Corstiaen Eldertszoon (more name information)

The captain of the Rotterdam hired ship Roscam is usually called Corstiaen Eldertszoon. I found a little bit of information while searching online: "kapitein Cristiaen Eldersz Groendal" of the ship "de Vergulde Roscam". Corstiaen and Christiaen seem interchangable. This makes it appear that Groendal is the captain's real last name, while he is just the "son of Elder".