This 17 inch wide by 21 inch high piece of 1/2 plywood is the back support for the entire seat assembly. We are attaching the top of this behind the existing fiberglass at the rear of the drivers seat. To get the front of this ply flush with the fiberglass we removed 1/8 inch of wood from the ply. We will add a block onto the back of this so we can screw through the fiberglass and into the block to attach this to the boat.

The bottom edge of this is attached to a block that is screwed to the floor.