I've stated on this blog that I believe that Thomas Clapham invented the racing scow out of Roslyn, New York in 1890. Just recently I came across, courtesy of the Aussie Open Boat page on Facebook, a reprint of the Illustrated Sydney News drawing of the 1871 Sydney Anniversary Regatta. Much to my surprise, front and center in this drawing there is a cat-rigged craft with some features of a scow-ish type bow, some 20 years before Thomas Clapham's Bouncer scow. There is no evidence from the top-down view that this early Sydney sailing craft had a scow hull shape; it is just as likely that the hull had conventional sections and a keel, but this does show that unconventional "pumpkin seed" sailing craft were present at the very beginning of the small recreational sailboat.
John Watkins has written that there was an East River (New York City) sailing scow that was raced post Civil War but I have yet to come across visual evidence (prints, drawings) of that scow clas.
The Illustrated Sydney News print.
A zoomed-in image of this unique Sydney sailboat.