My new finless board

[nomastomas]

I've already been mulling this one over, and will post conceptual drawings on a separate thread. Pretty much the same WP forward outline as most contemporary body boards, but with the TB foil and sloped rails, and a single to double "open" concave bottom. Biggest question is how deep to make the concaves.

[bgreen]

Thomas,

At the deepest point (right a the tail) on one board it is about 1/2" but on both it is generally a 1/4" or so.

Bob

[soulglider]

paipo11.jpg (168.83 KiB) Viewed 3922 times

would a foam finless board "need" to be different than the finless wood boards we have seen on this site as well as many others? maybe because of float? i believe that the hard rails (soft 50/50 and harder 50/50 didnt work as well as square. they look better but didnt surf better) and bottoms on the wood boards wood actually work just fine in foam as well. one of the boards i made with a single to double concave with hard rails had a hard time holding onto the face of the wave.as long as i could keep the rail engaged i was good to go but as i tried to engage the tail to turn it slid a lot and mainly in the critical/steep sections of the wave and when any whitewater started getting under it, trying to make sections. it was and is fun but hardly the best working board i've made.

[bgreen]

SG,
I've only had problems with tails sliding on a finless board if I was too far forward, in a fat section with no wall to engage or in whitewater. I hope to spend a lot more time in the water in a few day so will see.

Bob

[SURFFOILS]

SoulGlider, when you say "square" for the rails what do you mean?
This is what I've been using for years , the vertical is 1 inch. I start at the nose with just under 1/2 inch vertical and increase it to 1 inch at 18 inches back and then wrap that 1 inch square all the down the rails and around the tail.

[krusher74]

I've already been mulling this one over, and will post conceptual drawings on a separate thread. Pretty much the same WP forward outline as most contemporary body boards, but with the TB foil and sloped rails, and a single to double "open" concave bottom. Biggest question is how deep to make the concaves.

My first board had the most depth in concave (1/2" @ tail center, covering the rear 2/3rds of the board) and is the board I feel surfs best, on my second board i reduced the concave in the quest of a faster board, I did not like this board as much. I think maybe with less concave it has less suction and hold, I think with more hold i an my confidently put myself on the wave where it has more power and with more power come more speed.

So more concave maye be a slower board, but may allow you in more powerful pats of the waves making it a faster board

[krusher74]

SoulGlider, when you say "square" for the rails what do you mean?
This is what I've been using for years , the vertical is 1 inch. I start at the nose with just under 1/2 inch vertical and increase it to 1 inch at 18 inches back and then wrap that 1 inch square all the down the rails and around the tail.

image.jpg

So this is a vacuum rail? I have the same 1" rails on my board but at a 30deg down angle, I transition it out into a rounded up rail in the front half of the board to stop rail catching in turns.

[SURFFOILS]

Not a Vacuum rail at all, it's designed to utilise the complete hull area and create the least drag with the 90 deg bottom edge. I haven't found it catching at the front but I pull the nose in more than usual, about 11" across the front

[krusher74]

The attachment paipo11.jpg is no longer available

would a foam finless board "need" to be different than the finless wood boards we have seen on this site as well as many others? maybe because of float? i believe that the hard rails (soft 50/50 and harder 50/50 didnt work as well as square. they look better but didnt surf better) and bottoms on the wood boards wood actually work just fine in foam as well. one of the boards i made with a single to double concave with hard rails had a hard time holding onto the face of the wave.as long as i could keep the rail engaged i was good to go but as i tried to engage the tail to turn it slid a lot and mainly in the critical/steep sections of the wave and when any whitewater started getting under it, trying to make sections. it was and is fun but hardly the best working board i've made.

My designs were taken/influenced from tom wegners work on the alaia/seaglass tuna, I have seen no problem moving these hull designs from wood to foam (foam has just given be more float and made them easier to paddle and catch waves on.

I don't struggle to hold an edge at all on my board, easy to break free for a 360 and then easy to engage again, it would seem i have a similar 1" rail to you, so maybe the difference in hold is in the single concave to V roll that wegner describes as griping the water that's the key difference.

[krusher74]

Not a Vacuum rail at all, it's designed to utilise the complete hull area and create the least drag with the 90 deg bottom edge. I haven't found it catching at the front but I pull the nose in more than usual, about 11" across the front

image.jpg

I think i'm getting confused now, I was talking about the hold of a finless board like the one Bgreen started this thread about.

Are you now talking about the board in the picture with a fin/foil?

