So, cleaned my board off a few days ago and found a nice crack down the inside of one of the front fins(glass-ons), didnt seem too bad so i ground out the fillet and prepped the surounding area and repaired it all very neatly, job done i thought.
after i finished wetsanding i gave the fin the flex test to make sure it was up to the job and the glass lifted pretty much everywhere around the whole fin!,the glass was solid but it was just flexing up, i cut the fin off and blew over the area with the sander back to the foam, thinking it’ll be an easy re-glass and tack the fin back on scenario but once i got down to the foam it seems the top layer of foam it what has de-lammed, not the glass, about 3mm deep of foam has just lifted off/seperated?
is this a poor quality blank issue or just something that happens with eps?
i’m pretty frustrated as this is the first EPS custom i’ve had,i love the board but don’t know whether to approach the shaper about it or just hack out the affected area and backfill and carry on as normal.
Not really a delam. Never seen a delam around a fin? Delams usually happen where compression happens over time and glass delams from foam, like on decks. It sounds like this happen'd when you hit the fin, or the glasser didn't put enough glass around the fin area. The fin flexed and pushed into the foam, also it depend on the weight of the foam? 1 lb-3lb? The lighter the foam, the more reinforcing around the fin...you need to distribute the load and flex of the fin, or it's going to do bad things to your surfboard.
Eps foam is not super structural, its floatation, and it's lively (oops here comes the hell of the poly guys) Strength comes from the glassing schedule, or the thickness of the board. You want a lightweight board...it's going to be somewhat delicate.
I'd drop a router into the dead foam...hog it out in a nice oval shape...make a jig out of masonite. Dig into it about 1 inch or less, or until you hit good foam. Epoxy a patch foam piece into the hole and sand smooth. If you are worried about it doing it again, get some HD foam, or a chunk of 2 lb eps. Glass it and stick the fin back on, just make sure you get the fin placement right.
Do what Resinhead says, but I would use a plug of polyfoam instead glued in with Gorilla glue. Get some scraps from your local shaper. As an alternative, you can use 2-part Pour-Foam which is a 2 lb. urethane foam. In any case, you need to cut out the area where it’s delam’d with a Dremel cutting wheel. The trick is to not use epoxy for the foam repair since the risk of melting the exisiting foam is very high. Once you have the foam fixed and shaped, use an epoxy filler paste over it, sand smooth, then epoxy lam with a layer of 6 oz overlapping good glass about 2". When you re-glass the fin back on, there will be more glass covering the area. This is a big job just on the board, and also you’ll be sanding the fins down, filleting, attaching, and glassing.
filling the area is the bit that’s stressing me out, its quite a large area that’s going to be missing a 1/4" of depth with a lot of contours running through it,
the board is only 2 months old so i’m really annoyed that a knock to a fin has caused such large mess that’s going to be a real pain in the neck to make good.
cosmetically i think it’s going to be hard to get any good result so i’m just looking for the easiest way to get it back in the water.
resinhead,
yes it’s not a standard delam like you said, i’ve never seen a whole foam layer delam so cleanly before though, and over such a large area too, i presume this is the layer where the resin has drained into during glassing.
i don’t even recall knocking the fin, that’s the bit that’s bummed me out, i just found the crack after a clean off and it felt pretty solid before i did the initial repar,
i don’t know the blank density but the beads are tiny, yet nail apart with worrying ease, the board was made on the goldie in australia, no idea what blank was used.
is this a common thing with EPS? i’d wouldn’t get another board made like this if that were the case.
My guess is that the sander went a bit hard sanding down the fins and caused the board to delam. Err... could it have happened when you sanded?
EPS will delam from sanding just like any other board. I find it strange that it delamed in the same shape as someone sanding down a fin, or around a fin. I mean why didn't it delam a bit further into the flats?
Anyhow it should be easy to fill & reshape.Don't stress, that what we are here for....it's just a surfboard.
Doesn’t sound like a delam, at all. My guess is the fin got stressed to the point that the glass cracked at the base, which is the first thing you noticed. Now, when the fin was flexed past a certain point the glass/foam bond did not fail but the foam itself broke. It’s similar to what happens when you try to strip a glass job. The bond to the glass is often strong enough that the foam pulls off in chunks rather than just peeling the glass cleanly. I’d suspect low density foam as the cause. Your best approach is to use a router to make a clean cavity that a foam plug can be glued into. Trying to fit or or fill a randomly shaped crater is harder and actually makes for more work. Like someone suggested, use poly foam for the plug. Denser/stronger.
