The tune is actually from the wreck of the Edmund Fitzgerald, composed by Gordon Lightfoot, just in case you see that name credited. Bobby Sands appears to have been a prolific writer of both lyrics and prose whilst in The Maze. He also wrote another song recorded by Christy Moore "McIlhatton".

The Moore album that it can be found on is "Ride On" (that is both of the songs)

Sla/n