Maintaining all of the positive attributes of the Salmon Class, the "T" and Gar classes were blessed with the added speed and fire power that the navy was long striving for. Having a surface speed of 21 knots and the ability to traverse great distances, the T's were the first acceptable Fleet Boat in the US Navy. Design changes in internal layout, silhouette and hull form differentiate the Tambor Class boats from the Salmon / Sargos. The "Ts" featured a double hulled construction and included an external control room as in German U-boats. They were the last phase of development of US subs prior to the introduction of the Gato class in 1942. The Gar Class boats were virtually identical to the "Ts". These two classes of submarines shouldered the bulk of the combat duties during the early stages of the war, with the USS Tautog holding the scoring record in the category of "number of ships sunk" (26) .