 The gun turrets had 9 @-@ inch front and sides while their roofs were 2 @.@ 5 to 3 @.@ 25 inches ( 64 to 83 mm ) thick . The barbettes were protected by 9 inches of armour above the deck , but it thinned to 8 inches ( 203 mm ) above the upper armour deck and 3 inches ( 76 mm ) below it . The conning tower sides were 10 inches ( 254 mm ) thick and it had a three @-@ inch roof and communication tube . Nickel @-@ steel torpedo bulkheads 2 @.@ 5 inches ( 64 mm ) thick were fitted abreast the magazines and shell rooms . Her funnel uptakes were protected by nickel @-@ steel splinter armour 1 @.@ 5 inches ( 38 mm ) thick on the sides and one inch on the ends between the upper and forecastle decks . After the Battle of Jutland revealed her vulnerability to plunging shellfire , one inch of additional armour , weighing approximately 130 long tons ( 132 t ) , was added to the magazine crowns and turret roofs . 
