The late Platt Montfort was into ultralight aircraft and his Airolite designs borrowed technology from them. You gotta' admit falling out of the sky is a little more distasteful than getting the seat of your pants wet. Also, Montfort was a retailer of boatplans so he had to be a bit more conservative to avoid getting his pants sued off. In any event his engineering seems to have stood the test of time
The Airolites used KEVLAR the way the Wright brothers used wire to trusswork their Flyers. KEVLAR is about the strongest readily available cordage. It's 10 times stronger than an equal weight of steel. The form of the cordage is roving. I gather you need an electron microscope to measure any stretch. It's applied diagonally to prohibit racking.
Builders can do anything they like as long as it only endangers themselves. But claims to have broken the mold because you haven't had to swim for it yet lacks a certain scientific rigor.

: If it makes you feel any better my 11' canoe has the ribs spaced on
: 10 inch centres in the middle and 21 inch centres at the ends.
: It hasn't broken yet.
: http://dbynoe.blogspot.ca/search/label/Canoe

: If you want to get really nervous, have a look at wooden aircraft,
: specifically the scantlings on the wings. When I noticed that
: the landing gear struts were only about an inch and half by
: three quarter ash I got a lot more confident about paring down
: the structure.

: Admittedly this boat was a little extreme but it had to be to get
: the weight down enough. Even with that, I paddle it regularly
: and haven't noticed any hogging or deformation in the structure
: that would give me pause. I have also never noticed much
: flexing, even in steep white caps big enough to break over the
: bow. The structure gains its rigidity from the multitude of
: spaced out beams, tied together with the ribs and thwarts. It
: turns the whole thing into a truss. I can't understand what the
: kevlar would add that the ribs and skin aren't already doing.

: As for the skining my technique was to start by pulling it tight
: side to side and clamp it to the gunwales, with the clamps on
: pull the ends lengthwise and sew the ends together as tight as
: you can to the stems. Then pull the skin tight over the
: breasthook on top, put the needle in about a half inch to an
: inch wider than where it is touching and reef on it. Idea was to
: pull the skin on top just like a kayak. You will have about 4
: inches of sewn together skin on top but I personally like the
: look. Hope that makes some sort of sense.