OK, so all expressions used in blues are sexual, and no sexual reference in a shanty is what it seems. That's clear, these sailors were a sheltered lot. Where the hell's Beddw? The nearest Google maps will give me is Beddwgan, a farmhouse near Pentraeth, the right sort of area for a song that mentions Nefyn, but about 3 miles inland and not really the sort of place where a sailor would want to go to get flogged. Maybe a Welsh speaker will tell us what such a placename could mean- W's grave perhaps.

You'll be telling us next that their desire for a pie dish was actually a wish to be keelhauled and shot on the quarterdeck.