Accession Number : AD0895038

Title :   Analysis of Ships' Underwater Acoustic Pressures in the 7-35 cps Band as Measured at Waipio Point and Honolulu, T.H.,

Corporate Author : NAVAL ORDNANCE LAB WHITE OAK MD

Personal Author(s) : Bonwit, Kenneth S.

Report Date : 16 AUG 1946

Pagination or Media Count : 23

Abstract : 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 dynes/sq cm at Waipio Point and 54 dynes/sqcm 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 ship's 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.

Descriptors :   *HYDROSTATIC PRESSURE), (*UNDERWATER SOUND, EXTREMELY LOW FREQUENCY), (*SHIPS, STANDARDS, RADIOFREQUENCY FILTERS, HYDROPHONES, ACOUSTIC RANGES, HAWAII, SOUND TRANSMISSION, HARBORS, WATER TRAFFIC, VELOCITY, CARGO VEHICLES, LANDING CRAFT, DESTROYERS.

Subject Categories : Marine Engineering
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE