The 'U-Boat' of the twenty-first century is good—but not good enough to take on the best.
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.
----This Story First Appeared in The National Interest----
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.
Berlin announced recently that it will build two more Type 212As over the next decade, and Poland has shown interest in leasing two of the German boats. The small subs supposedly cost around 371 million euros ($394 million) each, which implies that the current German U-boat force cost less to build than a single one of the $2.8 million Virginia-class nuclear-powered attack submarines used by the U.S. Navy. (To be fair, fluctuating exchange rates complicate the price comparison.) The Italian Navy, meanwhile, fields four Type 212s, designated the Todaro class, the last of which completed construction in 2015. Rome intends to build an additional two.
Shipyards across the world have also license-produced more than a dozen German Type 214 export submarines, fuel-cell-powered successors to the popular Type 209 submarine, one of which saw action in the Falkland War  under the Argentine flag. The sixty-five-meter-long Type 214 lacks the 212’s nonmagnetic hull, and some sources maintain its systems are downgraded. However, the export submarine has longer range and a greater diving depth of four hundred meters, to accommodate waters beyond the Baltic, and its eight torpedo tubes are capable of launching Harpoon antiship missiles while submerged.
The Greek Navy operates four Type 214 Papanikolis-class boats with a special hoistable Low Probability of Intercept radar. However, the Greek boats initially suffered from significant teething problems. Portugal operates two Tridente-class boats launched in 2010, and Turkey is in the process of building six Type 214 vessels at its Gölcük shipyards, though the program has suffered some delays. These will have Turkish electronics, and be armed with American Mark 48 torpedoes, IDAS missiles and possibly Gezgin-D land-attack cruise missiles.
South Korea currently operates six Type 214s designated the Son Won-il class, with a seventh recently launched and two more under construction. The Son Won-ils boast customized sensor packages, and the most recent boat, the Hong Beom-do, has reportedly been modified to launch ground-attack cruise missiles. The South Korean Navy also intends to refit its older Type 209 Chang Bogo-class boats with AIP fuel cell propulsion. Similarly, the Israeli Navy is already operating three AIP-equipped Dolphin 2 submarines built by Germany, and looks set to acquire another three.
German shipbuilders have recently offered larger, longer-range versions of the 212/214 submarines, the Type 216 and 218. The Type 216 was intended for sale to the Royal Australian Navy , but was passed over  in favor of the French Shortfin Barracuda. However, two Type 218SGs are under construction for Singapore, and will be completed in 2020. Details are sketchy, but the seventy-meter-long “ocean-going” submarines will retain a small crew of twenty-eight and an X-shaped rudder. They are believed to have Horizontal Multi-Purpose Locks, which can be used to launch either torpedoes or divers, and also cruise-missile launch capabilities.
Admittedly, all of the small German submarines may seem to have unimpressive speed, endurance and weapons loads, compared to larger nuclear-powered American and Russians submarines, which can sustain well over twenty-five miles per hour submerged for three months while carrying dozens of weapons.
However, the fuel-cell boats are at least as stealthy as their nuclear-powered cousins, if not more so, and each individual torpedo carried can be just as deadly. Considering that multiple boats like the Type 212 or 214 can be built for the price of a single nuclear attack submarine, the firepower advantage of the larger submarines is not so clear-cut. This explains why the German submarines have proven so popular with navies across Europe and Asia seeking to assert their control over littoral waters.
Sébastien Roblin holds a Master’s Degree in Conflict Resolution from Georgetown University and served as a university instructor for the Peace Corps in China. He has also worked in education, editing, and refugee resettlement in France and the United States. He currently writes on security and military history for War Is Boring .
----This Story First Appeared in The National Interest----
Image : Greek submarine S-120 Papanikolis. Wikimedia Commons/Creative Commons/@GDK