 In order to save weight, they had direct-dive Brown-Curtis turbines rated at only ; however on trials "Tyrian" made with on 786 tons displacement.Initially five were to be ordered in April 1917, however two more ("Torch" and "Tomahawk") were added, replacing previous orders for two W-class destroyers ("Wayfarer" and "Woodpecker").This change was made at the request of Sir Alfred Yarrow to streamline production; otherwise, his yard would have had three different designs under construction at the same time.