In my own neighborhood of Maryland, we have:

Calico Jack
Ship's Company Chanteymen
Pyrates Royale
Calico Jack
Letter of Marque

and several other groups.

The most significant songwriter among those groups would be Jane Meneely, who is in Calico Jack and SCC. She wrote the song "Twiddles," which is performed by maritime groups on both sides of the Atlantic, and continues to write both serious and humorous maritime material.