Ten years of design work went into the previous Farragut class and its 1500 ton limit. Due to the abrogation of the various Naval treaties by Japan, the next, Mahan class, destroyers could be bigger again. To keep up the production of destroyers for the fleet, the Mahan class were only 10% bigger at 1,650 tons. Just enough to lengthen and broaden the hull to carry the fittings and fitments of the Farragut class with a bit of spare stability, to alleviate one of the Farraguts major problems. A change in the five main gun layout and torpedoes was trialed with this class
With the changes to layout, the US Navy had the blueprint for its future 5x5" destroyer classes for the next ten years culminating in the Fletcher class.
The wartime changes to the class show the US Navy was keen to keep as much of the main armament and torpedoes as possible to the detriment of other fittings. The Royal Navy had no problem deleting sets of torpedoes to give some extra space and weight to be used for wartime fittings. AA and electronics needed updating on a regular basis but US destroyers just did not have the stability to keep adding that equipment without some major weight saving somewhere.
Sourced from Wikipaedia:
