Although a large class, building over a number of years, the characteristics between the various groups within the class did not alter appreciably. Changes in form, dimensions and displacement were not sufficient to make any marked difference in speed and endurance. However, as a result of war experience, large guards were fitted around the hydroplanes - these appendages restricting the class to a surface speed of 14 knots and a submerged speed of 9 knots. With extensive superstructure, combined with a navigating bridge built over the conning tower, the class were a major advance as sea boats and were easy to navigate even in the roughest weather.
