Cannons and guns have been put aboard ships for centuries now, and having them there presents the same problem time after time: how to protect the ship (and the crew) from possible powder explosions and how to prevent them. This is the most important safety concern, besides keeping the vessel afloat.
On April 19th, 1989, an explosion ripped through the USS Iowa’s No. 2 16-inch gun turret, killing 47 crewmen. Immediately following, sailors flooded the #2 powder magazine, which in all likelihood prevented irreparable and catastrophic damage to the vessel. Although the cause of the explosion was never determined, naval experts believe static discharge ignited the powder charges for the ship’s guns. The USS Iowa was decommissioned in late 1990.