I suppose most of us know it, and it's sort of implicit in what's been said above, but to "make assurance double sure", not all sea songs (by far) are shantys. The real work songs, which is what shantys are, are better sung with minimal or no accompaniment.

IMNSHO, most non-shanty sea songs (which DO rate accompaniment) do better with banjo than guitar, although I use both instruments on occasion.

Dave Oesterreich