Concave deck in FW future?

[aurfalien]

Hi,

Any plans to do boards with a concave deck weather CBD or off the rack?

- aurf

[Slowman]

What is the advantage of a concave deck? It looks like it helps create a thicker rail without adding volume - not much bloody good to me!

I see it supposedly helps with leverage and foot placement (over on Swaylocks) but seriously does first hand experience back this up?

[aurfalien]

Kelly has been experimenting with em and the LibTechs have em. My local surf shop has some Libs so I may take a test drive. The guys who have, tell me it feels really good under foot.

Yep, the leverage thing.

Seems like why many love broken in boards.

[Chris]

it depends on the concaves you are discussing...

whole deck concave slater experimented with a couple years ago but hasn't really gone too far in that direction as of late, he has more begun to explore flex by riding EPS using different glassing/carbon stripping techniques.

I think the concave deck revolution is still pre-infancy and has very little adoption. we are always trying new things but definitely have things in the pipeline that will come out before we go down that road.

The pros like the footwells because they help with airs and centering themselves on the sweet spot of the board, but I haven't heard of that parlaying into whole deck concave preferences....

Cheers

[indodreaming]

Given up on airs, but ive always liked my deck to sink a little to get those footwells and would love to have a board with a little concave in the deck.

Just makes sense to me coming from a skating background where a concave deck gives you more control, i think in theory it also make sense on a surfboard as but there are problems that come with it like you either lose volume or you add rail thickness or you need to have like a stepped down rail like the tail of a hellfire, maybe even puddling of water?

I guess traditionally with a centre stringer you could also lose a lot of strength but with Parabolic rails thats shouldnt be so much a problem.

Fingers crossed it becomes an option in CBD.

[aurfalien]

I think that's why the Libs have concave decks.

Its only concave around the center of the board.

[FW - Fan]

There is actually a lot more to it that that guys. Thinner decks in the middle also effect flex and bottom concave during flex. A very very talented and experienced shaper who was kind of involved in the early FW days wrote a very good piece on it...his personal boards (which are eps , epoxy and timber rails) are all concave deck...he swears by them and its not about foot leverage only..If I can find the discussion I will post the gist of it.

[Herzalot]

I just got a board with a concave deck. I'll post up after a few rides. I had to trade my 606 Dominator for it - got nearly full retail store credit for the Dom, even though I bought it elsewhere. Thank you Huntington Surf and Sport (HSS)! The 606 was too buoyant. 604 I bought is just right, but what to do with the 606? Trade it for a PU board with a concave deck, of course!

[aurfalien]

FW - Fan, any news on the link? Would like to read it.

[FW - Fan]

Aurf here is the copy of it. There is a reason I cant identify the writer / shaper. You may have to read it several times. This guy has cred...a ton of it.

Hey Bohdi, yeah there’s more than three syllables to it, and you asked for it, so here goes...

There’s a couple of things I’m doing with those decks. On one level its not complicated, on another there’s a bit of head*&^% theory going on.

Firstly, changing where the volume is so your feet can be closer to the water even in a higher volume board. This gives a more sensitive ride- more in touch with the water than way above it. The volume thats taken out with the scoop in the deck needs to replaced without having a piggish-fat rail profile, so you see the defined apex in from either rail at the thickest point.

Having high-arched feet, I pushed this further -devised the double concave deck. Basically it’s an arch-bar, increasing the amount of board surface in contact with the foot, for a connected feeling. I liked them and refined it from the earliest ones which had a centre hump the length of the board.

The volume that the arch bar gives in the tail meant that the tail-rails can be nice and fine for hold...and flex.

Ahhh... Flex, the next bit!

The “parabolic” rails take the stiffest section of the board out of the middle and out to the rails.

So for illustrations sake imagine one of those dome shaped hiking tents with the fibreglass poles.

Then relate that to the board. When the tent poles bend, the nylon strung between them goes into...a concave!!! The more you bend it, the deeper the concave.

Now with the stiffer rail timber – When the board is bending under pressure in a high speed turn, the apex of the rocker at the rail goes down, (The tent poles bend) and the softer centre (the nylon) of the board goes up.

I.e – the concave gets deeper.

So why would that be desirable? In fact, why is concave so damn popular in current surfboard design? That depends on what you believe concave actually does.

There are greatly varying opinions and baffling waffle ad-nauseum amongst the boffins. Anything from “ Creates lift and speed” to “Sucks the board to the face and creates hold” – Two opposites there...

Here’s mine – and you can try this out for yourself.

Take a single-concave bottom board. The distance across the board from rail to rail is greater across a curve than across a flat. This means that water has further to to travel across a concave. This would equate to drag – slower...

BUT BUT ...The prevailing direction of water flow is not directly across a board or along from nose to tail. It changes during turns of course, but I’d say its predominantly running diagonal.

OK now lay a flat stick diagonally across the concave bottom of that board...

More of the flat stick surface sits FLAT against the board bottom!

Flatter means less distance between point A and Point B across the board, IF the water is flowing diagonally.

So, bending the board at high speed under pressure in a powerful turn increases the concave, means more flat surface...

Which means more speed!!!

Now the concave in the deck has a role here - The increased bottom concave during flex is influenced by the deck shape, in the same way that someones head inside the tent would influence the shape of the nylon if the two touch as the poles bend. You get a bulge right? The apex point inside from the rail line has more beef than the centre, so it helps to push the rails down further as the board flexes...so you get MORE concave more easily than a domed deck.


Do you like that?! Sounds good hey...


Now double concaves, rocker, vee, channels, outlines, fins and placement come into the equation to balance the speed with drag, so you can control it.