I found the original plans here. I tried to contact the site owner to see if he had ever seen one built, or knew where the plans came from, but so far have received no response.

So far I have spent far more hours than I would like on digitizing the old plans. I have never attempted a model with so many strange lofted curves, and Solidworks 2007's surface modelling is sketchy, if you'll excuse the pun. Rumour has it that the recent versions have some rather fancy tools for unfolding surfaces, but I don't have access to those.

In the end I decided to model the whole boat as a solid, and then use a multitude pf planes and carefully shaped surfaces to cut it into profiles.

The "sheet metal" tool was able to unbend one or two curved surfaces, but I anticipate skinning the whole boat with hand-cut 1mm ply, so I am not going to fight with it to do the trickier ones.

These surfaces are used as guides later on.

The multitude of planes are used to define where the various profiles will be. Since all the dimensions are dependent on these planes, I should be able to change the thickness of the stock without breaking the whole assembly. Then again, maybe not.

Each profile is a separate part, made by inserting the 3D solid into a new part and then cutting away the unwanted material, using the various planes and surfaces as guides.

I am currently beating my head against a wall, trying to model the "fuselage" as a detachable cover that fits into the available space while also being easy to fabricate and assemble.

You will see little holes at the intersection of almost all of the profiles, the idea is that they will be handy points to screw the plywood down when CNC cutting, as well as being used with zip-ties to hold the whole assembly together while glueing. It feels very clever right now, but only time will tell.