The three armoured decks ranged in thickness from with the greater thicknesses outside the central armoured citadel. The front and sides of the conning tower were protected by 11-inch plates, although the rear and roof were 8 inches and 3 inches thick respectively. The torpedo control tower aft had 3-inch sides and a 2-inch roof. In an effort to reduce weight, the "Colossus"-class ships reverted to the inadequate underwater protection scheme of and their anti-torpedo bulkheads only protected the shell rooms and magazines, although they had a maximum thickness of 3 inches.