 All of the " Six @-@ Six Fleet " armored cruisers used the same armor scheme with some minor differences , one of which was that the four later ships all used Krupp cemented armor . The waterline belt ran the full length of the ships and its thickness varied from 7 @.@ 0 inches ( 178 mm ) amidships to 3 @.@ 5 inches ( 89 mm ) at the bow and stern . The thickest part of the belt covered the middle of the ship for a length of 275 feet 2 inches ( 83 @.@ 87 m ) . It had a height of 7 feet 0 inches ( 2 @.@ 13 m ) , of which 4 feet 4 inches to 4 feet 7 inches ( 1 @.@ 33 to 1 @.@ 39 m ) was normally underwater . The upper strake of belt armor was 5 @.@ 0 inches ( 127 mm ) thick and extended from the upper edge of the waterline belt to the main deck . It extended 167 feet 11 inches to 174 feet 11 inches ( 51 @.@ 18 to 53 @.@ 31 m ) from the forward to the rear barbette . The Izumo class had oblique 5 @-@ inch armored bulkhead that closed off the ends of the central armored citadel . 
