Alter died Saturday at his Palm Desert home, according to a statement on the Hobie sporting goods website. A cause of death was not disclosed. The Orange County Register said he had been battling cancer.
"He wanted to make a living without having to wear hard-soled shoes or work east of California's Pacific Coast Highway," the statement said. "By 'making people a toy and giving them a game to play with it' he was able to realize this dream. And in the process, he introduced the world to an outdoor lifestyle and collection of products that made things just a bit more fun for all of us."
The self-taught innovator and surfer had his start in the early 1950s carving wooden surfboards in the garage of his family's Laguna Beach home.
When the balsa wood used for the boards became scarce, he and his friend Gordon "Grubby" Clark created surfboards out of polyurethane foam. The boards were durable, but had better flexibility and were less expensive than wooden boards. The invention revolutionized surfing, and Hobie became a top surfboard brand.
Clark went on to launch Clark Foam, which had a virtual monopoly on the unshaped foam blocks that were used for custom-made boards.
In the late 60s, Alter turned his focus to sailing and designed a lightweight sailboat inspired by the twin-hulled Polynesian catamaran. The more affordable Hobie Cat, which could be launched from the beach, is credited with bringing high-performance sailing to the masses. For his contribution to the sport, Alter was inducted into the National Sailing Hall of Fame in 2011.
He was survived by his wife, Susan, a daughter and two sons.