Grandfather

My grandfather came from Austmarka, Norway in 1888. He was fourteen years old and came with an uncle (Martin) who was two years older. I remember him telling me that they were in Liverpool for about three weeks before sailing. They arrived at their destination, Stoughton, Wisconsin on May 17th. Grandpa liked to tell unsuspecting people that they threw a big party the day they got there. Of course, we know it was Norwegian Independence Day. Grandpa's father was Johan Olsen Berg and his mother was Bertha Hagen. They were not married but both later married. Grandpa had three half sisters on his father's side and one sister or half sister and four half brothers on his mother's side. He went by the name Hagen in this country. Would that be the name he used when sailing? Thanks. Myrna Hoag