The rule
(http://www.uscanoe.com/2002canoespec.html) reads that width of the boat
has to be at least 14.375% of the length at the 4" waterline. That
works out to 32" wide for 18'6" (max length).

I also wondered why the shape is so weird. Sounds like a very
artificial
rule. I remember seeing other canoes without such pronounced wings,
probably
Olympic canoes. Darn things are so tippy, they capsize when empty...

Amazing that with shape so weird they are faster than kayaks and even
faster
than surf skis on long distance.

To save the weight no gelcoat is used, so cover is necessary to
prevent epoxy/carbon/Kevlar breakdown.

I will stick to my surf ski though, these canoes are no good in the
ocean
and outrigger does not suit my fancy ether.