There has been some discussion recently on buckling and I thought it might be interesting and perhaps useful to gather some informal information on the subject.
The key question is:
In your experience, where do boards (your boards, friends boards, customer's boards) buckle more often, the bottom or the deck?
Any additional supporting info (years, #of boards broken etc) would be good. Guesses don't count.
Thx
I'll go first: Deck
Most broken boards I’ve seen that have bucked have done so on the deck about in the middle third. Cleaner breaks in the nose or tail thirds. Personally, I’ve snapped two boards… both buckled on the deck.
crafty how many in the sixtys? how many in the seventys?
ah the eightys here comes the answer light silane glass jobs rude wet sands
and it has only got worse and yes its nearly always the decks that i have seen
shit 2’’ foiled out with one layer of 4 oz being punched through anything that moves
**we are going to need a super core to get past that haaaa’’
**
Compression side, predominant load side, which is almost always deck. Sometimes secondary portions of failure can ''trick'' one into believing otherwise. Nature of structure determines failure mode, so exact point of initiation varies.
Disclaimer: The above may not explain 100% of incidents. I've examined some strange failures over the years. Dynamic loads in breaking waves can do just about anything. Force vectors coming in from all over the place. "Stomping'' down big airs has added some unusual data points to my collection also. (No, I'm not doing the stomping personally)
2 on top.
-1 from lip hitting me and then deck, assume compression from top.
-1 from duck dive where I was flattened to reef.
3 on bottom.
-1 air drop to fail
-1 floater to fail
-1 not sure.
plastic stringers on 4 of them. Don’t do those anymore.
Almost always deck side, I have buckled/snapped 5 in the last 12 months, seen about 10 that were not worth repairing and repaired another 12-15.
Only two of those were bottom buckles. both caused by lip to upsidedown board.
Generally middle 1/3 of the board.if caused by the lip or riders weight, Front or rear 12" if striking an object (head, another rider, reef etc)
Most common is across the middle where the front foot goes (Failures sometimes follow the edge of the foot wells if they are deep)
Deep footwells on the deck near the buckle seem to cause large delams and glass stripping too. Probably weakened bond between foam and glass.
I agree with Mike. You see some strange ones but a careful look will often reveal the mode of failure.
Huie is right, way more common now than in the past. Boards are way lighter and thinner and people are charging on heavier and heavier waves - at least around here. Have seen a few 'modern' boards that have been broken into 3 peices in one hit! Ouch!
I had a epoxy/eps HP longboard with pvc stringer that buckled, but didn’t snap. First signs of failure were radius cracks around the rails. This happened long before any signs of delamination or buckling on the deck. My guess, however, is that there was a considerable amount of shear going on in the core. The rail fractures were simply cleaned out, filled, and patched, but the structural integrity was compromised. Soon after, the board buckled. I cut open the deck skin and re-laminated the deck. Bottom showed no visible signs of stress or strain. This repair lasted a while, but the board was run up on the sand and buckled again, this time cracking the foam core. Again the bottom showed no signs of stress/strain.
good idea Crafty!
PLEASE SPECIFY IF THEY WERE DELAM BUCKLES (POP OUT) OR FOAM CRUSHING BUCKLES(POP IN) !!!
**If it was a delam buckle, also specify how new or beat-up or old the board was!!! **
These are two different issues and for some reason I forgot to mention that the solution I posted is more geared toward pop-in buckling.
buckled my favorite board surfing a slab on a chest high day recently, im still mourning. It actually buckled on the bottom, I went over that falls as did it and im sure it got flipped over before the impact… was EPS/Epoxy 3x4oz deck 2x4oz bottom. One side of the stringer was “delam” buckle while the other side it seemed to buckle into the foam. Gonna be a fun repair.
From most recent to oldest:
GSI 9’6" Epoxy - clean pop initiated at the deck, about 12 inches aft of center - board was just over 1 year old, was free of dings (one paint chip appx 3ft from snap), conditions were pretty large surf - July’s South swell in Ca - I’m not exactly sure how big, it was 10:30 at night; big enough I guess! 
6’9" & 6’6" - Lumped these together since they’re identical, and happened within an hour of each other. Both snapped nearly dead center after I botched a thick wedged up section at Ventura Harbor (appx 10-12ft face height), the water was really shallow as evidenced bu the mud that the wave pulled off the bottom. Both boards were “well used”, the 6’6" had some heel delam just forward of the traction pad.
There have been a couple others, but board age & condition were definitley factors.
Boards didn't break until they went under 2 1/2 inches thick. About the same time everyone started using very light foam and 4 oz glass. That's been the challenge. There are many ways to reduce buckling today. Sandwich, rail channels, veneers, biaxial fabrics, etc. This shouldn't really be an issue but it is because surfboard builders don't really take any responsibility for product warantee. It's buyer beware and long as it is then why should they try to solve the problem. It's mostly decks that fold and they are usually failing at the top rail first. A reason rail channels are effective. The effectively support the place that fails first.
At Pipeline one day (this is back in the 70's) I saw 20 boards break in about 20 minutes. One broke in three pieces. 3 1/2 inch thick boards with all 6 oz glass jobs. Mine broke. One broke and the second half never came up. Water is some heavy stuff and moving water is extremely destructive. Ask New Orleans. I'm amazed sometimes the light boards we build today hold up at all. BTW, nice assessment MD.
