I see a few Grimes of Skerries - some here
http://www.willcalendars.nationalarchives.ie/search/cwa/home.jspSeveral dates for John Grimes of Skerries too in Crew Lists as there are for Grimes, Ringsend.
Robert shows Ringsend as his residence on marriage, as did Bridget Grimes.
Irishtown and Ringsend are close.
There is a newspaper snippet November 1871, Midland Counties Advertiser
Re a James Slattery, who drowned.
“…two fishermen named John Grimes and James Mordaunt were rowing with deceased from the beach at Ringsend, opposite the coast guard station.”
Maybe you could find records - desth, marriages etc for John Grimes, Skerries which may help you decide.