1870 British Sailor info please

[Guest]

I have a man born 1843 in Bethnal Green who is a labourer and I think I have found him arriving in Boston Massachusettes in 1870 described on passenger list as a Mariner? then later on in the 1880 Maine census as a Sailor.
Now what I am wondering is would he have maybe joined the American Navy while still here or would you say he was a Sailor in this Country before he left?
I know nothing about naval stuff .
Thanks very much

ooh and also what does it mean when it says by their name on the Passenger list Steerage ???

[Uncle John]

Steerage is the cheapest rate, down in the bowels of the ship.

[Guest]

thanks Uncle John I wondered how he could afford it ??

[Southwick]

Steerage and cabin class - PortCities Southampton

Not very nice to be confined below decks during bad weather.

[WendyP]

HI Val

May I ask whats the name of the man your looking into?

[Guest]

thanks for your replies it must have been horrendous with a young baby
Wendy yes its John Thomas keen