I have a M15. I ground out about a silver dollar size hole on either side of the pin. I then used glassed fibers over the pin. Then I sealed over the holes following the Interlux system for barrier coating. Actually I sealed the bottom of the keel, drilled a slightly larger and filled both sides with expoxy. I then redrilled it for the pin. I barrier coated the entire keel and board and then coated them with VC Performance Epoxy. I did this because I had a little water get into the ballast cavity. Bert Felton