Here you can see the double bead of 5200 laid down. I put it down before the thickened epoxy, which I also laid down in a double bead, because the working time of 5200 is much longer than even my slow hardener epoxy.
Eighty-some screws later, the sole was installed! There was enough squeeze out between the edge of the sole and the seat longitudinals and other vertical surfaces to fill this space in most cases, and there was plenty of squeeze out underneath. I cleaned the really big globs, but left most of it in place. When I do the seat tops, I think I will run one of my fillet sticks over the squeeze out instead.
Filled all the screw holes, and later scraped and sanded them. I have quite a few Car Talk podcasts on my phone, and I have found that listening to these make the tedious jobs of scraping and sanding go by, not faster, but at least with a fair number of chuckles.
I had been concerned about the time needed to mix and spread the thickened epoxy for the doubler, but I was able to do it in two big steps (on two separate days in fact), and so it was do-able. As a result, I was the sole sole installer.
You can see the thickened epoxy at right. I spread big globs of the stuff with a plastic trowel thingy, and then used a notched spreader to spread it around. Took about 45 minutes per doubler piece.
The stiffeners I added under the sole around the mid-sole hatch did the trick. That area doesn't flex, so I won't end up with leaks around that hatch - at least not due to flex.
The upper, seat extension part is from John Welsford's book, and is supposed to be more comfortable than a round over. The bottom part is the seat cleat. This will necessitate inserting the rowing seat from forward, and sliding it aft, but it will also keep the seat on board during a capsize.
A preliminary test (that is, a lie-down) shows that the extension really helps.
The round hole in the starboard longitudinal is for a Whale bilge pump - the seat extension has since been notched there to accommodate the pump trim piece. I didn't want to put the pump any closer to the sole, as it would restrict the down motion of the pump lever.