check this one out…
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=22710&item=7157182985&rd=1
one of my friends has one and i think that it adds more of a psychological benefit rather then any kind of real benefit. not worth the money in my opinion
The first time I saw one of those I just busted up laughing. It doesn't make sense that it would work. Couldn't say that I've ever tried one so really I'm just talking out my rear.
edit- I didn’t actualy check the website above, I thought it was just the normal turbo fin with a tube in the middle of it. The rectangular fin is a lot more interesting.
That is not the Turbo Tunnel:
I actually just got one tonight from the designer, Bob “The Greek” Bolen. Got a great deal so I thought I’d try it out. We’ll see.
yah the thread is based on the fact that i think the turbo tunnel is a joke… and then i saw this thing, get it, even dumbbererereremer… according to their web site it is based on a manta ray, but they show a photo of a stingray, i wanted to tell them that a 2x4 would fit the tunnel shape better…
sorry for the bad vibes an all, i just hate gimmicks…
ps photo used without permission from worldsurftech.com (any press is good press)
To me it looks like one way of solving the loss of energy at the tips, same as winglets on the tip of plane wings. Also they add a horisontal foil, much like the cheyne horan keels which must improve hold (much more so than a turbo tunnel fins). Also much like the small wings at the back of a plane. Is that really a stupid idea?
regards,
Håvard
Maybe not a stupid idea, perhaps just misunderstood.
They may look stupid but I know at least 5 guys on the longboard contest circuit that use them exclusively to compete with and they are in the top of their age bracket classes…
If you think that’s bad…
Alot of the longboard guys I surf with including the Surftech team riders who compete in the procicuit like to use surfco’s red and yellow super floppy longboard fin and side bits. They swear by them… (thanks Dave!)
yes…
i beleive anything fin wise out of vertical is just drag (on a surfboard)…
i don’t think surfboards need more “hold”…
airplanes need to be stable up and down and side to side, surfboards don’t… airplanes go fast surfboards go slow.
side keels work on sailboats where the energy is all being tranfered from the mast/hull connection on boats where the sails are pushing too large for the hull… surfboards are propelled from a very different source…
The word of a pro surfer is on par with that of a used car salesman…
They aren’t pro’s they are amateurs and not sponsered by anyone.
John Okamura is one I talking about…
Check the Hawaiian Longboarding Circuit results… In the Senior Men he’s usually in the top five actually won the whole thing a couple of years ago… Glen Pinho in the 50-60 years old bracket is another…
I usually respect guys who spend their own money for their stuff and have their own lives outside of surfing but still can rip the hell out of any sponsered pro like John can. These guys work Mon-Fri have a family to raise and buy their own boards, clothes, and accessories…
One the other end of the pro/amateur spectrum is Lance Hookano who pretty much can slap anyone in the head with a long or short board in any size wave. He was one hell of a short board hellman before converting 10years or so to his longboards.
They are weird though and I personally would’nt get one like I wouldn’t buy Dave’s super softy red and yellow flex fin.
But I gotta respect someone’s input who 10 times the surfer I am and doesn’t even get paid to do it…
yes.
…ambrose…
stupid is an induced state of mind…
Well, yes, Haavard, but…
With an airfoil generating lift, you do have high and low pressure areas, so you get flow around the tip and vortices formed and drag:
But with a single fin board, you have symmetric flow- no asymmetric pressures and so no tip vortices, leastwise in an ideal situation…
So the winglets or other perpendicular surfaces prolly don’t do a whole lot of good, no?
By the same token, the nozzle inclusive or planing surface inclusive fins- well, just what trim do they work in and what do they just cause drag in? Me, I suspect it’s 99% hype, like the majority of the surf biz…
doc…
If your board has the right rocker - where the water sheeting off the sweet spot is actually following the same path as the hole in any of these things - I can see it working for those incredibly brief moments when you’re going perfectly straight.
Other than that, I doubt it does much. Perhaps a little spot on a well-foiled, correctly sized fin (and there’s no doubt the TT has a nice foil - when you pour liquid plastic into a mold, chances are you spent some time on the mold) that interrupts flow can reduce drag.
I really doubt the water goes through the hole very often.
When the Navajo make rugs, they make an intentional flaw in the design. An otherwise perfectly symmetrical and precise pattern has a random spot where a color is woven out of a shape and into the background. The reason is so that if the weaver was thinking any bad thoughts during the production of the rug, that evil needs an outlet, or the rug will contain evil forever. Everything I build has a similar little intentional flaw, just because, well, what can it hurt. Perfection is disconcerting.
I think of the water flow off the Turbo Tunnel as acting on a flaw, as if that tunnel is just a mis-sanded blob of plastic on an otherwise good fin. Its where the evil gets out.
But no, I don’t own one. Most of my fins have post-production flaws from rocks and such. Plenty of escape routes for malice.
tried one once-the one with standard shape and cylinder in the center-it was slow…maybe that’s why it is good for noseriding.
Doc’s right. think about what happens when the axis of the tunnel is not parallel with the flow of the water under the tail. Which I calculate (right) to be exactly most of the time. Water just wraps around the tunnel draggin the tail down and back. You could plug the hole and never know it. Good for nose ridding, tho.
I’ve skirted past this thread for a while , I am very much meat and potatoes. bored on sunday arvo and turbotunnel it is . Know a guy that uses one and nose rides galor. They look shitty they may turn shitty and track like a demon but work for some . I personaly don’t like starfins or the wing things. they work to.
