More (and better) info on Ivan Petkov and his S Ski here:
https://www.skiinghistory.org/history/evolution-ski-shape
Excerpt:
Ivan Petkov retired from the Bulgarian ski team in 1976 and took up windsurfing. He designed and built a line of “Bora” sailboards and won the Bulgarian national championships three times between 1977 and 1980. He came to the US in 1987, to spend the summer in Hood River and the winter teaching skiing in Aspen. By 1989 he was managing a retail operation for Robbie Naish on Oahu, and while watching the craftsmen there carve custom sailboards, got the idea for a new carving ski. In the spring of 1992 he went back to the resort town of Pamporovo, in the Rhodope mountains of southern Bulgaria. There, Atomic had set up a factory to make some of their inexpensive constructions.
“I had them make a mold for a 187cm ski with a profile of 113-61-91,” Petkov says. “We couldn’t find a wide-enough base material, but they also made water skis there so we got some greenish-blue polyethylene and cut the base out of that. I took three or four pairs in different flexes and went to Mt. Hood. We were amazed at how well they held.”
Petkov called his new product the S-Ski, for its turn shape. He applied for a patent on the geometry. He ordered more skis in 183 and 193cm lengths, and went to the SIA Trade Show in the spring of ’93. “Everyone came to the booth,” Petkov remembers. “Warren Witherell (author of How the Racers Ski) was very excited.” He shipped 300 pairs. The 183cm sample in the Colorado Ski Museum measures 115-61-85, for a 19.5 sidecut depth and a 15 meter radius.
For 1994, there were shorter lengths, 163 and 178cm, and Petkov sold 1200 pairs. S-Ski was on a roll, but Petkov was unhappy with Pamporovo’s quality, and opened negotiations with Blizzard to build his ski.
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Many factories went bankrupt trying to keep pace with Salomon (which introduced its ski in '90). Among them was Blizzard, which slid into the control of the banks during ’94 and ‘95. But the factory already had Petkov’s S-Ski mold, and began producing its own cap-ski version that spring. Meanwhile Pamporovo made versions of the original S-Ski for other brands.
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That winter (1996, when Rossignol and Salomon introduced their own shaped skis), Petkov realized he’d been undercut by Blizzard and Pamporovo: both factories planned to compete with him using his own mold. He turned to K2, which offered to build skis in his dimensions. The Vashon Island factory backed out of the deal when Petkov threatened to enforce his patent against any and all factories, including his own supplier. With no one to build his product, Petkov’s S-Ski slid from sight.
