How do hull-mounted sonar and towed-array sonar differ?

How do hull-mounted sonar and towed-array sonar differ?

• A. Hull-mounted is fixed in the hull; towed-array is trailed behind the vessel to reduce self-noise and extend detection range.
• B. Hull-mounted is towed behind the vessel; towed-array is fixed in the hull.
• C. Both are fixed in hull but use different frequencies.
• D. Both are towed behind; there is no difference.

Answer: (A)

The key idea is how placement and isolation from the hull affect performance. A hull-mounted sonar has its transducers fixed inside or on the hull, so it faces the water from a fixed position. This setup is quick to deploy and provides immediate detection, but it can be compromised by self-noise from the ship and by hull reverberation, which can limit range and clarity. A towed-array sonar, by contrast, is trailing behind the vessel on a long cable. Being away from the hull reduces self-noise and vibration picked up by the hull itself, and the long, stretched array acts like a large listening column. This gives much greater sensitivity and a longer detection range, plus the ability to tune the depth to listen through favorable acoustic layers in the water. So the correct description is that hull-mounted is fixed in the hull, while the towed-array is trailed behind the ship to reduce self-noise and extend detection range. The other statements misstate the placement or the basic difference in how the systems are deployed.

The key idea is how placement and isolation from the hull affect performance. A hull-mounted sonar has its transducers fixed inside or on the hull, so it faces the water from a fixed position. This setup is quick to deploy and provides immediate detection, but it can be compromised by self-noise from the ship and by hull reverberation, which can limit range and clarity.

A towed-array sonar, by contrast, is trailing behind the vessel on a long cable. Being away from the hull reduces self-noise and vibration picked up by the hull itself, and the long, stretched array acts like a large listening column. This gives much greater sensitivity and a longer detection range, plus the ability to tune the depth to listen through favorable acoustic layers in the water.

So the correct description is that hull-mounted is fixed in the hull, while the towed-array is trailed behind the ship to reduce self-noise and extend detection range. The other statements misstate the placement or the basic difference in how the systems are deployed.