I was musing about the possibility that I had originally heard my tune for "Fifteen Men ... " in that Popeye cartoon, when an old memory bubbled up from the detritus of my misspent youth - There was an episode of the "Casper, the Friendly Ghost" cartoon, which must have had something to do with pirates. All I remember is that it ended with everybody singing

Fifteen Men on a Dead Man's Chest
Yo, Ho, Ho and a bottle of rum!
Casper's the one that we like best
Yo, Ho, Ho and a bottle of rum!

and I am pretty certain that it was sung to the same tune I asked about in my original posting.

I'm thinking that it had to be a well-established tune for the song. But I'm still looking for the orignal source.

Don