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Do concaves work? #2906341
01/31/19 01:10 AM
01/31/19 01:10 AM
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DublAK2 Offline OP
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I've been doing a bit of research because I'm seriously considering shaping a board myself.

I've read some simple articles and perused through the swaylocks archives but nothing is really selling me that concaves aren't just a bunch of marketing BS.

What do you folks think? Can you really tell a difference? And if so are there any admirable characteristics of a flat bottom?

Re: Do concaves work? [Re: DublAK2] #2906343
01/31/19 01:14 AM
01/31/19 01:14 AM
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Paging GG...


"I love it when people who are supposed to be surfers.....posting on a surfing forum.....don't know the difference between stoke and stock." - GromsDad
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Re: Do concaves work? [Re: DublAK2] #2906353
01/31/19 01:39 AM
01/31/19 01:39 AM
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retodd Offline
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Everything works

A lot depends on your style , boards outline / rocker / fin position and what kind of waves you are surfing

So lets say you are surfing head high Rincon on a low volume hpsb, a nice amount of rocker plus single concave will work very well . same exact board with a flat bottom nose to tail might not have as nice of feel .

Now get a wider outline , lower rocker and higher volume board with flat bottom . it will feel fast and skatey

Re: Do concaves work? [Re: DublAK2] #2906358
01/31/19 01:53 AM
01/31/19 01:53 AM
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surfy1476 Offline
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If you dont think they work try a Bonzer concave and then get back to me.

Last edited by surfy1476; 01/31/19 01:54 AM.
Re: Do concaves work? [Re: DublAK2] #2906360
01/31/19 01:59 AM
01/31/19 01:59 AM
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well the whole top 44 is riding concaves, i'll go with yes

Re: Do concaves work? [Re: DublAK2] #2906363
01/31/19 02:02 AM
01/31/19 02:02 AM
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Racer1 Offline
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They work, but not how you think they work.

They make the rocker flatter where they are deepest, so it makes the board faster.

Re: Do concaves work? [Re: DublAK2] #2906374
01/31/19 02:31 AM
01/31/19 02:31 AM
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If this is your first board and you plan on glassing it yourself. Go with flat or vee and you'll have less to worry about during the lam and sanding. KIS should be your focus on board number 1

I don't think you can separate one component of a design from another like the debate of flat versus concave versus vee versus domed. outline rail rocker fin setup and materials all play a part in as much as the bottom contour.

The only case where this can be done is when some say red boards are faster.
I think color is probably the one component of a surfboard that can be isolated from the rest of a design.

But then you never know the effect of pigments to the resin/cloth/foam bond. Does anyone really understand the impact of pigment to the chemical nature of a resin and its hardener. Kind of like using heavy pigments with UV resins.


Last edited by oneula; 01/31/19 02:34 AM.

waSUPcuz? shaka ala n da mooleh bulls..
Re: Do concaves work? [Re: DublAK2] #2906404
01/31/19 04:08 AM
01/31/19 04:08 AM
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Yes concaves work for performance shortboards. Look at any picture of a surfer in a bottom turn or cut back you'll see the water moving diagonally across the bottom of the board. If you lay a straight edge at a diagonal on a concaved bottom - you'll see the edge lays flat i.e the shortest line - the fast surface for water to move across on the unweighted side during a turn. Concave provides lift but also allows a curvy rail line which turns easier.

If you're nervous about creating concave. You can make a rig. After the blank is fully shaped. Get a strip of ply say 3- 4 mm thick, about 100 mm wide and slightly longer than your board width, glue 150 grit sand paper to it. Attach a handle of some sort to the centre of the plywood - at right angles to the long edge.

Get two long strips of wood (about 2 ft longer than your blank) say 10 mm thick. Lay either side of the stringer. far enough apart to run a router bit between them. Weight the ends so the wood conforms to the bottom curve. Now chock the ends to be the depth of the concave at it either end. The idea is to create a smooth guide for you router to cut deepest at the deepest point of your concave and fade to zero at the chocked points. Set router depth to concave depth - say 5 mm. After cutting a groove down the middle of the board, you use the plywood sanding block in long strokes to bring the foam down to the stringer. The ply will bend giving you a nice concave profile curve. Tape the rails if you're worried about cutting into the rail line.

