Hey Pierre,
While that video is impressive, the board flex is all messed up.
There’s more to flex than just flex.
Peter, I did actually more the cloth inboard a little before wetting it out… And it wasn’t that much carbon - Its cheap in the 12" wide uni cloth, well, cheap for carbon, I think I paid about $25 / yard. So that’s probably $30 or so of cloth.
Still, if I can get the same results with e glass… you know why I’m here. 
Pierre, I agree with craftee. The upside-down video looks like the board is stiff on both ends & soft in the middle. Was that on purpose, or just an unintended result of tighter compound curves on the ends? How did it surf? Sorry to hear its gone.
looks pretty good to me!
[i]Silly
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Do you believe that all the water from the water line till the other side of buried rail is flowing in the same direction as the spray?
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Or would it be more plausible that the water underneath is contained and flows in different directions?
Cheers
looking at the rear fin theres a lot of turbulence in the water
id say the waters flowing back and across the board in a diagonal direction
if it was flowing tip to tail there would be no turbulence on the fin.
im mean its easy to assume that board is actually traveling in straight line form nose to tail anyway
it may actually be sliding acrossways down the face of the wave at the same time
i actually dont know
and any discussion on the subject ends in tears
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- A nose where both skins flex in unison , but somehow have the board offering more resitance to flex in one direction than in the other (not possible )
forgive me if this has been dealt with already - Im late to the post… but this is totally acheivable… ask your glass supplier to look at some different fabrics that might help you acheive it… there are plenty. rif.
http://composite.about.com/library/glossary/u/bldef-u5834.htm
start here and google til you drop
rif.
also i think that the effects of flow of spray water across the bottom of the board would be significant
i mean we are talking liters of water per split second here
why just discount it as insignificant
The original statement was ambiguous ( at least to me). . . . I agree that flex bias is possible, I was answering another proposition entirely, apologies for the confusion.
.
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also i think that the effects of flow of spray water across the bottom of the board would be significant
i mean we are talking liters of water per split second here
why just discount it as insignificant
True, it is a major inefficiency, and should be avoided as much as possible. …
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No probs… I probably missed the point a little as I was only skimming… but I just thought I would throw in my 2c.
cheers,
rif.
“it is a major inefficiency, and should be avoided as much as possible. …”
I would say true, as long as your intent was conservation of momentum…
however there are those times when a speed surplus presents itself, and the thing to do involves hitting the brakes…
then,
it can be fun to throw a little water,
and if your pal is on the shoulder paddling,
LET THE FIREHOSE GO!!!
cough, cough gag cough…
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I’ve seen lots of those Benny. They are real common around here. I thought I said something about ‘middle concaves with hard edges’ like where someone might locate a typical single concave on a shortboard? I thought those nose concaves were such a different animal… to me for control and lift, that I didn’t mean to include it in some kind of umbrella statement or question.
If you want to use overlapping or underlapping as an example, … it’s your thread, take it where you want it to go. I didn’t mean to divert from that at first, if that’s what I did.
My last post doesn’t sound too good. Maybe I should’ve said “Is the way I said things make it hard to understand for everyone?” No offense DMP.
No offense taken. I replied to your post because I liked the direction that you were taking the thread. The only reason that I threw in the concave discussion is because I know that with higher density foam I can alter the flex pattern of the board by shaping in a progressive concave. Shallow towards the middle of the board deeper towards the tail. If I run the concave all the way to the edge and shape my rail edge to that junction then it will stiffen that area of the board. Shaping the concave into the board is only for ride characteristics not for stiffness distribution. Thats why I don’t take the concave to the edge. For practical considerations it is too much to try and control flex by thickness profiling, concave placement, and glassing all at once. I try to do all my flex control with thinning of the core and layup schedules and take the concave out of the equation. The concaves all have flats before the rail. That way I can get the concave benifits without adding stiffness to the tail area.
With eps I really don’t feel that I can control flex by thinning of the core and that has taken me back to altering bottom shapes to add a measure of control back into the shaping process. The other thing that I feel is totaly assinine is that dam center stringer. No matter how I profile, shape, and glass I have this super hard piece of wood that is famous for having flex inconsistencies right in the center.
So far I’m at using e glass on the bottom, full warp on the deck, and my deck patches are staggered so that each additional one wraps less of the rail. To control rail twist I’m putting a deep vee in the deck patch cut. So deck is full 6 warp, 3/4 S patch to the rail edge, and a 4 oz. s tail patch that only covers the deck and part of the deck rail. I really like the altering of the lap though, brilliant! Going to have to try a wide lap in the middle and taper it towards the tail, thank you Benny.
