In a multibeam sonar survey, which factor is NOT typically compensated for?

In a multibeam sonar survey, compensation for various factors is crucial to ensure accurate underwater mapping and data acquisition. The aspect that is typically not compensated for is "pit."

Roll, heave, and sound velocity in the water column are all compensated for during multibeam sonar surveys to correct for various movements of the vessel and environmental influences. Roll refers to the side-to-side tilting of the vessel, which affects the orientation of the sonar and must be adjusted to ensure that soundings reflect the true depth. Heave is the vertical movement of the vessel due to waves and swell, impacting the depth measurements, and corrections are made to account for these variations. Additionally, sound velocity in the water column changes due to temperature, salinity, and pressure, requiring compensation to accurately interpret the depth of sonar returns since sound travels at different speeds in different conditions.

On the other hand, "pit" typically refers to a feature often found on the seafloor, and while it may represent a geological or topographical aspect, it does not represent a factor that needs compensation in the same way the other aspects do. As such, multibeam sonar systems do not usually apply any correction for a "pit" unless it is a specific characteristic that