After the war, the shipyard shrank from around 700 to 100 employees. In 1918 the main plant in Aumund burned down and production was completely relocated to Vegesack by 1924. 1925 was a special year for Lürssen. They launched their 10,000th vessel, a 14-metre wooden motoryacht, a sister ship of the Onkel Fidi, and in addition, the company celebrated its 50th anniversary. Two years later they set another standard. With Oheka II, equipped with three Maybach engines that propelled her to a top speed of 34 knots, Lürssen builds the world's fastest commuter yacht. This boat was sold in the USA (Oheka was the abbreviation of its owner Otto Hermann Kahn, a banker of German origin); boats were initially developed in secret for use as torpedo speedboats. In 1929 the shipyard received the first official order from the Reichsmarine for a boat designated as UZ (S) 16 for testing purposes. It had a length of 28m, a displacement of 51.6 tons. It was not until 1932 that the camouflage designation was dropped and the boat was renamed S1. In the following years, with some changes, the model became the basic pattern for German speedboats. From 1929 the production of mine sweepers was started in cooperation with Abeking & Rasmussen. Later the same year, the company also built the world's longest and heaviest motoryacht: the 36-meter AAR IV weighed 130 metric tons.