Stringers have to be placed into the precut holes on the bulkheads. Bulkheads mean the vertical (perpendicular to the backbone), stingers mean the longitudinal (parallel with the backbone) structure parts of the sailboat.
After all stringers have been glued into their appropriate position the next step will be gluing the sheer clamp cleats, sawing and beveling the sheer clamp and place and glue the U shaped doublers onto the bulkheads.
Sheer clamps shape trapezoid, made from high flexible straight veins pine without wooden knots Epoxy used for gluing the parts onto each other,