The Tongass!
Step 12) Installing the Bottom Panel Assembly
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After building the framing and prior to installing the bottom panel assembly, several intermediate steps must accomplished. First, I installed the stringers and finished them up. To do this, I installed them both and leveled them to each other at the transom, then leveled both of them in the fore/aft direction by adjusting the cradle at Station 6. Next came the fitting of the stem to the bottom panel assembly. The bow angle matched, but the top (as viewed) of the stem struck the bottom panel assembly and prevented a good fit. So, I used a belt sander to create the 1" flat on the front as Renn specified, then shaped the stem to match the bottom assembly. Next (as shown), I marked off a 1/8" inset on the fitted stem and again used the belt sander to take off a bit more wood so the bottom panel would be inset about 1/8". This will hopefully reduce the fairing required to match the 1/2" thick bottom panels to the 3/8" thick (upper) side panels. |
| The next step was to make a final fit between the stringers and the bottom assembly. With the bottom assembly resting on the stringers and fit to the stem, I slid them forward a bit less than an inch (as shown) until the tips contacted the bottom assembly. Note the gap, about 5/8" in my case, between the stringer's curves and the curve of the bottom. These gaps will close when the bottom panels are screwed and epoxied to the stringers. At this point, I used a felt marker and drew the outline of the stringers on the inside of the bottom panels. I then drilled centerline marker holes, from the inside, to facilitate marking a centerline for screwing on the outside. This worked quite well, including over the curved section. |
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With the stem fit and the stringers in their best position, it was time to cut the stringers to length. I used the transom to mark both the inside and outside of the stringers, removed them from the jig, and cut them to length along the line. Then I used the outer diameter of a roll of masking tape to mark off the limbers. Fortunately, my Bosch jig saw was up to the task of cutting these out. Rather than cutting a curve that went out the end of the stringers like Renn does, I used the line from the inner face of the transom as a guide and cut the limber piece out in one operation. As a result, I will not have to cut a plywood plug to fill the gap as Renn mentions. I then routered the curved edges with a 3/8" radius bit (not shown) and gave the whole thing a good sanding before final installation. I used my usual high strength epoxy/milled glass/silica mix to glue the stringers in place at the transom and replace the blocking between the stringers, double checking that the stringers were centered at Station 6. Note: Fortunately for me, if my bottom panel assembly is placed on the stringers so it nestles into the stem and is centered at the transom, then it is also already centered at Station 6 (within 1/16"), so Renn's centering step was unnecessary. Note also that I'll be installing a bulkhead at the front of the dry well, but it will only extend to the decks in the areas outside the stringers, so no limbers are needed at this point for me. If you are installing a bulkhead all the way to the bottom panels, you'll want to provide additional limbers at that point to allow water to drain to the keel line. |
| With the stem and stringers all fit and permanently installed, it is now time to glue and screw the bottom panel assembly to the boat. I didn't quite understand Renn's intent as to how thick the glue should be, so I made my usual epoxy/milled glass/silica mixture and applied it to the top of the transom, stringers, and stem as you'd expect (after liberally precoating of course.) The bottom installation takes long enough that I'd suggest mixing your glue mixture a bit on the softer/slurry side. Otherwise it may become too gooey to clean up well. As it were with mine, it had cured enough to be nearly too gooey for me to clean up. But with patience, where there's a will there's a way. After applying the glue mix to the transom and stringers, I put it on very thick (like nearly an inch thick) on the stem to ensure lots of squeeze-out. The stem does not perfectly match the fillet (etc) at the bow, so I wanted to guarantee that all gaps were filled appropriately. The stem glue mixture was mixed thicker to make sure it wouldn't droop or slide out. Screw it! Using the block-and-tackle assemblies that I hung the bottom with, I lowered the whole assembly to within an inch of the framing, centered the transom and installed one screw in the corner. Then I put one screw into the stem and lowered the whole assembly on the boat ...no glue smearing! 6" on center along the transom top (premarked with a black line), including a screw into each stringer. 8" on center along the stringers up to the scarf to 1/4" ply. Now for the deviation from Renn's instructions ...when I started screwing down the curved sections (a couple on each side at a time, going back and forth as I went), it became apparent that 8" centers would not pull the bottom panels to the stringers completely. At that point, I switched to screwing on 3" centers instead (as shown) and this worked well, although I did place 50# sandbags and put most of my 240# on the boat to push the panels into contact while I worked. Note: I'm shooting for a fastener-free boat, so all screws that I used were left over fencing screws that I had (square drive 1-1/2" screws). The screws laying on the boat were the ones I used, but I took them out after a couple of days of curing. I would not recommend dry wall screws since I'm afraid they'd break, especially along the curved section anyway. |
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The results ...here you can see the neatly cleaned up glue lines and how the stringers do actually fit well to the bottom panels without sacrificing fit at the stem. |
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© Copyright 2004 Brian Dixon
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