Generating speed using skegs ?

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Generating speed using skegs ?

Unread postby zensuni » Sun Dec 17, 2017 5:51 am

In small waves, I noticed that shortboarders massively used their skegs to generate speed, doing these kind of "S" turns.
Is it possible to use a similar technic on prone boards, or are the skegs usefull only to add drive ?
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Re: Generating speed using skegs ?

Unread postby jbw4600 » Sun Dec 17, 2017 11:43 pm

I don't know about pumping like shortboarders do. But I find that skegs add speed on bottom turns.
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Re: Generating speed using skegs ?

Unread postby nomastomas » Mon Dec 18, 2017 5:44 pm

Well, yes and no.... its more complicated then most people realize. In general, a rider uses the movement of the wave towards the shore, the apparent movement of water up the face and the force of gravity to generate speed. The configuration of the bottom (including the fins) serves to interact with these three forces yielding a vector force which results in forward movement across the face of the wave. By positioning the board at the juncture of all of these forces, the rider is said to be in trim and his path across the face of the wave in what's called the trim line. Rider input in the form of weighing and unweighing different points on the board serve to enhance the effect of these forces. This is "felt" commonly during a bottom turn. As the board slides down the face of the wave powered primarily by the force of gravity, the stand-up rider begins to lower his upper body by bending his knees. At the bottom of the wave, the rider shifts his weight to the wave-side rail and pushes down against the deck which acts counter to the force of gravity, yielding a vector force in the general direction of back up the wave face. The shape of the rail and having one or more fins on the rail helps to grab hold of the wave face, creating a "toe hold" to push off on. On the way back up the wave face, gravity re-asserts it dominance, slowing the rider down. The rider feels this slow down and turns the board back down the face, taking advantage of gravity to increase speed once again. By repeating this process at a quicker pace, the rider can actually generate more and more speed.

Unfortunately, the prone rider can't weigh or un-weigh his board to any significant degree. However, a prone rider can link multiple short-radius turns together to increase speed. Having rail fins helps immensely with this maneuver.
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Re: Generating speed using skegs ?

Unread postby bgreen » Tue Dec 19, 2017 3:12 pm

Communicating with John Elwell recently, he was emphasising the fin as essentially a directional stabiliser. However, there is no doubt a correctly (or incorrectly) located fin can dramatically change a board's performance.

In relation to the original post, I wasn't entirely sure what an S turn was. I'm guessing it is referring to bottom to top turn movement. Growing up, an S turn was more to slow a board down from take-off to bottom turn on a bigger wave, a completely different type of S (Sean Ross used a similar move at Pipeline to perfectly time where he wanted to draw his bottom turn, on a small wood paipo). The action involved in successive quick bottom to top turns would seem contrary to the mechanics of being prone. There is the question of wave type affecting this as well. Sometimes a prone board just isn't going to be able to ride the same type of wave as well as other craft. It's a matter of drawing different lines.

In terms of speed, then there are surf mats.
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Re: Generating speed using skegs ?

Unread postby nomastomas » Tue Dec 19, 2017 11:33 pm

Not so much "top-to-bottom" but more up-the face-down-down-the-face" going up to the lip and down about mid-way (on a chest-high wave). Usually, on the G5 I can take the "express lane" in the upper third of the wave to beat a section. But there are times, when even this line is not fast enough and I can see the lip feathering ahead of me. Its at this point that I attempt to increase speed by releasing the wave-side rail and fin, gaining some speed by falling down the face mid-way, re-engaging the rail and fins, rising back up to the lip and repeat. "Feels" like I'm gaining speed but then without a radar gun, who knows? Pretty fun though...
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Re: Generating speed using skegs ?

Unread postby zensuni » Thu Dec 21, 2017 1:41 pm

Great explanations, thanks
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