Towing sonar
The towing sonar , abbreviated to TAS ( Towed Array Sonar ), is a passive sonar system and is a cable several hundred meters long to which hydrophones are attached. If necessary, the towing sonar is rolled out and towed. Towing sonars are mostly in military used area and primarily on submarines and anti-submarine used -Schiffen.
Military use
Advantages and disadvantages
A tow sonar has some advantages but also disadvantages. This increases the sensitivity of the passive sonar considerably, since, on the one hand, considerably more hydrophones can be attached to the towing cable, and on the other hand, the distance from the boat's propulsion system significantly reduces the background noise. This leads to a significantly increased sensitivity, which ensures an increased listening range and direction finding accuracy. Another tactical advantage is that a submarine can drive itself in a thermal layer and the towing sonar equipped with oars can be positioned in a layer below or above it. Since thermal layers obstruct the sonar, another boat can be monitored without being noticed.
One disadvantage of the towing sonar is its weight and length, which can reach over half a kilometer. The maneuverability of a submarine is limited as a result, as is the speed, the latter being the lesser problem, since the towing sonar can only be used sensibly in slow travel or creeping speed ; on the one hand the noise of the drive and the cavitation would counteract the usefulness of the towing sonic and on the other hand the cable would tear off due to its considerable weight and its resistance in the water. The retrieval time of the towing sonar depends on the length of the cable and can take more than a minute, which in critical situations can be too "long". If the speed has to be increased quickly in a crisis situation, a tight turning maneuver has to be initiated or the diving depth has to be changed rapidly, the only option is often to cut the towing sonar.
history
After the end of the Second World War , the performance of the sonar systems used improved rapidly with technical progress. The new submarines in particular, which, in contrast to the old models , were able to undertake very long diving trips under water, required better and better sonar systems in order to be able to eavesdrop on and identify their “surroundings” more efficiently. In particular, the Cold War period , when the submarines of the opposing camps often watched and chased each other under water for a long time, promoted the rapid further development of passive sonar systems.
A normal, passive sonar at the bow of a submarine guarantees a listening radius of around 270 °, amidships on the hull-mounted sonar system a listening angle of about 160 ° on each side and the towing sonar a listening angle of around 300 °. The blind spots result from the intrinsic disturbances caused by the submarine.
Civil use
Active towing sonars are also used in research to examine bodies of water and scan the ground. They are also used to search for wrecks. Usually civil towed sonars are side-scan sonar devices. These consist of a towed and stabilized gondola in which an active sonar is housed, which is usually directed downwards away from the direction of pull.