William Jones US Navy service 1869-1876

[Glynm]

On my GGrandfather William Jones's application for British Only Mate Certificate there is a statement that between 1869 and 1876 "he was serving in the American Navy and also American vessels". I would appreciate any help in finding information concerning his service during that time. It would appear that he left the Liverpool barque Santa Rosa on August 5th 1869 and guess the port would have been San Francisco. William was born in 1848 in Pwllheli, North Wales.