I was removing traction pad from my kite surfboard recently and notice the area under one of the heels had bubbled up.
I’ve done quite a few repairs from small dings to tail/ nose rebuilds but this delam could me biggest challenge yet! The board is an eps foam core/a thin layer of glass/ a layer of cork (seemes to be just on the deck) /glass / bamboo /glass.
The delam seems to have happened between the foam and the cork or mauybe the thin glass under the cork and the foam. It’s all bone dry but the cork had crumbled a bit. Anyway I’ve stripped it all back to the foam and to wear the cork and foam still have a solid bond.
But the question is how should I rebuild the layers?
I live in the UAE and access to good materials isn’t the easiest. Plus, I don’t have a vacuum bag set up. so any veneering would have to be done with weight pressure.
Should I be trying to find a suitable piece of cork to fill the gap ? Does it need the bamboo veneer as well? Or could I get away with a Q-Cell type fill job and glass? Aesthtics aren’t too important as the board is painted and I’ll spray paint afterwards and it’s going to be under a traction pad anyway.
The board is a North Nugget if anyone has had a similar experince.
Ideally, you want to fix it from the foam up, re-building each layer and tying it back into the existing layer. You’d want to feather the repair area out quite a bit more to not have such a steep step into the foam, but more of a gradual ramp exposing each layer to tie back into.
With that said, and your limited access to materials, you may need to improvise a bit.
Here’s photos of a repair I did to a bamboo veneer board that had a similar construction, but with less layers:
Worth reading back from the start of that thread too for some more useful info.
Under the heel is a punishing spot, so that’s a tricky repair in knowing that it will be subjected to a bunch of abuse (especially on a kiteboard) going forward.
Worst case is that is delams again, but then you’ve already got a bit of experience fixing it
Have you ever been to Eva the Board Lady’s website? Lots of info on sandwich board repairs and the Repair Menu and For my Customers sections have lots of pictures.
Seal foam with a mastic make with epoxy+qcell+a bit of cabosil lam some glass on this that go on cork. Feel over with a resin qcell mix, add as much qcell as you can up to a thick past even if it look dry it will stick and harden. Sand, lam over and finish. i repair many kite/surf/windsurf in sandwich with this tech with no problems.
If you follow conventional wisdom and others, they’ll say to rebuild using same materials. I ask, "If the original materials failed, why go there again?
I agree with lawless to feather out the damaged area. You can likely just skip the cabosil/epoxy paste and simply build up layers of fiberglass and epoxy to fill the hole and beef up the reinforcement under the heel. If you are able to feather out the damaged area and spread the reinforcement material (glass/epoxy) out, the heel pressure will be less concentrated on that one spot.
Once covered with new deck pad, you should be OK. Heel pressure points are really focused on kite boards and jumping/landing eventually takes a toll.
I suppose there might even be an argument for routing out a fairly large area and splicing in some high density foam in the area that is damaged. Then build up your reinforcements. There was a fairly lengthy thread here on Swaylocks awhile back about core+skin combining to form a complete composite structure. In an area of structural failure, reconsidering the core might be worth a visit.
Rout out the area evenly with a trim router 5mm deep, vacuum bag a patch of high density dyvinicell to flush, sand it to clean up and take down the glass a little then cover with 6oz patch and 4 oz over overlapping the repair and finish as usual…
Gents, many thanks for all the advice. What a fantastic forum this is.
It’s all helped clarify in my mind what needs to be done. I’ve just been scouting around trying to find the relevant materials.
Lawless: many thanks, I went back and read through that thread - very helpful indeed
Jrandy: Yep I’ve dipped in and out of the boardlady site in recents years it’s a fantastic resource, and I went back and read some of her repairs relevant to this one
Johnmellor: That’s great advice thank you. And very kind of you to offer to send some patch material. Unfortunately I live in Abu Dhabi! I assume you are on the other side of the world. I think the postage might be quite high! You make an interesting point about whether the existing materials are the best to go with. I don’t quite see why they went with cork in such a crucial area. Does it really offer a better skin over just eps/glass/bamboo. I went back and North’s “blurb” on their construction for this model and they talked about the cork as a “shock absorber” hmm. I think higher density foam would have been prefereble
Saying that, I’m struggling to find Divinycell and an offcut of bamboo veneer here in the UAE. I found some cork in the DIY store that matches the thickness. So I’m thinking to go with this and follow your instructions. From the advice here, and closer inspection of boardlady I really need to almost flatten the edge of the repair and then she seems to stick the layers on top so they have a bit of overlap, and then she cuts and sands them back after wards.
Lemat: when you put your resin and Qcell mix on to the foam, do you put the layer of glass on top when it’s still wet? Or do you let it dry, then sand and then put a glass layer, let that dry and then the cork?
nocean- interesting alternative to rout and drop in dyvinicell- might be a bit cleaner. but i’ll try the faired out edge technique for now.
I’ve managed to get away with handsanding for alll my repairs previously - but I think this may require the purchase of a small rotary sander!! Does anyone use a sanding disc attached to a regualr power drill? Not very precise I expect.
Anyway, many thanks everyone, I’ll let you know how it goes.
seal foam with mix, let cured, sand and laminate over
seal foam with mix lay glass over and laminate all in one go. In this case on light eps like your’s seem to be, you need a thick first mix or better add cabosil in it to make a no runny mix still easy to work with othewise you will have air drain.
So after some delay in pulling together the materials and a trip away I managed a repair and learned quite a lot along the way.
I started by purchasing a rotary sander and fairing out the edges of the damged area. Afte sealing the foam with a thin layer of resin and Q-Cell I lammed in a piece of cork from the DIY shop with a piece of glass underneath. I sanded this down and then lammed in a layer of bamboo veneer with flass underneath. Next came 2 layers of glass to cover the area, followed by a hotcoat, sanding, spray and then a spray of the whole area. Then, finally a traction pad which was what I was trying to do when I first found the delam!!.
Things I learned:
*It’s going to take time to become an expert with a a rotary sander !! - It definitely speeds things up but have to be super careful of doing damage
*There’s great board builder who set up in Dubai earlier this year. http://splus-surfboards.com/ His main focus is kite-surfboards and he was a wealth of information on construction techniques for these boards. It was cool to see his workshop and shaping bays and he very kindly gave me some spare bamboo veneer and a bag bull of different weights of fibreglass
*Factory made kiteboards, despite their price, are far from perfect. There’s a reason most of them are painted, and painted boards make DIY repairs tricky to finish! (See pics)
*Without a vaccum bagging set up, weighting lamination layers takes some ingenuity!
*I’m pretty happy with the repair. I over sanded the bamboo layer because I probably didn’t sand the cork flat enough and there was a bit too much resin on the bamboo layer but overall it seems OK
Many thanks to everyone for their advice - now on to the next project !
