Echo Sounder and Speed Log
The SOLAS V/19 depth and speed instruments: echo sounder and through-water log from 300 GT, over-ground log from 50,000 GT.
SOLAS regulation V/19 requires ships of 300 GT and upwards and all passenger ships to carry an echo sounding device to measure and display the available depth of water, and a speed and distance measuring device to indicate speed and distance through the water. Ships of 50,000 GT and upwards add a device to indicate speed and distance over the ground in the forward and athwartships directions, together with a rate-of-turn indicator.
The through-water log also feeds the ARPA required from 10,000 GT. The full article will cover sensor types, performance standards and the use of depth and speed data in under-keel clearance planning. See SOLAS Chapter V .