Repairing glass fibre damage where you can't reach

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andynormancx
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Repairing glass fibre damage where you can't reach

Post by andynormancx » Sun Oct 07, 2018 9:11 pm

I’ve got some damage to the very rear of my Tiderace Xplore, right at the stern, on one side right at the bottom edge of the hull.

I had thought it was just some gel coat damage, but then I realised there was a small leak. When I investigated it further I found that the area around the gel coat deforms more easily than it should. I can deform the hull there with my thumb, whereas the rest of the hull has very little flex as expected.

I took a look inside, I could see what looked like some delaminated glass fibre. It is very hard to get to back there behind the skeg box, but in the end I managed to pull out some scraps of lose fibres and small chips of resin.

I need to work out how to do more than just a superficial repair, obvious just filling the visible hole with resin isn’t going to restore proper structural integrity.

There is no way I can reach the damaged section from inside the boat. The only thing I can think of to repair it myself is:

- lift the boat to 45 degrees
- stuff broken up chopped strand mat into the area with the damage
- pour resin into the stern until a couple of centimetres past the visible damage is covered (I estimate that would be about 300ml of resin)

A further complication is that I’m doing my 3* assessment in this boat in 12 days time.

Does this sound like a sensible repair ?

If I get Tiderace to take a look at it are they likely to be able to do a different more effective repair ?

There are some photos of the damage and videos showing the deformation here (for some reason there is a club of gel coat stuck to the inside of the hull near the stern that you can see in the internal photo).

https://www.icloud.com/sharedalbum/#B0v5VaUrzGJIVXo

Chris Bolton
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Re: Repairing glass fibre damage where you can't reach

Post by Chris Bolton » Sun Oct 07, 2018 10:01 pm

If it wasn't a Tiderace, I'd wonder if it was always that soft, since I can't see any cracks in the gelcoat, but Tideraces are usually rock solid. The delaminated bit on the inside photos doesn't seem to go as far up the hull as the soft bit. I don't think you'll get enough solidity and bond pouring resin in and stuffing CSM into it (but I'd do it in that order if I did, not CSM first). A superficial repair to stop the leak would get you through 3*.

For a permanent repair, if it was my boat, I'd take the bold option of cutting out the soft bit, getting a good key on the far side and building up in layers back to the original surface. If that looks like it will be too solid, use lightweight filler (resin & microballoons) in the areas away from the surface. Build it up until just below the surface then a final layer of flowcoat (ie, resin with thickener or gelcoat with wax - same result) then sand it flush with progressively finer paper as you would a gelcoat repair (discussed elsewhere on the Forum and in the Almanac).

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Re: Repairing glass fibre damage where you can't reach

Post by andynormancx » Sun Oct 07, 2018 10:16 pm

Thanks. A complex repair like that is beyond me, I’ve done one single bit of glass work so far. And that was this week, patching damage under the front seat lip on my wife’s Romany.

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Jim
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Re: Repairing glass fibre damage where you can't reach

Post by Jim » Mon Oct 08, 2018 7:45 pm

I normally sand back the gelcoat, apply a patch externally and then flow coat over the top and just accept that there will be a slight bulge in the area to spoil the streamlining a bit. In your case there may not be a lot solid under the gel to appy a patch to.
Sometimes I do it the way Chris says.

Another method I have seen, in fact I have a racing boat with a very bad example of this, is to carefully cut a hole in the deck over the bottom damage, in order to get a hand in to sand the inside and apply an internal patch (maybe a couple of layers in your case), and then refit the bit you cut out of the deck. On my boat someone cut a piece of aluminium sign which they pop rivetted inside the hole and then stuck the piece of deck onto the sign using lots of gelcoat - it was real mess! I would suggest either using some resin and glass tape to make a flange (let it cure) and then bond the piece back to that, or screw some small straps into the corners - thin aluminium or ply. Bond the cut-out back in with a resin/filler mix and apply some narrow glass tape neatly around over the cut line (no need for the deck to be streamlined). Alternatively get a dinghy inspection hatch and make the cutout so that you can stick that hatch in afterwards and have future access to check the repair or re-do it. The hatch is probably designed to bolt in with a gasket, but if you use a decent marine sealant like sikaflex 291 instead of the gasket it would probably be better.

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Re: Repairing glass fibre damage where you can't reach

Post by Chris Bolton » Mon Oct 08, 2018 7:56 pm

A complex repair like that is beyond me
In that case, I'd do the superficial repair for the 3 star and take it to Tiderace afterwards. For the 3* assessment, take some good quality gaffer tape (eg, Gorilla), a small bottle of meths and an absorbent cloth, maybe an airbag to put in the stern compartment if it gets knocked and leaks. You probably won't need them, but being prepared is always useful on assessment (the assessor doesn't need to know you have an 'at risk' boat unless something happens, and if it does you'll fix it).

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Re: Repairing glass fibre damage where you can't reach

Post by SJD » Tue Oct 09, 2018 9:25 pm

I have made similar repairs with good luck using a stick with a bent chip brush taped to the end. Granted, it is kind of done in the blind. I typically use West System epoxy with appropriate fabric in two layers, but not chopped strand mat. Wet out the area with the brush mentioned above, with a separate stick drape the cloth over the epoxy resin, then dab more resin over the area. It helps to have the kayak positioned so the resin settles into the repair area. This is similar technique used to apply inside seams. No, it is not perfect but it seems to work, the adhesive quality of epoxy helps.

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Re: Repairing glass fibre damage where you can't reach

Post by Aled » Tue Oct 09, 2018 11:58 pm

Re-posted and expanded from Facebook (for UKRGB community and to preserve Tiderace response continuity)

Hi Andy, for a factory finish repair, consider sanding/grinding away the damage from the outside. Remove all the broken gelcoat, and stop just before you grind through the very last inner layer of glass (keeping a few strands of old cloth in situ will support the new cloth layers during the glassing, saving you having to work inside - failing this, grind a big hole and push a block of polystyrene inside to fill the void, sand this to shape and use it as a backing support during the glassing). Mask the area, and apply layers of woven cloth (200gsm 'ish for ease of use) with epoxy resin (I'm a fan of West Systems 105 / 205), and allow to cure. Sand the epoxy glass repair with coarse paper until the boat shape is restored, cutting no more than 1mm below the original surface, then gelcoat over the patch. Wetndry this and polish to an invisible repair - consider adding a keel strip for an easy cosmetic finish (though personally I'm not a fan of keelstrips).
If you're in a rush, just grind away the broken stuff, apply the glass/epoxy and sand it into an approximate shape, then go paddling - it should be watertight.

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