If you own a power boat, sailboat or yacht, whether it is a new boat or a project boat, at some time in the future you may have to replace or install bulkheads. If you have an existing bulkhead that may be a victim of dry rot, you can use it as a pattern it will speed up the process. First you are going to have to remove anything in the boat that might hinder the removal of an old damaged bulkhead. Because every boat is different, you may have painted bulkheads with wood trim, or you may have complete paneling running across them. If the bulkhead had a wood laminate, you can’t remove the laminate, but you should be able to get a new bulkhead with laminate, or add laminate after. If you have the panels or trim, carefully remove all the wood with much care to preserve the wood. You may have to drill out plugs, remove screws or even have to find away to carefully remove glued paneling. Once you complete this process you are going to have to cut out the existing bulkhead. Most likely the bulkhead will have fiberglass attaching it to the hull or it might be screwed to the sole as well? Check with boatyards or other qualified sources if you are confused about how they are attached. Wear proper safety gear when cutting them out. A mask or respirator, goggles, gloves, etc.
When you cut the old one, be careful not to cut into the hull, but don’t cut so poorly that the bulkhead will be difficult to use as a pattern to cut the new ones. Also based on the size of the bulkhead you are replacing you may have to cut it again so you can actually get it out of the hatch. This also means when you do cut the new one to get it through your hatch will probably mean you will have to cut in half and assemble it in the boat. I usually cut the in half vertically and join them by either using biscuits or other joinery techniques like plywood splines. Cutting the old bulkhead out may require combination of tools. Some people like a grinder, I prefer Dremel cutting tools. Marine plywood is the best, but some people use CDX exterior grade. I only use Marine Plywood. It does cost the most.
When it comes to fiberglass there are multiple schools of thought on epoxy vs. polyester resin. I prefer epoxy. There are many books out on fiberglass work. Things you will need for fiberglass work. Gloves, throw a way paint brushes, paint tray, fiberglass spreader, rags, acetone, fiberglass mat roller, fiberglass mat 3 ounce, 3″-6″ fiberglass tape depending on your boat. The basic concept is you are going to first cut strips of your tape and mat so you can glue them to your bulkhead and boat hull. Clean your boat hull and plywood with acetone for a good bond. Mix your epoxy or polyester resin. I prefer using a paint tray. I brush glue on the fiberglass mat, set in place and use your mat roller. Run the mat all the way around the bulkhead, and then the tape using your spreader. Run a second layer, so you have mat, tape, mat and tape.
Finally seal the wood, with paint or a sealer, and replace trim or paneling. These are the basics.
