From Tattie Bogle : "Another good song by Philip Gaston, simply called "Navigator": I first came across it when Kris Drever recorded it, but it is also done by the Pogues! Quite a popular session song now.
Will post the lyrics at a more godly hour!"

I'll save you the trouble as it's already on the Songs of the Inland Waterways website : http://www.waterwaysongs.co.uk/navigator.htm