That agrees with my observations too, lets say ~90% deck buckles with the other 10% deck and bottom, over-flexed both ways. Like you say, dynamic loads in breaking waves are very complex things. Heavily stomped decks, with a little delamination starting, those really catch it with what I think are much lighter loads than relatively pristine decks.
Also as you say, structure determines failure mode. I've found that the flatter the deck, the more likely it is to buckle. My half-baked theory is that the more cambered the deck is, the more resistance the resin-glass structure has to flexing when compressed from above. And again, heavily stomped areas go first...
doc...
[quote="$1"]
At Pipeline one day (this is back in the 70's) I saw 20 boards break in about 20 minutes. One broke in three pieces. 3 1/2 inch thick boards with all 6 oz glass jobs. Mine broke. One broke and the second half never came up.
[/quote]
I heard a theory (or maybe my friends and I made it up one night after a day of Aleutian explosions) that the sand on the North Shore was one third ground-up surfboards.
The pictured board is the 9’6" - 2 7/8" thick (probably 2 3/4" where it snapped) as you can see, the deck is domed, just not much. It was sandwhich construction, I don’t know the glass schedule, or what the center of the sandwhich is (a thin orange-ish material - isn’t most divinycel green?). I’m sure the board’s length (9’6") contributed to the snap - more leverage (insert more educated reason / formulae here!). I’ve bought 4 9’6" boards from this shaper for about 20 years, so I’m (more than a little) hesitant to point the finger there - I tend to think that a longitudinal strike by a thick barreling wave is more than a match for most anything. I’m planning to purchase teh same shape from the same shaper, just in PU - I know all the arguments - I just can’t argue with the fact that my long suffering, slightly overgalssed [glass schedule = 2 6oz all around, extra full length 4oz on teh deck, and a diamond shaped 4oz patch for knee paddling] PU board of the same shape is over 10 yrs old, and has suffered even more abuse! - perhaps the extra flex in the PU is more fogiving? Just an uneducated guess!
Good stuff, thanks for the feedback gents!
Thickness, or lack of, is one of the biggest reasons for buckling. Here's some math. Doubling the thickness of a composite increases stiffness by 8 times. Strength then is essentially thickness cubed. So here's an example:
A 2 inch thick board has the relative strength 2 X 2 X 2 =8
A 2.5 inch thick board has the relative strength of 2.5 X 2.5 X 2.5= 15.625
So essentially the thicker one has twice the stiffness and about twice the break strength.
There's also math for relative thickness per length. How thick does a 10 foot board have to be for it to have the same break strength as a 6 foot X 2.5 inch thick board?
6 foot = 72 inches. Divide the thickness, 2.5 by 72 = .03472222
Multiply that times the length of 120 inches (10 foot board) = 4.166666 inches
I wholeheartedly agree! TYVM for the math (much more eloquent than my slope browed “Big wave busted my stick!” logic)
How much do materials account for (what if I was riding a well made HWS or PU instead of an epoxy pop out board that night)?
I just wonder though - what would happen to most boards (9’6", or 6’0"…) when struck lengthwise by a thick, barreling lip on a fairly malicious DOH wave? (hehe, back to “Big wave busted my board” logic!) I guess what I mean is, at what point does structure submit to nature?
Is there a way to quantify what boards are more prone to snapping (longboard in big waves for instance! - loaded question I know!). I ask this since the shaper, and everyone in his shop seemed shocked that it had snapped, especially since the surf spot it snapped at is not known for being “heavy”.
The break on my board is exceptionally clean - obvious buckling on the deck sandwhich stretches back about 1 1/2" and 1/4 inch high, but a nearly perfect break - the foam shows minimal signs of compression (about 1/8" depth from the deck is very slighty deformed), and can actually be puzzle pieced together pretty well. The bottom sandwhich was intact, though delammed to about 6" back from the two pieces of the board flapping while dragging me underwater and further abuse while getting to shore.
I’ll post some close ups of the break.
Again, I lay no claims to structural engineering (or even basic arithmetic!), I just wanted to post what I thought was a good example of a buckled board, and hopefully contribute to a better board in the future (like the ones I see here on these discussions!).
Howzit Greg, Had a friend who I saw break 2 boards back in the mid 60's, 1 at Cardiff and the other at Rincon and on maybe shoulder high waves. Both were double 10 oz bottom and decks with 1" redwood stringers. I do have to say those were were only old style boards i ever saw break. Aloha,Kokua
I snapped two boards last month on a surf trip in Nica. Don’t know if this will help you, because I didn’t see either snap happen – just before and aftermath.
First snap was clean – two pieces; looks like the pic above. It was a 6’3" shorty; 4+4 / 4 pupe, 2 5/8" thick. Board was ~ 7 mos old. Surfing barreling beach break all day. Made some, didn’t make some. The snap happened on seemingly normal wave for that session – it was not quite full stand-up barrel, closed out, came up with not nearly enough resistance on my leash. Other piece got washed to the beach. Swam in and got board #2:
Second break the bottom was snapped, but the deck glass was still holding the two foam pieces together. It was a 6’ 9" step-up; 6s+4s / 6s poly+resin-x, also 2 5/8" thick, but much more foiled than #1. Board was almost exactly a year old. This was about 3 hours later. Swell had come up. Made some and missed some, again. I was tired, and botched a takeoff on a set wave, maybe DOH. My feet were way out of position, tried to save it, could not. As I was falling I tried to kick my board away from me. Saw it rotate in the air so the bottom was up. Next chance I had to see it was in the whitewater where it was flopping like it had been hinged :(