 The cylindrical turrets were protected by eight layers of wrought iron 1 @-@ inch ( 25 mm ) plates . The sides of the hull consisted of three layers of one @-@ inch plates , backed by 15 inches ( 380 mm ) of pine . The deck was heavily cambered to allow headroom for the crew on such a shallow draft and it consisted of a single iron plate .75 inches ( 19 mm ) thick . The pilothouse , positioned behind and above the fore turret , was protected by 3 inches ( 76 mm ) of armor . 
