There are several good websights with nautical flags. I haven't found one with 18th/19th century flags.
http://www.boatsafe.com/nauticalknowhow/flags.gif
http://www.ussslater.org/visitus/fil...al%20Flags.JPG
http://www.molossia.org/milacademy/flags.jpg (this one has numbers)
http://www.sea.edu/images/k-12/signalflag1.GIF (also has numbers)
I would recommend adding a signals phase before movement, to prevent bogging down play. Flag signals should be formatted. 1st Flag who message is for, Repeater flag if message didn't originate from the hioster, if repeater used 3rd flag is who message orginated with, and last segment is the message. Also, players should hiost an anknowledgement signal.
Just some thoughts, this thread has some great concepts. It will be interesting to see how people implement them.
Bob
Bob