Lürssen Oheka II 22.5m built 1927
22.5 m long,
Displacement 22.5 tons.
Speed of 34 knots
Pictureand information was taken from:
http://www.prinzeugen.com/DesignManufacture.htm
The attention of the German Navy was drawn to Oheka II , a highly innovative luxury motor yacht built in 1927 by the German boatyard Luerssen for a Jewish banking tycoon who emmigrated to the United States from Germany. The name "Oheka" originated from a monogram of its owner's name, Otto HErmann KAhn. It's round bottomed hull was 22.5 m long, and displaced 22.5 tons. It reached a top speed of 34 knots, making it the world's fastest boat in its class. There is no basis in fact for the common misconception that Oheka II was a "rum runner" used for smuggling.
In Oheka II, Luerrsen overcame many of the drawbacks of the round bottomed displacement hull. The boat ploughed through the water by the brute force of three 550hp Maybach engines. The composite use of wood planks over alloy frames reduced weight. The innefficient tendency for round hulls to "squat" stern-down in the water at high speeds was counterbalanced by a hull form that flattened towards the stern, providing hydrodynamic lift where it was needed.
Oheka II's combination of speed, strength and seaworthyness was exactly what Naval command wanted. In November 1929, Luerssen was given a contract to build a boat to the same basic design, but with two torpedo tubes on the forecastle, and a slightly improved top speed. It was to become S-1, the Kriegsmarine's first Schnellboot and the basis for the all other S-Boats built during World War 2.