Hi Terrance and Rick,
Thanks to both of you for your research. I have his marriage cert. where he is described as a mariner. He married 1861, just before the census, so maybe he was promoted just after his marriage.
I am under the impression that the naval college at Dartmouth wasn't there until around 1900. If so, it could not have had any bearing on his promotion. Although, I could be wrong!
He does sound an interesting chap. My mother often used to talk about her gr. grandfather, the master rigger!
Jill