Straight-sided kayak

 I saw an advertisement in WoodenBoat magazine (page 71, Fall edition) with a picture of a kayak whose stems were flat sided with no visible curvature, yet it looked nice.  I thought to myself, 'I wonder how you would describe that mathematically', and then I started toying with numbers and approximate dimensions.  After all, with the launch of my recent canoe-type hull, I have no boat projects to fuss over.

Finally at a nearby lake.  A small canoe for two persons.  Performance was as expected: more stable than a kayak but less 'glide' between strokes.  

A nice size for two persons, but my wife had her own kayak today.

What are the advantages and liabilities of a hull shape with all shear curvature confined to the center section?  I can think of several possibilities, but the best way to find out is to build such a hull.  I have calculated all the numbers needed for such a design, my only remaining question is optimum hull length, re-spacing the frames (and recalculating the stems and keel).  Molds could be substituted instead of frames for a cleaner interior, but I hate to throw away carefully shaped molds, and frames add strength to the hull.

This sketch shows the deck outline for a hull 28 inches wide and 12 feet long (to the inside of the planking).  Shorter is lighter, easier to handle and store, longer would be prettier and more graceful on the water.  Something to think about.  We are planning a winter move to Florida; this would probably be a project to build while there.

If anyone is interested, I could publish the offsets, 'numbers', needed for the frames, keel, and stems.  Kayaks are not usually symmetrical; it is not difficult to re-space and extend one end as the bow.