Well, that’s the thing: it’s a one-trick pony. Definitely lowers the ability to turn, slows ya down, and all it does is add to noseriding:
As shown above in 3 , there are better ways to go about it. That’d likely cause less drag and all.
'Course, if you wanted to make ‘one hell of a noserider’. the way to go about it might be to laminate in about 20 KG of lead in the tail. No drag beyond what was inherent in the shape, and it’d noseride like a bandit. Just don’t get in the way of it if ya fell off…
doc…
A skilled Indian can shoot any arrow.
But a symetrical foil will have a low pressure and a high pressure side as soon as you change the angle of attack, right? So as soon as you start turning you will have tip vortices, right? Secondly, if the fin contributes with a downward force once you angle the board (ie. turn) this force is now providing a sideway force component which help you turn.
Someone sayd that planes need to be stable up and down, surfboards don’t… That does not make any sense, a surfboard need to be stable in all the same directions, it’s just other ways of designs that do it. Secondly, surfboards and planes move a different speed, true for most planes. But the water is much denser than air. (Which to me say that foil for air are wrong for water, but that’s another story).
I think one of the benefits of the TUNL is that when the tail slides sideways the water in the sideway motion will hit the corner of the square rather then then a sharp fin tip(which kind of catch) which propably result in a more controllable motion. Secondly, I wonder if the TUNL doesn’t just work more like a quad…
regards,
Håvard
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But a symetrical foil will have a low pressure and a high pressure side as soon as you change the angle of attack, right? So as soon as you start turning you will have tip vortices, right? Secondly, if the fin contributes with a downward force once you angle the board (ie. turn) this force is now providing a sideway force component which help you turn.
Well, yes, Haavard, but if you kinda visualise it, you’ll note that when the angle of attack changes and the pressures change, then those pressures and resultant forces tend to bring the board back to straight line travel. Actually, the tip vortices do as well, causing drag at the back of the board. Let me coin a term, ‘dynamic stability’ which refers to the tendancy of the board to find an equilibrium between forces and proceed along a straight path. As you can visualise, the longer the board ( and the bigger or more drag force exerted by the fin) , the more it will tend to be directionally stable.
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Someone said that planes need to be stable up and down, surfboards don’t… That does not make any sense, a surfboard need to be stable in all the same directions, it’s just other ways of designs that do it. Secondly, surfboards and planes move a different speed, true for most planes. But the water is much denser than air. (Which to me say that foil for air are wrong for water, but that’s another story).
Y’know, it’s interesting that you mention that. Some aircraft are designed stable - wing dihedral, center of mass vs center of lift and so on. On the other hand, such aircraft as the F-16 and the Stealth B-2 and F-117 are inherently very unstable and can only avoid falling out of the sky like drunken bats because their fly-by-wire computer controls adjust for the really very unstable aerodynamics. In the case of the stealth aircraft, they are so inherently aerodynamicly ‘touchy’ that they have to have this. The Martin B-48 (??) ‘flying wing’ of the late 1940s was the same way, to the extent that even the best pilots couldn’t fly it safely. In the case of the F-16 the idea was that an ‘unstable’ aircraft would be able to turn very, very quickly - there were no ‘dynamic stability’ forces acting to keep it travelling in a straight line when somebody is shooting at you and you want to get out of the way. As to the question of hydrofoils vs airfoils and the same shapes working on or in both ‘fluids’, water and air and how the surfaces compare, etc - I don’t know a whole lot about that and it’d be silly for me to say anything about it when Terry Hendricks is available. He has been working with hydrofoil boards the last few years and…lets say he can do all the maths and I sure can’t.
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I think one of the benefits of the TUNL is that when the tail slides sideways the water in the sideway motion will hit the corner of the square rather then then a sharp fin tip(which kind of catch) which propably result in a more controllable motion. Secondly, I wonder if the TUNL doesn’t just work more like a quad…
Ahmmmm - interesting. Let me think about that a sec… What immediately comes to mind is that the squared off tunl fin setup is gonna have some interesting flow patterns at anything other than an ideal angle of attack. And really interesting vortices where lift and drag are coming together at right angles… and then there is the mental picture of it with an angle of attack figured in three dimensions… wow, that actually goes beyond my ability to imagine just now. Maybe after more coffee - Now - as to the tunl working like a quad. That gets a little tough for several reasons. First off, the quad fins are canted and skewed with respect to the centerline of the board, so that they contribute to what I’ll call a ‘dynamic instability’ - quads tend to be looser and turn like a bandit because of this. At least that’s my understanding of it - to put it mildly there’s more than one opinion on how they work. The tunl, on the other hand, seems ( to my view, anyhow) to be pretty much parallell to the centerline of the board and to the part of the board bottom surface that it’s mounted on. If you will, it behaves in some ways like a single fin foiled symmetrically - that is, it tends to cause ‘dynamic stability’ in a directional sense. Plus a ‘dynamic stability’ in vertical angle of attack - the trim of the board will have a kind of ‘sweet spot’ where the waterflow is paralell with the plane of the horizontal section of the tunl and any other trim/angle of attack will cause a helluva lot of drag. Now, that’s fine for some situations, I guess, but I suspect there would be some very strange behavior with some combinations of trim and turning. For that matter, a board equipped with such a fin might be truly difficult to turn, of a whole different order than just the turbo tunnel fin.
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regards,
Håvard
And my best regrards to you. Hope all is well Doc…