Captain Hans Helmer Leth

My GGG Grandfather Hans Helmer Leth B 1785 was a ships captain and the son of Isaac Leth a shipping owner from Arendal Norway. Can anyone tell me where i could find a maritime history or log of the ships he captained. My grandfather George (Jorge) Emil Leth born 1854 in Tromoy Arendal (son of Samuel Nicolai a ships carpenter who died when George was 9) jumped his grandfathers ship as a cabin boy in Port Adelaide during the 1860s or 1870s when gold was discovered in Australia. I am trying to confirm this story and cant find the ships name. It was a large sailing ship which took part in the wheat race.