Just to absolutely clear, although this does appear in the long posting by Torre, up to 1869 the Greenwich Hospital meant the one instituted by Queen Anne in 1694 as the Royal Hospital Greenwich which was exclusively for former sailors in the Royal Navy. It was not a hospital in the medical sense, but a place of shelter for the in-pensioners. It had a sickbay and it was this facility which later became the Dreadnought Building. It was only after the Royal Hospital for in-pensioners closed in 1869 that the hospital for ordinary mariners moved into the buiding and it took the name Dreadnought. The rest of the buildings which comprised the former Greenwich Hospital became the Royal Naval College, until that closed in 1997 and Greenwich University moved in.
Therefore the sailor from the 1830s who was the subject of the first post was formerly in the Royal Navy.