 The turret was first used in naval combat on the USS Monitor in 1862 , with a type of turret designed by the Swedish engineer John Ericsson . A competing turret design was proposed by the British inventor Cowper Coles with a prototype of this installed on HMS Trusty in 1861 for testing and evaluation purposes . Ericsson 's turret turned on a central spindle , and Coles 's turned on a ring of bearings . Turrets offered the maximum arc of fire from the guns , but there were significant problems with their use in the 1860s . The fire arc of a turret would be considerably limited by masts and rigging , so they were unsuited to use on the earlier ocean @-@ going ironclads . The second problem was that turrets were extremely heavy . Ericsson was able to offer the heaviest possible turret ( guns and armour protection ) by deliberately designing a ship with very low freeboard . The weight thus saved from having a high broadside above the waterline was diverted to actual guns and armour . Low freeboard , however , also meant a smaller hull and therefore a smaller capacity for coal storage — and therefore range of the vessel . In many respects , the turreted , low @-@ freeboard Monitor and the broadside sailer HMS Warrior represented two opposite extremes in what an ' Ironclad ' was all about . The most dramatic attempt to compromise these two extremes , or ' squaring this circle ' , was designed by Captain Cowper Phipps Coles : HMS Captain , a dangerously low freeboard turret ship which nevertheless carried a full rig of sail , and which subsequently capsized not long after her launch in 1870 . Her half @-@ sister HMS Monarch was restricted to firing from her turrets only on the port and starboard beams . The third Royal Navy ship to combine turrets and masts was HMS Inflexible of 1876 , which carried two turrets on either side of the centre @-@ line , allowing both to fire fore , aft and broadside . 
