Iver Gjertin Iverson, crewman on Borrassa

I am interested in finding records of my great-uncle Iver G. Iverson, in his youth a sailor on Norwegian merchant ships. His USA naturalization document says he arrived in the USA in May 1900 at Mobile, Alabama as a crewman on the "Borrass, Norwegian fruit steamer". I found records of a Norwegian ship called Borrassa. Iver was born Iver Gjertin Iverson in August 1879...illegitimate. When he was a child his mother married and, for a time, he was called Iver G. Olsen, after his stepfather. I have found quite a bit about Iver's childhood in western Norway and his life in the USA. Am particularly interested in any records from the merchant marine...crew lists, etc. Growing up in Seattle, I met Iver. He was not a talker, no sea stories. Ron Iverson