Don-

Frigates came in various sizes, from economy sized of 24 guns or so to the 50-gun family-sized. The rating by number of cannons was also approximate, generally only counted the "great guns" used in the broadside when originally commissioned. For example the U.S. Constitution is generally described as a 44-gun frigate but generally mounted well over 50 cannons. But you don't need to know those kind of arcane things as well to enjoy the movie or the books.

Hope the movie is still around Maine by the time we return to Maine!

Cheerily,
Charley Noble