Last edited by Spinafex; 01/31/19 04:09 AM.
Re: Do concaves work? [Re: DublAK2] #2906416
01/31/19 04:29 AM
01/31/19 04:29 AM
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dont over think it, if this is your first board it's most likely not going to come out exactly like you imagine.

so at this point, just have the balls and go for it concaves or not.

be a player and get high on the action.

add water and enjoy!

calling grandpa griff to the suction cup.


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Re: Do concaves work? [Re: DublAK2] #2906424
01/31/19 04:53 AM
01/31/19 04:53 AM
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Ride a flat board, and then ride a DEEP concaved board like a Maurice Cole. You'll feel it. I'm on the fence still about the very deep concave's like Cole's; I've had both excellent and meh results with them. But at the same time one of my worst boards I've had was a flat bottom.

You should shape one flat, and one deep single and compare the two. Then build off those; lessen the depth, double concave, vee, ect.

Bottom contours weren't made arbitrarily or as a marketing gimmick.

Re: Do concaves work? [Re: manbearpig] #2906434
01/31/19 05:10 AM
01/31/19 05:10 AM
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Originally Posted By: manbearpig
Ride a flat board, and then ride a DEEP concaved board like a Maurice Cole. You'll feel it. I'm on the fence still about the very deep concave's like Cole's; I've had both excellent and meh results with them. But at the same time one of my worst boards I've had was a flat bottom.

You should shape one flat, and one deep single and compare the two. Then build off those; lessen the depth, double concave, vee, ect.

Bottom contours weren't made arbitrarily or as a marketing gimmick.


my MC:


my deep single (right two):



Now, I'm on a flat bottom. Not much difference.


Organized competition is entirely peripheral to surfing qua surfing. People surf for love. - William Finnegan
Re: Do concaves work? [Re: ghostshaper] #2906435
01/31/19 05:14 AM
01/31/19 05:14 AM
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Re: Do concaves work? [Re: ghostshaper] #2906438
01/31/19 05:18 AM
01/31/19 05:18 AM
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Originally Posted By: ghostshaper
Originally Posted By: manbearpig
Ride a flat board, and then ride a DEEP concaved board like a Maurice Cole. You'll feel it. I'm on the fence still about the very deep concave's like Cole's; I've had both excellent and meh results with them. But at the same time one of my worst boards I've had was a flat bottom.

You should shape one flat, and one deep single and compare the two. Then build off those; lessen the depth, double concave, vee, ect.

Bottom contours weren't made arbitrarily or as a marketing gimmick.


my MC:


my deep single (right two):



Now, I'm on a flat bottom. Not much difference.


Whoa bro when did you get corked? Did I miss that somehow?

I have boards with all sort of varying concaves. They all work.


"The size / dimensions don't matter. What does matter is that it's flammable. Because you should set it on fire and get a real surfboard" Witchipoo
Re: Do concaves work? [Re: silentbutdeadly] #2906445
01/31/19 05:23 AM
01/31/19 05:23 AM
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6-7 years ago, when I was still on my quad trip.


Organized competition is entirely peripheral to surfing qua surfing. People surf for love. - William Finnegan
Re: Do concaves work? [Re: ghostshaper] #2906467
01/31/19 06:05 AM
01/31/19 06:05 AM
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Originally Posted By: ghostshaper
Originally Posted By: manbearpig
Ride a flat board, and then ride a DEEP concaved board like a Maurice Cole. You'll feel it. I'm on the fence still about the very deep concave's like Cole's; I've had both excellent and meh results with them. But at the same time one of my worst boards I've had was a flat bottom.

You should shape one flat, and one deep single and compare the two. Then build off those; lessen the depth, double concave, vee, ect.

Bottom contours weren't made arbitrarily or as a marketing gimmick.


my MC:


my deep single (right two):



Now, I'm on a flat bottom. Not much difference.

Boards look killer. Looking similar to a few boards I was given to ride for a week or so by a shaper in AUS when I lived there, blanking on the name. Do you wax those?

I do prefer concave's over flatter. But I think it really comes down to the board design and waves intended for how much depth you want on the concave's.

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