V-5 and V-6

Design and Construction Notes

The nine V-class fleet submarines were originally authorized in 1917, but construction did not start until well after the end of the Great War. By then, the concept of what the Navy wanted in a fleet submarine had changed numerous times. The Submarine Force came away very impressed with some of the long-range German cruiser U-boats that had been developed so the design for V-5 and V-6 morphed from a fleet support unit into that of a globe spanning commerce raider. This requirement dictated a very large boat to obtain the fuel bunkerage necessary for long range, and also a heavy gun armament to finish off merchantmen quickly. Consideration was given in the original concept to include an aircraft hangar, but this idea was dropped after the very disappointing tests that had been conducted on the USS S-1 (SS-105). The final design closely mimiced the previous USS V-4 (SM-1), but with the aft minelaying gear replaced by a after torpedo room with two tubes. The gun platforms for the two huge 6"/53 caliber Mk 17 guns were raised slightly from the V-4 design, and additional torpedo stowage tubes were mounted underneath the gun platforms. These boats, like the V-4 before them, were of mostly riveted construction, but welding was used in certain non-critical areas such as support framing, pipe brackets, and deck joinery. V-5 was built at Portsmouth Navy Yard, but the V-6 construction was assigned to the Mare Island Navy Yard, the first submarine to be built from the keel up at that Vallejo, CA. based facility.

These two boats were renamed Narwhal and Nautilus on February 19, 1931 and redesignated into the general submarine series later that year.

As cruiser submarines, it was desired that these boats have a heavy armament so they carried extra reload torpedoes stowed in watertight non-firing tubes in the superstructure. As built they had two of these tubes down inside of the forward superstructure aft of the small boat stowage cradles. Four more tubes were directly above these under the forward gun deck. Two more storage tubes were under the aft gun deck. The weapons in these tubes would have to be manually extracted while the boat was on the surface, then struck down below to the torpedo rooms. This was a long and tedious process and the inherent danger of spending several hours stuck on the surface in enemy waters was apparently lost on the designers.

Nautilus was refitted in 1941 to carry 19,320 gallons of aviation gasoline, in a scheme to use her to refuel long range sea planes. While the concept was judged successful, the Nautilus was not used in this capacity during the war,

Under overhaul at Mare Island when the war began, in an attempt to increase her firepower, Nautilus was refitted with two forward facing shootable tubes inside the superstructure, angled out to port and starboard, just forward of the amidships point. She also received two aft-facing shootable tubes angled out to port and starboard underneath the aft gun deck. These were single shot tubes and were not intended to be reloaded at sea, only in port. The two amidships tubes were moved closer to the bow in a later refit.

Narwhal received two topside shootable bow tubes and two shootable stern tubes at the very tip of the stern in a refit in April 1943. The topside tubes were of dubious value as the weapons in them were subject to damage from a depth charge attack and routine maintenance could not be performed once the boat was underway.

They were underpowered and their great size and large decks made them slow divers and rather clumsy underwater. Despite these issues, they were moderately successful during the war, sinking a number of enemy ships. Thoroughly modernized, they served the Navy well as special mission submarines, their large size allowing them to land raiding parties and running supplies to guerilla groups in the Philippines and elsewhere.

By the summer of 1945 they were thoroughly worn out and were sent back to the states for an honored retirement and decommissioning.