On BoardGameGeek some time back they outlined wave 4 as such:

We are prototyping wave 4, which will feature one of the ships "voted" by our Anchorage fans - John Paul Jones' Bonhomme Richard, French 80-guns ships of the line, English 64 guns, and Spanish frigates of the Mahonesa class. We expect wave 4 to be released around the end of 2016.