saw someone surfing a Gemini this afternoon but he had sawed off the two forks on the nose. Cut down, the board must have been about 4-feet long. With or without forks, the guy was ripping. I think he’s listed as a “team rider” on the Gemini website.
Here’s a similar concept by Rolf Aurness :
He calls it the “3 points hydroplane”, the purpose of it being to capture an air pocket in the center channel so that the board lifts up and that only the tail and the side wings stay in contact with water. He says it’s the fastest board he ever surfed and that it allows him to surf extremely fast waves that wouldn’t be possible with a regular board.
Are u in Hawaii?
Thanks for the positive feedback, Jack.
Well to state the obvious, the fins are there to provide both hold and drive! But I suppose what you are really asking is, what is the idea behind their design?
The deep channel will provide some directional stability, so I felt it didn’t need full Fish fins (i.e., 9“ by 5“) which might cause the board to track too much. The larger front fins have a 6” base, 3 ½” depth. Foiled on outer surface with a very slight concavity on the inner surface. Rear fins are basically just tabs to direct the water flow off the front fins. All are made from solid Philippine mahogany. Just something I dreamed up. Whether or not they will work as intended is yet to be determined!
Apparently some people didn’t read my description of the board in which I clearly stated that it is NOT FINISHED! That is why it is so bumpy and the fins may appear to have a thick trailing edge (they have already been filed down smooth). I just wanted to post some pictures now since it was a current thread asking about twin hull boards. I will post more pictures once it is FULLY COMPLETED.
For some reason, when I laminated this board the epoxy just wouldn’t flow smoothly and I ended up with a lot of bumps. (I think it was due to the weather as I was glassing during a dry hot spell a couple of weeks ago). Anyway, I filed/ground it down as much as I could or dared, and then put on a thick gloss coat, figuring that would fill in the bumpy texture and/or I could then sand it down smooth (bumps are still there but not as bad). Still waiting for it to fully cure before sanding. I’ve had to do this on other boards and is a lot more work, but I end up with a good finish. I start with very coarse Emory cloth to remove the bumps, and then go through increasingly finer grades of sandpaper, finishing with 600 grit wet/dry, ending up with an incredibly and unbelievably smooth finish! (An alternative approach would be to put on yet another gloss coat, and then another, until it all evened out. But now I would have used up expensive resin and added even more weight to the board.)
In regards to Christopher’s comment that it looks like a “bad copy of a Gemini”, aside from the fact that that is a very asinine and cynical statement, I freely admit (and have stated elsewhere on this web site) that I was INSPIRED to build it by seeing a Gemini in action, it is not an attempt at making a carbon copy. It has its own unique design elements, which are:
- To begin with, this board has a true channel, whereas the Gemini has a deep concave (there is a difference between a channel and a concave). The channel basically does not change width at any point, running at 6” wide throughout the length of board. It does start out as a wide shallow concavity in the first 6” or so of the nose and widens only in the last inch or so at the tail, for release. (According to my understanding, a channel does not need to narrow. It provides lift by directing/increasing air/water flow.)
The idea is that the nose will capture air and lift up on take-off. The board should then get up on one hull and run very fast (less wetted surface equals greater speed). Quick turns are not as much of a consideration as is speed. It is very much an experiment and intended for use primarily in smaller (<OH), fast, hollow waves.
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I have not seen any tails like this on a Gemini. Gemini are standup boards and usually have a very narrow bat, swallow, or diamond tail (at least the few I have seen). This board is a kneeboard and has a wide tail that is a variation of a Fish tail.
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Fin set up is different than Gemini.
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This board’s outline is really that of a Lis Fish. In fact, if it had a standard Fish tail (and keel fins), it would basically be just a modified Fish (with a very deep channel and cut-off nose, of course.) To me, the Gemini seems much more Thruster-like in its outlines.
In addition, as I have no absolutely no intention of making this board on a commercial basis, no one should feel threatened or cry foul (i.e., copy right infringement).
BTW, Honolulu, rail handles on kneeboards are fairly obsolete. Some kneelos have a hands free style. Some still go for the rail grab. Just depends on the rider’s individual style, approach, equipment, conditions, etc.
Hey retroman,
have you finished that twin hull board now? Have you ridden it? How does it ride? I like that board.
Pierre
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I’ve been shaping this Simmons inspired mini for a few years. All of the contours are blended but I still consider it a “twin hull” in the respect that is really is two displacement hulls side by side. Down the line it surfs like a hull, very smooth and forward driven. When you step on the tail it feels more like a stable fish. I can’t imagine it not tracking if the contours weren’t so smoothly blended. Cheers!
Heres one I did.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/Picture002.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/Picture003.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/Picture004.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/Picture008.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/Picture007.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/Picture006.jpg[/IMG]
Surfoils, that looks like expanded metal lathe for plaster/tile work. Wouldn’t it be faster if the flow through section paralleled the rails? This is question not a commentary. Do you get a big “flush” through while turning?
Yeah its just expanded metal grid glassed onto each side ! Cheap, but it works, I made this board about 10 years ago,I didnt do a full divided nose because I wanted to keep all the planing area at the nose.
Not sure when you say "if the flow thru section parralleled the inside rails" but I thought about making the 'inside' rails straight or concave but I kept the convex curves to keep as much area as possible.
There wasnt any "flush" but there was some froth from the inside rails near the tail.
Taylor Olson showed up in Big Sur once with one of his...
Robbyson - looks like a Gemini quad - they're radical looking! I'd love to try one, but I know at least one of my surfing buddies who would probably disown me if I showed up for a surf session with one these puppies LOL!
The Wave Skater bodyboard is a twinhull design.
From their site:
Patented dual tapered pontoon technology: All Wave Skater® Pro bodyboards have a unique, twin tapered pontoon system. Hydrodynamic in design, this unique and patented dual tapered pontoon system directs water through the entire length of its central, elongated, hour-glass shaped channel beneath the board in such a fashion as to lock you into the wave for superior, precise and nearly effortless turning. In action, our dual pontoon system actually creates a cushion of air underneath the bodyboard. And as the Wave Skater® Pro moves faster and faster through the wave, its dual pontoons begin to act like "hydrofoils," elevating the board higher and higher out of the water, as it continues to move faster and faster through the wave. As clearly illustrated in both our web video and in our still pictures, when traveling at high enough speeds and in big enough waves, the Wave Skater® Pro bodyboard nearly lifts out of the water entirely, becoming almost "airborne."