Having a listen to their live version I reckon it's close to this. I've never heard them before this morning so thanks for putting me into them they'd like that one at the mocal pub!

On the album they play it in Dm but I've transcribed it in Am with capo on 5th fret -

  Intro (single notes on bass strings)
  
  E G A C EE G A C etc
  
  Am
  It was June and it was hot, when on board the ship we got
                               F          C                Em 
  With shot and powder for the guns and a hogshead full of rum
                                        Am    *
  And salt cod to last until the winter squalls
  
  We made for the southwest where the hunting would be best
                               F              C           Em
  Where the Spanish ships of trade down with Aztec silver laden
                                         Am (big strum!)
  Were the fairest game for gentlemen of fortune
  
  Chorus
           C               
  And with tar on our pigtails and blood on our rapiers
        F                 C                 G                 
  We'll fly the skull and crossbones and by God we'll take no prisoners
       C                     Am                  F
  It's hiho away boys, we'll sail from Traighli Bay boys
  Dm        F                   G         C C/B Am *
  Hoist the Jolly Roger at the break of day
  
  The little riff E G A C potters along all over the place*