Thanks for this guys.
Jim, right now I can only aspire to the level of precision and, well, beauty of the boats you produce. I am working on it but still have quite a ways to go. I find it interesting that the capped approach you use will get virtually identical results as a one-piece design, but looks like it can be done with much beefier gunnels than what I find manageable to install in a single piece. I will definitely remember this for my upcoming "spring" build. And I really like those "arrowhead" decks that wrap around the inwale ends. Do you glue the remaining outer gunnel ends as well, or use screws at that point to go through to the edges of the decks?
I am committed to the two remaining one-piece gunnels I have left for this build (I basically chewed through almost all my ash, including having one gunnel split on me under some light persuasion from a rubber mallet at the point of install, and one ruined when I stupidly forgot to lock the table saw fence for my last cut of the slot). On top of 3 or 4 failed or unsatisfactory attempts to make one-piece gunnels from cedar, I don't have any stock (or patience) left to try another.
Because of that, the point that Stripperguy made about the deflection of the gunnel side pieces, possibly to the point of cracking, when screwing them on has put the fear of God in me. I did not think of that but it is for sure a risk. I cut the slots wide enough to fit over the sheer lines without too much drama, and in dry fitting them I can get everything lined up and flush with the sheer line with duct tape alone (very gradual rise from centre to bow/stern in this boat). But this means there are definitely some side to side gaps at various points, such that they can wobble just a little them side to side once dryfitted. A quick measurement shows the gaps to be a little over 1/16 at the widest points, which the ash probably can handle in deflection, but even if it does its an additional source of constant tension once installed that might make them more vulnerable to splitting when they inevitable get whacked by something. So I am scrapping the screws and going back to gluing them on with thickened epoxy.
So on this, what exactly is Cabosil? I have seen it referenced a bunch of times in this forum but don't know anything about it. I was planning to just use wood flour to thicken the epoxy - I am using West System, and I know they have a bunch of fillet and bonding thickeners that if advisable I can get if I need something more or less equivalent to Cabosil. Also, how thick should the epoxy be - ketchup, mayo, or peanut butter?
Thanks again for all this input and help from everyone. Very much appreciated.