Radio Operations Aboard Submarines

By Robert E. Straub - KC2AIO <>

Submarine Radio Operations

     The only means of getting information such as changes in orders and letting other submarine crews know what was happening around them was by means of the radio Fox schedules. Base radio stations located in Honolulu and Australia, along with other locations, would transmit these Fox schedules which consisted of encoded 5 letter words. These schedules were usually transmitted 24 hours a day. To fill any void in transmission time, previous messages would be repeated. Therefore, no increase or decrease in submarine activity would be revealed to the enemy by an increase or decrease in Fox schedule activity.

     Submarines used two secret codes, one being the BIMEK code and the other was the FEMYH code. The difference between the two is that the BIMEK code was encoded and decoded on the ECM (Electronic Coding Machine) located in the Radio Room and the FEMYH code was encoded and decoded on a slotted aluminum board along with lettered paper strips. Qualified officers only were authorized to encode and decode both of these codes. However, radio operators were taught the use of the FEMYH code when attending the Advanced Radio School at New London. CT.

     In both cases, BIMEK or FEMYH, the received messages and the transmitted messages would have the first and last 5 letter words of the message start and end with either the word BIMEK or FEMYH. The second and next to last word of the message would be the same 5 letter word. This word was used as the means of setting up the ECM and the paper strips for encoding and decoding purposes. These 5 letters were the choice of the encoding officer.

     The message headings were pretty well generic in structure. The heading would start out with NR followed by the numerical number for the message transmitted that month, such as NR102. At the beginning of each month the numbering system would revert to the NR1. Each month the radio operator would start a new pre-numbered sheet with numbers going from 1 to 1000 and as the numbered Fox schedule messages were received the operator would draw a line through that received number. Any missing numbered message could be noticed merely by looking at the numbered sheet. A message could have been missed due to the submarine being submerged, but the sheet would indicate that the missed message be copied during a repeat session.

     The second indicator in the message heading would be the operational importance of the message. The letter R would indicate the message was "routine," the letter P would indicate "priority," the letters OP would indicate "operational priority" and the letter O would indicate "secret or top priority."

     The third indicator in the message heading was the date of the month and the time of day in Greenwich Mean Time. Example: 151221Z

     The fourth indicator in the message heading was indicated by a call such as Z4N, which would be the addressee - meaning "all submarines in Task Force 72."

     The fifth indicator in the message heading would be the word count of the message. Example GR 105 - meaning there are 105 five letter words in the text of the message.

     Note: All action addressees were named in the encoded text of the message.

     All messages were copied on an official U. S. Naval Communications Service blank form. Two forms were used as a carbon paper was inserted between the two forms.

     The double form was inserted into the manual typewriter and the heading of the message was typed into the provided space at the top of the form. The typewriter had capital letters only.

     A text count of 200 words could be typed on one message blank and it was done in the following manner; type the first 5 words, double space, and type the second 5 words. This is 10 words per line. Then repeat this procedure 4 more times, giving 5 lines of 10 words, or 50 words and double space vertically. Repeat this procedure 3 more times, giving a word count of 200 per message blank.

     If the word count was greater than 200 words, the same procedure would be followed and accomplished by slipping the next message blanks, along with the carbon paper, in behind the blank in use. When the first blank was filled and ejected from the typewriter, the new and empty message blank would flip into place. This procedure would be repeated until the message was copied in its entirety on the message blanks.

     Before removing the message from the typewriter the TOR (time of receipt), From. To and Date had to be added to the bottom of the form. Example:
TOR 0106GCT,
From: RDO HONOLULU, To: All Subs, and Date: 14 AUGUST 1945

     The message is now ready for the decoding officer.

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