Next I started working on the floorboards. While looking around for something to trace as a template for rounded ends, I saw the cardboard pattern I'd used for cross-section 3 - it worked out perfectly.
I used extra rib stock to glue the floorboards together as shown. The cross ribs were spaced to fall between the existing ribs on the frame. The floorboards themselves are made from pre-cut baseboard trim from the local lumber yard.
Here's a top view of the completed floorboard assembly with the rib ends trimmed. (Looks like the start of a toboggan!)
The completed frame, with floorboard assembly resting in place, is ready for varnishing.
Here is the frame after several coats of varnish - floorboard assembly and rub rails are still unattached.
The varnish really brought out the grain and color.
The floorboard assembly rests directly on the ribs and stringers and was lashed into place.
Here's a view of the lashing from the underside.
The finished frame awaits the next task, the addition of Kevlar roving.