Tune! What does that fellow (sciencegeek) mean? Tune?
The chorus would be just shouted out, as would the verses the shantyman or leader chose to go with. Not too much room for a tune in a howling nor'wester when the rags are being split assunder and the lines are snapping like stock whips.
Unless of course it be a Welsh crew out of Swansea, boyyo. Then Jones the baritone would lead off, and Jones the tenor, Jones the soprano and Evans would sing harmony. This left Hughie and Morgan to do the actual work. :-)
If you have ever heard Dead Horse Shanty Crew singing in the pub after a few pints, you wouldnt waste breath on silly words like 'tune' mate!