British coded naval charts

[Jens Andersen]

Hello

I am researching the naval battle in the Kattegat and Skagerrak during the German invasion of Norway and Denmark.

During my research in the British submarines' patrol reports I have found some positions which puzzles me, for instance:
MBRR 5527 (HMS Narwhal 12.4.40)
MBCU 5514 (HMS Truant 9.4.40)

It seems as if this way of coding the positions was also used by the Coastal Command.

Can anybody tell me, where I can find maps with these codes?

Off course, I asked at the National Archives, but they could not help me.
The Royal Navy Submarine Museum was of much help, either.

Best regards
Jens

[rafcommands]

Hi Jens,

You are correct that Coastal Command and the Admiralty used the same codes. In general the letter groupings were changed every three months but sometimes more frequent.

I do not know how much you know about them but:

The codes are of the form XXYY aabb where

XX is the Lat Degree
YY is the Long Degree
aa is the Lat minute
bb is the Long Degree

I do not have the codes for April 1940 to hand until I get back home at the weekend but both are the same Lat Degree and Minute eg MB 55.

The codes are in the National Archives but hidden in an obscure location so I'm not surprised the staff could not guide you. I am producing a decoder 1939 to 1945 (53N to 62N) as an appendix for Vol 3 of RAF Coastal Command Losses.

I'll answer with more detail at the weekend.

Regards
Ross

[Jens Andersen]

Dear Ross

Thank very much for your answer - sorry about the late answer, but I thought I would get a notice per mail.

With help from one of my friends (a former RDAF colonel) I had found out the way the system was constructed, and I have been able to unveil the codes of some eight of the grids, e.g.:
MBAQ = 57 N, 11 E (Triton, 11.4.40)
JSGD = 58 N, 10 E (Triton, 9.4.40)

However, that is not enough to make a good plot of the submarine patrols.

I therefore would be very thankful, I you will help me to find the map. It is quite frustating to have do a lot of work to deduce the positions, when you know that the map must be somewehere (and probably loads of copies).

Best regards
Jens