If you do not yet have it, get a copy of Thomas Hill's book, "Ultralight Boatbuilding". Amazon has it on sale right now for under $14, and I think you would find it very worth while.

http://www.amazon.com/Ultralight-Boatbuilding-Thomas-Hill/dp/0071567038/ref=sr_1_1?ie=UTF8&s=books&qid=1301387084&sr=1-1

Hill does build on forms, and he does so because they define the size of the plywood strakes he cuts. It is simple to just set a piece in place and trace the edge, then cut it and it fits. The forms also serve as a guide for his router (or you could use a plane). He mounts the tool to a short, straight piece of wood, and it follows over the building form, using the form as a full length jig for perfectly beveling the glue joint between each plank or strake.

Using 1/8th inch plywood, his overlaps are 1/4" thick (the thickness of both layers of plywood), and about 3/4" wide, or maybe a bit wider. If you were to build a SOF design with 1/8th inch thick ribs placed continuously side by side, with no spacing between them, and then cover that with chines which were 1/4" x 3/4", running the full length of the boat, and about 4" apart, then you would get some idea of the design strength of this type of construction. It is strong with using fiberglass, although Hill does suggest using a football shaped piece of fiberglass as a grunge-absorbing skid plate on the bottom of the hull.

If you don't want a lapstrake look, then just cut the parts to butt against each other instead of overlap. here you can do a bevel edge, or you cna make a seam like S&G and fill the inside with a fillet of fiberglass to waterproof it and strengthen it.

I think you would work faster using forms instead of those flexible ribs. Cost is not an issue. Forms can be made from scrap cardboard, or cheap particle board. Anything which does not flex like a rib is going to do will help keep your design intact. Many designs only need three to five forms to define the basic shape. A cross seciton of the middle of the boat, and one near each end to increase the capacity of the boat. Bend your full length strips around these and secure them to the ends. You would have five points of solid contact for each strip. Put on a patch 3 strips wide along the keel. do the same along each gunwale. That is 9 strips you can put on the first day. and you can do more. Jump about inches from the gunwale and lay on 3 more strips in the middle of each sidewall. That is 15 strips the first day. Once you got a bunch of strips on the forms you could bend ribs into the developing shape and glue them to the strips. You can cut 2 1/4" to 3" strips of plywood and use those in these areas instead of cedar strips. These areas are fairly flat and the wide material goes on pretty well.

If you want to save time on fitting individual strips, lay out the rest of the strips on the bottom perfectly paralell with the three you put along the keel line. let the ends overhang. You may not need to do much planing ot get thses to fit tight, and you may be able to do 5 to 10 strips to each side at one time. Once the glue has set up, draw a curved line about an inch inside where the strips go araound the bilge, and cut along that line to remove all the overhanging ends of your bottom strips. Now you just need to trim and fit the strips which go around the bilge. Those take some time anyhow.

Just some ideas for you to consider playing with on your next boat.

Happy building

PGJ