Port & Starboard Cockpit Drain Through Hull Patch

For Monday and Tuesday, the 29th and 30th of June, I prepared the holes created by removal of the cockpit drain through hulls - both the port and starboard.

I measured the outside radius of the repair area using the 12:1 bevel rule - creating sufficient area in order to help spread load. Once I marked the outside circumference of both the starboard and port repair areas, I prepared to sand the bevel.

For sanding the bevel, I used a 5", stiff sanding pad attached to my corded drill. I have a Dewalt VS random orbital sander and the Porter Cable 7335 (both 5"), but the soft pads would not allow me to efficiently create the bevel, nor would they allow me to control where on the repair I would want to apply the pad for material removal.

The inexpensive option of a drill-attached sanding pad seemed to work best. I used 5" adhesive, 40-grit discs to create the bevel. I started with the starboard side, and learned pretty quickly how to apply the sanding pad to the repair area in order to avoid sending the sanding disc flying off into orbit.

Once I was satisfied with the bevels, I cleaned up the interior by vacuuming and then applying a solvent wash to remove potential contaminates. I applied a solvent wash to the exterior repair area as well - generally preparing for the coming epoxy patch. Finally, I created backing plates for the repair areas by wrapping a small panel of cardboard with plastic sheeting. The cardboard is firm enough to allow thickened epoxy somewhere to be pressed into from the exterior side, but is also flexible to form around the repair opening. I wedged a few pieces of scrap 2x4s on the interior to keep the cardboard backing plates in place. This concluded work for Monday the 29th.

On Tuesday, the 30th, I arrived and immediately began setting up for the patch work. I cut two sheets of plastic sheeting and taped to the through hull repairs areas. With a sharpie marker, I traced the outside circumference of the repair area, and then progressively drew smaller circles until finally tracing the actual through hull hole. For each side, I drew approximately 6 to 7 circles - which would be used as layers in each patch. Once I finished tracing for the patches, I mixed a pot of neat epoxy and painted the repair areas to wet them out. While I waited for the epoxy to become tacky so that I could proceed with the thickened epoxy filler, I turned my attention to cutting out the fiberglass patches. You can see from the picture above all parts for the repair patch: plastic sheeting, release fabric, six 6oz fiberglass circular patches. Once I had the starboard patch ready to assemble, I mixed a pot of epoxy and added 404 high-density filler and applied to the actual through hull hole - spreading firmly into the hole and against the plastic covered cardboard backing plate. I also spread a thin layer across the outside surface of the repair area. The thickened epoxy provides a good bedding for the fiberglass patch, fills in the random low spots, and finally adds some additional strength to the repair. Once I had applied the epoxy thickened with the 404 high-density filler, I turned back to prepare the port patch, again cutting out the circular fiberglass patches. Once I had both patches ready to assembly, I cleaned up the job site a bit while I waited for the thickened epoxy to tack up. Once the thickened epoxy was ready to receive the patches, I began assembly of the starboard patch. I used a box for a work surface. First I taped a sheet of plastic down. The plastic would serve as a surface on which I could prepare the patch, and then pick up to apply to the hull. On top of the plastic I placed a piece of release fabric, and then my largest fiberglass circle - which I then wet out. I placed and wet out the fiberglass patches working progressively large to small, working the epoxy into the fiberglass cloth with a squeegee, and working to remove all trapped air. Once all circles had been wet out, the fiberglass patch was ready to place onto the hull. I then placed the entire assembly, centered, onto the repair area.

I worked the patch against the hull with the squeegee to remove trapped air and to generally smooth out the patch. I then pealed the plastic sheeting off, leaving the release fabric covering the patch to prevent contaminates from coming into contact with the patch as well as preventing amine blush from forming. I then applied the same technique to the port side, cleaned up, and called it a night. Final photo is of the applied port cockpit drain through hull patch. Next step is to fill and fair until smooth, and then drill out for proper seacock and through hull assembly.