Another James Dowell, whose Will is dated Mar 23 1840, is described as a "mariner" which implies higher status than ordinary seaman ?. I wonder if it's his Aylburton grave wrt the Black Dwarf ?
His entry is listed as "Place, Berkeley", is this referring to his place of residence, or maybe just where the Will was officially dealt with ?

http://ww3.gloucestershire.gov.uk/genealogy/Results.aspx