What impact does rough water surface have on echo-sounder beam projection?

The correct answer highlights that the angle of the illuminated area may differ from the target area due to rough water surfaces. When there are waves and turbulence on the water, the echo-sounder beam can be distorted. This distortion affects the angle at which the ultrasound signal is transmitted and reflected back, leading to discrepancies between the area being illuminated and the actual position of the underwater target.

In a calm water environment, the sonar signal travels in a predictable manner, ensuring that the depth and features of the underwater terrain are accurately measured. However, with a rough surface, the refraction and reflection of sound waves can alter the path they take, making it challenging to pinpoint the exact location of underwater features.

Other choices might suggest that the beam is broadened significantly, which could happen but isn’t the primary concern in relation to the target area. Signal loss could occur under extreme conditions but is not the typical outcome in moderately rough water. While rough conditions can introduce some variation, they do not inherently mean that depth measurements remain unaffected; rather, they can lead to inaccuracies that need to be accounted for. Thus, the focus is correctly placed on how the illuminated and target areas can diverge in such conditions.