Capt. Nathaniel Tatum, The Immigrant - Capt. ?

I was reading Nathaniel's story of being an orphan in London, England and being deported to Virginia when he was 14 years old. I haven't found anything indicating he was a Captain. I

Also, his wife is listed as Ann but I haven't seen her maiden name listed anywhere.

Is there documentation for his having been a Captain and for Ann's maiden name. I'm curious to know if she was actually an Underwood, as I'm an Underwood descendant on my dad's side but these lines are on my mom's side and the two 'could' be connected.

Thanks in advance for any additional info.