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1889 Arthur Krebs & Jean Rey periscope for the French submarine Gymnote. Periscopes allow a submarine, when submerged at a relatively shallow depth, to search visually for nearby targets and threats on the surface of the water and in the air. When not in use, a submarine's periscope retracts into the hull.
At depths below periscope depth submarines determine their position using: Dead reckoning course information obtained from the ship's gyrocompass, measured speed and estimates of local ocean currents, this could also be considered an estimated position as long as the ocean current is computed in.
This is the maximum depth at which a submarine is permitted to operate under normal peacetime circumstances, and is tested during sea trials.The test depth is set at two-thirds (0.66) of the design depth for United States Navy submarines, while the Royal Navy sets test depth at 4/7 (0.57) the design depth, and the German Navy sets it at exactly one-half (0.50) of design depth.
The U.S. Navy gives the maximum operating depth of the Los Angeles class as 650 ft (200 m), [16] while Patrick Tyler, in his book Running Critical, suggests a maximum operating depth of 950 ft (290 m). [17] Although Tyler cites the 688-class design committee for this figure, [18] the government has not commented on it.
[57] [139] When surfaced or at periscope depth, the Collins-class boats can use a Kelvin Hughes Type 1007 surface search radar, which is situated in a retractable mast on the fin. [10] [139] The fin of Sheean. The CH093 attack periscope mast is extended, and one of the panels for the distributed sonar array can be seen at the bottom right of ...
Based on later wartime experience, the tank was normally kept full or nearly full at the surface, then emptied to a certain mark after the ship was submerged to restore neutral buoyancy. At the start of the war, these ships could go from fully surfaced to periscope depth in about 45–50 seconds.
Also, "periscope feather" (the wave created by the snorkel or periscope moving through the water) can be spotted in calm seas. During the early months of the Battle of the Atlantic in World War II, British ships using the radar set Model 271 were able to detect the periscope of a submerged submarine at a distance of 800 m (0.50 mi) during tests ...
At 08:46, periscope depth was again ordered. The cruiser and two of the destroyers were now out of range; echo ranging by the third appeared too accurate for comfort. At 09:00, the periscope was raised again and an aircraft carrier was sighted. Nautilus changed course to close for an attack. The enemy destroyer followed suit and at 09:18 ...