the belt terminated in 12-inch and transverse bulkheads respectively. The waterline belt extended forward at a thickness of 6 inches that reduced to in two steps. The funnel and boiler room ventilation shafts were surrounded by an armoured box long intended to prevent shells fired from behind the ship reaching 'X' magazine. The box narrowed at an angle of 21° as it rose and had a maximum thickness of 12 inches nearest to the magazine. Aft it reduced in a series of steps to , 6 inches, and . The armoured deck matched the length of the waterline belt and sloped down 2.5° to meet the upper edge of the belt. It had a maximum thickness of from the 'A' barbette to partway over the mid-boiler rooms and thinned to a minimum of 4 inches over the rear engine and boiler rooms. The deck's thickness increased to partway over the rear engine room and covered the aft 6-inch magazines. The armoured deck extended forward 46 feet over the torpedo compartment with a maximum thickness of 8 inches, thinning to 6 inches. The armoured deck's rear extension was long and was 5 inches thick until the last when it thinned to . The turret faces were thick while their sides ranged from in thickness, and the roof was 8 inches thick. The armour of the barbettes ranged from in thickness and it was carefully arranged to minimize the likely risk. The conning tower armour was 9 to 12 inches thick and its communications tube to the upper deck was 8 inches thick. The fire-control director atop the conning tower was protected by an armoured hood 3 to 5 inches thick. The anti-torpedo bulges of the G3 battlecruisers were intended to withstand the explosion of a torpedo warhead. They consisted of an outer air space, an inner buoyancy space and the torpedo bulkhead that consisted of two layers of high-tensile steel. The bulkhead was situated some inboard from the side of the ship. Postwar tests done on a replica of this system showed that filling the buoyancy space with water rather than the sealed steel crushing tubes as used in was just as effective and weighed less. A compressed air system was fitted to blow the water out of the buoyancy spaces and bring the ship upright in 15 minutes after two torpedo hits. The ship's double bottom ranged from in depth.