Switch to all-big-gun designs

The replacement of the 6-inch (152 mm) or 8-inch (203 mm) guns with weapons of 9.2-inch (234 mm) or 10-inch (254 mm) caliber improved the striking power of a battleship, particularly at longer ranges. However, uniform heavy-gun armament offered many other advantages. One advantage was logistical simplicity. When the U.S. was considering whether to have a mixed-caliber main armament for the South Carolina class, for example, William Sims and Homer Poundstone stressed the advantages of homogeneity in terms of ammunition supply and the transfer of crews from the disengaged guns to replace wounded gunners.[23]

A uniform caliber of gun meant streamlined fire control. The designers of Dreadnought preferred an all-big-gun design because it would mean only one set of calculations about adjustments to the range of the guns.[A 3] Some historians today hold that a uniform caliber was particularly important because the risk of confusion between shell-splashes of 12-inch (305 mm) and lighter guns made accurate ranging difficult. However, this viewpoint is controversial; fire control in 1905 was not advanced enough to use the salvo-firing technique where this confusion might be important,[24] and confusion of shell-splashes does not seem to have been a concern of those working on all-big gun designs.[A 4] Nevertheless, the likelihood of engagements at longer ranges was important in deciding that the heaviest possible guns should become standard, hence 12-inch (305 mm) rather than 10-inch (254 mm).[A 5]

Furthermore, the newer designs of 12-inch gun mounting had a considerably higher rate of fire, removing the advantage previously enjoyed by smaller calibers. In 1895, a 12-inch gun might fire one round every four minutes; by 1902, two rounds per minute was usual.[6] In October 1903, naval architect Vittorio Cuniberti published a paper in Jane’s Fighting Ships entitled “An Ideal Battleship for the British Navy”, which called for a 17,000 ton ship carrying a main armament of twelve 12-inch guns, protected by armor 12 inches thick, and having a speed of 24 knots (28 mph/44 km/h).[25] Cuniberti’s idea—which he had already proposed to his own navy, the Regia Marina—was to make use of the high rate of fire of new 12-inch guns to produce devastating rapid-fire from heavy guns to replace the ‘hail of fire’ from lighter weapons.[26] Something similar lay behind the Japanese move towards heavier guns; at Tsushima, Japanese shells contained a higher than normal proportion of high explosive, and were fused to explode on contact, starting fires rather than piercing armor.[27] The increased rate of fire laid the foundations for future advances in fire control.[6]