Did Germany Make America and Russia's Nuclear Attack Submarines Obsolete?
The German Navy was a pioneer in large-scale submarine warfare, its U-boats able to contest the United Kingdom’s superior navy in ways that German surface warships could not. While modern-day Germany no longer has the ocean-spanning naval ambitions of its predecessors, it has become a global leader in designing small, stealthy submarines that can effectively patrol littoral waters at a fraction of the cost of nuclear-powered submarines. The secret sauce in the new generation of German submarines is the use of hydrogen fuel cells for power, which allows submarines to operate nearly silently for weeks at a time without using expensive nuclear reactors.
During World War I and II, submarines were at their most vulnerable when their noisy, air-breathing diesel engines forced them surface to recharge batteries, exposing the boats to detection and attack. The Kriesgmarine built several experimental Type XVIIB submarines with an Air Independent Propulsion (AIP) system, using hydrogen peroxide fuel that theoretically enabled extended underwater endurance. In practice, the boats were considered dangerously unsafe and unreliable. Although the United Kingdom, Soviet Union and United States all experimented with AIP submarines after the war, development was abandoned in favor of higher-performing nuclear-powered submarines.
It was left to Sweden, in 1997, to deploy the first operational submarine using an AIP system, the stealthy Gotland-class boats that employed a heat-converting Stirling engine. German submarine developers were close on their heels with the Type 212 in 2002, which uses hydrogen fuel cells. Though more expensive and complicated to refuel compared to the Stirling, the German PEM hydrogen fuel cells benefit from greater power output (and thus higher speed), have no major moving parts that betray acoustic stealth, and do not impose limits on diving depth.
The modern German Navy has two principal missions: participating in expeditionary operations, such as combatting piracy or supporting peacekeeping operations, and sea control of the Baltic Sea—which has grown in importance, given recent tensions with Russia. To operate in this maritime theater characterized by shallow, cold waters averaging around fifty meters in depth, the German Navy has a flotilla of six Type 212A submarines, numbered U-31 through U-36. The small vessels are only fifty-seven meters long and are manned by crews of just twenty-seven each—including both men and, as of 2014, women.
The Type 212’s double hull displaces 1,800 tons submerged, and is made of nonmagnetic materials so that it is not susceptible to detection by magnetic anomaly detectors. The softer metal limits the operational depth to just two hundred meters, but this is not a major limitation in shallow Baltic waters. The Type 212’s fuel cells, with hydrogen fuel stored in between the outer and inner pressure hulls, allow it to sail underwater for three weeks before surfacing. Reportedly, a Type 212A set an underwater endurance record for conventionally powered submarines in 2013 by transiting eighteen days submerged without use of its snorkel. While the Type 212 can achieve underwater speeds of up to twenty-three miles per hour, its sustainable cruising speed is closer to nine miles per hour while using just the AIP system.
The Type 212A is intended as a stealthy reconnaissance boat and ship hunter, which is why its armament was initially confined to torpedoes. Its six tubes can fire off up to thirteen 533 millimeter DM2A4 Seahake torpedoes connected to the submarine by a fiber optic cable, allowing the crew to guide the weapon to a target up to fifty kilometers away. The torpedo’s wide-aspect conformal sonar also allows it to send sensor data back to the launch vessel. A Norwegian combat management system is intended to integrate data from the Type 212’s various sensors, which include both a towed passive sonar array deployed from the sail and a hull-mounted flank array.
Recently, the German Navy has started installing the capability to fire IDAS fiber-optic missiles while submerged from four-cell magazines in the torpedo tubes. Based on the IRIS-T air-to-air missile, IDAS would be used primarily to shoot down hostile aircraft, but can also attack ground targets and medium-sized or small surface ships up to twenty kilometers away.
The Type 212’s ability to operate in waters as shallow as seventeen meters deep, enabled in part by its X-shaped rudder, makes it ideal for creeping close to the coast to deploy Germany’s elite naval commandos, known as Kampfschwimmers. Reportedly, the German Navy is working on installing a retractable thirty-millimeter Moray autocannon to provide fire support for special forces, which would seem like a throwback to the days of deck-mounted guns. In a modern twist, however, the cannon’s retractable mast will also supposedly be able to deploy three Aladin reconnaissance drones.