As designed, the "Daring"-class ships had a standard displacement of 2,950 tons, with a full load displacement of 3,580 tons. Length was overall and between perpendiculars, with a beam of and a maximum draught of . Propulsion machinery consisted of two oil-fuelled boilers (for "Duchess", these were supplied by Forster Wheeler), connected to Parsons double reduction geared turbines from English Electric, which supplied to the ship's two propeller shafts. Top speed was , with an effective range of , while a cruising speed of allowed the ship to cover . "Duchess", along with three of her sister ships, were fitted with alternating current internal electrics; a break from Royal Navy practice. The intended ship's company for "Duchess" was 278.