After "all that sanding" of the O.I, I decided to also re-varnish the Cape. This involved the usual routines of a full day of cleaning the basement, horsing the boats in and out of the basement, powerwashing, etc.
I used the previous technique of masking the sheerline with the "fancy green tape" and doing the three hull coats first. I used Epiphanes vanish, and "standard" paint thinner. Either I didn't press the tape down firmly enough, or the thinner attacked the tape, because the tape crinkled at the masking line. I'll have to let it harden enough to sand.
Other discoveries: the "standard" paint thinner doesn't smell, but it takes much longer to dry. Also, you can varnish in more humid conditions-it just takes longer to dry.
Upon flipping the boats over, I discovered that not only did the tape "crinkle", it leaked wholesale to the deck! 😞 I think it was the thinner-I am advised not to use "random" thinners, and to try 3M Fine Line tape. Its mainly a do-over at this point.