Forty-four of these anti-submarine patrol boats were built between late 1915 and late 1917. They had a low silhouette, hardened steel bow, a 4-inch gun and depth charges. They were reponsible for sinking at least four German submarines and of damaging one so severely that it had to seek internment in a Spanish port. One is shown in near starboard-broadside view with the 4-inch gun prominent, moving at speed; the other is in starboard-bow view, apparently more distant but also coming out towardsss viewer's right. The dark background may be a distant coastline, or just a dark horizon of cloud.