THE BIMINI INSTALLATION 



1, Abstract. 



A two-hydrophone cable assembly was installed on the ocean 

 bottom off the west coast of Bimini, Bahamas on 9 November, 1960 by 

 The Marine Laboratory, University of Miami, The cable was terminated 

 in the Lerner Marine Laboratory, Bimini, by magnetic tape recording 

 and analyzing equipment. The installation was made in order to study 

 marine animal sounds under natural conditions, ambient noise, and sound 

 propagation across the Straits of Florida. Preliminary observations 

 indicate the presence of a variety of marine animal sounds and propa- 

 gation conditions of theoretical and experimental interest. 



2, Introduction. 



A hydrophone-cable assembly has been installed on the east 

 bank of the Gulf Stream with the cable terminating in the Lerner Marine 

 Laboratory on Bimini, Bahamas. The assembly contains two hydrophones 

 located on the bottom. One is a mile from shore in water 17 fathoms 

 deep. The other one is in 200 fathoms of water about two miles from 

 shore. A nominal frequency range of 10 to 12,000 cps is provided by 

 the assembly. 



The installation was made in connection with a study of the 

 feasibility of using hydrophones to obtain information on marine animals 

 in natural surroundings. It is also being used for studies of the 

 effects of such oceanographic factors as surface waves, temperature 

 versus depth and internal waves on sound propagation and ambient noise. 



The operational procedure for the present, is to record the 

 output of each hydrophone on magnetic tape. The tape is played back 

 through earphones or loud speakers, at speeds up to eight times the 

 recording speed. Observers note the occurrence of sounds of possible 

 marine animal origin and retain recordings of such sounds for further 

 study. 



Recordings of samples of ambient noise are also made for study 

 and analysis. In addition, graphical records of the noise levels at 

 each hydrophone are made on a 24 hour basis. Preliminary propagation 

 tests from Fowey Rocks on the west bank of the Gulf Stream to Bimini on 

 the east bank, are being made. The objective is to carry on continuous 

 measurements of propagation between the two points along with continuous 

 ambient noise measurements . 



It is planned to continue the above program for several months 

 in order to obtain a statistical picture of the occurrence of events of 



