Hi folks...I've spent the last few days learning 'Pirate Songs' to play for a Pirate Day gig at a long term care centre (read:old folks' home)...This is definitely one of the best pirate songs out there...the chord changes are a bit tricky but very cool...just a tip :always listen to the bass part first when trying to figure out chords for a song...In most songs the bassist will play the root note of the chord-at least on the first beat of any new chord...
So the song starts on a Dm chord with pick up notes on the A string of A then C and then finally the D open on the D string with the rest of the Dm chord sounding above the D-root note...
As the lyrics start the guitar plays Dm for 5 bars then changes to the Bb ,then F then Am....the second half of the verse is the same chord progression but after the Am it ends on a big flourish on the Dm

The chorus is F until "we'll fly the skull..." ,it then changes to Bb then back to the F then to the C on 'by god ...'....back to F for 'it's high ho...'then to the Dm on 'sail for...' then Bb for 'Traighli Bay boys...' then Gm for 'Hoist the ...' the Bb for 'Roger at the...' the C for 'break of ...' then back to the F for the word 'Day' as the vocals sing the F chord the band immediately starts the opening A,C, D riff which is fine technically because the Dm is very similar in structure to the F...it is referred to as the 'relative' minor......
I'm sure after fifty listens that these are the right chords....enjoy!!