[SURFFOILS]

And I thought you were asking if the square rail was a Vacuum rail ?!
Oh well.
Do you think the angled rails like on the Wegener board create a vacuum similar to the rails on Bobs board ?

[soulglider]

krusher, you are right, the concave does hold the board down to help in turning as well as with drive, kind of like having a twin fin. a, b and c are really fast and sticky, d is the one i was talking about that was a pocket hog.

surfffoils, i can see why your rail works, its the hard edge on the bottom, maybe, what goes on above that doesnt really matter. above you can see some of the rails i have used in my boards, the only one that doesnt work very well is (e). that was on a wide foam board that i made and rode that bob mitzven copied and altered the bottom. it looked really cool but slid out like a mother. the others work great. (f) is a rail that i use with my foam/glass displacement hulls. it also works great when i remove the fin(s), flip it over and ride backwards. the nose becomes reverse rocker and becomes a great pivot point. i think i will make a foamy that is finless and see how that goes.

[bgreen]

Global Ernie sent me this:

"I had a look at the forum thread on your finless board, let Brett C know that Peter Killen has done research on flat/concave/ vee bottom modelling in the worlds first wave machine. I think I sent you a copy of his work on CD several years ago. Appears to me that people continue to neglect the drag fundamentals with these various assertions about flat v concave etc. Brett is spot on about a good deep concave being flat through the centre, the boards that Outer island and Valla were making in the 70's were built this way, heaps of rocker but flat through the middle. They certainly did not feel to ride slower but they went best in clean conditions. Another thing that I have been wondering about is the merit of a slight Vee or spiral Vee bottom for a paipo, there is no reason why this design would not bring a lot of joy to a paipo rider..... the boards that Joske made for me with spiral vee were different from a double concave. on a double concave, if you were to place a small straight edge from the edge of the rail to the middle of the base of the fin you would be able to observe a slight concave curve, with a spiral vee the straight edge would not sit from the two points because the curve should be slightly convex. The S vee is really a subtle mound with its apex at the base of the fin and is blended into the general foil, there is nothing spiral in a strict geometric sense".

Attached is a photo: " of Allen Yates extreme concave Valla kneeboard to demonstrate the designs morphing the flat with the curved".

[attachment=0]1inch deep.jpg

[krusher74]

rails.jpg

krusher, you are right, the concave does hold the board down to help in turning as well as with drive, kind of like having a twin fin. a, b and c are really fast and sticky, d is the one i was talking about that was a pocket hog.

I use C on my boards , but I thought any flat rail at any angle was a vacuum rail?

[nomastomas]

When you guys say "vacuum rail" you don't literally mean suction, do you? I don't see how that would be possible. I could understand the use of the term "vacuum" as in "it holds into the waves AS IF IT WERE a vacuum cleaner". But, I'd be really interested to hear a scientific explanation if it is being stated that the rail somehow creates a vacuum or suction. Likewise, the whole idea of concaves creating "suction" also befuddles me, when the simple spoon-in-the-water-flow proves otherwise. Enlighten me, please...

[OG-AZN]

I think what they're referring to is the "boogie board" style rail, Like in Soulglider's example C. Tom Morey originally marketed his Boogie Board saying it had "vacuum track rails". I don't know if there's a scientific basis behind the term or it was just marketing, but that style rail obviously worked out well on bodyboards.

[krusher74]

Yes, I was reusing tom morays term "vacuum rail"

Only really meaning it grips the water (or the water tension grips onto it) rather than a rail that would release water.

I guess the name stuck because Tom morey felt it was like it sucked his board to the wave face (although in reality there is no suction )

From the wegner interview:

What about the vacuum rail. I’ve heard people say the hard rail on boogie boards was a stroke of genius. The vacuum rail, how does that apply?

There’s a story about this. I’ve actually researched this. When I was in California one and a half years ago I went to Tom Morey because I had made my first Tunas. I said, “How did you invent the vacuum rail?” This is what he told me. He said, “When I needed this board to hold into a wave I was surfing in Kauai at the time, there was a little wave, a right and a left.” He was surfing this little wave and he said he wanted a soft board that would ride this wave because he couldn’t actually get foam soft enough back in the late-1960s. He couldn’t get any materials other than wood on the Big Island of Hawaii, so he started fooling around with these foams and he made a boogie board kinda shape and he was riding it upside down. He didn’t say this, but George Greenough was supposedly there and said, “Tom turn the board upside down, you have it upside down” and it actually worked better the other way. I heard this story from a good friend of George's. But Tom Morey told me the story that he said that he looked at that rail and said, “I want to make a Vee bottom like a Hot Curl" because he was actually around when the Hot Curls came into fashion. He said, “you have the flat bottom boards and you put a Hot Curl tail on it and they really hold into a wave. So he thought, I’ll just put two Hot Curl’s on a boogie board. I’ll just put a Hot Curl bottom on that rail and on that rail and it will hold,” and bingo. It held. But his idea for a vacuum rail is a Hot Curl. That’s what he told me anyway. [For more information on the vaccum rail see Note 2.]

