I found a record that I believe is your Thure Andersson. It is on ancestry in the 1813-1963 New Orleans passenger list. It is really a manifest of aliens employed on the vessel as part of the crew. The arrival date was May 15 1920 from Angus Chile. Looks as if he boarded in San Francisco CA Jan 25 1920. Name of ship is Herakles, it is Norwegian. His age is 33 and is Swedish, occupation fireman, same as on the WWl card in Galveston. His address on that card was a rooming house, and there were no other Anderson/Anderssons there at that time.
I have kept in mind that he was a sailor, while searching. I also thought that maybe Arthur would be the Americanized name for Thure. Sure enough, there is an Arthur Anderson, b 1887 Sweden in the 1920 census for San Francisco Co CA. He is enumerated as a sailor of the deep seas, a roomer and is single. He immigrated in 1912 and is naturalized. The census date is Jan 9 1920, so it was taken before he shipped out on the Herakles. There are also a couple of other guys, John Carlson b Sweden 1885 and Frank Anderson b Norway 1888.
I have not been successful finding anything else on him. Would there perhaps be some sort of death notice between 1920 and his parents deaths in their local newspapers?
Rayedene Seal Graves