I’ve had 1 eps board with glass ons and the stress from the fins flexing the outer glass at the bases eventually caused the foam to break away from itself.I think glassons are not a good option over eps foam,its just not a strong enough core.
I’ve fixed too many broken fin boxes, broken glass-ons, etc. and there is invariably delamination and/or splitting of the foam. Maybe not from one incident, but others where there wasn’t any external damage. On side fins, most of the rail is usually taken out, so that’s also common. Don’t stress about the filling. Just get the foam level using the methods I previously recommended, and then use layers of cloth inside the cut to build it back up level with the exisiting glass. Laminate up to 3 layers at once, then use an epoxy filler and sand until it’s all flush. Use a single 6 oz. layer to overlap the edges to the exisiting glass. When filling large areas with cloth, it’s a good idea to sand the edges of the exisiting glass to a tapered edge. Just be careful that the sander doesn’t catch or gouge out foam. Using the dremel with a cutting wheel will give you nice straight edges to work along. Cosmetically, just use a small amount of white pigment to your filler (or nothing if using white micro-balloons + cabosil); just enough to be somewhat translucent and it’ll hide things. Once you got the board repaired, mark the location for the fin. Sand the fin and hot glue in place while setting the angle. Follow the archives for reglassing the fin back on. On fillets, my preference is just filler not rope, and on both poly and epoxy I use UV poly filler with a very clear cabsoil. Again, heating is the concern using epoxy in any concentrated area like fillets. Fillets are not structural anyhow, and you’ll be glassing on the fin with epoxy so you’ll have a good bond back to the board. Small fillets; not some 2" radius like a 60’s D fin. The rounded end of a wide mixing stick is about right.
Howzit bobbins, Sammy and Pete are dead on right. I would say that 90% of the lassed on fins I have repaired has had the same problem so it is not an unusual situation. Since I was always a poly guy I would just pull up the foam flap and make some runny q-sel mix and spread it between the layers and put some weight on it to fix the gap. Then just sand it and glass the area with a couple layers and put the fin back on. You can also just cutout the foam flap and fill with a thicker mix of Q-sel ans then just go from there. Like I said it happens all the time and a lot of people don't realize it has cracked the foam so they just glass over it and put the fin back on only to have the fin come off really quick. It's like that saying about building on quicksand. Aloha,Kokua
i was wondering about trying to stick the larger area back down but wasnt sure if it was realistic solution, it would certainly help to keep the channels intact which was the major hiccup from my point of view,it would also help to keep the weight down which is always good on a 5 1/4 lb board.
is it worth drilling a few small holes and using a plastic syringe to help get resin all the way under the lifted area?
i only have some kwik kick in the shed, is going to be safer to get some of the slow(er) kicking RR resin for this job to avoid a meltdown type scenario?
routing the new plug of harder foam out isn’t a problem so maybe over this long weekend i’ll have at it and see what happens, it’s got to be more fun than watching royal weddings with the wife.
Howzit bobbins, If you are just going to stick the foam back together then when it's done there should be just a thin layer of resin between the 2 pieces which should not add much weight and after you put the 2 sides together wipe as much of he excess epoxy off as you can ,then put a piece of wax paper on top and then something a bit heavy to make sure the pieces have a good adhesion but hardly any epoxy other than enough to stick the sides together. If you can pull up the 2 pieces and separate them enough to force the epoxy into the split as much as possible.I think that covers it but if you need more help just PM me since that way I will know to open and reply. Aloha,Kokua
This happened in years gone by with 1.5 foam or lighter. In part it’s the quality of the foam but it happens primarily with lighter foams and larger fins or larger waves which puts more torque on the fins. This is one reason why we went to 2# density which I’ve never seen do this. Boxes fixed the whole issue though quite a while ago.
I’ve had 1.5 pound eps with a small bead and 2 pound eps with a large bead.Right now I use a 2pound with a medium bead and small beads filling the voids,good stuff.