May she spawn many more overnight, while I'm asleep!
You can see in the above picture that I've changed over to running the masking tape along the join lines, rather than along the full length of every batten. For the most part I'm using 10" planks, with three screws through each batten. And I never did try to track down a better screw, so I'm still using the panhead screw + two washers combination that worked well for me on my floats. I'm getting a really tight "suck down" with the screws, and the foam is following the battens very nicely IMO.
As soon as I got the above plank in place, I realized that I'd forgotten to make provisions for the high-density strip that runs along the keel. It's only two inches wide (4" in the finished hull), and I'm going to use marine plywood for that part. I didn't want to make the join hanging in open space between battens, so I mounted an extra batten right beneath the keel batten and ran some tape the length of the battens:
At the "bottom" of each plank, I do a quick-and-dirty scribe so that the planks follow the rising edge transition:
Nothing precise here, I just use the jigsaw to cut to the line as best I can. Any gaps in the join will get filled in with putty\bog. Note that I'm running some masking tape along the batten that helps form that edge, since I expect a lot of putty squeeze-out in that area.
I finished five planks today, doing almost five feet of hull:
I'm somewhat conflicted regarding the heatbox versus the heat gun techniques. Frankly, as long as your screws have good holding power it doesn't seem necessary to have each plank perfectly thermo-formed to the battens (at least for the F22, other boats might be different). For example, here is my second plank ready to be screwed down, after a tiny bit of thermo-forming; obviously I didn't spend much time with the heat gun here:
I would agree that a perfectly thermo-formed plank will lay more nicely and makes the screw holding power less important. It also might put less stress on the final composite (and the half-laminated composite, before the hull halves are joined and the exterior laminated) -- but I don't know how important the latter point is, or if it matters at all. Anyone know?