So here we have the 20 foot by 16 inch 3/4 inch plywood platform on the basement floor. It has been shimmed and leveled and some parts are held down with bricks. I have laid out the pattern using offsets from CAD and have screwed in pieces of angle aluminum at each bulkhead, which is every foot. The center 8 feet has a constant cross section and the tapered ends are 5 feet long and symetrical. The hulls are 10 inches deep and 10 inches wide with 4.5 inches of rocker at each end. The round hull will be made with 1/4 thick red cedar strips and the top will be flat for now. The sides ar 5 inches high and are marine plywood, as are the bulkheads and top. I was going to use a backbone but in the end decided not to. Still a little nervous about having a flat thin top that I might step on and through....but.....
The bulkheads, sides and tops were cut on a CNC router table by my pal Kevin at Atlantex Creative Works in Porter's Lake, NS. I supplied the CAD files and voila!!! Kevin has already been a big help on this project and many others. We ripped and planed the nailing strips while the CNC was cutting the plywood.

The V-goove in the bottom of the bulkhead is to allow water to run from one end to the other to make easier to drain in the highly unlikely event of water getting in!

The square cut outs are for the 1 inch by 1 inch nailing strip to attach the deck to the hull. I did end up cutting notches every three inches over the last 6 feet to make them easier to bend. The sides were cut from an 8 foot sheet so I hade to add a section in the center. I made the joints between bulkheads and used the  trimmed ends to form a lap joint instead of scarfing. I did scarf the nailing strips (badly, no pictures) and added a block to each end to allow an anchor point for lifting and for rudder attachment. I also added a double strip at the points where the cat frame will attach to the deck.

Clearly I should have put a little more thought into the joint between the nailing strips and the end block so I will have to make some adjustments. It was suggested that I screw the sides into the nailing strips when I glued them together but I was concerned that the nailing strip was so strong that it would dimple the plywood instead. As it turns out I should have been a bit more carefull about wedging the strip out, and I will have to check for gaps when I remove the hull and turn it over. It may be necessary to cut a bit and fill with thickened epoxy but most of it looks good. Since much of this will be very hard to get at when the cedar strips are in place I decided to seal as much as I could with epoxy at this stage. I used the bulkheads to hold the nailing strips and then used bricks to hold the nailing strips flat to the platform until the epoxy was dry.

At this point I did not have the cedar strips ready so I pulled the hull and hung it from the ceiling while I built up the second one to the same stage. I corrected a few of the mistakes and made a couple more but I now have two frames pretty much exactly the same.

I am going to use a slightly different method of stripping this boat and see how it works. I tried a demo with cutting each strip from full width at the 5 foot mark, down to a sharp point at the end. I am making a cap to cover the very end of the tip of the hull and provide a small landing strip for each strip. I will cut them off 2 or 3 inches from the end. The strips will alternate between 11 feet long and 7 feet long. I installed a doubling section on the 2 bulkheads 7 feet from each end. This will allow a better surface for the adhesive and make fitting the pointy ends of the strips much easier than cutting both ends of an 18 foot strip. The strips ended up being a bit wider than planned but we (the royal we with the help of Kevin!) only cut enough for one hull so I think it might be a good idea to make them a little narrower for the second hull. Either way, much of the strip will be sanded away and then some of the craks filled with thickened epoxy before adding one layer of glass to the hull at least. All this adds weight of course but I think I will need the extra protection  operating in the bay.

I have learned a tremendous amount from people posting on the Boat Design Forum and many of these ideas will find their way into the propulsion and steering systems etc.

I am currently drawing up the frame for the cat and trying to come up with a clever (quick and easy) way to attach the frame to the hulls. I have been designing outriggers for the single hull version of this too but my designs are all 4 feet long. This may be due to the gale force wind that came from behind and snapped the gold plated sheet of marine plywood on my roof in half and sent it flying over the hood of my car.  "Should have seen that coming...." ......I see more scarfing in my future.......

Progress is being made......