1882 departure Stavanger

Need help in finding the ship/passenger list in which my great, great grandparents emigrated from Stavanger. Halvor Halvorsen born 1840 Abigael Andersdtr born: 1842 they were living on farm Vestbø in Finnøy, Rogaland at time of departure. They left Norway with seven children (I know who the children are)....they show up on digitalarkivet emigration database, but it is probably a reconstructed entry due to records (most anyway) being destroyed for Stavanger...can find no refrence to ship they sailed on, where they went to, or where they landed on this side of atlantic. I assume they maybe went to England or somewhere and boarded a larger vessel for the atlantic crossing, but have had no luck at all in finding the family on a ship. Later census records and the information available from Norway, do indicate the year 1882. Any assistance is greatly appreciated. Stacey