Mersigs

sidsal
19th February 2009, 20:20
Convoys in ww2 were manouvered with the use of a manual - MERSIGS and I have tried to get hold of one without success. International code flags were used to pass messages from ship to ship, as were ships' hooters, morse light signals and semaphore. It was all very clever.
The commodore ship would carry one or more RN signallers who could communicate at RN speeds with the escorts, there being radio silence.
A simple example - If it was neccessary to turn the convoy quickly to port or starboard the commodore ship would hoist the I flag for port or E for starboard and each ship, would hoist the same flag indicating that they had seen it. The commodore would then lower the flag, followed by all ships and a turn of 45 degrees made. Thus the whole convoy would be moving together on a new course.
Similarly a flag signal would be hoisted telling all that zigzag number so-and so would be implemented and time would be given for all ships to study the zigzag book and chalk up the courses on a board in front of the wheel. A clock with electric contacts around its rim would be set for a buzzer to sound when a course alteration was to be made. Then the commodore would lower the flag, hoot and assume the first course and all the ships hopefully would do likewise.
On my first ship - Blrocklebank's MAIHAR which was commodore ship in the Meddy the 3rd Mate's writing caused the helmsman to mistake a 1 for a 7
and instead of steering North 72 East ( quadrantal magnetic compass then), he put her on North 12 East. It resulted in the whole convoy steering N72 East and the MAIHAR merrily leaving the convoy on N12 East. It took quite a while to regain our position as her speed was about 12 knots.
Any suggestions about getting a copy appreciated.

murrayis
29th December 2011, 11:13
Hi Sidsal
Very late resposne to your question, nearly 3 years but you can't rush these things.
Have a look at the following website, it appears to outline how the Germans decode the MerSig and gives some examples.

http://www.tandfonline.com/doi/pdf/10.1080/01611194.2010.485412