[neto]

Post a picture of the non skid to see what you are working with, you can try to drill small holes and use a high pressure glue injector with gorilla glue and later cover those holes with gel coat. If your nonskid is little squares, you can try drilling in the middle of 4 squares. Another option is to cut using an oscillating tool on the area's where there is no non-skid, lifting it and replacing the core in there.