South African Jack Koper designed three plywood scows, starting in the late 1950's with the junior scow, the 11'9" Dabchick, and then followed with the 15'6" Tempo scow and then with the 14' 6" Sonnet Scow (featured in the header photo). All three enjoyed great success in South Africa and the Tempo also achieved some numbers in Europe, notably Holland and Germany. The Tempo has faded from the scene but both the Dabchick and Sonnet still have good fleets in South Africa (500 built for the Sonnet). Those readers who guessed the photo might be the American Y-Flyer scow were close -from the photo they look similar - but off by 4 feet in length.
Bald but my eyebrows are growing at a prolific rate. Sailed Windmills and Y-Flyers in the 1960's. Founded Miami University (OH) sailing team. Sailed International 14's and Lasers in the 1970's. Sailed International Canoes in the 1980's to mid 1990's. Sailed Classic Moths since 2002. Enjoy boatbuilding though I'm very, very slow at it (the Internet doesn't help matters). Name in real life: Rod Mincher
After choosing this username (Tweezer is the name of my Classic Moth), further research on the Internet turned up that Tweezerman is a corporate name for a line of pedicure products. Let me emphasize that I do not work for, nor endorse these products.