Hull dimensions, machinery, and the transition to salvo fire

At full load the five ships displaced between 6,491 and 6,705 tons, were about 110.5 metres long, and drew between 6.58 and 7.08 metres. Twelve fire-tube boilers supplied three triple-expansion engines and three shafts, producing a design speed between 18.5 and 19.5 knots and a cruising radius of 3,412 nautical miles at 12 knots. At contemporary battle ranges, the eight 15-centimetre guns supplied the practical volume of fire while the two 21-centimetre pieces offered individual heavy hits and prestige. Longer-range combat changed that balance because gunnery officers needed grouped splashes to correct their aim. Two isolated heavy guns could not deliver a useful ranging salvo, pointing toward the later preference for more uniform batteries with four or six guns available.