"Defence" displaced as built and at deep load. The ship had an overall length of , a beam of and a mean draught of . She was powered by a pair of four-cylinder triple-expansion steam engines, each driving one shaft, which developed a total of and gave a maximum speed of . The engines were powered by 24 Yarrow water-tube boilers. The ship carried a maximum of of coal and an additional of fuel oil that was sprayed on the coal to increase its burn rate. At full capacity, she could steam for at a speed of . "Defence" was designed to carry 779 officers and men.