In late November 1922, after having been laid up for two years, Laënnec was sold to a German shipping company H. H. Schmidt & Co. from Hamburg.
After refitting she was renamed Oldenburg after the city of Oldenburg and, through an agreement with the German school ship association Deutscher Schulschiffverein, she became a school ship for the German merchant navy.
Among the men who received their training onboard Oldenburg over the years was the German U-boat ace Günther Prien.

In 1925, while rounding Kap Horn, Oldenburg lost her main mast in a storm and had to seek shelter due to damaged rigging.
After emergency repairs in Montevideo, Uruguay, she crossed the Atlantic and headed back to Hamburg.
However, due to strong easterly winds she was forced to pass the British Isles on the northern side instead of the English Channel.
78 days after leaving the Río de la Plata estuary, Oldenburg was taken into tow by a German tugboat and towed to Hamburg.

In 1928 Oldenburg was sold to another German shipping company, Seefart Segelschiffs-Reederei GmbH from Bremen.
In 1930, on her last voyage under the German flag, Oldenburg was almost lost when the cargo of phosphate shifted in heavy weather.
After two weeks in a heavy storm, the longitudinal bulkhead gave way and the ship assumed a list of 55 degrees.
Lifeboats, spare yards and the kitchen stove were lost overboard.
However, the crew managed to righten the ship and sail her to Malmö, Sweden.
After unloading the ship was moved to Bremerhaven to be laid up.
In late November 1922, after having been laid up for two years, Laënnec was sold to a German shipping company H. H. Schmidt & Co. from Hamburg. After refitting she was renamed Oldenburg after the city of Oldenburg and, through an agreement with the German school ship association Deutscher Schulschiffverein, she became a school ship for the German merchant navy. Among the men who received their training onboard Oldenburg over the years was the German U-boat ace Günther Prien.
In 1925, while rounding Kap Horn, Oldenburg lost her main mast in a storm and had to seek shelter due to damaged rigging. After emergency repairs in Montevideo, Uruguay, she crossed the Atlantic and headed back to Hamburg. However, due to strong easterly winds she was forced to pass the British Isles on the northern side instead of the English Channel. 78 days after leaving the Río de la Plata estuary, Oldenburg was taken into tow by a German tugboat and towed to Hamburg.
In 1928 Oldenburg was sold to another German shipping company, Seefart Segelschiffs-Reederei GmbH from Bremen. In 1930, on her last voyage under the German flag, Oldenburg was almost lost when the cargo of phosphate shifted in heavy weather. After two weeks in a heavy storm, the longitudinal bulkhead gave way and the ship assumed a list of 55 degrees. Lifeboats, spare yards and the kitchen stove were lost overboard. However, the crew managed to righten the ship and sail her to Malmö, Sweden. After unloading the ship was moved to Bremerhaven to be laid up.
Suomen Joutsen