Speedy's comment about Stiffness Distribution

General Discussion
101

cause he didn’t give a rat’s a** and just built them anyway

pretty much how I live my private life…you should try it.

Re Bert’s connection.

I am almost certain that Bert’s prior lofty performance claims refer to his own personal boards and team boards. Paying, off the street customers get the standard durable. If you doubt, read Silly’s Quarter Sawn thread. Only 50 balsa sticks out of a 1,000 are good enough for personal/team boards. Unfortunately, reading much of his stuff its easy to conclude that all his stuff performs that way.

Not the case. The lightest boards (esp longboards) with the most twang. Thats it. Bert’s making boards professionally all day long…he can make one in two days. Its easy for him. But not for many of us. Just a fact of life.

So take the claims with a big grain of salt my friend, then move on with your own “I dont give a rats ass” method of board building. Just dont expect to same results.

Mental freedom will set you free.

ps - I dig Paul’s last post wrt flex. Humbacks.

102
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No magic bullets here.

Huh? Did you not understand my last post, or my first post (or maybe it was my second) in this thread? Sorry, I didn’t mean to be so cryptic.

I have never seen or heard of a middle concave with hard edges. Non-functional in my opinion. If there is such a thing out there on ‘surfboards’ I don’t know about it. That’s why I was picking it for a generic example independent of related factors to help steer the thread back on topic. Stiffness Distribution. And any possible flex or stiffness characteristics would prolly be so small in my example that I doubt someone could feel whether it was helping or hurting anyhow.

Anybody else want to throw an example out there for discussion?

103

This thread is sure wandering around in the forest :slight_smile:

Bernie, make a buck? Really? Everyone? You know me better than that.

Ozzy, some longboards have a concave with a rim all the way around under the nose. I think the most extreme are some of the Robert August shapes. But its not for flex, like a step deck or a spoon, its (supposedly) for some kind of lift. Of course, the spoon & faucet trick would indicate that such a thing would suck the nose down, not lift it up. I’m not a believer in longboard nose concave, but some great surfers swear by it.

Honestly, I think they’re chasing a red herring - in fact, much like how Paul says concaves are in shortboards to alter flex patterns, not affect water flow. I believe that nose concaves in longboards aren’t for the water in the concave, but for what it does to the rail volume. If you’re standing over a the concave, you’re riding a catamaran (or maybe a Gemini, yeah Bernie?) and you’ve effectively got a nice fine little 4" wide hull buried in the face of the wave. Lots of bite, lots of control… if you subscribe to the idea that it works at all. But I doubt its a flex mechanism (or damper).

But back to the glassing, if its still possible. Bill B, hopefully you might check in again. If I wanted a longboard with flexible ends and a stiff center, am I better off - both strength- and weight-wise - to cut wider laps in the middle like my illustration on the front page, or is it better to just plop down a knee-paddle patch? The knee patch puts stiffness right where I want it, but also adds more weight than expanded laps, creates an asymmetry of board strength, and (possibly) creates weak spots where it ends (even if cut in curves or points) that can lead to a snapped board. Similarly for a shortboard - does a fin area patch create a break point, or is that actually a more flexible option than cutting wider laps?

What role does symmetrical use of materials play in either flex or failure? Same schedule, top to bottom, on either a glass & foam or a compsand? Boards typically sacrifice a hull layer of glass in favor of weight savings, but would they last longer, would they maybe even flex more uniformly, if they were symmetrically made?

Hey Paul, do you really believe that its easier to use different skin thicknesses or resins in your build than to just change the way you cut the final glass? Think about it for a minute - if you could build all your compsands with the same core material, same inner glass (and resin), same thickness of skin material, same rail schedule…and then tailor them to the customer or wave with nothing but the final glassing…wouldn’t that be a pretty neat trick?

That, after all, is what I’m trying to get to with all this. :slight_smile:

104

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.

