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New Race Board Shapes

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davesails7
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New Race Board Shapes

Postby davesails7 » Fri Oct 06, 2017 3:07 pm

There is a new trend towards raceboards with extra thickness/volume from the nose to the front footstraps, and then a sudden change in thickness. Camet board shown here:
camet.jpg
I've heard two reasons for this new design, more aerodynamic and allows for a thinner board by having extra volume in the nose to get you waterstarted in marginal conditions.

The aerodynamics thing doesn't really make sense to me. I guess every little bit helps when you're at the top, but out of the projected area of the rider, kite, lines, and board, this affects only a very small percentage of the area. Also, it's typically much more important to add fairings on the trailing edge than on the leading edge to reduce drag. So even if reducing aero drag of the footstraps is significant this doesn't seem like the way to achieve it to me.

I can see where having a slightly narrower board does give an advantage though. Being able to lean over a few more degrees upwind without clipping waves could really make a difference, and I can see where extra volume in the nose would help with marginal wind waterstarts on a super narrow board.

Enata has this type of board on their website too. Then saw today in this video at 2:30 looks like a soft cover over the top of the footstraps:

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Re: New Race Board Shapes

Postby BWD » Fri Oct 06, 2017 3:51 pm

typically much more important to add fairings on the trailing edge than on the leading edge to reduce drag
then again, this is usually done to things that already have a front end that is either aerodynamically shaped, or functionally constrained to a certain shape. With anything that is moving through air at significantly variable AOA and has draggy, strange-shaped things sticking out of it (such as a human), the flow is going to be detached and turbulent after the front 20-30%, so nearly all the easily obtainable gains will be in fairing the front end. But it looks like they are trying to get something out of the hunchbacked rocker line as well, letting the back of the board hide behind the bulbous nose.... very strange, but not as much so as the "tiny moth hull" shaped board tested a few years ago...

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davesails7
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Re: New Race Board Shapes

Postby davesails7 » Fri Oct 06, 2017 4:06 pm

BWD wrote:
Fri Oct 06, 2017 3:51 pm
but not as much so as the "tiny moth hull" shaped board tested a few years ago...
Yeah, that one made no sense to me at all.

Ah well, good to see people trying new things. Lots of the developments in race gear over the last few years didn't make any sense to me at first. I just hope I don't need to buy a new board next year to keep up :D

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Re: New Race Board Shapes

Postby TomW » Fri Oct 06, 2017 4:27 pm

I totally agree about volume distribution, even in a beginner board.
When surface riding or transitions, the foil is lifting tail, you need to stand forward to keep foil down, board slows sometimes, need flotation in nose so board doesn't nose dive.
If you have a lot of volume in tail, that lifts tail too, causing more nose dive.
This is my beef about Dwarfcraft

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Re: New Race Board Shapes

Postby Lokihel » Fri Oct 06, 2017 5:34 pm

Any theory about the hunchback board?

Seems like the bottom is not a simple curve...

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davesails7
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Re: New Race Board Shapes

Postby davesails7 » Fri Oct 06, 2017 6:20 pm

Lokihel wrote:
Fri Oct 06, 2017 5:34 pm
Any theory about the hunchback board?

Seems like the bottom is not a simple curve...
On planing hulls, hook is the opposite of rocker. Rocker is where the keel curves up as you go aft, hook the keel curves downward as you move aft. Hook causes more lift aft and trims the nose down, similar to a trim tab or interceptor. I don't think that makes sense here though since you can control the trim very easily with your feet.

One of the descriptions on the facebook page for this board said, "when she is done you will really see the dynamics of all the curves designed to help reduce drag."

Maybe something about unsticking from the water? I've heard a lot of people talk about that, but it never made any sense to me. I've never had any trouble picking up a surfboard out of the water because it was stuck, so I don't see how a hydrofoil board can get stuck to the water when it's moving, at an angle, and has lots of air getting in from chop/waves/ripples on the water. I've always though the stuck feeling was just overcoming gravity, going from being supported by planing forces and buoyancy of the board to suddenly only being supported by the foil.

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Re: New Race Board Shapes

Postby Mossy 757 » Fri Oct 06, 2017 8:28 pm

It's just because the world isn't ready for the best raceboard yet:

Image

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Re: New Race Board Shapes

Postby faklord » Sat Oct 07, 2017 9:07 am

“Maybe something about unsticking from the water? I've heard a lot of people talk about that, but it never made any sense to me”

Try holding a spoon (spoon vertical, hanging lightly by the end of the handle) in a stream of water from a tap and compare the effect of touching the stream with the convex and concave sides of the bowl.

The convex side gets sucked into the water and the concave gets spat out...makes a big difference.

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Re: New Race Board Shapes

Postby Tone » Sat Oct 07, 2017 2:03 pm

Mossy 757 wrote:
Fri Oct 06, 2017 8:28 pm
It's just because the world isn't ready for the best raceboard yet:

Image
yeah that thing that Adam Cock made was utter nonsense. If I recall it resulted in him breaking his ankle.

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davesails7
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Re: New Race Board Shapes

Postby davesails7 » Tue Oct 10, 2017 12:03 am

faklord wrote:
Sat Oct 07, 2017 9:07 am
“Maybe something about unsticking from the water? I've heard a lot of people talk about that, but it never made any sense to me”

Try holding a spoon (spoon vertical, hanging lightly by the end of the handle) in a stream of water from a tap and compare the effect of touching the stream with the convex and concave sides of the bowl.

The convex side gets sucked into the water and the concave gets spat out...makes a big difference.
Yeah, but boards are mostly flat on the planing surface for that reason. That's how planing works, there is a pressure on the bottom of the board that lifts it up. If the board was too convex it would suck down. If the board is planing you're being lifted up, not sucked down


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