Below shows the starboard side 9mm ply web, with 25mm spacer then 30mm x 45mm upright. You can see on the upright to the right how they finish flush with the front surface of the solid hardwood base. As shown in an earlier post they fit into an angled cut out piece, that goes from full width at the top face of the hardwood to 5mm back from the forward face on the bottom hardwood face.
Below shows the starboard side again, with the forward doubler then solid frame and aft doubler which is epoxy glued to the laminated beam.
Below is completed from forward.
Completed from aft.