Hi, im looking for some advice on what to do with my body. ive made some holes for exhausts and suspension and since re fitted the body. What ive noticed is 2 hair line cracks in the gel coat on the exhaust hole. I remember being told to drill the very end of the crack to stop it spreading, is this correct or is there a better method? I think the area is currently stressed so once thats sorted il make the holes bigger as they were far to small for the exhausts.
cheers
Adam

Hi
Are the hairlaine cracks in the gelcoat only, or in the fibre as well? (that wouldn't be a hairline crack, would it?? )

A manufacterer of GRP freefall lifeboats told met that hairline cracks in gelcoat do not affect the strength of the GRP. It must be said it was a Chinese manufacturer

For the esthetic part, I would widen the crack and fill it up with raisin. Paint the small damages and ready.

Cheers
Rescued attachment Resize of DSC_0209klein.JPG

The cracks don't have any influence on the strength of a panel, gel coat cracks very easily which is why I use filler rather than gel coat if making a new panel. Like you say drilling a hole at the end will stop it spreading but paint will never cover the crack it will just reappear in a few weeks or less. If you have a painted car then cut a groove and use filler to fill in or if not painted do the same but use gel coat instead of the filler and sand then t-cut back to a polish.

cheers im actually thinking as we need to make the hole larger i could drill the end of the crack(just in the gelcoat) and then cut the hole outwards.

maartenromijn why would i want to put raisins on my car i dont want to eat it

The crack will extend through the gelcoat. A small drill at the very end (preferably slightly countersunk with a bigger drill) will stop the crack spreading...

Just get a gelcoat repair kit, and follow the instructions.
Ive used this on boats, and it works fine.