 Yorktown 's main battery consisted of six 6 @-@ inch ( 152 mm ) / 30 caliber Mark 3 guns , with each gun weighing in excess of 11 @,@ 000 pounds ( 5 @,@ 000 kg ) . Two were mounted on the forecastle deck , two on the poop deck , and the other pair amidships on the gun deck . The two guns on the gun deck were mounted 10 feet ( 3 @.@ 0 m ) above the waterline , while the other four were 18 feet ( 5 @.@ 5 m ) above . The guns fired 105 @-@ pound ( 48 kg ) armor @-@ piercing projectiles with a propellant charge weighing 18 @.@ 8 pounds ( 8 @.@ 5 kg ) at 1 @,@ 950 feet per second ( 590 m / s ) . At an elevation of 30 @.@ 2 ° , the guns had a range of 18 @,@ 000 yards ( 16 @,@ 000 m ) . Each gun was shielded with steel plating 3 inches ( 76 mm ) thick . 
