Schnorchel (submarine)

Schnorchel (submarine)
Name	Schnorchel
Type	Submarine snorkel
Service	1943–present
Used by	Kriegsmarine, Royal Navy, United States Navy, Soviet Navy, Bundesmarine, Royal Netherlands Navy
Wars	World War II, Cold War

Schnorchel (submarine) is the German-language term for a submarine snorkel device that permits diesel-electric submarines to run diesel engines and recharge batteries while submerged at periscope depth. Developed during World War II by the Kriegsmarine and later adopted by navies including the Royal Navy, United States Navy, and Soviet Navy, the schnorchel represented a significant shift in naval warfare and antisubmarine warfare dynamics. The device influenced postwar submarine classes and doctrinal changes among fleets such as the Bundesmarine, Royal Netherlands Navy, and French Navy.

Introduction and Terminology

The term schnorchel derives from the German word for a breathing tube and entered English naval usage during World War II alongside concepts like wolfpack tactics and convoy system. Invented to mitigate air-surface vulnerability exemplified in engagements like the Battle of the Atlantic, the schnorchel allowed submerged endurance extensions comparable to earlier innovations such as the schnorchel mast used by U-boats. Alternative terms used by states include "snorkel" in Royal Navy and United States Navy parlance and "snort" in Royal Navy slang during World War II operations with U-class submarines and T-class submarines.

History and Development

Development traces to Dutch engineer designs tested by the Royal Netherlands Navy before World War II, later seized and refined by the Kriegsmarine following the occupation of the Netherlands. The Type VIIC and Type IX U-boat classes saw wartime retrofit programs after experiences in battles like the Battle of the Atlantic and encounters with HMS Bulldog, USS Borie, and HMS Seraph. Postwar, captured schnorchel-equipped boats influenced programs in the Royal Navy, United States Navy trials with Gato-class submarine conversions, and Soviet Navy adaptations feeding into classes such as the Whiskey-class and Romeo-class.

Design and Operation

A schnorchel assembly typically includes an air intake mast and an exhaust mast extending above the surface while the hull remains submerged at periscope depth; installation was performed on hulls analogous to those of Type XXI and Type XXIII concepts. The system links to diesel engines, battery charging circuits, and ventilating fans; integration involved components similar to those in periscope mountings and radio antennas. Operational use required coordination with U-boat Command doctrine, watchstanding procedures informed by Admiral Dönitz's directives, and onboard modifications comparable to those fitted on U-boat B-boat prototypes. Safety and detection issues implicated acoustic signatures assessed by Huff-Duff and ASDIC operators on escort vessels such as HMS Inglefield.

Tactical and Strategic Impact

The schnorchel altered tactics by reducing surface exposure, complicating detection by aircraft like Short Sunderland and B-24 Liberator and escorts from Royal Canadian Navy and Royal Navy task groups. It affected convoy escort doctrine shaped by experiences in operations involving Convoy HX and PQ convoy actions, and prompted countermeasures including improved radar and high-frequency direction finding deployments by forces such as the United States Coast Guard and Royal Navy Home Fleet. Strategically, adoption influenced postwar procurement choices in navies including the French Navy and Italian Navy, and factored into Cold War episode planning between North Atlantic Treaty Organization members and the Soviet Union.

Variants and National Use

Variants ranged from simple retractable masts on wartime U-boats to integrated systems on postwar designs like the Type XXI-inspired conversions in the Bundesmarine and Royal Netherlands Navy. The Soviet Navy developed snorkel-equipped Whiskey-class and later Foxtrot-class boats; the United States Navy experimented with schnorchel retrofits on GUPPY conversions and Tang-class modernizations. Nations such as Japan had independent snorkel-like developments late in World War II, while Australia and Canada operated snorkel-fitted submarines acquired from allies during the Cold War era.

Operational Challenges and Limitations

Schnorchel use introduced risks including water ingestion during heavy seas, mast detection by aircraft employing surface-search radar, and reduced speed and maneuverability constraining evasion from escorts like HMS Cossack or USS Kearny. Operators faced physiological issues from exhaust fumes and pressure changes documented in reports by crews on vessels such as captured U-boat U-505 and U-boat U-2540. Mechanical failures of valves and seals, acoustic noise amplifying passive detection by SOSUS arrays in the Cold War period, and tactical limitations in littoral environments constrained effectiveness despite doctrinal adaptations by commanders trained at institutions like the Naval War College.

Legacy and Influence on Modern Submarine Design

Schnorchel technology bridged diesel-electric and air-independent propulsion trends that culminated in submarine classes employing air-independent propulsion systems, nuclear propulsion adoption by fleets such as the United States Navy and Soviet Navy, and modern diesel designs like the Type 212 and Scorpène-class. Lessons from schnorchel operations informed hull streamlining in designs by firms associated with Howaldtswerke-Deutsche Werft and Kawasaki Heavy Industries, and influenced sensor suites used on contemporary boats operated by navies including the Royal Norwegian Navy and Republic of Korea Navy. The device remains a key historical milestone in the evolution from WWII U-boat tactics to Cold War submarine doctrine and twenty-first century undersea warfare concepts exemplified in exercises by NATO and ANZUS partners.

Category:Submarines