announced in a Shark signal. From the decode (for which Archery was available) it was clear that there was little connection between the tables of the 2nd and 3rd editions and that the first letter remained the indicator. No further WW messages were decoded till March 28th.
Between March 27th and 29th U 703 was sent to the North Iceland area to send 12-hourly Dolphin WWs. The signature NV was rodded on three consecutive signals and from the 26 answers to each the following decodes were selected:-
| 1507/27 | RYS | DMCH | MCHX | ELNV |
| 1812/27 | RYL | EPCH | LCHX | HMNV |
| 0546/28 | RYS | GYCD | CCDJ | GNNV |
| Using the crib: | RY | NV |
4 other (3-letter) settings were rodded out and one used to decode a Shark WW on March 30, the decoded signature showing the setting to be correct, and disposing of the idea that 4 wheel settings had been introduced.
Most decodes available at this stage had Archery available and Temperature, Wind and Pressure tables were identified, and partly reconstructed. With the help of these and information from Shark Decodes showing which boats had been asked to send WWs, several messages were rodded out.
By April 4th 61 WWs had been decoded, and all tables except Tables 5 and 9 had been partly built up, though in many cases only one dimension had been identified (e.g. It was not known that Table 7 gave not only wind direction but the direction in which this had changed in the last 3 hours). It was by then realised that the indicator table was similar to those used with the 2nd edition with 5 columns instead of 4.
The first three letters had at first presented difficulties and Longitude tables could not be constructed. However information from P/W N1539 was received showing that these three letters gave position according to a special map-grid using a large chart and 15 small charts (actually 17). After this information arrived the most frequently used part of the grid was reconstructed without difficulty.
After April 4th, almost all WWs were decoded, the tables improved, and certain errors corrected. A considerable amount of work was devoted to trying to complete the tables but beyond a certain limit this proved impossible, owing to the reversal of the previous position by which more information (especially about past weather) was included in the WW than in the Archery.
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