I thought a thread showing pics/describing buckled/snapped veneer boards might be useful for those of us learning the basics.
Here’s the one I creased in 3’ waves (head high). Made about 1/4 the drop before the lip picked me off. Lip probably landed on the board.
Board is 4oz 1/42 bamboo 2oz (spay glued then resined to veneer) 1.5 lb stringerless 4oz
Cloth and epoxy from FGI (their standard stuff is not recommended (this board), get them to supply you good quality cloth - Colon, Bay Mills etc., and there are better resins out there)
To me it looks as though the crease happened from the top deck flexing down at the ends because the crease is indented.
I think what Resinhead has been saying about keeping the top and bottom builds close to equal should be heeded.
Let’s say the bamboo is roughly equivalent to 6oz in strength. That makes a total of 12 oz. on deck and only 4 on the bottom. 3 x stronger on the deck. Kind of lopsided. Also the board looks very thin…
I don’t understand why everyone is abandoning the bamboo on the bottom. That’s where it will do the least damage as far as locking up the flex (it’s flat). Panel shape affects stiffness and the compound curves in bamboo on the deck will do more to lock the flex than bamboo on the bottom.
I'd agree, a thin board like that needs more glass or a veneer on the bottom. Veneer if you want to stiffen it up, glass if you want to keep some flex.
yet another board with only 8oz of glass on the rails that has buckled.
for me, 12oz rule is gaining more traction.
to lillibel’s point…veneer is like another layer of 6oz…it’s $20 more and weight overkill, IMO.
I think the fact that you can tune the compound curves and layout of the deck veneer gives you some interesting tools to muck around with the concept of localizing flex in some areas while inhibiting it in others…plus it’s an insane amount of strength underfoot.
I love the part where he says 3’ waves (head high)…didn’t jive until I saw that it was a kneeboard. haha…
Ha, 3ft means 6ft faces… we’re backwards in the south pacific, is it because we’re upside down?
I gotta say there’s no hard and fast rules for glass schedules, it depends on what the blanks built with.
And as for having a balanced glass schedule, that is a good rule of thumb, but there is a problem with that -
My compsands would likely not snap even without exterior glass. But the deck wouldn’t survive. So, you have to reinforce the deck… and that means that putting the same glass on the bottom just for the sake of having a balanced schedule is overkill.
So, balance your glass job to address snappage, then add whatever more is required to strengthen the deck, thats my opinion.
The board that snapped obviously wasn’t strong enough, but adding 4oz -bamboo - 2oz to the bottom just for “balance” would not be necessary, over 1.5# core
Glass has excellent tensile strength, and fiberglass skins have poor compression strength. Foam has almost no strength. Something like wood (very good compression strength), or corecell with inner layer of 2 oz. would have kept it from folding.
The crease happened where your knees would have been if indeed this is a knee board.
A standing surfer would have spread her weight over at least half the board.
So unbalanced skin schedule and weight put through knees (rather than feet) right in the middle of the board would create a focusses stress point instead of spreading the stress. Particularly if this happened on a late drop.
4oz over 1.5 eps doesnt work, regardless of whats on the deck.
you need 10oz, BARE MINIMUM.
easy fix: fill the crease with epoxy micro balloon mix, sand/fair, scratch the bottom with 100 grit, add another 6 oz full board layer, wrapping around rails at least half way around and youre good to go surfin'. good luck!
Good thread. A lot of times more can be learned from failure than from success. You find out what’s really going on with the materials and where stresses are building up and being released.
This is the 2nd veneer board on here with only a 4oz. bottom that has buckled. Seems like a double 4oz. bottom is the minimum to prevent creasing, moreso for the rail strength than the bottom tensile strength.
You may be able to get away with some wide tape on the rails if you really want to play around with minimum glass schedules, but a double 4oz. bottom lapped onto the deck will likely do the trick.
I’ve got a bamboo veneer in 1.5# EPS that’s 4-bamboo-2-EPS-4-4 with carbon rails that’s held up excellent in some big beachbreak.
Looks like your point of failure was the rails. You could start reinforcing there if you really wanted to experiment, but likely another layer of full bottom glass will fix it for good.
[quote]
Glass has excellent tensile strength, and fiberglass skins have poor compression strength. Foam has almost no strength. Something like wood (very good compression strength), or corecell with inner layer of 2 oz. would have kept it from folding.
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I think KK’s on the money. And I think wood on the bottom (adding compressive strength) would have prevented it from creasing in.
Last known recipe from Mr. Loehr (from top to bottom) - 4oz/veneer/4oz - 1.5 lb EPS with 1/16 poplar stringer- veneer/4oz. Sound about right? Maybe he’s onto something?
I’ve got multiple boards with only 4oz on the bottom (plus 4oz patch in fin area) that are rock solid…one in particular has taken quite a beating on overhead point surf.
I’m trying to get 12oz on the rail itself by lapping 4oz from the bottom and the 8oz on the top…if you’ve got the deck built out and enough glass on the rail I feel like you can skimp on that bottom lam.
my boards (stringerless) with bamboo top and bottom are inflexible…but I’m also building pretty thick boards…3" or so.
without the stringer I’m depending on the rail for stiffness and the bamboo on the deck for spring (and added stiffness).
“Compsands are generally sandwiched on both sides. We did decks only 25 years ago at Ocean Avenue. They’d actually break easier because when you only do one side all the force to to the weak side. So it’s best to have both sides done.”
Afoaf, just put some wood on the bottom damn it! Give the fish something to look at!
On another note- have you have any fin box issues with 1.5 lb eps and no wood? Using inserts or not?
sock, roving, multiple pours, no problems on any installs thus far.
I don’t doubt the validity of what the more engineering-minded say here…not in the least.
but the way I look at it, my trip is a little different…it’s not composite sandwich or even really timberflex/WMD so much as a bastardization of all that and then some that gets me to something that’s quick, cheap, durable and fun to ride.
If you were to laminate 1.5lbs EPS without using any veneer, what would the minimum laminate schedule be? If I read the atua-cores website correctly they suggest 6oz or 2x4oz on the bottom. If that’s so, I don’t see how you could get away with less because of adding veneer to the other side of the board.
I think you’re onto something with 12oz min support for rails in a stringerless.
LLibel03
I take your point about balancing the build.
I did a veneer top and bottom that turned out too stiff. This was a response to that build. It had great response from loading but wasn’t durable enough.
Crafty,
Thanks for the repair advice. It’s sitting in the shed and I keep going “Fix it or scrap it?”. I’ll try to beef it up with another layer. Still lots to learn from the microrail / flat bottom concept. It’s fast and loose, bt the rails might be a touch too micro)
I have a concave bottom (this one is flat bottomed) in the same outline. I’m thinking 3 options:
4oz/Veneer bottom, 2oz veneer 4oz top (but this still carries only 8oz rails, so is still likely to fail - probably not my best option.
4oz /4oz innegra bottom (innegra full lap) and 2oz veneer 4oz top
