Mending a crack in fibreglass

[Jon W]

Hi All

I have a long thin crack in my fibreglass quarantine tank along the bottom parallel to one side (bought it second hand and was already there when I bought it). It is not a hole but rather a delamination of the flowcoat from the CSM layers.
I would be grateful if someone could critique my plan of attack for mending it;

1. Grind out the crack so that there are no hairline cracks that can't be permeated by resin.
2. Fill the resulting "gouge" with car body filler to level off with the bottom of the tank.
3. Mask off around the crack, allowing sufficient area to lay glassfibre up to 4" either side.
4. Sand the whole area inside the tape to key for applying resin.
5. Lay a thin strip of CSM along the crack, followed by a wider strip to add strength.
6. Apply a layer of flowcoat.

I'm not concerned about the mended area being proud of the base, although obviously I'll take care to ensure there are no sharp edges.

Any comments gratefully received.

Regards

Jon W

[Bob Hart]

Sounds like a good plan Jon

[Jon W]

Thanks Bob, I was hoping you might give it the seal of approval. The main thing I wasn't sure about was whether I would need to gring the flowcoat back to the matting for the whole area to be covered in new glass.

Cheers

Jon

[netsukekoi]

I'd grind back to the matting - tried 'just sanding' before and regretted it - read somewhere that 'any trace of gelcoat will cause a problem' and I know gelcoat and flowcoat are different, but this is one of those jobs you only want to do once.

Also, I'd use tape along the crack just to make sure, rather than just csm.