First Comp Board, First Repair

So I finally found the time to put up some pics of my first comp board. It’s 6’1", 19.5" wide and max 2" thick. I weighed the board just before its first surf a few weeks ago, and with fins and wax the board weighed exactly 5.0 lbs.

5.0 lbs seemed too light considering this is only the second board I have ever shaped and my first glass job ever. That’s right, having never done a glass job in my life, I choose to build my own vacuum pump and create an eps, balsa composite. (Screw learning to crawl before you can walk.) But knowing that most the vac guys aren’t building boards under 5 lbs for one reason or another I felt certain I had screwed something up and the board was going to snap on my first wave. It didn’t.

The board although not magic and not the best board I’ve ever owned, certainly held its own in Florida surf. I’d consider the board better than 3/4 of the boards I have ridden and I am pleased with the results. And I am certainly pleased with what I have learned in the process. (I have new respect for glassers everywhere.)

But last Tuesday, the inevitable happened. About an hour into a good session, I made a hard cutback and heard a “CRACK”. I immediately straightened out and headed in.

As you can see from the pics below, the rail line right where I put my back foot cracked. It is hard to see but the crack goes all the way through the balsa rail. It is pretty severe, and I am hoping to get some advice on what is the best way to fix it.

Do I need to cut the entire section out and rebuild it. Or can I just inject a bunch or resin in the cracks and cover with several layers of glass. Not sure how much of a repair this needs and I am curious what the balsa crew thinks.

Thanks in advance.



the rest of the pics



Final Close up

can you tell us about the glass. how much is under the skins and how much is over the rail etc? nice looking board. good luck with the repair.

john

what is your glass schedule?

what is your balsa skin thickness?

what is your balas rail thickness?

other than the crack it looks good

where is the crack relative to the fins?

the fins box may have provented flex through that area and increased the stress where the crack occurred; just some thoughts

The board is made of 1# eps with 1/8" balsa on the bottom and 3/16" balsa on the deck. The rails are two 1/4" pieces glued together with gorrila glue and glued to the eps with gorilla glue as well.

The bottom has 1 layer of 3oz glass between the eps and balsa and 1 layer of 3 oz glass on the outside (plus a patch of 3oz over the fin boxes.)

The deck has 1 layer of 3 oz between and and 1 layer of 3 oz on the deck that wraps over the rails plus a layer of 3 oz where I stand.

The rails only have the 1 layer of 3 oz from the deck wrapping around them.

4est you may be right. The crack is about 2 1/2 inches behind the back of my side fin box. I reinforced the fin boxes with H100 divynicell (didn’t have H80). H100 is hard as a rock so the area immediately around the boxes are really stiff. This crack would be about an inch behind the end of the H100, so it makes sense that a lot of stress would be at this point.

You ended up with very little balsa on the rails ((2)x1/4"). That makes for a very flexy rail. I couldn’t see if balsa strips lined up around that area, but if they did they you only have 1/4" rails. I would guess that the failure was because of not enough strength in the fin area.

About an hour into a good session, I made a hard cutback and heard a “CRACK”.

Awesome! You must be one hellofa power surfer!

5lb on your first is simply astonishing.

sorry no advice on the repair but next time you might want a little more tail rocker.

Otherwise, congrats.

Cheers

I agree with needing a little more tail rocker. I just didn’t know how much the board was going to flex, so I erred on the flatter rocker side. My thinking was, if it is really flexy, I want it to flex into my preferred rocker curve, not past it.

So that is one change I will be making on my next one. Plus I want to put some concave in the bottom, this one is flat. Plus I want to … I have a bunch of changes in mind.

Right now my plan for fixing the board is to inject resin into the crack and then cover with 2 layers of 3 oz to strengthen the area. I think I will put an additional layer of 3 oz on the opposite rail as well.

Quote:
You ended up with very little balsa on the rails ((2)x1/4"). That makes for a very flexy rail. I couldn't see if balsa strips lined up around that area, but if they did they you only have 1/4" rails. I would guess that the failure was because of not enough strength in the fin area.

do you guys think 1/2" balsa rails are enough for a short board. If I understood Bart he had 1/2" balsa rails built up out of doubled 1/4" balsa strips. This was the same I was planning todo for my 6’8".

In July 2005 meecrafty had a “my first 5.5 pounder” thread that indicated…

its got balsa rails about 3/8" thick…

It sounds a little thin for balsa rails to me. Even Bert’s shortboards (like the one in that photo of his which needed foam replacement surgery over the fin area) have around 3/4. I also think it would be advisable to laminate the bottom oversize, with a lap around the rails as well. Bart, on your next one, I wouldn’t change much, except put 3 pieces of 1/4" on each rail and lap both bottom & deck glass around the rails. Like Meecrafty said, more tail rocker. But your glassing (except the rails) sounds adequate as does your foam core & wood skins.

To do your repair, I’d avoid putting a couple pieces of glass over the break, because the rest of your rails will still be a little underbuilt…so where your patch ends, will be the next place it will crack.

I would cut a v into the balsa & glue in a new piece of wood with epoxy. Shape it down, put one small glass patch over. Then get hold of some 3 or 4 inch glass tape and add that all the way around the rails to create a more durable perimiter, without the weight of an entire lamination.

