38-40 cannon is definitely not a big ship. Let's make a simple caculation. 2 for stern, 2 for bow, one level cannon deck 6 for port and starboard, this makes a total 16 cannon. This looks reasonable layout of the original Franch slave ship. "Blackbeard" caught it, and the historical source says he likes it because its speed and maneuverability. The slave ship has a lower deck to captive slaves, pls be noticed the lower doesn't mean the deck is below the sea level. So make "slave deck" into a canon deck is not tough. Let's say stern and bow remain 4 cannon total, 18 cannon on each deck for port and starboard, which makes a total 40 cannon warship. The key is the Queen Anne's Revenge has never been a frigate.
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Now i understand better what are you saying. I can see how that ship can be fitted with that number of cannons, so why the ingame ship have only 16 cannons since i am playing as Edward Teach?
Also i can say that a french 4 rate of that era had by average 40 cannons so it is not a small number either.
Thanks again for you kind answers.