The Sunfish (length 200 feet, beam 19 feet, draught 8 feet 7 inches; displacement 310 tons) achieved an average speed of 27.581 knots during a three-hour trial. The mean speed for six runs over the measured mile at Maplin was 28.082 knots, with a mean steam pressure of 188 pounds per square inch, and mean revolutions of 351.2 per minute, the average indicted horsepower was 4,174.