For a kayak from lauan ply to have a hope of structural integrity and a long
life, a full glass sheathing is needed. If quality plywood such as bs1088
okoume or even marine fir is used, taped seams are fine. For two sheets of 1/4"
ply, you'll save maybe $90 by using the lauan, but the added cost of glass and
epoxy for sheathing will eat up most of those savings.
When you consider also the greater weight of the sheathed lauan boat, the extra
time spent building it and its certainly lower resale value, the economy of
cheap plywood is no bargain.

Fat Bass wrote:

I saw luan at the home store, 1/4" thick, seems relatively flexible.. Anyone
use this for building a kayak?