There were two main design alternatives to the broadside . In one design , the guns were placed in an armoured casemate amidships : this arrangement was called the ' box @-@ battery ' or ' centre @-@ battery ' . In the other , the guns could be placed on a rotating platform to give them a broad field of fire ; when fully armored , this arrangement was called a turret and when partially armored or unarmored , a barbette .