: Could it be so that when you saw out the recess you have a little
: room for the blade to not hit the form???

Could be the cut out provides an inset to lay two longitudinal strips to support the cockpit deck as it drops below the line of the cut out.
This allows one to continue the plane of the deck when it drops below the cutout line, creating a recess towards the stern of the cockpit.
I'm not familiar with the Guillemot. In the Petrel, Nick prefabricates the recessed deck of plywood and veneer (for the recess), then glues it in as one piece, but erhapes this was how he achieved the recess in the Guillemot?