I hope you’re encouraged, not discouraged. Your first board is awesome and your next will be even better. Glad you’re getting the most out of them too…nothing worse than buying Granny a Ferrari. You’re no granny :slight_smile:

Quote:
Right now my plan for fixing the board is to inject resin into the crack and then cover with 2 layers of 3 oz to strengthen the area. I think I will put an additional layer of 3 oz on the opposite rail as well.

epoxy resin is a strong glue but in any thickness is brittle.

I would think you’d be better of rebuilding part or maybe all of the cracked rail area with new wood. Maybe set up a router guide and remove 1/4-3/8 of the balsa and build up a new rail section with staggered 1/8th inch?

just an idea.

yeah but…

ive done test pieces of vertically oriented balsa rails/stringers and they dont flex much and break very easily. The rail cross-sectional aspect ratio plays a big part…

4est the board in question is very thick and quite stiff. I still use it for grovel surf, good board not great. I used enough balsa on the rail the make the rest of construction easier so that was the minimal amount needed to do the job. Dont think I was very calculated, just trying to make’m is challenging enough.

not exactly sure what Bart’s failure mode is but broken balsa is one of the reasons why I dont use b-rails any more. I actually like the idea of cutting the balsa rail vertically in several places along the rail to prevent too much rail stiffness.

Or just use dcell.

Cheers

Benny1,

wrapping the entire rail of the board definitely sounds like the best long term fix. I think I will give that a try.

BTW, I didn’t mean to imply I’m some little ripper - I’m not. If I was, I probably would of cracked the rail first session! It just took me 4 or 5 surfs before I started to get it dialed.

Quote:

I actually like the idea of cutting the balsa rail vertically in several places along the rail to prevent too much rail stiffness.

On my last board I preformed the rails. By accident I came close to lining up 3 out of the 4 balsa strips. There was almost no strength on that section of the board. I patched in one small piece and things dialed in just the way I wanted it. However, doing microcuts in the rail might be a good way to fin tune the rails befor you glassed the rails. Then its just a matter of knowing how you want it to flex.

hey bart

same happened to me on my 5 pounder

unfortunately cant see the pics on this puter

ill have a look tommorrow ( are they futures boxes?)

i tried another layer of glass and it popped again next surf

so i ended up chuckin on a 10oz worth over the rail at the tail

stiffened up the tail and the board seemed to get a better

i reckon you need thicker rails or more glass

or a spread the foam reinforcement on the boxes out a bit more

please keep this thread alive and we can figure it out

ive made 6 and it happened on the lightest with thinest rails and futres boxes

i believe xtra glass under balsa around the rails at the tail would sort it out

i just blew out the water and filled and glassed

i may try and restore it cuz it been working great

just a thought since is was your first one and all… did you sand into the cloth much? that is an easy place to hit the cloth and with that light of glass any nick from the sander is taking away strength… just a thought.

I think others here have nailed it, change the wood and add glass along the rails. Would love to here what Bert has to say about it though.

regards,

Håvard

a number of issues …

fin system reinforcing …

when a board has load ,an even flex will distribute the load over a greater area …

an uneven flex will focus the load at the point where a stiff section finishes …

this is the biggest reason a fixed snapped board breaks again at the edge of a repair …

i had similar problems on many super light boards with futures boxes …

ive even seen light urethane boards snap and crease first session between the front and rear boxes fitted with futures …

it creates a rigid lengthways section focusing the load on the area between the boxes …

i ended up developing a flexible fin box to help with this issue …

that is one factor …

next is rail volume …super thin and it can happen easier … but ive got boards thinner than that so thats not the problem …

you dont have much glass on the rails , but i have one board with a 2 on the bottom and a 3 on the deck total of 5 on the rails , so thats not the problem either …

2 x 1/4 is no problem either …

all my shortboards run 3/8 so that wasnt the issue …

i would be inclined to blame the rigid fin system install , considering that if it ties to the deck in any way you will lose shear movement and flex, also magnifying the load more again …

also i dont see alot of fibre sticking out of the damaged area , im inclined to think that your glassing was to resin rich and when you sanded your board ,you took off valueable weave …

lighter fabrics have a bad habit of gathering and leaving high spots if you dont stretch it tight or bag it down …

this means if your fabric floated while glassing, you would sand it off when finishing …

ive seen almost identical damage when an employee sanded the hell out of his board trying for lightness and weakened it …

so i believe its a combination of poor glassing over sanding and the fin system install …

incidentally , this is one reason i now use fcs , as it allows the natural flex of the board with out creating rigid areas …

even the flexible fin system wasnt as benificial as fcs …

ive even seen similar damage on super light boards with set fins , but fcs still allows a more even flex again …

dont lock any areas up , strong is not always strong …

strength from flexibility …

regards

BERT

Yes, those are futures boxes, Sabs.

And yes JJP, I did have a few spots where I exposed a bit of weave and had to repair, but this was an area where I thought I did a pretty good job. But that said, it being my first glass job, I am positive my technique is part of the problem.

Still, it is good to hear what design components may have also caused the problem. (I’m sure my glassing techniques will get better, but if my design remains poor, even the best glass job won’t solve the problem.)

It is interesting to hear Bert is now using FCS, since it wasn’t so long ago that he was talking about his flexible boxes. That’s a pretty big design change. Would love to hear more thoughts on the good and bad of going with FCS for composites.