1952 APBA Gold Cup
Lake Washington, Seattle WA, August 9, 1952
Slo-Mo-Shun IV, Speed 118.491 MPH
Major speed boat records were set by Slo-Mo-Shun IV in 1950 when the 28-foot hydroplane took the Gold Cup award. In 1952, she set the world water-speed record of 178.497 miles an hour on Lake Washington. Her latest achievement, winning the 1952 Gold Cup race, makes her the boat of the year.
Slo-Mo-Shun V took the Gold Cup award in 1951, proving she can carry on the championship line begun by her sister boat. Both boats were designed by Ted Jones, and are owned by Stanley Sayres.
Sayres and Jones have been working together on racing boats for nearly ten years. A primary difference between "IV" and "V" is a special secret hull design of Slo-Mo-Shun V that allows her to make sharper turns at higher speeds.
As various methods were developed to increase the speed of boats, Sayres and Jones nearly always found unexpected complications that accompanied the higher speeds.
To meet these complications, many newer materials were used. The problem of shearing propeller shafts, for in-stance, was met by the use of a high strength corrosion-resistant Monel shaft, without which Sayres says he would not start a race.
The problem of a bending rudder was met in three ways. First the rudder was offset by seven inches to starboard to place it out of the propeller blast. The rudder itself was cut from cold rolled steel, and the rudder shaft and posts were replaced with those made of Monel. Strength of the posts became more and more important as speeds increased, to withstand the strain of fast turns. The strut was replaced with one of fabricated steel, and the fins were remade of a heat-treated aluminum alloy.
Terrific vibration encountered at high speeds indicated the use of Monel corrosion-resistant nails for attaching the skins on Slo-Mo-Shun IV. These nails derive a holding power greater than screws of equal size by virtue of annular grooves which depress the wood fibers and form dozens of small wedges which firmly grip the fastenings. They proved so successful that on the "V" they were used to fasten the hull as well as the skins.
Slo-Mo-Shun IV is powered by a 2000 horsepower Allison engine using special aviation gasoline.
(Reprinted from Motor Boating, September 1952)
Hydroplane
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