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Board design - also a boring question

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Kamikuza
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Board design - also a boring question

Postby Kamikuza » Sat Aug 04, 2018 3:32 pm

Why do outlines have to be curved?

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Re: Board design -- also a boring question

Postby rynhardt » Sat Aug 04, 2018 6:38 pm

Kamikuza wrote:
Sat Aug 04, 2018 3:32 pm
Why do outlines have to be curved?
Good question.


I've got a very square TT and the front lower corner tends to get buried in chop and slows you down. Maybe one of the reasons to tuck in the tips.
The back lower corner also tends to dig deeper which takes more effort to edge.

Surfboards on waves are curved to sit in the pocket without the tips that can dig in.

Foilboards.. Dunno :cool2:

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Re: Board design -- also a boring question

Postby SolarSet » Sat Aug 04, 2018 7:03 pm

Kamikuza wrote:
Sat Aug 04, 2018 3:32 pm
Why do outlines have to be curved?
Why not? :jump:

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Re: Board design -- also a boring question

Postby TomW » Sat Aug 04, 2018 7:32 pm

It looks cool.

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Re: Board design -- also a boring question

Postby Jukka » Sat Aug 04, 2018 8:48 pm

Spin a coin on the table. Now spin a rectangular piece of metal.
Instead of the on-off nature of this example, I’m thinking board outline curvature adds ”turnability” incrementally.

I like to think these kind of things comparing the opposite exteme shapes.
A rectangular twintip against fully round frisbee shape. Makes a lot sense regarding how easy the board keeps the set direction or turns.

I have read about water release direction and some other theoretical reasons, but did not find the explanations tangible.

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Re: Board design -- also a boring question

Postby fluidity » Sun Aug 05, 2018 11:39 am

Kamikuza wrote:
Sat Aug 04, 2018 3:32 pm
Why do outlines have to be curved?
They don't.
Curving off the corners reduces the end width while leaving length. This makes them ride softer and give some stability against nose diving while being more responsive to rear foot control. Also, when you are carving the edge is shorter so the board becomes more responsive.

Leaving the corners on? The last part of the board when you leave the water for a jump, the last part of the board you are carving up wind with.

So a rounder board: more fun.
Squarer board: Better for jumping.

And less rocker will give you more air time as you will get up wind faster, easier.
More rocker, more responsive, carves faster, easier to handle in waves and easier to go very fast without catching the front, needs more power though.

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Re: Board design -- also a boring question

Postby Kamikuza » Sun Aug 05, 2018 11:46 am

rynhardt wrote:
Sat Aug 04, 2018 6:38 pm
Kamikuza wrote:
Sat Aug 04, 2018 3:32 pm
Why do outlines have to be curved?
Good question.


I've got a very square TT and the front lower corner tends to get buried in chop and slows you down. Maybe one of the reasons to tuck in the tips.
The back lower corner also tends to dig deeper which takes more effort to edge.

Surfboards on waves are curved to sit in the pocket without the tips that can dig in.

Foilboards.. Dunno :cool2:
I've got two Flydoors (partially concave) and had a Flyradical3, which are the squarest boards I've used. The 'doors were bad in chop because they bounced around a lot, not because the tips dig in. They all had thinner corners though, and I find them by far to be the best non-spraying boards -- my personal theory is that the further the corners are in front of the heels, the more you get spray.

And I seem to use the edge more than standing on the back, so the more edge in the water the better.

And my other theory is that the additional area under the back foot makes for better bottom end.

In other words, narrow tips ruin bottom end, take away easy edge holding, and increase spray especially in chop.

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Re: Board design -- also a boring question

Postby Kamikuza » Sun Aug 05, 2018 11:51 am

Jukka wrote:
Sat Aug 04, 2018 8:48 pm
Spin a coin on the table. Now spin a rectangular piece of metal.
Instead of the on-off nature of this example, I’m thinking board outline curvature adds ”turnability” incrementally.

I like to think these kind of things comparing the opposite exteme shapes.
A rectangular twintip against fully round frisbee shape. Makes a lot sense regarding how easy the board keeps the set direction or turns.

I have read about water release direction and some other theoretical reasons, but did not find the explanations tangible.
I've been searching and searching on and off, and haven't seen anything that makes a good explanation.

How does a TT carve?

Skis and snowboards have sidecut the same radius as their best carving turn radius. Waterskis look pretty much straight to me...

I'm guessing TTs came straight from wakeboards, so why are THEY convex?

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Re: Board design -- also a boring question

Postby Kamikuza » Sun Aug 05, 2018 12:12 pm

fluidity wrote:
Sun Aug 05, 2018 11:39 am
Kamikuza wrote:
Sat Aug 04, 2018 3:32 pm
Why do outlines have to be curved?
They don't.
Curving off the corners reduces the end width while leaving length. This makes them ride softer and give some stability against nose diving while being more responsive to rear foot control. Also, when you are carving the edge is shorter so the board becomes more responsive.

Leaving the corners on? The last part of the board when you leave the water for a jump, the last part of the board you are carving up wind with.

So a rounder board: more fun.
Squarer board: Better for jumping.

And less rocker will give you more air time as you will get up wind faster, easier.
More rocker, more responsive, carves faster, easier to handle in waves and easier to go very fast without catching the front, needs more power though.
Couldn't you soften the board by construction methods and keep the greater planing area? eg flex tips

How is the edge shorter when you're carving?

Why does more rocker carve faster? Wouldn't the whole board just flatten out as it loads up?

I can see how it'd be faster or easier edge to edge because the tip is thinner... but by enough to matter? I really notice the spray and difficulty planing on narrow tip boards...

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Re: Board design -- also a boring question

Postby rynhardt » Sun Aug 05, 2018 5:57 pm

Kamikuza wrote:
Sun Aug 05, 2018 12:12 pm
fluidity wrote:
Sun Aug 05, 2018 11:39 am
Kamikuza wrote:
Sat Aug 04, 2018 3:32 pm
Why do outlines have to be curved?
They don't.
Curving off the corners reduces the end width while leaving length. This makes them ride softer and give some stability against nose diving while being more responsive to rear foot control. Also, when you are carving the edge is shorter so the board becomes more responsive.

Leaving the corners on? The last part of the board when you leave the water for a jump, the last part of the board you are carving up wind with.

So a rounder board: more fun.
Squarer board: Better for jumping.

And less rocker will give you more air time as you will get up wind faster, easier.
More rocker, more responsive, carves faster, easier to handle in waves and easier to go very fast without catching the front, needs more power though.
Couldn't you soften the board by construction methods and keep the greater planing area? eg flex tips

How is the edge shorter when you're carving?

Why does more rocker carve faster? Wouldn't the whole board just flatten out as it loads up?

I can see how it'd be faster or easier edge to edge because the tip is thinner... but by enough to matter? I really notice the spray and difficulty planing on narrow tip boards...
I think board length plays a big role here.
My wave twinny has pointy ends, and it's the easiest board to hold an edge with. In fact I can hold insane amounts of edge with it, long after my square tip boards start skipping out.
Also no issues with spray or planing or upwind.
Then again I haven't ridden any of my square tip boards in the last few years.
Your mileage will vary.


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