I would make a set of cardboard forms. Run temporary stringers over the forms and make the ribs by wrapping around the stringers, then lay the final stringers over top of the ribs. You can then cut the internal stringers to get them out. This method would let you place as many ribs as you choose, where ever you choose.

You could start with the outer stringers and make the ribs on the inside, but this would be more awkward.

Platt sometimes increases the spacing of the ribs towards the ends. More ribs in the middle, fewer towards the ends. Since the ends don't support as much weight they don't need as many ribs.

How many is sufficient and how big they should be depends on how you define sufficient. If you are looking for a pond boat to lily-dip around sheltered areas, fewer, smaller ribs are required. If you want to go surfing, more, bigger ones would be called for. Do you want the boat to never fail, or are you trying for the lightest possible and eventual failure is not a big deal?

A continuous ring is pretty strong. Fewer ribs would be required than for an open boat of similar dimensions. A kayak would tend to be much narrower than the boats Platt is building this also reduces the strength required although making the boat longer requires more strength. The longitudinal strength of the boat depends on the ribs ability to withstand compression.

I have thought of making a kayak this way since I first saw geodesic boats over 10 years ago. I still think you could make a really slick kayak this way. BTW don't think about it too much. Just build it. You will have a finished boat in the time you would have been thinking and then you can actually look at a finished example to determine what to do different next time.

: Ah geez, Rehd was right! This has given me some more to think about. I like
: the idea, but my steaming success so far has been limited. Laminations
: would work. This would also halve the number of ribs I was planning on,
: i.e. I was going to rib at each form and in between. Was I aiming for over
: kill? Will your idea be sufficient? Is there a good way to interpolwhatate new
: forms in between the existing ones? The number of ribs in my plan was
: similar to what Monfort uses on a same size canoe. The final beam would be
: larger than designed too, unless I recut the forms to account for that
: (rib and stringer depth). Me-Oh-My ... guess I'll hold off on applying the
: keelson tonite, until I think this through. Thanks much for the thoughts.

: Bill