Based on the K Class design, K26 was intended to eliminate or at least reduce the known defects of that class. Although the general layout in K26 was practically the same as the K Class, the introduction of six 21-inch bow torpedo tubes in lieu of four 18-inch bow tubes was responsible for an overall increase in length of 12 feet. A great advance was made in K26 by the introduction of battery compartments - which became standard in the designs of the 1920s.
The main machinery of K26 was the same as that fitted in the K Class, but her design surface speed of 23.5 knots was 0.5 knots slower. At the time, the loss in speed was blamed on the repositioned after hydroplanes being in the wake of the
