 The side of the Amiral Charner class was generally protected by 92 millimeters ( 3 @.@ 6 in ) of steel armor , from 1 @.@ 3 meters ( 4 ft 3 in ) below the waterline to 2 @.@ 5 meters ( 8 ft 2 in ) above it . The bottom 20 centimeters ( 7 @.@ 9 in ) tapered in thickness and the armor at the ends of the ships thinned to 60 millimeters ( 2 @.@ 4 in ) . The curved protective deck of mild steel had a thickness of 40 millimeters ( 1 @.@ 6 in ) along its centerline that increased to 50 millimeters ( 2 @.@ 0 in ) at its outer edges . Protecting the boiler rooms , engine rooms , and magazines below it was a thin splinter deck . A watertight internal cofferdam , filled with cellulose , ran the length of the ship from the protective deck to a height of 1 @.@ 2 meters ( 4 ft ) above the waterline . Below the protective deck the ship was divided by 13 watertight transverse bulkheads with five more above it . The ship 's conning tower and turrets were protected by 92 millimeters of armor . 
