Look for the fabulous late Lou Killen's output - not to be missed.
Deb Cowan is inclined to pick some choice ballads, sung in a voice that conveys truth and emotion. Her acapella rendition of "Rose in June" is a spellbinding 7 minutes, and a tribute to Lou Killen. She also sings some sea songs with the aforementioned John Roberts.

Contemporary ballads of the sea - many fine writers: Stan Rogers, Gordon Bok, John Conolly.

The performer roster of sea - oriented festivals like Mystic will lead you to many performers with broad repertoires.
The range is huge if you consider all maritime- themed songs, not just ballads. Lots of sources include Maritime along with lots of other sorts of songs: a couple of the Rudyard Kipling ballads, to Jez Lowe, Pete Seeger,

Some songs pop up in unexpected places, too -" Run Come SeeJerusalem" sort of Caribbean blues. You can spend the rest of your life on this- someone above asked questions to limit the parameters some, and this would certainly help dealing with a manageable range of songs.

Joanne in Cleveland (where the Tall Ships sailed away this morning).