Images below show work in progress for a skin on frame kayak.
This kayak replicates
Aleut single MAE-AC
found in 1845 and discussed in David Zimmerly's book
QAYAQ: Kayaks of Alaska and Siberia
At 18 feet long and only 17 inches wide, it is intended to be very fast for those who
can keep it dry-side up.

The Aleut kayaks were designed to flex as they moved through the water.
The splice shown in the upper left image allows the bow and stern to flex down,
while the shoulder of the splice prevents the bow and stern from flexing up.
Placing these splices in the keel helped prevent damage in rough seas.