[SURFFOILS]

I'm with nomastomas on this one and I'll give you my reasons why...
1. Y is a smart guy, he was no construction or marketing noob at the time so he knew how to play the game.
Initially he was selling kits and if you're working with foam it comes in flat sheets. And flat is easy. And angled flat is just as easy.
2. Putting together anything that has a top surface and a bottom surface you need to join both with some sort of shape. If you leave the perimeter as a square corner top and bottom, then these corners are going to suffer over time and use, esp if it's just soft foam. Rounding any edge to connect the top surface and the bottom is complex as any surfboard shaper will tell you and it's going to cost money to tool,up to create any curve in foam.
But if you make the top, bottom and apex angle around 120 degrees you get 3 blunt corners that connect both top and bottom surfaces without making a curve. Brilliant.
3. Water travels along the board and along the rails, there's no upward direction of water "wrapping" around the rail, sure there is a small angle of rise due to the speed vectors but it's about 17 degrees.
4. Water coming off a bodyboard inside rail sheets directly off a hard hull slick and sharp edge, how does water stick to that ?
5. Under testing, angled rails have minimal grip, suction, vacuum or hold based on their design. They actually slide very easily.
6. No other Surfcraft has the same shape rail along its entire length, much less copy the angles of a boogie board. it's just not an effective rail design.
7. Calling it a Vacuum Rail is a stroke of genius because it's the complete opposite of its real performance. Initially as a marketing catchphrase, its caught on as lore due to the popularity of the product. Yet no other maker of Surfcraft, powerboats or yachts uses this seemingly simple but highly efficient rail design.

[soulglider]

"Yet no other maker of surfcraft, powerboats or yachts uses this seemingly simple but highly efficient rail design." surffoils, i beg to differ a little, almost all modern surfcraft use a varying form of this rail configuration, at least on the tail. pboats and yachts may not but they arent made for clinging to vertical water masses. i dont call them vacuum rails either and wouldnt just like i dont call the Suck Machine in my house a vacuum or deep concaves a venturi. i just make them and ride them, thats how i find out what works best for me and what doesnt. i aint no "modern theory" equals truth type guy trying to make a living selling boards. theory is theory and facts is facts, theories are for the thinkin types and facts is for the doin types. Greenough being the earth king of thinkin and doin.

so again, here are the surfboard facts, http://www.surfscience.com/topics/surfb ... your-waves. try making and riding for yourself a bunch of boards, i mean a lot of boards, for yourself, all different types, lengths, widths, rails, bottoms , decks and actually lie down on them in the water on a beach and see. you'll see, i can attest to it, that what necessarily works for standup boards, wont work for kneeboards and neither may not work for paipos/bellyboards. i take that back, everything will work,it whether or not you like the way it works.

all of the boards i had made by surfboard shapers didnt work the way i wanted them to work. they wouldnt create the feel i was looking for. and these were by some of the top shapers in the world. the guy that got the closest to it was Brian Hilbers and his displacement hulls. He was my major inspiration. and it was him that was actually recommended to me by Greg Liddle and P.G. bottom line, try 'em and ride 'em!

[SURFFOILS]

"Yet no other maker of surfcraft, powerboats or yachts uses this seemingly simple but highly efficient rail design." surffoils, i beg to differ a little, almost all modern surfcraft use a varying form of this rail configuration, at least on the tail.

I can't see any connection between an angled bodyboard rail and the square tail of a surfboard.

Bodyboard rails are 70 mm thick, project 30 mm out from the bottom edge and are angled.

Surfboard tail rails are 10 mm thick, vertical and square.

So surfboards don't use a varied form but a completely different rail in both shape and size. And their location and function are opposites too, the "Vacuum Rail" is on the side of the craft and are alleged to increase hold while the square tail rail of a surfboard is positioned at the trailing edge of a surfboard and it's purpose is to provide complete release.

Size, shape, location and function of angled and square rails are totally different. Maybe black is white ?

Maybe I'm looking at it all wrong...?