 The ship 's waterline armour belt had a maximum thickness of 6 inches ( 152 mm ) and was closed off by 5 @-@ inch ( 127 mm ) transverse bulkheads . The armour of the gun turrets and their barbettes was 6 inches thick while the casemate armour was 5 inches thick . The protective deck armour ranged in thickness from 1 – 2 @.@ 5 inches ( 25 – 64 mm ) and the conning tower was protected by 12 inches ( 305 mm ) of armour . 
