The following text and images were kindly
supplied by Tony Bigras. Visit his site for details of his other sailing designs.
I remember my excitement when I first found 'The 40 Knot Sailboat' in our public library
when I was in high school. I had been messing about with dingies and a catamaran for a few
years and like the absence of heel and the speed potential and simplicity of the
aerohydrofoil. I was thinking about building a boat to take me to the South Pacific and
seriously worked on this design from that perspective. These models were
built in the period 1973-76 or thereabouts.
The first model used ureathane foam with foils of 12:1 chord with a conventional mainsail. It had balance problems as well as some structural problems with the foam foils.
The second was a modification of the original with ureathane foam foils covered with paper and sealed. As well, the rig was a boomed out jib with the ability to set the tack of the sail well to windward. This model performed very well. The photo below is one of my favourite photos of my boats.
Both models one and two were about 24 inches long with 6 inch wide and 9 inch long primary foils and a similar windward foil with the bottom half being reversed 90 degrees to provide dynamic displacement.
The third model was a bit truer to Smith's concept with high bouyancy foils and a modification that used the AYRS eliptical square sail. This was a large model about 6 feet long and 8 feet high. It was not at all successful. I attribute that to the very poor performance of the thick foils (4:1 at the top) and to the uncontrollability of the sail.
I did do some additional design work on a small cruiser version of the #2 model. It would have been about a 48' vessel with around 1000 lbs of carrying capacity. I don't remember the exact numbers and do not have paperwork on the design anymore. One major consideration for the design was the draft required, probably 9 to 10 feet which would have been a problem for the intended cruise.