IV.10.2Acoustic seabed survey equipment

2. Underwater survey equipment designed for seabed topographic mapping and having any of the following: Note: For the purposes of 6A001.a.1.a.2., the acoustic sensor pressure rating determines the depth rating. a. Having all of the following: 1. Designed or modified to operate at depths exceeding 300 m;2. Sounding rate greater than 3.800 m/s. Note: For the purposes of 6A001.a.1.a.2.a.2., sounding rate is the product of the maximum speed (m/s) at which the sensor can operate and the maximum number of soundings per swath (assuming 100% coverage). For systems that produce soundings in two directions (3D sonars), the maximum sounding rate in either direction shall be used. b. Survey equipment, not specified in 6A001.a.1.a.2.a., having all of the following: 1. Designed or modified to operate at depths exceeding 100 m; 2. Designed to take measurements at an angle exceeding 20° from the vertical; 3. Having any of the following: a. Operating frequency below 350 kHz; or b. Designed to measure seabed topography at a range exceeding 200 m from the acoustic sensor; and 4. Enhancement of the depth accuracy through compensation for all of the following: a. Motion of the acoustic sensor; b. In-water propagation from the sensor to the seabed and back; c. Sound speed at the sensor.