The V-boats were a group of nine United States Navy submarines built between World War I and World War II from 1921 to 1934 under authorization as the "fleet boat" program.
V-boats (left to right): Cachalot, Dolphin, Barracuda, Bass, Bonita, Nautilus, Narwhal, with submarine tender Holland.
A fleet submarine is a submarine with the speed, range, and endurance to operate as part of a navy's battle fleet. Examples of fleet submarines are the British First World War era K class and the American World War II era Gato class.
Gato class fleet submarine USS Wahoo
Fleet submarine HMS Ambush