Now that you mention it, it's not even that nautical -- beyond the single 'hoist the colours' line ( and 'lay [a course] to Fiddler's Green').
And of course no real-life shanty would feature the refrain "yo ho" :-)

I think it's in one of the early Hornblower novels when C.S.Forester has his tone-deaf protagonist comment on how unseamanlike the lyrics of the popular 'sea songs' actually are, and how the sailors singing them would never tolerate any such situation in real life! (He's quoting "Tom Bowling" or "Hearts of Oak" or something of that ilk composed for parlour performance...)