So I finally got around to fixing some cracks in the hull to deck joint on my M15, and wanted to report how I did it. These were there when I purchased the boat, likely from "docking at hull speed" or some similar activity. First, I widened the crack with a cutoff wheel attached to a dremel. Next, I taped over the crack leaving a small opening on each end. Then I filled a 12cc curved tip irrigation syringe with epoxy thickened with cotton fiber (e.g. West System 403 microfibers). I cut a hole in the center of the tape, and used some butyl tape to temporarily seal the syringe, and then applied pressure while holding the butyl tape seal with the other hand. This injected the epoxy at pressure deep into the crack. Once it started pouring out the ends of the tape, I wiped them clean and taped them up one at a time, and finally taped up the injection hole in the center. See the attached photo of the setup. Sincerely, Tyler '81 M15 #157 S/V Defiant