Shortly before Ben Lexcen’s Australia II shook up the New York Yacht Club and the world by walking off with the America’s Cup, some other upstart Aussies were making themselves known Down Under.

Richard Ward and his mates were into multihulls. Like a fellow aficionado named Hobie, they thought everyone should have one. By 1982, “Maricats”—built in Wollongong (the Sydney suburb where Seawind is located today) and sailed off the beach—were going 3,000 strong around Sydney. Then came the Seawind 24. One of the success stories of the 1980s, this mini-cruiser sold more than 350 boats. …