Joint Tas.
Gam
force SEVEN
Task Group 743
Washington 25, D. C.
31 December 1953, 1200R
Operation Plan
CTG 743 No. 1-53
Appendix I to Annex J
HydrophoneContactDevelopment Procedure ENIEOK Atoll
1.
General,
The underwater detection system in use is the Acoustic Systen
Mark 6 Mod 0, a passive listening device which receives underwater sounds in
the audio frequency band. Pairs of hydrophones are connected by submarine
cable to the control equipment ashore. A line of hydrophones, spaced 300 to
350 yards apart, is located on the bottom across the Deep “ntrance and across
the Wide Passage of ENIWETOK Atoll. The rectangular area surrounding each
pair is the approximate area in which that pair of hydrophones might be expected to detect the presence of a submarine attempting to enter through the
channel by stealth. These areas are numbered to correspond with the tactical
numbers of the respective pairs of hydrophones, numbers one through three being
located in the Deep Entrance and numbers four through seventeen being located
in the Wide Passage. This system is not capable of discriminating between
an underwater contact and a surface contact, nor positively between a large
ship and a smaller craft. This requires that each contact via hydrophone be
checked visually, if possible, or else by radar to ascertain whether the
suspected contact is a surface contact, and if on the surface, the type of
contact. Because of the experimental nature of the Mk 6 Mod © Acoustic System,
the contact reports indicated in Annex J (Contact and Identification Develovment Procedure) and based solely on MK 6 hod O Acoustic 3ystem indication shall
not be sent to addressees outside of the Forward area except by CTG 7.3.
2.
Tasks:
TE 7.3.6.0 (Underwater Detection Element) shall:
(1) Report suspected contacts by telephone, and/or radio on the harbor
circuit 2716 kes, to CTU 7.3.8 and to CTE 7.3.1.0 using the following message
system:
She Oemmm
on
ae
CODE
MEANING
ean
MOG MOG
-
Underwater Detection Unit.
1 THROUGH 17 - Station number of hydrophone indicating contact.
RaD
YELLOW
Wilts
Wee
-
Definitely unfriendly contact.
+
~
DNA
Unidentified oontact.
All clear,
Contact definitely identified as false
or as friendly.
J-I-1
CHANGE #21
4°