How do I find information about a Chief Engineer

Can anyone please help me in regards to finding what ship my great grandfather was on. His name is Jahn Beathon (Beaton) and he was a Chief Engineer. His wife's name if Regine Arneson and they were residents of Eker Parish. Unfortunately I believe the records from Stavanger were destroyed by fire, which has made chasing this side of the family tree very difficult. I do have a Certificate for Innoculation for Cowpox for their son Karl Johan Beathon (Beaton) which I had translated from Norwegian and it was dated 7th July, 1880 . They immigrated to Scotland - not sure when. I would appreciate any help anyone can offer. Many Thanks [:)] Linda Gray