OVERVIEW: The SSN 751 *San Juan* [Improved Los Angeles Class] is a nuclear-powered fast attack submarine operated by the United States Navy. Entering service relatively late, the *San Juan* represents a significantly upgraded variant of the venerable *Los Angeles*-class, incorporating advancements in acoustic stealth, sensor technology, and combat systems.

DETAILS: The *Improved Los Angeles* class, sometimes informally referred to as the *688I* or *Los Angeles*-Flight III, represents the culmination of lessons learned throughout the operational history of the original *Los Angeles*-class submarines. The design focused on reducing self-noise signature, enhancing underwater speed and maneuverability, and improving the submarine's ability to operate in littoral environments. Compared to earlier boats, the *Improved Los Angeles*-class moved the bow planes from the sail to the bow, increasing hydrodynamic efficiency and reducing flow noise around the sonar dome. Internal arrangements were also revised to further dampen vibrations and reduce acoustic emissions. This class was intended to provide a crucial bridge in capability until the introduction of the *Seawolf* and later *Virginia*-class submarines. The late commissioning date of the *San Juan* suggests that the vessel likely received further upgrades and modifications during its construction, incorporating the latest available technologies.

The *San Juan* is primarily tasked with anti-submarine warfare (ASW), anti-surface warfare (ASuW), intelligence gathering, and special operations support. Its advanced sensor suite is geared toward detecting and tracking even the quietest modern submarines. The boat can be deployed independently or as part of a carrier strike group, providing a critical ASW screen. In the ASuW role, the *San Juan* can engage surface combatants with torpedoes or Harpoon missiles launched from its torpedo tubes or vertically from its Mk45 VLS. The submarine's advanced communications and data processing capabilities enable it to serve as a forward node in network-centric warfare, providing real-time intelligence to fleet commanders.

The *San Juan’s* sensor suite provides a formidable advantage in underwater battlespace awareness. The AN/BQQ-10 sonar system provides comprehensive active and passive detection capabilities, supplemented by the AN/BQS-15 close-range active sonar for navigation and mine avoidance. The AN/BLQ-10(V)2 electronic support measures (ESM) system allows the submarine to passively detect and analyze radar emissions from surface ships and aircraft, providing valuable targeting information. The AN/TB-29A thin-line towed array and AN/TB-34 fat-line towed array further extend the submarine's passive detection range. The AN/WLR-9A acoustic intercept receiver provides alerts to potential threats, while the AN/BPS-15A radar provides surface navigation and search capabilities. The Type 18 Periscope SUBIS Mod likely incorporates advanced image intensification and digital imaging capabilities, greatly improving the submarine’s periscope operations. Furthermore, the Mk45 VLS system enables the launch of Tomahawk cruise missiles, providing a significant land-attack capability.

SPECIFICATION: Length: 109.7 m || Beam: 10.1 m || Draft: 9.75 m || Disp: 6300 t

SENSORS: AN/TB-29A || AN/BLQ-10(V)2 || AN/WLR-9A || AN/BPS-15A || AN/BQS-15 || AN/BQQ-10 || AN/TB-34 || Type 18 Periscope SUBIS Mod

ARMAMENT: 3-inch Signal Ejector || CSA Mk2 Mod 4 [Mk151] || Mk45 VLS [12 Cells] || 533mm Mk67 TT