What must be compensated for when using a single beam sound in hydrographic surveying?

In hydrographic surveying, when using a single beam sounder, it is crucial to compensate for the sound velocity in the water column. The speed of sound in water is affected by various factors, including temperature, salinity, and pressure. Failure to account for these variables can lead to inaccuracies in depth measurements, as the sound waves travel at different speeds under different water conditions.

Adjusting for sound velocity allows surveyors to accurately translate the time it takes for the sound wave to travel to the seabed and back into a precise depth reading. By ensuring that the measurements reflect the actual conditions of the water column, surveyors can enhance the reliability of their data, which is vital for navigation, underwater construction, and marine research.

While other factors like tide and heave may also need to be considered during a hydrographic survey, they pertain to vertical positioning adjustments or surface movement rather than the fundamental measurement of depth via sound propagation. Consequently, ensuring accuracy in sound velocity is paramount for the effectiveness and validity of the survey results.