whats caused the holes?

Thatd be the first thing to work out. If you cant get at the inside, without seeing a pic maybe clean the holes out with a drill bit, key it in (make the middle of the hole bigger than both ends by twisting the drill with the end only just deeper than gelcoat).

Then use a pointy small screwdriver or similar to push resin/glass strands deep into the hole

Hi, i went through this recently, found underneath was getting a few stress cracks in the old fibreglass hull, so wasnt happy, didnt want to have any problems out wide, so i ripped up the front half of the floor only to find there was delamination and an old patch were someone had recently repaired it. I bought a heap of fibreglass and that antirot stuff for the wood, i treated the wood and basically fibreglassed everywhere it looked a bit week, took a couple metres of fibreglass. The horrible part of the job was making a new deck for it.

Anyway i could go on in more detail but bottom line, don't go buy old fibreglass boat, if you have ANY doubts at all about the hulls integrety, the floor will have to come out.. Sorry but its only way.

You can try grind down the old gelcoat and do a couple layered patches over the top if you not worried about apearance, i have done this with my transom and all good, but if you do it that way, keep a close eye on it every trip.

few clips on u-tube would show you what to do.

use as little resin as possible but make sure the glass is fully wet for the strongest mix (resin with little glass can crack). shouldn't come off at all providing surfaces are clean for a good bond (light carefully wipe with acetone).

I know the kit you have and suggest you don't use the glass where it is folded as this breaks the strands and it is weak(glass matting should be rolled not folded) can either cut it or pull small sections off which makes it easier to blend the edges but in you case given your talking very small patches probably just cut it (circular) and make the top piece just larger than the others.

As rob suggests find out the cause first - anything else on the hull to suggest an object strike.

If you can get access to the inside of the hull would pay to put a patch on the inside as well but can be done from the outside only if access is too difficult. If doing from the outside only I'd poke a bit of resin through first to make sure the edges of the hole are wet and water doesn't;t seep into the glass from the inside causing potential rot down the track.

Any chance you can take a few pics. I have built and repaired a few glass boats and can assist with some info.

Key is to find out if the holes are in a high stress area, or are from the trailer. Need to know those bits of info otherwise your repairs may be fruitless.