**OVERVIEW:** The SSN 671 *Narwhal* is a unique nuclear-powered attack submarine operated by the United States Navy, notable for its distinctive design modifications implemented during its lengthy service life.

**DETAILS:**

The SSN 671 *Narwhal* was authorized in 1966 and commissioned in 1969 as an experimental platform for advanced submarine propulsion technology. The most significant difference between the *Narwhal* and other contemporary U.S. Navy attack submarines was the installation of a natural circulation reactor, a departure from the forced-circulation reactors used in previous designs. This natural circulation reactor was intended to reduce the submarine’s reliance on noisy reactor coolant pumps, thereby improving its acoustic signature. The hull form was initially derived from the *Sturgeon*-class, but was lengthened during construction to accommodate the new reactor design. The operational experience gained from the *Narwhal* informed the development of subsequent submarine reactor designs, particularly those used in the *Los Angeles*-class. While it was classified as an attack submarine, its primary role was often dedicated to special missions involving intelligence gathering and surveillance due to its advanced sensor suite and quieter operation.

The *Narwhal*’s primary roles centered around anti-submarine warfare (ASW) and intelligence gathering. Its enhanced acoustic signature characteristics allowed for covert tracking of Soviet submarines and surface vessels during the Cold War. The AN/BQQ-5A(V)2 sonar suite [incorporating the BQS-12 spherical array] provided long-range detection and tracking capabilities. The AN/WLQ-4 Sea Nymph electronic support measures (ESM) suite enabled passive detection and identification of radar emissions from surface ships and aircraft. The AN/WLR-9A served a similar purpose, providing broadband radar detection and analysis. Data gathered from these sensors would be relayed back to U.S. intelligence agencies, informing strategic decisions and operational planning. Deployment of the AN/TB-16 towed array further enhanced the submarine's passive detection range, allowing for greater situational awareness in noisy ocean environments.

The vessel was fitted with the AN/BQS-14 active sonar for close range object detection and mapping as well as the AN/BPS-14 surface search radar and a BRD-6 direction finding suite to determine the source of electronic emissions. Armament consisted of 533mm torpedo tubes capable of launching the Mk67 torpedo, primarily for anti-submarine warfare. The inclusion of a 3-inch signal ejector suggests an emphasis on covert communications and signaling, furthering the submarine's role in clandestine operations. The two generic submarine periscopes, one optical and one utilizing low-light television (LLTV), provided visual reconnaissance capabilities, supplementing the electronic sensors and enhancing situational awareness in shallow water or coastal environments.

**SPECIFICATION:** Length: 96.0 m || Beam: 9.7 m || Draft: 8.8 m || Disp: 5027 t

**SENSORS:** AN/WLR-9A || AN/WLQ-4 Sea Nymph || AN/TB-16 || AN/BQS-14 || AN/BPS-14 || AN/BQQ-5A(V)2 [BQS-12] || AN/BRD-6 || Generic Submarine Periscope, Optical || Generic Submarine Periscope, LLTV

**ARMAMENT:** 533mm Mk67 TT || 533mm Mk67 TT || 3-inch Signal Ejector