A gun deck is a level of a warship, usually a wooden-hulled vessel, which is primarily used to carry guns for broadside firing. Large warships often had several different gun decks, while very small warships entirely lacked this type of dedicated deck. Space was at a premium on wooden warships, and gun decks served other functions when a ship was not actively engaging enemy forces. During combat, conditions on these decks were very dangerous, as crewmen were at risk from both enemy action and their own weaponry.
The great warships of the age of sail relied on large banks of guns mounted so as to fire primarily from ports in the sides of vessels that were opened when engaging the enemy but kept closed under normal circumstances. The guns were typically mounted on one, two, or three dedicated gun decks. Such decks were usually dominated by rows of cannon along either side of a ship. Supplies could be stored in the middle of these decks, and sailors would sleep in these spaces.
Smaller warships, such as frigates, did sometimes feature one or two decks dedicated to guns. Parts of these decks were sometimes sectioned off for other uses, such as cabin space for the captain, when they were not needed for the mounting of naval guns. In some cases, smaller ships mounted all of their guns on the upper deck and on raised decks both fore and aft. The first covered deck on such ships was still sometimes referred to as a gun deck, however.
When wooden ships engaged the enemy, all non-essential items on a gun deck were secured, and ammunition, bandages, and damage control gear made ready. Naval guns were tremendously loud, could misfire, and produced clouds of hazardous smoke, all of which served to make life on a gun deck very dangerous for a ship’s crew. Enemy shot could penetrate the wooden hulls of most ships and had the potential to set off explosions or to send clouds of deadly wooden shrapnel tearing through the confined space of a gun deck, making the lives of gunners even more dangerous.
The advent of metal-hulled warships led to the disappearance of gun decks. Metal warships could withstand tremendous amounts of damage, and very large guns were needed to engage them effectively. These guns were best mounted in turrets on top of the main decks of ships and replaced the rows of broadside guns mounted on gun decks.