I had a look at 1871, and you are probably right about William jnr being the unfortunate sailor. The only one I found from a brief search was a sailor in 1871 on the "Choieo"? in Peel, with John Ball aged 13. In 1861 William had a son aged 3, John Henry, so this was probably them together at sea. In 1871 his wife Jane was living in Jurby, married rather than widowed, with several children, but no son John. I haven't put all the details as I expect you will find them now.
Best wishes
Susan