Junk Rig Conversion - Part 2: Cabin Reinforcement Progress

22 01 2013 Posted by Daniel

This one is mostly pictures, so hang in there.

I’ve finished up the floors and prepped them for the mast step which will go on top. The batteries got relocated forward of the mast step area, and are firmly strapped in place, as well as being held securely by the sole support beams.

The next major project was to create a heavy ring frame across the underside of the deck, going from the port side of the hull all the way across to the starboard. The point of the frame is to stiffen the deck and cabin sides and to transfer the side loading of the mast to the hull and distribute it over as wide an area as possible.

To connect the frame with the deck itself required cutting away the headliner in order to prep the deck underside for a solid epoxy bond. Those fuzzies are from the chopped strand that was apparently used to help hold the headliner and the deck together when building the boat. I then had to grind away everything in this strip. I absolutely hate grinding fiberglass, and this time I got myself a Tyvek suit to help keep the itching to a minimum since all the dust was going to get blown into my face. Money absolutely well spent - it helped a LOT! Of course, my eyes were itching the worst even despite the protective gear I was wearing.

After the grinding, a much more fun job began. I used 1/4” luan as a template, tracing the outline of the deck and cabin sides and trimming with a jigsaw until it fit to my satisfaction. Once I had a solid template, I transferred it to 1/2” AC exterior plywood. I staggered the joints so they would not overlap and was able to keep each layer of the 3.35 meter (11 feet) frame to only 3 pieces of wood, with some even coming out as 2. It took exactly 2 sheets of plywood to make the frame plus two stiffening knees I added a bit more forward in the cabin trunk.

The first layer of four getting epoxied into place. I did the first layer by itself to serve as a guide and clamping layer for the next three, which went up nearly simultaneously. By putting each layer in place one at a time I was able to minimize the amount of voids between the deck and the layers of plywood, as well as mix smaller batches of epoxy rather than larger batches - this minimizes waste and prevents the epoxy from kicking too soon. I was using extremely thick epoxy and colloidal silica (cabosil, fumed silica, all the same thing), just shy of peanut butter consistency, for the bond to the deck underside and a thinner mix about like ketchup to laminate the plywood layers together.

The three layers clamping together.

After the entire frame was cured, I used a grinder with a 40-grit disc to smooth the edges of the layers to a generally pleasing curve, then took a router to the corners to help lay fiberglass cloth more easily over the whole frame. At this point, I did not have the fillets in place.

The two knees (one each port and starboard) were constructed as a complete laminate of 4 layers first, then the whole thing was bonded in place. While I didn’t have enough time to do the fillet on the ring frame along with the deck bond, I was able to do that with the knees, adding the fillet just after this photo was taken. That lets the layer of epoxy that is bonding the knee to the deck chemically interlink with the fillet, adding a smidge more strength to an already overbuilt joint.

Once I put the fillets on the ring frame, I applied two layers of heavy biaxial tape staggered across the fillet, then covered the entire rest of the frame in 10 ounce fiberglass cloth.

Overall, it took about 12 ounces of silica and 1.5 gallons of epoxy to complete the entire frame along with the knees.

Oh, and look what came in the mail the day after I finished this project section:

I haven’t chosen a name for it yet, though I have a few good ideas.

Stay tuned as next time we’re heading to the v-berth to repeat this entire process, floors and frame, in a slightly smaller and more awkward space!

__________ /) __________