Tonight I finished installing the parts of the top of the cabin. I used up almost all the remainder of the 4x8 sheet. This finishes a step that was fraught with some difficulties. Recall that I glued the second piece in place and used drywall screws to hold it. Here the drywall screws turned out to be a bad move. I unscrewed the first one in the expected way. Then I got the vice grips to remove others. I was able to get about 6 screws out completely. I twisted the heads off of three others, leaving a piece of steel in the wood. Is this ok? I will have to use a soldering iron to heat up and soften the epoxy around the remaining screws and ease them out, then drill and install bronze screws.
With this lesson in mind, for the third and fourth pieces I fitted and screwed in place using the bronze screws. I got all the countersinks set right. At this point it was 2230 and was quitting time. Tonight I glued and screwed and clamped things in permanently. These screws are not coming out unless the boat burns or rots.