 Kaiser Friedrich III 's armament consisted of a main battery of four 24 cm ( 9 @.@ 4 in ) SK L / 40 guns in twin gun turrets , one fore and one aft of the central superstructure . Her secondary armament consisted of eighteen 15 cm ( 5 @.@ 9 inch ) SK L / 40 guns and twelve 8 @.@ 8 cm ( 3 @.@ 45 in ) SK L / 30 quick @-@ firing guns . She also carried twelve machine guns , but these were later removed . The armament suite was rounded out with six 45 cm ( 18 in ) torpedo tubes , all in above @-@ water swivel mounts . The ship 's belt armor was 300 mm ( 11 @.@ 8 in ) thick , and the deck was 65 mm ( 2 @.@ 6 in ) thick . The conning tower and main battery turrets were protected with 250 mm ( 9 @.@ 8 in ) of armor plating , and the secondary casemates received 150 mm ( 5 @.@ 9 in ) of armor protection . 
