Hello, I hope someone can help!

I'm told that the attached photo, taken in the 1860s, is of my great grandfather William Ritchie, who was a marine engineer. (And his son, and his grandson ...) He lived in Runcorn, Cheshire, and when he died in 1885 (he was found drowned off Crosby) he was chief engineer of the screw tug Liberator, but I don't know what he did before that. It's not a very good photo, but his cap badge does seem to have an anchor. Can anyone tell me any more about it please?

Fran