Analysis of Ships' Underwater Acoustic Pressures in the 7-35 cps Band as Measured at Waipio Point and Honolulu, T.H.,
NAVAL ORDNANCE LAB WHITE OAK MD
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Ships underwater acoustic pressures in the 7-35 cps band were measured at Waipio Point and Honolulu, Hawaii, and were found to fall off, respectively, as the 1.4 or - 0.2 and 1.2 or - 0.6 powers of radial or slant distance from ship to hydrophone. These pressures were standardized to 50 ft and analyzed statistically. The mean pressure for all ships was found to be 62 dynessq cm at Waipio Point and 54 dynessqcm at Honolulu, with the pressures at each range approximating a lognormal distribution about the mean. The location along the keel of the peak pressure was found to approximate a normal distribution about 0.6 to 0.7 of the ships length behind the bow. Only the USAT COMET and two classes, Liberty ships and Freight Supplies, showed any correlation between standardized pressure and speed. Peak location showed no dependence on speed between three and eleven knots. The data show good agreement with the results of similar measurements at Puget Sound.
- Marine Engineering