D-class
From PigBoats.COM
Design, Construction, and Naming Notes
The three D-class harbor defense submarines were built to an Electric Boat Company Design at the Fore River Shipbuilding Company in Quincy, MA. All three boats were commissioned in the Navy with their original "fish" names. On November 17, 1911 the Navy changed its naming convention for submarines and these boats were renamed with their D-class names. They had their original general submarine series designations changed to the SS series on July 17, 1920.
Narwhal/D-1 (Submarine No. 17, later SS-17)
Grayling/D-2 (Submarine No. 18, later SS-18)
Salmon/D-3 (Submarine No. 19, later SS-19)
