USS Chicago at periscope depth.

A submarine snorkel is a device that allows a submarine to operate submerged while still taking in air from above the surface. It was invented by the Dutch just before World War II and copied by the Germans during the war for use by U-boats. Its common military name is snort. Download high resolution version (1050x726, 237 KB)Larger version on the commons: commons:Image:USS Chicago (SSN 721) at periscope depth off Malaysia. ... Download high resolution version (1050x726, 237 KB)Larger version on the commons: commons:Image:USS Chicago (SSN 721) at periscope depth off Malaysia. ... Alvin in 1978, a year after first exploring hydrothermal vents. ... Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000... U-boat is also a nickname for some diesel locomotives built by GE; see List of GE locomotives October 1939. ...

Until the advent of nuclear power, submarines were designed to operate on the surface most of the time and submerge only for evasion or for rare daylight attacks. In 1940, at night, a U-boat was safer on the surface than submerged because ASDIC sonar could detect boats underwater but was almost useless against a surface vessel. However, with the continued improvement in methods of RADAR detection and attack, as the war progressed, the U-boat was forced to spend more and more time underwater running on electric motors that gave speeds of only a few knots and with very limited endurance. The F70 type frigates (here, Motte-Picquet) are fitted with VDS (Variable Depth Sonar) type DUBV43 or DUBV43C tugged sonars Sonar (sound navigation and ranging) is a technique that uses sound propagation under water to navigate or to detect other watercraft. ... This long range radar antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll. ...

The 1940 defeat of the Netherlands by the Wehrmacht was a stroke of luck for the Kriegsmarine. The Dutch had been working on a device that they had named the snuiver (lit: "sniffer"). The Dutch navy had been experimenting as early as 1938 with a simple pipe system on the submarines O-19 and O-20 that enabled them to travel at periscope depth operating on its diesels with almost unlimited underwater range while charging the propulsion batteries. Combatants Kingdom of the Netherlands Germany Commanders Henry G. Winkelman, Jan Joseph Godfried baron van Voorst tot Voorst Fedor von Bock (Army Group B) Strength 9 divisions, 676 guns, 1 tank (inoperational), 124 aircraft Total: 350,000 men 22 divisions, 1,378 guns, 759 tanks, 1150 aircraft Total: 750,000... Wehrmacht   (armed forces, literally defence force(s)) was the name of the armed forces of Nazi Germany from 1935 to 1945. ... The Kriegsmarine (or War Navy) was the name of the German Navy between 1935 and 1945, during the Nazi regime, superseding the Reichsmarine. ... Look up Literal in Wiktionary, the free dictionary Literal can mean: Literal and figurative language, taken in a non-figurative sense Literal translation, the close adherence to the forms of a source language text Terminal symbol in regular expressions and in descriptions of formal grammars any notation for representing a... The O-20 was a Dutch O-19 class submarine in the Royal Netherlands Navy that saw service during World War II. O-20 along with her sister ship O-19 were the first boats in the world to be equipped with a getrimd diesel systeem or snort system that...

The Kriegsmarine, at first, gave some consideration to the snorkel as a means to take fresh air into the boats but saw no need to run the diesel engines underwater. In 1943, however, as more U-boats were lost, it was retrofitted to the VIIC and IXC classes and designed into the new XXI and XXIII types. The Kriegsmarine (or War Navy) was the name of the German Navy between 1935 and 1945, during the Nazi regime, superseding the Reichsmarine. ... Type VII U-boats were the workhorses of the German World War II U-boot-waffe, and appeared in several sub-types. ... The Type IX U-boat was designed by Germany in 1935 and 1936 as a large ocean-going submarine for sustained operations far from the home support facilities. ... Type XXI U-boat U 3008, postwar photo Type XXI U-boats, also known as the Elektroboote, were the first submarines designed to operate entirely submerged, rather than as surface ships that could submerge as a temporary, awkward mode of operation. ... Type XXIII U-boats were designed to operate in the shallows of the North Sea, Black Sea and Mediterranean Sea where larger Type XXI Elektro boats were at risk in World War II. They were so small they could carry only two torpedoes, which had to be loaded externally. ...

The first boat to be fitted with a snorkel was U-58 which experimented with the equipment in the Baltic during the summer of 1943. Boats began to use it operationally in early 1944 and by June 1944 about half of the boats stationed in the French bases had snorkels fitted. Unterseeboot 58 or U-58 has been the name of several German submarines or U-boats during the First World War and the Second World War. ...

On Type VII boats the snorkel folded forward and was stored in a recess on the port side of the hull while on the IX Types the recess was on the starboard side. The XXI and XXIII types both had telescopic masts that rose vertically through the conning tower close to the periscope. Type VII U-boats were the workhorses of the German World War II U-boot-waffe, and appeared in several sub-types. ... The Type IX U-boat was designed by Germany in 1935 and 1936 as a large ocean-going submarine for sustained operations far from the home support facilities. ... Type XXI U-boat U 3008, postwar photo Type XXI U-boats, also known as the Elektroboote, were the first submarines designed to operate entirely submerged, rather than as surface ships that could submerge as a temporary, awkward mode of operation. ... Type XXIII U-boats were designed to operate in the shallows of the North Sea, Black Sea and Mediterranean Sea where larger Type XXI Elektro boats were at risk in World War II. They were so small they could carry only two torpedoes, which had to be loaded externally. ...

Snorkels created several problems for their users. A U-boat with a snorkel raised was limited to six knots to avoid breaking the tube and its sound detection gear was deafened by the roaring of the air being sucked down the tube. A submarine that stayed underwater for more than a few hours encountered various disposal problems and had to store garbage internally, further fouling boats already infamous for their odors.

Most dramatically, snorkels were equipped with automatic valves to prevent seawater from being sucked into the diesels, but when these valves slammed shut the engines would draw air from the boat itself before shutting down, which was extremely painful to the ears of the crew and sometimes even ruptured eardrums. This last problem still exists in later model diesel submarines, but to a limited extent because of high vacuum cut-off sensors that shutdown the engines when the vacuum in the ship reaches a pre-set point.

Modern snorkel induction masts use a fail-safe design consisting of compressed air, controlled by a simple electrical circuit, to hold the "head valve" open against the pull of a powerful spring. Seawater washing over the mast shorts out exposed electrodes on top, breaking the control circuit. This vents the compressed air and allows the head valve to slam shut. When the electrodes are again clear of the water, the circuit is re-energized and the valve reopens.

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