i’ve got a couple of large pressure dings on the underside of longboard after an incident with some boulders - about the size of a hand, max depth must be 7mm or so. the glass has a few pressure cracks but no punctures and still looks watertight.
what’s the best way to go about repairing this? cut out the old glass, fill and re-glass or just sand the surface of the the old glass, fill flush with filler (or layers of cloth) and glass over the top?
i’d rather the latter option to preserve some of the original integrity of the board, however I’m worried with such a large flat repair I’ll end up with de-lam issues further down the track.
If its not leaking, don’t fix it, unless the board is not working as it did before the dings. If the repair is done well, you may not be able to feel it, but you will always be able to see it. If you decide to fill it, just sand it before hand and you shouldn’t have delam issues. Use filler then cloth, multiple layers of cloth will just add more weight.
If it is not de-lamed now, it probably won’t in the future. Because it is on the bottom, it is not going to be repeatedly hammered by your body, like the deck would.
If it is dented, but the glass is still attached to the foam, don’t cut it out. If there are circular stress cracks around the pressure dent, then it may leak. It is hard to tell how deep those cracks can be. You can ride it and if it turns brown, well, it leaks.
Or you can sand down the dent, carefully, to remove the resin, until the glass weave is just beginning to show. Then add a layer of 4 oz, hot coat, sand, and you’re done.
my reason for worrying about delam is that the dings are quite large and sit pretty central along the boards length, and being a 9’ board I was concerned that the flexing that takes place around this area may cause the new layer of glass/filler may come away. it’s a poly board, i’ll be using poly resin.