Brian Dixon's Tolman Jumbo Project

The Tongass!
Step 19) Glassing Interior Seams

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After getting somewhat burned out getting to the point where I could turn the boat over and with the '04 Christmas holidays looming, I decided to take some time off from building the boat. One day turns into another, then before I knew it 6 weeks had gone by. But, I'm finally back at it again. Just to get going again, the first thing I did was use a Japanese pull saw to trim the excess ply above the (sheer) shelving. I planed the ply flush with the shelves and moved on to glassing.

In this picture, you can see the pre-cut glass for the interior chine seams hanging over the gunnels. I needed to fill all the little holes from where I screwed on the outer layer of hull plywood on the bow and the splash rails, so I did that next. Finally, I also took this opportunity to smear silica-thickened epoxy inside the limbers at the transom to guarantee the endgrain in this are was sealed super well ...it's going to live in bilge water quite often. I went ahead and glassed in the stem also (in-progress in this picture.)

Renn called out a total of 16 ounces of glass on the interior chine seams, but I went with 22 ounces instead. Each interior seam was glassed with 4" wide 12-ounce biaxial followed by 6" wide woven E-glass, wet-on-wet so I wouldn't have to worry about fairing any biaxial later on ...the knitting tends to cure kind of rough and it makes it hard to put the second layer of glass on without fairing or filling. Putting the glass on wet-on-wet works better.

After glassing the interior chines, stem, transom seams, and the ends of the stringers where they meet the transom, it was time to glass in the stringers. Renn uses 6" wide Style 1708 fiberglass for this. Style 1708 fiberglass is 17 ounces of biaxial knitted together in 2 layers (like always for biaxial) plus 8 ounces of fiberglass mat on the back side. This type of glass is harder to wet out, so I built a 14" wide by 8' long shallow box for pre-wetting the glass and I worked with 5-1/2' sections of glass at a time. NOTE: Maybe I was feeling anal or something, but I apparently bought 12" wide Style 1708 rather than the specified 6" wide. I like how it reinforces a wider area on the stringers, but it's not necessary nor is it necessary to have it lap onto the hull so far. Maybe I made that decision before I decided to glass the stringers prior to installation? For example, you could leave the stringers unglassed, then use wide glass as shown here, then put a cap layer of glass over the top of the stringer later on.

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In this picture, you can see the glass on the inside of a stringer and the glass work on the chines and transom areas. Specialization is the key to efficiency, Henry Ford (the first.) The fillets on the stringers are fairly large and getting epoxy into the fiberglass is a little involved. In order to maintain some sense of efficiency, I did all my filleting first then went back and did all the glassing at once. I found that I could do about 15' per 2 hours in the shop. I used wood flour + silica as a thickener and a 2" diameter piece of PVC pipe to form the fillets. The glass had liberal amounts of epoxy rolled into the mat side first (in the pre-wetting box), then it was turned over and epoxy rolled into the biaxial yarn side. Then I rolled up the wetted-out glass, mat side out, carried it to the boat and unrolled it onto the stringer-hull joint. It helped a LOT to pre-mark where the edge of the glass should go so I could unroll it straight. The heavy wet glass tends to go anywhere but where you want it, but the marks keep you on track so you can correct as you go. After finishing the stringer glassing, the under-deck area is coated for the last time and then you start on the sheer deck and cuddy cabin components (see next steps.)

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Please E-Mail At: briandixon7@comcast.net