Section 55 

 OKINAWA, SOUTHWESTERN ISLANDS OF JAPAN — U. S. PACIFIC FLEET SECTION BASE 



A55 . 01 Location of the Test Station and Test Board 



A test "board of the panel type "waa installed at the U. S. Pacific 

 Fleet Section Base at Okinawa, Southwestern Islands of Japan, on 

 February 6, and was operated until September 2, 19^6, after which date the 

 test "board, together with the decking facilities to which it was attached, 

 were carried away during a storm. The failure to install another test 

 "board was pro"bahly "because of the decommissioning of this Base. This 

 test "board, which was designated "by the symbol USNO-1, was submerged 

 near the "base of the Eatchln Hanto Peninsula in Buckner Bay. 



A55.02 Hydrographic Data 



The depth of water where the test "board was installed was 20 

 ft "below mean low water. The daily range of tide for Fe"bruary 19^6 

 varied from 0.5 to 6.9 ft. The strength of current was not measured 

 "but was estimated as 5 to 5 knots. The "boeird was secured to a pontoon 

 dock at the edge of a tidal chajmel 100 ft wide, in clear and constantly 

 changing water. Several small ships that discharged their waste into 

 the "bay were usually tied up to the dock. The teraperatvire of the water 

 during Fe"bruary 19k6 averaged 68° F. The "board was in the vicinity 

 of treated piling. 



A55.O5 Marine Borers 



1, Teredlnidae . While the operation of the test "board at 

 this location was discontinued shortly after Teredlnidae "became active, 

 it was clearly apparent from their extremely rapid development that 

 they were very destructive, and the attack was rated as very heavy. 

 They appeared to "begin "breeding veiy slowly early in April and rapidly 

 from June through August. It is quite likely, however, that a more 

 extensive test would show the "breeding season to "be continuous at this 

 location. The control panel su'bmerged during June ivas one- third filled 

 with specimens up to 68 mm long; the one su'bmerged during July had 

 only 5 minute pits; while the one submerged during August was 85^ 

 filled with juvenile specimens. Test panels su"bmerged on February 6 

 and removed 5^ 6, and 7 months later were 50^ filled with specimens 



up to 60 mm, 75^ filled with specimens up to 125 mm, and filled with 

 specimens up to 222 mm long, respectively. 



2. Llmnoria . Llmnorla did not show axiy sign of development 

 until Atjgust, and only a trace was recorded during that month. The 

 loss of the test board and discontinuance of the test made it impossible 

 to follow their further development. 



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