M.V.SEAFDEC: 1178-GT purse seine research vessel and training vessel has been utilized for the conduct of regional collaborative surveys in the waters of the Southeast Asian countries. M.V. SEAFDEC has conducted oceanographic surveys, bathymetric surveys, and studies on the sea of specific offshore areas, such as the Gulf of Thailand, Andaman Sea, and South China Sea.
- Echo sounder is used to measures the depth of water by measuring the time for a pulse of energy from travel to the seabed and backward on the principle of reflection of acoustic energy.
- A short pulse of sound energy is transmitted vertically down from the ship. This pulse having been reflected from the sea bottom returns to the ship in the form of an echo.
- Travel time (t) taken for its return, depends upon the depth of water (d), and on the velocity of sound (v) through the water.
- Performance and the efficiency of a sonar system depends on the accuracy of measuring the speed of sound exposure from source.