105

Harder crisper tucked rails with concaves…I personally ride them. I run them more forward, harder than the mainstream. Guy’s comment “those sure are hard rails.” I check their boards with the the larger radius blaaaszay profile and tuck…look and feel slow release to me. But I drive my front foot more than the rear…so why shouldn’t I have a crisper “tail like” tuck? Especially in smaller wave board design …more rail volume slightly steeper crisper tuck…more speed release. Even on larger waves that water moving across the board on a massive bottom turn,… a lot is force channeled down the concave race track right to the fins, however at the wide point, at exact rail entry the laminar flow skips the concave across the crisp tuck and reattaches further in bord, so theres a pocket there. And the opposite rail, exiting water doesnt track and roll around the rail…its a crisper exit. This gives an edgy feel …but not really skidish, other design elements control this. I’m not hanging up at the top either, even more release up there, and gravity. I get a little overall board flex here at the tuck plane break, where as a rounder baseball bat radius dome strength radius is slightly stiffer feel. Its airplane ( lift, release, flex) wing foil verses gripppy attached water flow feel. At times, it seems useless to discuss individuall design elements without accounting for other elements that contribute to the the board as a whole. But I like edges, planes and foils…its like riding a giant fin.

106
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Harder crisper tucked rails with concaves…I personally ride them.

I never even meant to include the rail edges, or the distance of the concave from the rail. I was just trying to isolate one thing as a discussion concept. I think it’s obvious now. I need to buy some HookedOnPhonics tapes and get to work. hahaha

107

No, no problem, Ozzy. Those nose concaves are the only ones I’ve ever really personally studied - the only examples I know. I just don’t look at shortboards very carefully or critically.

109
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This a really stupid question

but it probably needs to be asked at this point with all the hype…

But can anyone here

quantifiably and prove statistically

that any of the new tech stuff

can actually make someone surf much better

than they could

with just a well crafted and properly designed surfboard made from standard raw materials

for the individual in the first place for where they surf?

and if so

by how much?

10%?

25%?

Roy,

I can’t vouch for others. But I have found my surfing has improved by 34.234% since using EPS / Epoxy and perimeter stringers.

Now it is all subjective on what you would personally call an improvement: EPS boards don’t improve glide, EPS boards don’t cut through chop, EPS boards don’t "have that classic 60’s feel.

What I have found that my boards are doing: They are climbing faster on a wave face, turning tighter, recovering faster bouncing off the whitewater, and projecting faster out of a bottom turn. The EPS board lets me recover some of the manuvers of my youth…and to me, thats priceless. And I have a small, but cult like following of deciples, that if I lead them astray, I would wake up with a horse head in my bed.

So in my humble and somewhat limited surfing world I think the new tech is great, the draw back is that it takes more thought, design, and time to build…I guess not for everybody.

Board on the racks right now, 8’6" perimeter stringer EPS / Epoxy California style Gun. 8’6" x 21 x 2 5/8. Fast & Burn…or crash & die. I don’t know, but I’m going to find out?

110

Hi Resinhead, that is Oneula’s question you are answering there

I think that the human organism is a remarkable instrument and can detect all kinds of differences between surfboards, but there’s no way that the sensations we feel can be ‘proved statistically’ ( Oneula’s question ) without using recording instruments. . . . that doesn’t mean that those differences don’t exist ( which Oneula seemed to be implying )

:slight_smile:

111

hey peterg

yep front foot surfer is me

i think you guys should look closer at dmps post wrt to kiteboard flex and thickness

its the same principles

Quote:

Hey Paul, do you really believe that its easier to use different skin thicknesses or resins in your build than to just change the way you cut the final glass? Think about it for a minute - if you could build all your compsands with the same core material, same inner glass (and resin), same thickness of skin material, same rail schedule…and then tailor them to the customer or wave with nothing but the final glassing…wouldn’t that be a pretty neat trick?

hey benny

it would be a great trick

assuming every blank turned out the same

i didnt say resin but it does have and influence if you use flexible resin on the inside

whilst i agree that glass does do something to alter flex

when dealing with compsands

their nature has been decided long before the outer glass goes on

sure 12 to 18 oz of glass over the rail does something

but do you really want to add that much weight

when just going 1mm thicker in the skin is gunna do so much more to stiffen a board, with so little weight

in fact i dont think the balsa ones even need outerlgass for breakage strength(possibly)

btw

im talking pvc and san foam here

because its the same every sheet

balsa is a different story as dave mentions and you need to check every piece for weight and stiffness

to get any uniformity and predictability

if you not doing that

then its all guess work cuz density and stiffness of the boards has a huge effect

i use wood cut from the same plank of 4 by2 for a start!

