Young Jorgen Emil Leth from Arendal

I've been trying for some time now to discover the truth about my Great Grandfather George Leth. He claimed he was a cabin boy on a sailing ship around 1870 and told family he escaped in Australia aged 16. I'm trying to trace his life as a boy in Norway to discover if he was recruited to the navy at 16 as was normal and deserted in Australia or was he actually a cabin boy on a commercial vessel as he told my mother many years ago and jumped ship in Port Adelaide to find gold in new South Wales. His correct name is Jorgen Emil Leth, born 25th October 1854, ch; 3/12/1854 at Tromoy. His father was Samuel Nikolai Leth (died 28th April 1864). The only other record I have of him is the 1865 census for Ostre Moland, Aust Agder. http://digitalarkivet.uib.no/cgi-win/webcens.exe?slag=visbase&sidenr=10&filnamn=f60918&gardpostnr=30&sokefelt=skjul Is there a record of his recruitment somewhere or a ships crew list with his name?