Okay, some detail on Southern Empress and Clausen, found on the Crew List index online.

SE was built at Sunderland in 1914 but from 1928 she was registered at Stanley in the Falklands. She was previously called the San Jeronimo and as Phil says torpedoed in 1942. Was Clausen still in the crew perhaps?

On Crew Lists there is an F Clausen from Germany listed who sailed aboard British vessels. He was 27 in 1913 so perhaps born about 1885. In 1912 he was an AB on the 'Wimbourne' of London and in 1913 on the London registered 'Aros Castle'. There is another earlier F Clausen in the lists but the former looks likely to be our man. He would have been about 50 when sailing with Bert. The 1930s census forms are not yet available to us so I can't use these and if he was not in Hull in 1931 or 1941 they wouldn't be much help anyway.