Using the existing 2', 4', 6', and 13' cross sections would probably work without any changes, but I'd opt for cross sections at ~9' and ~11'. The "9'" cross section would support the back of the coaming, and "11'" would just be half way between 9 and 13... No need for a rib in the middle of the cockpit. You won't need the cross section at 1', that end of the keel and chines will tie into the front stem peice. You could probably get away with leaving 13 out, but it would help keep the chine in place since its placement is extreme.

Keep in mind the extra chine on the bottom of the gunwale - following the lines shown in the drawing will twist the gunwales away from where they should be.

I'm also very tempted to try building the F1 in the "yost" style. If it lives up to half the hype, it should be a great kayak.

: Right. The problem is that that would mean steam bending 28 pieces of bamboo.
: If I can think of a way to build this kayak Yost style, I'll go for it.

: Looking at the diagram, it appears as though Yost cross sections at
: 1,2,4,6,10,12,13 with a rib at 8 would build the shape accurately. Any
: thoughts would be appreciated.

: Going after this as a first SOF (and first kayak since the Night Heron is
: stalled) is a really, really bad idea. I can't resist though. Any help
: planning this would be really appreciated. It looks like all the necessary
: information is on the F1 and F1 Technical page.