I should add that I have concerns about the durability of the Titebond II if the lumber and join get wet. I think that will waken the bond - the glue is not for continuous submersion. So I applied 2-3 layers of floor-grade Minwax polyurethane that I had left over from doing our wood floors some years ago. That sealed the wood fine so the glue will not see water.

: I used exactly the same lumber from Home Depot for my first and
: only SOF so far. I had exactly the same concerns as you share
: and got similar answers. I made a but(t?) joining and compared
: to a scarf join of similar length. Waited for both to cure
: (using Titebond III) then set off to break the two. The
: butt-joined sections obviously had increased stiffness and when
: bent, the wood just outside of the butt piece broke due to the
: stress the edge of the butt piece put on the stringer. The
: scarf-joined pieces just bent as if there was no joining. I bent
: that scarf a lot and it did not break - I figured in my kayak it
: will never bend as much so I just used it.

: I did not want to have to make 2 scarfs per stringer just to avoid
: having a scarf near the cockpit - scarfing took some time and
: needed certain precision so I wanted to avoid that work if I
: could. So I finished the kayak with a single scarf on each of
: the 4 equally thick stringerrs - these scarfs fall in the front
: of my cockpit.

: I've tested the kayak (18 feet, almost all of it waterline) in some
: wind chop (up to 2 feet) and in white water with waves and
: currents (Class II) that does stress the frame some. No problems
: at all.

: The problem with that particular lumber is that the 1x2" is
: actually something lile 3/4x1-3/4" so the frame is rather
: skinny. I felt if I drilled holes for things like rigging or
: lashing it would weaken the frame a lot. So I did not drilling -
: all was lashed only (except the bow and stern boards, where I
: used glue and a couple of small dowels each).

: I also have an extra chine compared to the Yost single chine
: design. That and the center keel are made from the same scarfed
: 1"x2"x8', except each is cut in two along its lengh so
: it is half the width. I think the frame came out stiff enough
: and if I had used the thinner variety skin rather than the
: heaviest, the kayak would have been closer to 30lb than to the
: 40 it is now.