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Some snorkels have float-operated valves attached to the surface end of the tube to keep water out when the swimmer submerges. Most, however, are allowed to flood, and the water expelled by a sharp exhalation through the snorkel when the swimmer returns to the surface.
The maximum length of the tube is around 50 cm / 18 inches. A longer tube would place the lungs in deeper water where the water pressure is higher and the lungs would be unable to inflate when the diver inhales because the muscles that expand the lungs would not be able to operate against the higher surrounding pressure.
A snorkel (also spelled "schnorkel" and "schnorchel") is also 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 perfected by the Germans during the war for use by U-boats.
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 could detect boats underwater but was useless against a surface vessel. However, with the continued improvement in methods of detection and attack as the war progressed, the U-boat was forced to spend more and more time underwater, running on electric motors which gave speeds of only a few knots and had very limited endurance.
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 the German called somewhat rudely the "Schnorchel". The Dutch navy had been experimenting as early as 1938Events January -June January 3 The March of Dimes is established by Franklin Delano Roosevelt. January 11 Frances Moulton is the first woman to become president of a US national bank. January 20 Wedding of king Farouk I of Egypt and Farida Zulficar in Cai with a simple pipe system on the submarines O-19 and O-20 , which enabled them to operate at periscope depth to operate its diesels and thus have almost unlimited underwater range.
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 19431943 is the common year starting on Friday. Events January January 4 End of term for Culbert Olson, 29th Governor of California. He is succeeded by Earl Warren. January 11 The United States and United Kingdom give up territorial rights in China. January 1, however, as more U-boats were lost, it was retrofitted to the VIICType VII U-boats were the workhorses of the German World War II U-boot-waffe and appeared in several sub-types. Type VIIA The Type VIIA boats were designed in 1933 and 1934 as the first of a new generation of attack U-boats. They were popular with their c and IXCThe 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. It was derived from the Type IA, and appeared in various sub-types. Type IXs had six torpedo tubes, classes and designed into the new XXIType XXI U-boats also known as the "Elektroboots," 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 XXIs had much better facilities than prev and XXIIIType 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 types.
The first boat to be fitted with a snorkel was U-58 which experimented with the equipment in the Baltic during the summer of 19431943 is the common year starting on Friday. Events January January 4 End of term for Culbert Olson, 29th Governor of California. He is succeeded by Earl Warren. January 11 The United States and United Kingdom give up territorial rights in China. January 1. 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.
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.
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 modern submarines, though their larger internal volumes of air mitigates the pain somewhat.)
A snorkel is also an aftermarket accessory fitted to some four wheel drive vehicles to allow them to drive through deep water without drawing water into the engine. They are typically routed out through one of the front wings and up beside the A pillar to the level of the roofline where they are terminated with either a mushroom intake or a forward facing intake.
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