A little progress; I'm not setting any speed records here.....but still moving forward.
Stringers are bedded in PB, and tabbed with two layers of 1708, first one 3" up the stringer and 3" out on the hull; second layer 4" up the stringer and 6" out on the hull. Tops are capped with CSM.
I used a butt joint with sister boards to join to the existing stringers. I read that 36" sister boards were good, so I made mine 50".
Actually, my port stringer needed to be 10' long, so I would have needed two butt joint that would have been 4" apart, it seemed logical to make the sisters one piece.
Close up of port stringer splice. Sisters were PL'd, screwed and clamped to the new stringer(3/4 marine ply) outside the boat,I let them cure for 3-4 days, then PB'd, screwed and clamped them to the existing stringer. I was surprised by how strong the bond is. With the 10' stringer only attached to the existing stringer at the glue joint(before bedding), I pulled up on the rear of the stringer; I'm sure I could have splintered the 1x6 pine stringer without damaging the butt joint. Sister boards are 3/8" exterior ply.
Starboard stringer repair : Tabbing under the seat base was a pain, but still easier than cutting it out and reinstalling it. Sisters are about 36" long.