A tip for a quick DYI repair job.
6 years ago I ran my old naish epoxy board into a reef. Put a hole about 5cm long in it. It was not worthy of a professional repair.
Here is what I did: (as instructed by my brother who knows a thing or two)
Sand back the area - even if it's the rough top of deck.
Clean with acetone or nail polish remover that contains acetone.
Let it dry
Apply sellys aqua kneed it.
Allow to go slightly firm then trim with sharp knife.
Once hard and cooled down, sand back.
Paint it you could be bothered.
That was 6 years ago and it's still good.
For smaller cracks do the same as above but just put a bit of full strength areldite on it instead of kneed it.
FYI. I'm not wasting time painting.
Don't use this tip on fiberglass
Some of it needs to be clarified.
Sand back the area as long as you don't expose the polystyrene core, cos then the acetone will melt it.
Or if it is a deep hole thru to styro, just clean edges with metho