While doing research for a a piece that I'm writing on, I learned that cannons weren't normally kept on the upper decks as they proved to be a tripping hazard and could potentially sink the ship if cannons are put there. I'm curious if there is any legitimacy to this. If so, then where would the cannons be kept? Just the Gun Deck? Would there be multiple gun decks then on bigger ships?
I think whoever told you this was wrong. Purpose-built warships in the Age of Sail had cannons shoved wherever they would fit, including the top decks. Here is HMS Victory, USS Constitution, and the French frigate L'Hermione. Crew convenience was a pleasure always a secondary consideration to fighting ability, and these were ships where the crew didn't need to steal to survive.
Now, all of these ships had multiple decks capable of mounting cannon, which most pirate ships did not. Pirates preferred small, fast vessels that could be lightly crewed. These were better suited to running down merchantmen than bigger ships, and smaller crews meant everyone got a bigger cut of the booty. Blackbeard famously sailed for a time a time on the Queen Anne's Revenge, a ship-rigged vessel that may have mounted as many as 40 guns on two decks, but found it so difficult to crew and maintain that he abandoned it in the Outer Banks off North Carolina.
Good books on pirates:
David Cordingly, Under the Black Flag
Marcus Rediker, Villains of all Nations
Benerson Little, The Sea Rover's Practice
