first board tested: cracked in deck - what's wrong?

General Discussion
1

I finished my first board. Big thanks to everyone here who gave advice! (I’ll post proper pics of the final board here and at hornmelon.blogspot.com in the next days)

The board is a 6’ quad fish, shaped from two glued sheets of Dow value-R polyiso faom, glassed with Greenlight bamboo glass and RR epoxy.

I tried the board for the first time last week, in a hh+ session at Ocean Beach SF. It surfs really well! I was superstoked for a day…

…Unfortunately when I took the board out again in the next day, the lamination cracked in the deck, see picture.

I don’t know what caused the crack - I didn’t hit anything, and nothing unusual happened. I’ve never seen a ding that looked like that - just a tear in the deck.

The lamination is 1 layer of bamboo glass (4.5 ounces) on the bottom, 2 layers on top, and three layers on the rail, thick hotcoat, not sanding after hotcoat and no gloss coat. The 3-layer rails feel bombproof, the 1-layer bottom can be pressed in with a finger, the 2-layer deck can be pressed in a bit if you apply a lot of force. Overall the board feels strong compared to other boards I have, and there was no denting of the deck whatsoever after the rather punishing first session.

What could be wrong that would cause this type of defect? I’m hoping some of you can recognize the problem from the picture.

Since it’s my first board, I can only guess… Was the resin/hardener ratio wrong? Do I need more glass for this type of foam? Did I sand too much before hotcoat in this spot? Another theory I have is that there was an airpocket in the foam that caused a failure in this one place. This isn’t high-quality foam - I noticed some smaller airpockets in other places while shaping, and the foam under the crack seems to be a bit pressed in. Another thing I noticed was that deck/foam adhession was not so good in the dinged area.

The next question will be how to fix this. If there was an airpocket or lamination problem in this particular spot, then I would fix it like any ding. If there is some overall structural weakness, then maybe I should add another glass layer, to make the deck as strong as the rails. Any advice would be most welcome!

thanks,

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Quote:

…Unfortunately when I took the board out again in the next day, the lamination cracked in the deck, see picture.

http://www.swaylocks.com/images/gforum/files/image.gif

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Image no worky.

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thanks, I edited the post, now the pic is there

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Is it just a tear in the glass, or is the foam compressed to any degree? Looks very much like it got punched in by a knee or elbow.

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I got to agree with Sammy. It looks like a knee ding from duck diving. I had a same thing happen to a board I made for a guy once. That board was poly.

6

One of the reasons we normally glass with woven fiberglass cloth is because it’s capacity to stretch is more/less in line with the flexibility of the resins we use. Actually, I think the way it went was the resins were engineered to work with the properties of the fiberglass cloth.

The bamboo jersey is a knit (not a flat weave) and it stretches a lot. A glasser friend of mine has some of it and is of the opinion that if it isn’t completely stretched all the way out and laminated dry it could outstretch the resin matrix. Moreso with poly than epoxy, but bad enough either way.

Or as others have commented, you might just have really sharp knees.

7

Quite simply, that deck lam is too light.

Dow foam is only 30kg/m3 (2#) density. (i’m assuming thats the stuff you used?)

You’ve basically done a double 4 ounce glass job.

A clark foam board can be around 40 - 60kg/m3 density, depending on how you shape the deck.

A double 4 ounce on one of those boards doesn’t last, so it’ll be even worse with the foam you’ve used.

I bet the board is light and lively though!

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Quote:

I got to agree with Sammy. It looks like a knee ding from duck diving. I had a same thing happen to a board I made for a guy once. That board was poly.

What happened after you fixed that ding - was it a one time occurrence, or an indication of overall weakness?

9

Thanks for the comments, guys.

Yes, the foam was a bit compressed under the ding.

When I researched the foam and glass I noticed that Greenlight (were the bamboo glass comes from) routinely uses RR epoxy+two layers of bamboo glass on top of 2 lbs/cubic-foot EPS foam. So I figured my foam with similar density would be fine with the same type of glass job. Hm… maybe not?

Btw; I just posted some pictures of the finished board at hornmelon.blogspot.com.

10

My friend, Pancho the destoryer was real good at breaking things. I was able to put a deck patch on that board, but I made him wait a week before giving it back to him. I’ve never had that happen since then.

Good luck,

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I’m finally getting around to fixing the cracked deck, and will add a deck path to make sure it doesn’t happen again… How much glass do you think is needed for the deck path? (on top of the existing two layers of 4-ounce bamboo glass)

thanks for your advice,

12

Excellent job for a first board.
I dig the green stringer and cream… is that the natural colour of the bamboo cloth, or did you add pigment?
I’d suggest when you add the deckpatch, sand the rest of the board, especially the cutlaps on the bottom, and give it a proper finish coat.
That board looks too good to leave unfinished.

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Thanks sine! The bamboo cloth might have added a little to the cream color, but I think it’s mostly from the polyiso foam, which is sortof an unbleached polyurethene. That foam is dirt cheap, but unfortunately it has discolorations, dark spots, and small holes here and there, so maybe not an appealing choice for production boards. But it was very easy to shape and personally I also like the look a lot - it almost looks like an old, yellowed board, but not quite.

