How Sonar Works: Sonar, which stands for “Sound Navigation and Ranging,” is a technology that operates on the principle of sending out sound waves and listening for their echoes. Here’s how it generally works:

1. Sound Wave Emission: A sonar system emits a burst of sound waves, often in the form of a “ping” or acoustic signal. These sound waves travel through the water in all directions.
2. Object Detection: When the emitted sound waves encounter an object in the water, they bounce off the object and return as echoes to the sonar sensor.
3. Signal Processing: The sonar system’s sensors receive the echoes and measure the time it takes for the sound waves to travel to the object and back. By analysing the time delay and the characteristics of the returning echoes, the system can determine the distance, size, shape, and sometimes the composition of the objects in the water.

Now, let’s look at how sonar is utilised differently on military submarines compared to surface vessels:

Sonar on Military Submarines:

1. Quiet Operation: Submarines, especially military ones, need to operate stealthily to avoid detection by enemy vessels. Therefore, their systems are designed with a particular focus on minimising self-generated noise.
2. Sonar Domes: Submarines often have a sonar dome or bow sonar array located on the hull. This dome or array contains the sonar transducers and helps in transmitting and receiving sound waves without interference from the submarine’s hull.
3. Passive and Active Sonar: Submarines employ both passive and active sonar systems. Passive sonar listens for sounds in the environment, such as those generated by other vessels or marine life. Active sonar, on the other hand, emits sound waves (the “ping”) and listens for echoes. The use of active sonar can reveal the submarine’s presence to potential adversaries, so it is used judiciously.

Differences from Surface Vessel Sonar:

1. Stealth and Concealment: Submarines prioritise stealth and concealment. Surface vessels are less concerned about noise and are more likely to use active sonar for object detection and navigation. Submarines, however, use active sonar sparingly due to the risk of revealing their position.
2. Sonar Types: While both submarines and surface vessels use sonar, submarines tend to have more advanced and sensitive sonar systems due to their covert nature. Surface vessels may rely more on other detection technologies, such as radar and visual observation.
3. Deployment: Surface vessels often have sonar arrays that are external to the hull and can be deployed into the water. Submarines usually have integrated sonar systems within their hulls to minimise drag and maintain stealth.

In summary, sonar technology is a critical tool for submarines and surface vessels, but its deployment and usage differ significantly due to the distinct operational requirements of each platform. Submarines prioritise stealth and quiet operation, whereas surface vessels may use sonar more liberally for various purposes, including navigation and object detection.