| Popis: |
A series of about 40 small (2‐in. diam) inexpensive (approximately $70 per thousand) plastic spheres were sunk and thus imploded at sea near Westfall Seamount (30.5° N, 120.5° W). The implosive signals were monitored on both shallow (50‐ft) and deep (1100‐ft) hydrophones, suspended from the ship. Three types of spheres were tested and found to implode at 1800‐, 2350‐, and 2680‐ft depths, respectively. Sink rates of 225–300 ft/min. were achieved using sections of pipe, or other hardware, as sinkers. Energy per unit area spectrum levels in the 0.5‐ to 5‐kHz frequency band were, for one type of hydrosphere having an average implosion depth of 2680 ft, comparable to those for a 0.002‐lb detonator (TNT). Use of such safe, inexpensive, and reliable implosive devices is recommended for acoustic work at sea when short pulses of relatively low signal strength are required. |
