Hi, Anyone got any tips or a how to guide on repairing the bottom of a formula board? I've managed to punch a hole in it the size of a 50 cent coin. Actually it looks like its been hit with the head of a hammer. The nearest professional repairer is 300km away so any advice would be appreciated.

Thanks

sounds like you may be a distance from a fibreglass supply shop.
If that's the case you can use araldite to fill the hole, just sand any depressed area first to give it some grip.

You can mix almost any light weight powder in it to stiffen and lighten it, talcum powder will do the job.

But if you can source epoxy resin, Qcells and fibreglass that would be better. fill hole with qcell mix, sand back a centimetre or so around the whole then 1 or 2 layers of fibreglass over the top. Sand back and paint.

Possibly a slower, but easier, alternative to the vacuum pump method for removing water, is the wick method. stuff something with good absorbent properties, (paper towel toilet paper, old towel etc.) and quite large into the hole, leaving lots of it hanging out. leave in wind and sun, with hole at lowest point and material exposed to the air.
Every nigh pull the stuff out and check for dampness, when it comes out dry you can proceed to the fixinf stage.

This size ding is on the border between "just fill it", or "do it right". Smaller, jeah just rought it up and fill, but if it looks like a hammer hit, there could be substantial styro damage which will lead to a bigger delam later.
Depends where it is and how much damage radiates out from the ding that you can't see.

If it is anywhere other than within 2ft of the nose or 1ft from the tail I reckon it is worth grinding it out and replacing the sandwich. Formula boards can be subject to a lot of stress due to their size and getting hammered over chop.