No fins, only channels!?

Who can help me on this one?

I saw an old fish hanging in a shop a couple of years ago with no fins, only deep channels, awesome.

I’ve shaped my first four boards that worked out quite good (fish, gun, mal and windsurfer) and want to try something…out there.

I want to build a board (6’2" fish) without fins but haven’t got a clue, any tips?

Nope, won’t work!

But don’t let that stop you from trying!

By the time you deepen the channels and drop the rails enough to hold in and turn, you have more drag than any fin, ever!

Is this what you are talking about? If it is I saw vid of Donavon killing it on this design.

If you’re looking for “out there” then you should check out Doc’s U.S.O ( Rather than create extreme channels, he’s toyed around with extreme double concave. You’ll have to start out with a pretty damn thick-in-the tail blank, and you’ll want to order it with little to no tail rocker. I’m not even sure that it’s possible to shape something like this out of a polyurethane blank. You may have to order the blank with a thicker stringer too to prevent the “fin” area from snapping off. Best of luck though.

You beat me to it Stash


If you go to the “Resources” section and check under “Diagrams”, you will find drawings of a couple of boards done by Dale Solomonson that incorporate the features you mention. As I recall, the drawings were also discussed in the forum as well.

Hope this helps. Patrick

Jeesh LD don’t be so positive all the time.

Look under the thread “finless shapes” for a poster named Carl Olsen. He posted these pics of finless boards and claimed they worked just fine.

Finless boards work soooo well that almost 1/2 the surfing population are using them nowadays, so you should get one too.

Lets just call the fins something else, like shaped in rudders, and you gots yourself a finless board.

Some people here may remember Bing Auga boards. Someone I once knew from Hermosa Beach had one and surfed really well on it considering it tended to always be doing 360’s. Dimensions as I recall were approx 5 or so feet x 20" x 22" x 20". Thinner in the nose and boxy hard rails in the tail. One big slot in the middle of the tail about 16" wide that disappeared about halfway towards the nose - about 1- 2 inches deep at the tail. Just a few days ago someone mentioned there were some “Aqua” devotees surfing them on Maui.

Concaves give lift…not exactly the best thing with no fins. Channels might act like shallow fins but LeeDD’s got a point…What about a boogie board. Will hold on at Pipe so there is something working with no fins. I don’t think flow riders have fins, do they? Mats hold a pretty high finless line. I’m guessing controlled suck is the way to go finless. The Grandfather’s knew…Hopefully we’ll see in a couple of weeks…

Yo, heaps of info, thanks everybody for that.

I saw Doc’s vid as well with donovan surfing the deep channeled board but to me that looked too much like the keels my grandfather designed on his sailingships.

I was thinking more in this direction: Heaps of shallow channels with ‘razor sharp’ edges. Making them shallow shouldn’t increase the wet area too much increasing drag, but would give enough resistance to keep the board from sliding out of its bottomturn?

…duh…or no way?

This is roughly what I had in mind.

The questions that come to my mind are: over what lenght of the board should i shape the channels and where (more in the rail area?).

And the other question, probably with a bigger impact on the surfing characteristics of the board, how should the channels be formed?

Regarding the channels in drawing 1 and 2, this would be the side of the board with the rail biting into the wave. The waterflow would be mostly from front to back but the flow i drew is what should keep me from sliding out. Number 2 is my bet, but i’m afraid that the channel might fill with a pocket of water effectively giving the board a flat bottom surface!? Channel number 1 might create suck with the vortex but might also cavitate resulting in a spinout!?

What to do!??

hey, how do i get the sketches visible with the text

can somebody do that for me?

Sweet… now here is something I can babble on for hours about. :slight_smile: A bunch of channels on a board with no fins? one of my friends built a board like that last year. It looked just like a normal shortboard with channels, except the channels were about 1-1/2" deep. It didn’t work in the slightest… it actually seemed to slip out more than a normal board with no fins in it, or pretty close to the same thing. All those flats and edges that channels create in the bottom created to much release of the water flow in the tail. Since the water wasn’t sticking to the board, he was sliding all over the place. So what he did was add little “finlets” in each one of the channels, I believe there are 7 total, each about 1" high. He really likes the board now… thinks he’s really onto something, although I tend to remain skeptical, because I tend to concentrate on going in the opposite direction, total finless surfing. My ideal board would have no bottom contours on it because like LeeDD mentioned above, the more contours you put on the bottom the more drag is increased. As for Doc’s boards, I wouldn’t really call what Donvan is riding these days “finless” because that keel in the middle of the board is starting to look a lot like a long shallow “single fin” to me. To each his own though. The Bing board also pictured above incorporates a concave in the tail, which from my experience would work pretty well. If you shape a concave properly, you can create a low pressure area in the back of the board, creating suction… look up Bernoulli’s Principle sometime on google. Oh- and the boards in the picture that Whaaahoo posted of me above don’t work “Fine,” they just work. The blue one goes in straight lines, it works best on fast, steep waist high waves, but doesn’t turn at all. The brick red one went down the line pretty well, it tended to slide out in more mushier sections, but it turned a whole lot better. But it fell victim to my disk grinder awhile back… I was trying to make it work better. I have other finless boards that are more current designs, but without pictures I won’t bother to get into the design concepts. But I will say that I have pretty much ditched concaves and channels altogether, they create to much drag. -Carl

Sorry, I don’t know.

Seems the leading edge of the beginning of the channels should be reversed, so the rail is free from any directional guidance, so you can turn.

The reason a fin or 5 works good is that it is isolated on the tail of the board, where your back foot is standing, and the rest of the board is free to slide, allowing you to subtlely drop the nose while hanging high on a wall.

Some guys around here made semi finless boards, with 1" tall channel fins, and they worked until the surf got bumpy, then instant spinouts.

The problem with multichannels is you have to use such a large portion of the planing surface as holding power, so your board is sticky to turn, then completely releases when you shorten the surface area.

I’d have accelerating depth of concaves, as you go out the back, but that’s a lot of work.

I know I come off as an old crotchity grumbly fart, but I’ve always been the guy experimenting with one off oddities in shaping, and like to check out other eccentrics in the making.

Hey Carl, sorry for upgrading your boards performance but if you saw me surfing you would agree that just going straight down the line would be fine indeed.

Anyway, I like this finless thread because it seems like - along with a board that could be surfed in either direction like a snowboard - the next natural step in surfboard development.

I keep thinking about small tunnels built into the board itself to take the place of fins. Maybe a main center tunnel and smaller tunnels along the rails?

Hey LeeDD, isn’t it all about building the stuff that your friends say will never work. :slight_smile:

Sketch#3, with assistance of a friend studying aerodynamics, he says though: make 'em shorter…fins…

Please forgive my ignorance, but could someone please explain to me exactly why it is you don’t want (a) fin(s)?

From what I’ve read on this thread so far, finless boards don’t seem to work, and it looks like a hell of a lot more work to shape (and glass) all those channels into the board.

Experimenting is a good thing, of course, but I think nature has a few hundred million years or so on us in this department. Can anyone name a fast manueverable fish or marine mammal that doesn’t make use of fins?

reptiles don’t have a problem at all moving at high rates of speed w/o fins. Pure muscle and flexibility. the problem is…they cannot sustain speed due to physical limitations. I’m thinking of trying the design Dale uploaded way back (7’6").

To answer your question about why???

I have no freaking idea. Sounds cool. Build it and they will come…Or laugh their asses off.