"Shannon" was armoured in an unconventional manner. An armoured belt 9 ft tall and between 9 in and 6 in thick ran for most of the length of the ship, but stopped 60 ft from the bows. Above the belt was an armoured deck 1.5 in thick, the first such armoured deck on a British warship. At the point the belt ended, a 9 in armoured bulkhead ran across the ship, the top of which formed the embrasures for the 10-inch guns on the upper deck. From the bottom of this bulkhead, a 3 in thick armoured deck extended to the bow, at a level 10 ft below the waterline. The space above this forward armoured deck was filled with coal bunkers and stores to limit any flooding.