Thanks so much! And sorry for the extremely tardy reply!!
I didn't really have a system in mind when I was writing it, to be honest (I think if I had answered then, I'd have said "I dunno, Shadowdark? Whatever you like to use with TMO!"), but now I'm gonna say Tales of Argosa would be pretty fun. Pretty robust rules for Age of Sail style naval combat and blackpowder weapons and such!