You probably looked at the pics in my blog. I was really surprised how the bottom cutlaps showed up in that first picture - there is actually a hot coat on top, and in real life you almost can’t see them - as you can see in the pictures further down. I should have removed the first picture before posting here :stuck_out_tongue_winking_eye:

14

Yeah, I looked at the blog.
That one image makes the overlap look like step.
Good luck with the repair job.

15

Sorry to rain on your parade, but the foam you used was the wrong stuff. Poly isocynate

doesn’t have the properties required to withstand the stresses that surfing will put on it.

The biggest problem is its friability. It turns to powder when pressed.

Sorry if I sound like a pain in the ass, but the best part of swaylocks is the willing info from

those who have gone on before. The trap many fall into is trying to re-invent the wheel.

For first attempts, keep with what has been done before. If you want to play around

with new techniques, think small and work on samples. That’s a whole lot better than

wasting a couple of hundred dollarson a board. There are so many experts on this site that just give

away their knowledge to anyone who will listen.

My biggest thanks go out to all the guys who have spent tons of money and time

working out the kinks, and giving me their hard learned lessons for no reward other than

to share the stoke of helping out their brother. I’ve noticed that some of the “down under”

compsand guys get a little squirrely at times, But their hearts are huge when you consider

what they share.

For designs, Greg Griffin, Bill Barnfield, Surfteach, Dead Shapper and TONS of others with

lifetime of knowledge on what to do with that chunk of foam.

Even Greg Loehr with RR epoxy, (Although he does make a buck off every gallon, so he’s

more of a salesman) take an unexpected amount of time top answer all kinds of questions.

Many of those answers are given again and again and again… to those who won’t do a search!

From a “green” perspective, what could be worse than making a board that crumbles on its first go out.

So to get back to your first question, what to do with your first board. Let it take up space in a landfill.

That’s better than pouring time, money, and materials on a dog that’s rotten to the core.

Sorry

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everysurfer; could you elaborate on your experience with polyiso? I searched the forums (and the web) extensively before starting out, but couldn’t find anyone who had actually built a board with that foam. afaicr there was one guy who built a blank but glued it up the wrong way, then switched to a different foam for the next try.

17

No more boards in landfills PLEASE!

We have quite a few ways to make use of those boards now without throwing them in the trash.

Sorry to step in on that note, but this mentality has got to change.

Please…spread the word…NO MORE BOARDS IN LANDFILLS!

If necessary I can start a thread on alternatives.

Did I say…no more boards in landfills? I did? Oh…OK

Now back to your regularly scheduled program.

Mahalo

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Everysurfer just put the ‘Every Surfer’ in “Everysurfer’s Worst Nightmare”. I sincerely hope that this foam is not utterly the lost cause he says it is. If you’re all set up to do it, then by all means I say slap that deck patch and give it a go. Worst case scenario is you get some riding on it before the same thing happens again. That way, at least you start to feel how your design works and get some real life feedback from your shaping experience. best case scenario; with extra deck patch it rides fine for at least a short board life or maybe longer, who knows!? Try. You’ve got nothing to lose except a maybe 30 bucks worth of resin and glass, and a couple hours of work. Small price to pay to get some more out of the whole experience.

And amen, Todd! …We’re all a bunch of creative folks here, tossing in the landfill seems much too dismissive an approach. Especially with an un-yellowed, fresh looking board like this. Me, if I had a board that for one reason or another couldn’t function (and wasn’t a 10’ noserider, let’s be practical) it would get some kind of sick graphic on it (good time to practice a resin tint? Acid splash? Wine stripes, anyone?) and become a wallhanger, coffee table, or with the addition of some cinder blocks perhaps a functional shelving unit. Chicks of all ages love it! (except your mum, who will tell you to clean up your room and to stop dripping resin all over the back yard, thank you very much!)

Good luck with the rest of this project, however it goes.

Btw, the board looks pretty nice to me! …and I dig the green stringer also.

19

Hello boys,

All this green shanagians is exactly that…You going to have to be prepared to throw away a few boards in the name of the planet. If your going durable and want to save the planet with your green surfboard, then for gods sake make it durable. Next time glass the little fish thingy, and make it out of a tried and true material…don’t go to the home depot looking for a deal, and glue 2 sheet of whatever together. get a EPS blank with a proper rocker, glass it with the equalivent of double 6 oz top, and single 6 bottom. Make it to last. Do it right and it will be right. if you want extremely durable look up the WMD thread, make a board that way with all this bamboo tom foolery.

If that board was glassed properly it should have never slit open, your lucky you didn’t get your knee stuck in there. i know it’s your first shape, so there is a lot of trial and error, and it could have very well been your glass job. But i suspect it was total combination of everything that lead to that failure. Keep surfing it until it blows up. After seeing the brittleness of the glass epoxy, and the compression factor of the foam, I’d pay close attention to fin boxes and leash plugs.

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Hey Horn,

My experience with polyisocynate insulation foam is as a building contractor. The stuff sheds just by rubbing your hand on it. (Insert yor own joke here) Not only will it ding like crazy, but it will delam too. Also doing internet research not on surfboard websites, but industrial foam sites.

Also it sounds like your experience with it points out its weakness.

If you need to patch it after every go out, after around 10 days of surfing, you might as well start over from scratch.

Hey Synergy Todd,

Landfills aren’t so bad. After one of their 100 ton Dozers runs over it during compaction, that board won’t take up much room at all! What do you think Resinhead does with all the Inedible seal parts. Bones and guts gotta go somewhere.