The decision to produce High Speed machines in America had, of course, been taken many months before and in July 1943 two production models were in action and had their first success early in the month. The American bombe was in its essentials the same as the English bombe though it functioned rather better as they were not handicapped by having to make it, as Keen was forced to do owing to production difficulties, on the framework of a 3 wheel machine. By late autumn new American machines were coming into action at the rate of about 2 a week, the ultimate total being in the region of 125. In May 1945 there were 64 machines in action here.
At first it was simple enough to make use of the American bombes. In the autumn a satisfactory system of rapid communication by CCM was introduced and cribs were despatched for running with instructions as to wheel orders, priority, etc: cribs were normally referred to as Amirs, Amir being section one of the stereotyped form for sending cribs and containing the number which was used as a reference number for the crib. There were plenty of Amirs to keep the few available bombes busy and there was general agreement that Shark as a key was worthy to absorb all 4 wheel bombe time as long as there were good cribs to run.
The only reputable cribs available were reencodements from Dolphin and for these we had to wait until Dolphin was broken or until the Arctic U Boats saw fit to repeat some Shark messages. The effect of this was that there was normally one or two days current Shark traffic unattacked, waiting for reencodements. As long as there were reencodements, the bombes were kept busy on these, but, when all recent days were out, the sight of current unbroken Shark was more than Op-20-G could stand and they launched into an independent crib programme. Apart from reencodements, the only crib was a weather crib in the Bay of Biscay which had a large number of forms and was only rarely worth running; just how bad it was may be judged from the fact that it was not until Oct. 24th that we succeeded in breaking a day on it. Sometimes Op-20-G turned their attention to this, sometimes to another form of crib of which they may justly claim to be the inventors, or at least the only exponents, - the Intelligence crib. This was a pure product of inexperienced enthusiasm. The argument in favour of a given crib might be roughly like this: boats returning to the Biscay ports are told to switch onto the local W/T Service when roughly x miles from home; here is a list of such messages as sent to previous boats and they show a marked similarity; on the last day's traffic I read, Lueth was x + 150 miles from home, so today I expect this sort of message to Lueth; here is a suitable looking message, I know what it says. By this method right cribs were occasionally produced but, as we know already, the skill in cribbing is not so much finding a right crib as ignoring a wrong one and this Op-20-G signally failed to do; their weakness was not lack of ideas but a complete absence of judgement and sense of proportion and they were content to pour bombe time down the drain