The waterline main belt of Asahi consisted of Harvey armour 8 feet ( 2 @.@ 44 m ) high , of which 3 feet 8 inches ( 1 @.@ 11 m ) was above the waterline at normal load , and had a maximum thickness of 9 inches ( 229 mm ) for the middle 224 feet ( 68 @.@ 28 m ) of the ship . It was only 4 inches ( 102 mm ) thick at the ends of the ship and was surmounted by a six @-@ inch strake of armour that ran between the barbettes . The barbettes were 14 inches ( 356 mm ) thick , but only 10 inches ( 254 mm ) behind the upper armour strake . The barbette hoods were protected by 10 inches of armour on their face while their sides were 6 inches thick and the roof was 1 @.@ 5 inches ( 38 mm ) thick . Diagonal bulkheads connecting the barbettes to the side armour were 12 – 14 inches thick , but only 6 inches thick at the lower deck level . The frontal armour of the casemates protecting the secondary armament was also 6 inches thick with the rear protected by 2 @-@ inch ( 51 mm ) armour plates . The flat portion of the deck armour was 2 @.@ 5 inches ( 64 mm ) thick and 4 inches ( 102 mm ) thick where it sloped down to the sides of the ship . The conning tower was protected by 14 inches of armour .