Captain Andreas Ellingsen Gjaesdal

My gg-grandfather, Andreas Ellingsen Gjaesdal, left Stavanger, Norway, with his wife, Johanne Gurine Roaldsdatter, and children, Erling, Martha Lovise, Henrik, Reinhard Christophersen (stepson), and Severin Christophersen (stepson) in 1879. We do not know which ship and we don't know where they landed. We do know that in 1881 they were in Chicago. Can anyone help with names of ships leaving Stavanger in 1879 and maybe even the name of their captains? Thank you!