 As built , Vasco da Gama was armed with a main battery of two 10 @.@ 2 in ( 260 mm ) guns , placed in individual barbettes side by side amidships . She was also equipped with a single 5 @.@ 9 in ( 150 mm ) gun mounted on her stern , and four 9 @-@ pounder guns for close @-@ range defense against torpedo boats . She was protected with a complete iron armored belt that was 4 inches ( 100 mm ) thick on either end and 9 in ( 230 mm ) thick amidships . The main battery guns were protected by 10 @-@ inch ( 250 mm ) thick barbettes . 
