Iowa Class Battleship The Iowa Class Battleship was a battle ship class used by the United States of America . It was commissioned and decommissioned several times between 1943 and 1992 . Two of them are now being used as museum pieces . , while the other two are looking to be sold , but whoever buys them must keep and maintain them in a constant state of readiness encase the United States Navy ever needs them again , in which case they would be transferred back to the Navy . Armor . Like all battleships , the " Iowa " carried heavy armor protection against shellfire and bombs with significant underwater protection against torpedoes . The " Iowa ’ s " armor scheme was modeled on that of the preceding " South Dakota " class , and designed to give a zone of immunity against fire from 16 - inch / 45 - caliber guns between 18 , 000 and 30 , 000 yards ( 16 , 000 and 27 , 000 m ) away . The magazines and engine rooms were protected by an armored belt 12 . 2 inches ( 310 mm ) thick , which sloped to give an effective vertical thickness of 13 . 5 inches ( 340 mm ) . Their armor was not sufficient to protect against guns equivalent to their own 16 - inch / 50 - caliber guns ; increasing the armor would have increased weight and reduced speed . " Missouri " and " Wisconsin " incorporated the most significant change in armor from the " South Dakota " class : the increase from 11 . 3 inches ( 290 mm ) to 14 . 5 inches ( 370 mm ) of the vertical armor on the forward armored bulkhead , the conning tower , and the turret barbettes . The extra armor provided protection from fire directly ahead , which was considered more likely given the high speed of the " Iowa " class . The installation of armor on the " Iowa " - class battleships also differed from those of earlier battleships in that the armor was installed while the ships were still " on the way " rather than after the ships had been launched . Armament . The primary guns used on these battleships are the nine 16 - inch ( 406 mm ) / 50 - caliber Mark 7 naval guns , a compromise design developed to fit inside the barbettes . These guns fire explosive – and armor - piercing shells , and can fire a 16 - inch ( 410 mm ) shell approximately 23 . 4 nautical miles ( 40 km ) . The guns are housed in three 3 - gun turrets : two forward and one aft , in a configuration known as " 2 - A - 1 " . The guns are 66 feet ( 20 m ) long ( 50 times their 16 - inch ( 410 mm ) bore , or 50 calibers from breechface to muzzle ) . About 43 feet ( 13 m ) protrudes from the gun house . Each gun weighs about 239 , 000 pounds ( 108 , 000 kg ) without the breech , or 267 , 900 pounds ( 121 , 500 kg ) with the breech . They fire projectiles weighing from 1 , 900 to 2 , 700 pounds ( 850 to 1 , 200 kg ) at a maximum speed of 2 , 960 ft / s ( 820 m / s up to 20 miles ( 32 km ) . At maximum range , the projectile spends almost 1½ minutes in flight . The maximum firing rate for each gun is two rounds per minute . Each gun rests within an armored turret , but only the top of the turret protrudes above the main deck . The turret extends either four decks ( Turrets 1 and 3 ) or five decks ( Turret 2 ) down . The lower spaces contain rooms for handling the projectiles and storing the powder bags used to fire them . Each turret required a crew of between 85 and 110 men to operate . The turrets are not actually attached to the ship but sit on rollers , although they do have retaining clips . The original cost for each turret was US $ 1 . 4 million , but this figure does not take into account the cost of the guns themselves . The turrets are " three - gun " , not " triple " because each barrel can be elevated independently ; they can also be fired independently . The ship could fire any combination of its guns , including a broadside of all nine . The large - caliber guns were designed to fire two different conventional 16 - inch ( 406 mm ) shells : the armor - piercing Mk . 8 round for anti - ship and anti - structure work , and the Mk . 13 high - explosive round designed for use against unarmored targets and shore bombardment . Interestingly , when firing the same conventional shell , the 16 " / 45 caliber Mark 6 gun used by the fast battleships of the " North Carolina " and " South Dakota " classes had a slight advantage over the 16 " / 50 caliber Mark 7 gun when hitting deck armor — a shell from a 45 cal gun would be slower , meaning that it would have a steeper trajectory as it descended . At 35 , 000 yards ( 20 mi ; 32 km ) , a shell from a 45 cal would strike a ship at an angle of 45 . 2 degrees , as opposed to 36 degrees with the 50 cal . The Mark 7 had a greater maximum range over the Mark 6 : 23 . 64 miles ( 38 . 04 km ) vs 22 . 829 miles ( 36 . 740 km ) .