I am fascinated by the idea of "Drunken Sailor" originating from a mondegreen of "Oro Se Do Bheatha Bhaile" and the more I listen the more I think it is conceivable there is something in it. There is certainly abundant evidence of similar treatments, in which a familiar song is "heard" differently by speakers of another language and it ultimately becomes another song, and since the original words are not meaningful, a ripe tune source for parody or other recycling. In Andenes, Norway, there used to be a Norwegian band whose big hit was "Yes, We Have No Bananas" which they learned entirely phonetically with no English in any member of the band. I am told one reason it was so popular was it was easy to make something really silly and rather rude in Norwegian from part of it. I can understand this, having heard Bob Walser sing "Johnson Girls" in Polish, in which the refrain, "Walk around, honey, walk around," sounds very like, "itch your ass, [something] itch your ass."
Of course, when I hear "The Sailor's Way" my brain goes, "Mr. Ed."
("around the Horn and home again, for that's the sailor's way" = "that is of course unless the horse is the famous Mister Ed.")