USS Nautilus in pre-war trim. The two 'Narwhals' were thought to be too slow for fleet submarine work during the war, and were often used for clandestine operations, although it was Nautilus that finished off the stricken Soryu after Midway.
The two 'Narwhal' class units USS Narwhal and Nautilus must be classed as a group with the USS Argonaut that immediately preceded them. The large German transport submarines that worked the eastern US seaboard during World War I made a great impression on an oceanically-minded navy, and the early 1920s saw designs produced for a minelayer (V-4, later Argonaut} and two cruiser submarines Narwhal (V-5) and Nautilus (V-6). They were all large, even the latter boats (3.20 m/10.5 ft the shorter) being of greater length than the monstrous French Surcouf. As a minelayer, the V-4 could load 60 mines, which were laid through two tubes exiting beneath the counter.
Forward of the after bulkhead of the engine room the 'Narwhals' were nearly identical, mounting two torpedo tubes aft in place of the mine stowage, a smaller demand on space that accounted for their shorter length. To match the boat's endurance, torpedo stowage was on a grand scale, upwards of 36 being carried both within the hull and the casing topside. To stretch them even further, two 152.4- mm (6-in) deck guns were mounted, the largest in any American submarine. Scouting for targets was the task for a small seaplane, the plans for which were, however, dropped.
All were considered slow by US standards but, though all were due to be re-engined, only the Nautilus was so modified by the outbreak of war. The latter was fitted also with two extra tubes in the after casing and the other two gained four, all in the amidships casing, two firing forward and two aft.
Despite the US fleet's shortage of submarines in 1942, these three boats were considered too slow and vulnerable for combat patrols and were modified in various degrees for clandestine operations, running personnel and supplies. The Nautilus had facilities for refuelling long-range seaplanes, an echo of Japanese practice, but was never so used during hostilities. All operated particularly between their west Australian bases and the Philippines. The Nautilus finished off the stricken Japanese carrier Soryu after Midway, and landed personnel on an unoccupied island near Tarawa to build a secret airstrip. Other raids were carried out on Makin Island and Attu in the Aleutians. The Argonaut was lost in 1943.
'Narwhal' class (as built)
Displacement: 2,730 tons surfaced and 3,900 tons submerged
Dimensions: length 112.95 m (370.58 ft); beam 10.13 m (33.25 ft); draught 4.80 m (15.75 ft)
Propulsion: combination drive with four diesels delivering 4026.8 kW (5,400 bhp) and two electric motors delivering 1894.1 kW (2,540 hp) to two shafts
Speed: 17 kts surfaced and 8 kts submerged
Endurance: 33354 km (20,725 miles) at 10 kts surfaced and 93 km (58 miles) at 5 kts submerged
Armament: two single 152.4-mm (6-in) guns and six 533-mm (21-in) torpedo tubes (four bow and two stern) later increased to 10 tubes for 40 torpedoes