Hydroplane is successfully tested on Lake Washington on October 1, 1949.

  • By David Wilma
  • Posted 1/01/2000
  • HistoryLink.org Essay 2106

On October 1, 1949, the hydroplane, a racing boat that used aerodynamic principles to ride above the water instead of through it, is successfully tested for the first time on Lake Washington. The hydroplane's team is Ted Jones, a Boeing engineer; Anchor Jensen, a boat builder; and auto dealer Stan Sayres (1896-1956).

Jones, an amateur boat builder, began experimenting with hull designs in the 1920s because he lacked the money for larger engines to make his boats go faster. By 1934, he had developed a three-point hydroplane and although it was "just fast as hell" (Woog), it was unstable. In the late 1940s, Jones partnered with auto dealer and racing-boat driver Stan Sayres to build a racing boat and Sayres recruited Lake Union boat builder Anchor Jensen (1918-2000) to the effort. They first built Slo-Mo-Shun III and then the more successful Slo-Mo-Shun IV.

While Slo-Mo-Shun IV was being tested from 1948 to 1950, it was nicknamed "The Hunts Point Ferry" because it was seen crossing Lake Washington repeatedly. In 1950, the boat set a world speed record of more than 165 miles per hour at the Gold Cup Races in Detroit.

Slo-Mo-Shun IV maintained its winning streak through 1954 when it brought hydroplane racing to Seattle. According to Seattle hydroplane fanatic Paul Lowney, Slo-mo IV "made Seattle hydroplane-conscious and turned half the population of the city into unlimited hydroplane enthusiasts and fanatics." The Gold Cup race became the centerpiece of Seattle's annual Seafair celebration.

As of 2000, Slo-Mo-Shun IV  was owned by Seattle's Museum of History and Industry.


Adam Woog, Sexless Oysters and Self-Tipping Hats: 100 Years of Inventions in the Pacific Northwest (Seattle: Sasquatch Books, 1991), 26-30; Paul B. Lowney, This is Hydroplaning (Seattle: Paul B. Lowney, 1959).

Licensing: This essay is licensed under a Creative Commons license that encourages reproduction with attribution. Credit should be given to both HistoryLink.org and to the author, and sources must be included with any reproduction. Click the icon for more info. Please note that this Creative Commons license applies to text only, and not to images. For more information regarding individual photos or images, please contact the source noted in the image credit.
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License
Major Support for HistoryLink.org Provided By: The State of Washington | Patsy Bullitt Collins | Paul G. Allen Family Foundation | Museum Of History & Industry | 4Culture (King County Lodging Tax Revenue) | City of Seattle | City of Bellevue | City of Tacoma | King County | The Peach Foundation | Microsoft Corporation, Other Public and Private Sponsors and Visitors Like You