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Beveled rails vs. stability, speed

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Created by AlexF 1 month ago, 7 Jul 2020
AlexF
284 posts
7 Jul 2020 6:20PM
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Hi,
weighing 91 kg i currently use a Tomolike custom board, the shape is a rough copy of a F-One Papenoo 7'11 x 30.5", 130 liters.
The special shape detail of the board are the beveled rails, all along the rail and most apparent at the middle of the board reaching about 7 cm in the bottom and reducing the rail thickness about 10mm, and fading out to the nose and tail.
In glassy and uncrowded conditions it surfs really nice, but as soon it gets crowded or choppy my problems start.
Stability decreases significantly, so i'm often swimming and also it lacks some speed for early takeoffs in a crowded lineup.

I'm about to order a new board, since i like how the board surfs in good conditions i'd like to keep the shape, but tweak it to get a little more stability and paddle speed.
My idea is to have a classic concave bottom and eliminate the bevels, keeping the other measures, but i have no idea how much that could improve stability. Barley noticeable or significantly, i don't know?

Also paddle speed, the same question regarding the elimination of the bevels.
Or do i need to get it longer for better speed, if yes how much. I'm think about 8 cm to have a 8'2". Is this enough?

Give me your thoughts.

Alex

Kovert
67 posts
7 Jul 2020 7:11PM
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Drop the volume will help, get the board to sit more in the water rather than corking around. Short parallel rail boards are definitely not designed for paddle speed! May be better off on more of a pocket rocket type shape with a longer water line for that.

The bevels are probably there to help the board roll on to the rail in the turn, likely in response to the parallel outline. You may gain a fraction of stability by losing them but lose turning power and then need to add something else to regain it.

anchorpoint
118 posts
7 Jul 2020 9:24PM
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The only board with bevels i have is an old F-one manawa, i can feel you....lovely on glass conditions but a nightmare stability wise once wind and chop started! I had a love hate relation to bevels but kept the board for those perfect conditions...As to your question i do not have the technical level to answer that....

colas
3942 posts
8 Jul 2020 3:33PM
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Bevels were a trademark of the legendary French shaper Gerard Dabbadie (had his SuperFrog brand, and became the lead shaper for Bic), and they date back to Brewer and Aipa in the seventies. My surf quiver was only SuperFrog boards, and they all had bevels. Bevels makes the board unstable, so it is very useful for prone surfing, as it enhances the rail to rail performance significantly, especially on big boards like longboards, and for lightweights.

Remi Quique, the F-One designer, said in a forum post(*) that he was also hooked to Dabbadie's bevels on the Bic 9'0", and this is why he copied them on his shapes for F-One, because as a lightweight, it allowed him to put these big SUP boards of the time on the rail.

So, alas, unstability and quick rail-to-rail go hand to hand, and bevels, narrow widths, and low volume rails are design features that provide it. Getting rid of the bevels will help you significantly, as they have no effect on paddling speed, and thus you could trade the bevels for a bit less width, that will help paddling speed. And if you are not using the board in hollow conditions, add volume to the rails as it will also both add stability and a bit of paddling speed.

(*) www.forumdesup.com/t4802-f-one-2012-madeiro#52420

Nozza
VIC, 2442 posts
8 Jul 2020 8:40PM
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Think a bloke called Blane Chambers did a board or two with beveled rails

goggo
NSW, 109 posts
8 Jul 2020 9:48PM
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Select to expand quote
Nozza said..
Think a bloke called Blane Chambers did a board or two with beveled rails


Michell Rae, and Mike Stewart also and anyone who had built a boat with chines. Found them benefical on late drops.

AlexF
284 posts
8 Jul 2020 9:37PM
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Select to expand quote
colas said..
Bevels were a trademark of the legendary French shaper Gerard Dabbadie (had his SuperFrog brand, and became the lead shaper for Bic), and they date back to Brewer and Aipa in the seventies. My surf quiver was only SuperFrog boards, and they all had bevels. Bevels makes the board unstable, so it is very useful for prone surfing, as it enhances the rail to rail performance significantly, especially on big boards like longboards, and for lightweights.

Remi Quique, the F-One designer, said in a forum post(*) that he was also hooked to Dabbadie's bevels on the Bic 9'0", and this is why he copied them on his shapes for F-One, because as a lightweight, it allowed him to put these big SUP boards of the time on the rail.

So, alas, unstability and quick rail-to-rail go hand to hand, and bevels, narrow widths, and low volume rails are design features that provide it. Getting rid of the bevels will help you significantly, as they have no effect on paddling speed, and thus you could trade the bevels for a bit less width, that will help paddling speed. And if you are not using the board in hollow conditions, add volume to the rails as it will also both add stability and a bit of paddling speed.

(*) www.forumdesup.com/t4802-f-one-2012-madeiro#52420



Thanks guys for your helpful feedbacks.

If i skip the bevels i'll gain almost 10mm of rail thickness, so i guess i'll keep the width at 30,5" and volume at 130 liters and gain enough stability.

After looking a the changes JP did to the Slate i think additionally pulling in the tail and nose a little more and stretching nose and tail and the middle section about 2,5cm or 1" each to get a 8'2 instead of my 7'11 should help paddle speed.

One more question you may help me with. How deep do you think should the bottom concave be?
Rather shallow or deeper. On the Sunova Speed 8'10 it seems about 10mm in the middle of the board.

Alex

colas
3942 posts
9 Jul 2020 2:44PM
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Pulling in the nose a bit will also help paddling speed, with maybe a bit of belly (convex hull) at the tip. Look for instance at the modern foil boards, the ones with a kind of "bullet nose" aim at the best paddling speed for their short size, while keeping some width for stability.

For the bottom flat is faster, so concaves and V add drag, but they also can add benefits, so it is always a compromise.
Also concaves and channels are hard to sand properly, so they generally add weight as you tend to leave extra resin in them to avoid sanding the fibers.
Concaves tend to reduce the rocker in the midline, so you get a faster rocker when the board is flat, and more rocker in turns. And they add stability when paddling (the reverse effect of the bevels).
One the rail to rail, some shapers (Bert from Sunova) claim that they help putting the board on the rail, while other shapers claim the opposite. Personally I must say the effect is too subtle for me to notice one way or another.

Personally I like some concave in my board for the added control compared to a flat bottom , and it doesnt add as much drag and paddling instability than V. I would favor a shallow (or no) concave for weak waves, as I need there as much speed as possible, and control is not really an issue.

LastSupper
VIC, 227 posts
9 Jul 2020 9:02PM
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Not sure pulling in the nose helps ! When taking off late u need to get up the front to get speed up ! Then back to tail to feather the drop ! Now hopefully back to the topic of beaveled rails because im interested ??

colas
3942 posts
10 Jul 2020 1:03PM
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"Pulling in the nose a bit will also help paddling speed" ... Late take offs do not rely on paddling speed at all, for these you must play a lot with your body weight and feet placement, and being extremely aware of what the wave is doing.



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"Beveled rails vs. stability, speed" started by AlexF