The "Oceaan VII" was built in the Netherlands in 1939 and had spent most of its life operating out of the Belgian port of Antwerp. During World War II it had been commandeered by the German occupation authorities. It was approximately 118 feet long and 160 tonnes in displacement. The vessel was refitted in the east coast port of Grimsby before being brought to Scarborough where it was renamed "Oceaan 7". The refit involved the addition of 20 tonnes of permanent ballast in the hull in order to give extra stability. The vessel was fitted with a 150 feet high radio mast and a 10 kW RCA BTA 10J1 transmitter. The vessel's main engine was a four-cylinder 240 hp diesel. Two newly installed 50 kva Dale Marine generators supplied all electricity needed for operational purposes.