
The design uses a wooden toggle to 'clamp' the floorboard in place making it secure and strong. I decided that the best approach would be to cut the floorboard so that the removable section would only span the area between two frames, directly above the location of the bilge pump strum box. Of course this could come back to bite me if the limber holes get clogged up over time and will require that I remove the section that is screwed down to clear those, but I think that could be limited to a yearly maintenance sort of thing.
I started by building an assembly that would screw to the frame and be held above the bottom of the bilge but would support the cut floorboard and serve as an alignment clamp for the toggle. I tapped a 1/4" hole in the center of the assembly to install a 3" bolt to serve as an axle for the toggle. For the toggle, I found a scrap of mahogany and shaped it down to a 'bean' shaped toggle about 1-7/8" long and 5/8" wide.

Moving on, I cut out a second 2" hole with the holesaw and rounded over both holes to smooth out the appearance with my router. The second hole will serve as a 'handle' to pull the floorboard, but I made it 2" so that I can fit an auxiliary pump into the hole if the other pump fails. Of course, there will be a bailing bucket on hand for 'special occasions' if/when the boat is swamped.
Finally, I notched out the forward end of the floorboard where it butts up against the daggerboard trunk and installed another mahogany cleat to the trunk to align the floorboard once it is in place and keep it from sliding. On the underside of the floorboard, I installed a few pieces of mahogany to 'grab' the floor timber and keep the forward end from lifting. This whole contraption is much harder to describe than it is to post a picture, so here are a few pictures once it was installed: