raybnz ... where are you in this fine country ???
I am collecting and studying various books on the Battle of the Atlantic at present. I recommend two volumes by Chay Blair "The Hunters" and "The Hunted" These take you through from 1939 - 1942 and from 1943 - 1945. Basically those are the time the U-boats had an ascendancy and their demise. Another volume which analyses the pros and cons is "The Atlantic Campaign" by Dan van der Vat. If you have those 3 you can have a good perspective of the battle. You will also come to see some myths exposed.
The American tankers were certainly important but it is much more complicated. Churchill was making noises about how close things were but in fact it wasnt quite as bad as that. The Americans improved their whole transportation infrastructure ... pipelines, rail and road delivery of oil. This freed up the sea transport which they also needed in anycase as the "Happy Time" for the U-boats was causing them major problems on their coast let alone Britain ..... The U-boats luckily had lots of problems too and when you get into matters they didnt have a chance right from the start in anycase. Things went in phases ... the German magnetic and contact torpedos were unsatisfactory for the first two years, 50% failure rate. Whilst they had a good number of U-boats there were only about 30% available for patrol. The weather as we all know was terrible for both sides....... it goes on and on. The T2 tankers didnt start coming on stream in numbers until 1942. From then on things thats when everything started turning pear shaped for the U-boats. When you look at the Convoy details there were numerous convoys steaming across the Atlantic each month and only a relative few were hammered. Ships steaming alone were the ones which suffered. You really shouldnt read too much into those History programs they are not a balanced account at all. I may offend some people but the U-boats were out of date and ill equipped for the task, they suffered by interference from Hitler and high command so Doenitz had his aims diluted and frustrated thank goodness. The U-boats did not commit the atrocities so much talked about and feared. There were only 2 such incidents and for quite a large part the commanders gave water, food and aid to survivors. There were also some incidents where they were attacked when obviously carrying out help ... a U-boat was towing 3 lifeboats and had a hundred odd people on its deck with an improvised red cross on the conning tower when an American aircraft attacked.
Oh yes, now that the propaganda has been peeled away and good factual information from both sides has been published. Another volume I have was written by Gunter Hessler who was in Doenitz command centre and is from the German documents. Published before the release of the knowledge that the Allies had broken the Enigma machine coding it gives the German side of the battle. Coupled with Chay Blairs and van der Vats book you have a fascinating story which anyone half interested should read about. People need to know the unfettered truth and not History Channel manufactured for TV garrbage ... lest we forget the horrors such events brought about.