I’m feeling more and more that this will fall more onto use of a material that has better mechanical properties to alter flex patterns and in the glassing. So for now I’m going to give a stab at my perimeter stringers with some unidirectional ply. Gluing in the stringers is going to be a hassle. I’m already starting to feel that tapering a piece of corecell and vacuuming it to the deck and bottom will produce better results.
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Thats why I don't take the concave to the edge. For practical considerations it is too much to try and control flex by thickness profiling, concave placement, and glassing all at once. I try to do all my flex control with thinning of the core and layup schedules and take the concave out of the equation.
Wow - talk about distilling information! That’s the goods, right there. 
Its like what engineers say about cars: You can have fast, realiable, and cheap…pick two.
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… The only reason that I threw in the concave discussion is because I know that with higher density foam I can alter the flex pattern of the board by shaping in a progressive concave. Shallow towards the middle of the board deeper towards the tail. If I run the concave all the way to the edge and shape my rail edge to that junction then it will stiffen that area of the board.
I didn’t use a very good example, or didn’t describe it right, or something. When I brought it up I was thinking a hard edge around it would be stiffer than soft blended edges, but neither carried all the way to the rail edge. Of course any effect like that, if any, would be extremely small, if not less. I was only trying to kick something hypethetical out there for discussion.
Shaping the concave into the board is only for ride characteristics not for stiffness distribution.
I agree 100%.
… For practical considerations it is too much to try and control flex by thickness profiling, concave placement, and glassing all at once.
Why? The better I understand each little thing, the more I understand what each brings to the party and how it works with other things. I look at it in a total concept with lots of elements. What I spend most of my time on is the way the things work together and how I blend them in the most effective way possible for the customer. The best “I” can do anyhow. And I rarely get the chance to play with anything non-standard.
I try to do all my flex control with thinning of the core and layup schedules and take the concave out of the equation.
Agreed. I feel concaves are a different animal. Different types and variations for different results. None of which are flex related. If a progressive concave adds some measurable stiffness, couldn’t you get back to zero by doing something else in that area to nullify it? Or would the lack of volume in the concave do that for you?
… With eps I really don’t feel that I can control flex by thinning of the core
Besides going past the too thin mark, why not? Of course with eps and epoxy you get more bang for your buck. IMO Sometimes I worry about too much flex. Too much flex, especially in the wrong area, can turn a good shape into a total pig. This is not much of an issue with pu/pe for me.
and that has taken me back to altering bottom shapes to add a measure of control back into the shaping process. The other thing that I feel is totaly assinine is that dam center stringer. No matter how I profile, shape, and glass I have this super hard piece of wood that is famous for having flex inconsistencies right in the center.
If you are trying to make it flex right in the center, why not try something besides a super hard piece of wood. Or a thinner one?
So far I’m at using e glass on the bottom, full warp on the deck, and my deck patches are staggered so that each additional one wraps less of the rail. To control rail twist I’m putting a deep vee in the deck patch cut. So deck is full 6 warp, 3/4 S patch to the rail edge, and a 4 oz. s tail patch that only covers the deck and part of the deck rail. I really like the altering of the lap though, brilliant! Going to have to try a wide lap in the middle and taper it towards the tail, thank you Benny.
There’s more than one way to skin a cat, and lots of ways to skin a surfboard. If you’re not satisfied with your results, try a variation or something more different.
I’m feeling more and more that this will fall more onto use of a material that has better mechanical properties to alter flex patterns and in the glassing. So for now I’m going to give a stab at my perimeter stringers with some unidirectional ply.
What I see in parabolic stringers is the resistance to twisting. Twisting that might cause you to loose speed and projection in high load turns in bigger more powerful waves. I don’t really see a measurable benefit in small waves. But I could be way off. Perimeter stringers I’m not sure.
Gluing in the stringers is going to be a hassle. I’m already starting to feel that tapering a piece of corecell and vacuuming it to the deck and bottom will produce better results.
