The old 'sprit has a flat top, but the underside is odd. At the widest (18") part it is also flat on the bottom, but the front and rear both taper up and out. The planks were planed and milled slightly oversized to reflect those cuts. The sides will be cut out after everything is laminated. To prevent each board from getting "hangnails", we'll put a milled edge for protection.
We started work on the center plank, drilled pilot holes every 10" or so,rubbed the surfaces liberally with acetone, and coated with black Lifecaulk (Polysulfide).

Through trial and error we figured out that even this coating of Lifecaulk wasn't enough.