Can sonar transmitters locate submarines

Answer 1

In the early days of ASW, active sonar was used quite a bit for trying to locate submarines; however, today active sonar is primarily used only by aircraft, in the form of helicopter dipping sonar. Ships do use active sonar, but modern nuclear submarines are extremely adept at using the ocean environment to their advantage in avoiding active transmissions. The main disadvantage to using active sonar is that a ship automatically gives away their position; this wasn't as big a problem with older boats which used "John Wayne" style torpedoes that required you to be in visual range of a target, meaning you were exposed during an attack. Modern boats use passive sonar tracking, and use torpedoes that can be fired thousands of yards away,without ever getting near a target. Modern torpedoes have their own sonar tracking systems that are extremely difficult to evade once they acquire a target.

Modern submarines' speed and depth capability also means that they can egress an area where active sonar is being used very quickly, or avoid it altogether as it can be detected miles away before a boat ever gets in range of the transmitting sonar.

Active sonar is used by ships to find diesel-electric submarines that are running on the battery, though. Such boats are extremely difficult to detect, even by other submarines at close range. In many cases, active sonar is about the only way to find and track them, but unlike nuclear submarines, once a DE boat is located, they're pretty much history. They don't have the speed and depth capability that nukes do to egress an area if they're caught, but they can still use the ocean environment to their advantage if the sound conditions are in their favor.