also just using balsa creates a nice stiff board with good flex

but as soon as you get over 2 1/4 on a shortboard

look out

they become too stiff for me personally

as soon as your outside that thickness parameter when using balsa

then you in a different compsand school as the one im in

it would be the “thin skins and higher density core school”

im not in that school

im in the “thick skins low density core school”

so for the thin skin high density core school of though i would say that rail glass does make more difference

for thick skin school, it doesnt do much at all(especially with the weights of cloth we are using)

high density rails allow a stiff board to flex without failure at the rail

(high density rails are different to perimeter stringers ,and do different things)

112

benny

I think almost everything youv’e said is right on the money. I know how to make a board strong and stiff its fairly simple.

But If you wanted to make part of a board very flexible but still strong how do you think you might do that? i’ve taken my own sandwhich boards as far as i can … they are breaking very easily … right where i want them to bend.

Kind regards

113

rsl, I had a similar problem in that as soon as I got my composite longboards light & flexible enough, my knees were denting the deck where I knee-paddled. So I had to think of a way to add panel strength without necessarily adding panel stiffness or weight. I’m sure there are many ways to do it, but I put 2 strips of unidirectional carbon cloth right under my knees, and hidden under the skin. The uni carbon adds strength to the composite, but since its not done in a sandwich, it doesn’t limit flex. And since its only running longitudinally, it doesn’t limit twist (which is also important in a 10’ x 24" wide noserider when you want to stay engaged).

The tape was there so I could flip up the cf, wet it out, and then flip it down. That’s the only way to ensure good saturation, without soaking epoxy into the eps. Then peel the tape, wet out the regular glass on that balsa skin, drop the glass & wood on the blank, and into the bag.

It worked - this one was nice & flexible, but no knee dents :slight_smile:

114

RSL

Hey give us a bit more info with pics and maybe we can help you problem solve why your boards are breaking right where you want them to bend.

If we are talking shortboards I don’t think there is anyplace where you would want one to be very flexible. Definitely more flexible in some places than in others.

When you start using glass to stiffen up parts of your board you end up possibly creating weak spots on either side of the extra glass.

Christian

115
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When you start using glass to stiffen up parts of your board you end up possibly creating weak spots on either side of the extra glass.

Christian

Yeah, that’s exactly why I ran that uni carbon all the way to the ends. But I also made sure not to run it around any curves except the slightest curve on the whole board - the deck rocker.

116

Thanks for the ideas benny, i’ve tried some similar things.

I think what i’m trying to acheive is probably something much more flexible… almost like a a bodyboard. They often use epanded polypropelene which doesnt seem to be available in a low enough density for a vac formed board, Ive actually already tmade one with a polyprop core, it was a fraction heavy… but performed reasonably well(unfortunatly the foam was black!, what a mess).

Yeah so i’m thinking much more flexible…not the whole board ofcourse.

cheers

117

Hey cj3

yeah i it definatly does create weak spots i agree. I know it may sound a bit counter intuitive but i i’m definatly looking for more flex, its easy to stiffen a board up.

cheers

118

flex like this??

its a bit too much imo

but close

http://www.youtube.com/watch?v=GXpvYASzZNQ

this ones more like it

http://www.youtube.com/watch?v=NS2XSyo4C2U&mode=user&search=

119

Thats a lot of carbon for a couple knee wells; are your knees splayed that far out bord? It wouldn’t have anything to do with those crutch stand glassing tee’s. Classic!

120

Or flex like this…

http://www.youtube.com/watch?v=P_usYvflEV0

http://www.youtube.com/watch?v=budwVLw6qRc

That board never dented (I don’t have it anymore, it’s been stolen on the balcony at the second floor). Maybe this is not enough for you but flex like on a bodyboard is probably too soft, not springy enough.