Perhaps he just vanished for some totally unexplained reason of his own, the girl I mentioned did leave a note saying she was leaving and did not want anyone to look for her - no ration book, no ID card which were essential at the time. Suicide? No body. On a brighter note I happen to know that Tyneside Archives which I think are in Newcastle have a lot of information on the sea-going world (have a friend in South Shields who does a lot of research in that area) it might be worth a visit and asking their advice, also I think if you google something like Master Mariners' Certificates yuo will find the records are deposited at the National Archives - saw something about it recently cannot remember exactly where. Good luck.