On 21 April, jan Wrote:
-------------------------------------------------------
>
>
> For a personal software simulation project I'm
> looking around for the geographical data (lat/lon)
> of the kriegsmarine grid system. As described at
> [www.uboat.net]
>
> I've seen there are conversion tools available on
> line where you can convert a grid cell name (ie
> AE1711) into a geographical location. But what I'm
> looking for is the data behind these tools. Simply
> a list of cell names and their corresponding
> locations.
>
> Does anyone know where I can find this data ?
>
> Btw, the on-line tools I've found have no data for
> AE1111. If I'm right it's the topmost left cell in
> AE. Or is it ?

Sorry for the delay, but I've been a way from this forum for a long time.

This is quite complicated, since not all Grossquadraten (large 'squares', with sides 486 nautical miles long) were perfect squares, especially in the far north and south (e.g., AD) and some, such as AN, covering the North Sea, were very uneven. I’ve seen an excellent program, using DB3, to convert most references. It requires a considerable amount of basic data. Even then, I’m told by a navigation expert that there may be distortions at the very far north and south

Reinhart Reche ("'Die Quadratur der Meere' zur Umrechnung der Marine Quadratkarte 1939 1945" Marine Rundschau, 81 (1984), 120-122) explains how to convert some grid references to latitude and longitude. However, it lists the relevant ‘base’ coordinates only for 14 large squares in the North Atlantic, and 15 in the Arctic. I have a copy, and will send it by email as a pdf if you contact me off-site. It’s in German, but I wrote a short introduction explaining it. I will also send it to any one else who has requested it if they contact me.

Very small scale grid charts are reproduced in Jürgen Ro¬hwer, Axis Submarine Successes 1939-1945 (1983; or Greenhill, 1999) at the back. A bigger chart of the N Atlantic is reproduced in Ministry of Defence (Navy) [Günter Hessler], The U-boat War in the Atlantic (London: Her Majesty’s Stationery Office, 1989).

“The German Naval Grid in World War II” (Cryptologia, 16 (1992), 39-51) describes the grid in general terms, and some of its uses and complexities. The U-boats used it in disguised form after about 10 September 1941. First by encoding letters using bigrams, and later by using an ‘Adressbuch’.

The allies never fully reconstructed the Adressbuch, which caused them problems at times eg on 24 May, Dönitz sent 16 U-boats (later Group Trutz) to "naval grid square 87 of the large square west of [disguised square] TT". Commander Rodger Winn, head of the Admiralty’s Submarine Tracking Room, thought that the effect of the "TT" signal was that the U boats had been assigned to an area "south of Sable Island (about 200 miles east of Nova Scotia)" while Commander Kenneth Knowles (in its USN equivalent, F-211) considered that they had been ordered to a position about "600 miles south west of the Azores" a difference of about 1,000 miles. Knowles was correct. This helped to save convoy GUS 7A, a westbound convoy from Gibraltar to the US.

NSA withheld the Adressbuch from the US archives until 1996. Some papers on it by USN WWII codebreakers are still withheld by NSA.

AE 1111 is indeed the top left cell in AE. Its centre lies at 68-57 N, 24-07-30 W.

Ralph E