Dye Penetrate Test.
There are three spray cans manufactured by Crown. The dye, developer and cleaner. The cleaner is basicly acetone, don't bother buying
it. Too expensive for so little amount. Just use a rag and acetone out of a can. AND DON'T GET THE DYE ON YOUR GELCOAT
You can also get the stuff at welding suppliers. You spray on the red dye first, wait a few minutes, then wipe it off. Then spray on the white powder. Any cracks will show up as red line in the white. Clean it all up with a rag and the acetone. If you apply a little heat (heat gun) to the part before spraying the dye, it'll soak in better.