There might be other ways to get perimeter stringer effects without actually using them. I would like to know if it actually does produce better results. Post up if you do it. Good or bad.
perimeter stringers allow a board to flex further without failure than if the board didnt have the stringers
if the rails were hollow they would crease and fail easily when the board is bent
increasing the density of the rail under the skin gives load support to the skin and enables it to bend without creasing
this is why a compsand is so damm hard to snap
i try hard every surf to snap mine but still not succsesful
thats where surftech have so f#$ked up
spend all that energy getting a full rail wrap
and it doesnt work!
there ive said it
agree or disagree
but imo thats what the REAL advantage of a high density rail
and does a completely different thing to a normal stringer inserted 1 or 2 inches from the rail
2 entirely different animals with same name
Agreed. I feel concaves are a different animal. Different types and variations for different results. None of which are flex related. If a progressive concave adds some measurable stiffness, couldn’t you get back to zero by doing something else in that area to nullify it? Or would the lack of volume in the concave do that for you?
The lack of volume at the tail might do it but then again I try not to shape the concave to control the flex. The bottom curve/foil, rails, thickness and outline is more for how the board performs statically. The flex is so that it will perform better. How and why is why I’m here. I can do flex control in another medium it’s just that I’m having a hard time with the extra complexities of a surfboard.
Besides going past the too thin mark, why not? Of course with eps and epoxy you get more bang for your buck. IMO Sometimes I worry about too much flex. Too much flex, especially in the wrong area, can turn a good shape into a total pig. This is not much of an issue with pu/pe for me.
Yes too much flex can be bad, but what makes it bad and why? I’ve made kiteboards that were way to flexible but a surfboard is a much more complex animal. Do I want it stiff between the feet or stiffest under the front foot with progressive flex towards the tail or do I want an even flex through out the whole board?
If you are trying to make it flex right in the center, why not try something besides a super hard piece of wood. Or a thinner one?
No not in the centerline of the board but rather the whole board. The center stringer in my mind is like an axis. With the rails being so far away it promotes twisting during hard turning or choppy conditions. The twisting is one of the ways that you can have bad flex.
There’s more than one way to skin a cat, and lots of ways to skin a surfboard. If you’re not satisfied with your results, try a variation or something more different.
I couldn’t agree more. Just fishing for info on what others have tried. Making boards is expensive and I’m doing this for my own satisfaction. I’ve been enjoying using the less expensive cloth to make the boards and not dealing with the whole vacuum process. Just looking for tricks and tips to make a better riding board for myself. However I might have to bust out the carbon uni and kevlar for a one off project.
There might be other ways to get perimeter stringer effects without actually using them. I would like to know if it actually does produce better results. Post up if you do it. Good or bad.
Just waiting on the ply. I’ll try to take pictures of my project and post for others my riding impressions. I jumped on this thread because I’ve been loving the ride of the epoxy/eps. Light weight, thinner rails, better paddling. I’m just looking to try to put a bit more flex into it without making a disposable board. Thank you for your input I really value this discussion. Gives me more motivation to mow some foam. I really feel that you can quickly reach the point of diminishing returns though. Too much hassle, too much money and all for what? Lately I’ve been trying to keep in mind the post I read a while back from Bill Barnfield about the true cost of making boards and how time away from your family has no price but the price of regret. For now though shaping while the kids are at school and glassing at night has been o.k. besides I’ve gone up a notch on the cool meter with my son’s friends.
Aloha, I’m pau.
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Pierre, I agree with craftee. The upside-down video looks like the board is stiff on both ends & soft in the middle. Was that on purpose, or just an unintended result of tighter compound curves on the ends? How did it surf? Sorry to hear its gone.
It was not on purpose, maybe a consequence of the concaved deck that was deeper in the middle (although one would think it would make it stiffer there). It surfed good anyway. The deck had herring bone balsa lay-up, but I won’t do it again probably, I keep it longitudinal now. I think this helped the deck flexing (too) much.
I think we are thinking in the same area, but the difference between kiteboards and surfboards have some inherent differences and approaches.
Bad flex? Imagine surfing a big spoon and pushing water. That’s the immediate picture I have in my mind. It’s the issues of where someone might want it different than the typical full length flex from the basic shape and skin of a surboard that this thread is for.
Interesting thought, but I don’t know that the distance of the rail from the centerline is something that contributes to twisting nearly as much as the forces being put on the board by the surfer and water. I don’t even know that ‘all’ twisting would be bad. This, like all the other stuff, depends on so many factors that are constantly changing.
Definitely post up progress on that project. I’d like to see it, and I’m sure lots of other people would too. I think diminishing returns are true, but is also relative to the person doing it and their situation. Probably much more so in production work. It might be different for me being single.
Aloha
Hi Silly P.
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Not discount it, but looking at it in comparison to all the water that is touching the board up elsewhere.
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Discussion forum swaylocks does its work well, i am going to put money in their account again.
No surf around here.
Wouter