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Uboat question

Discussion in 'Submarines and ASW Technology' started by Andreas Seidel, Jan 5, 2002.

  1. lwd

    lwd Ace

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    From what I've read it wasn't Enigma so much as the transmissions themselves. The British had a very good intercept program that got better as the war went on. Google HUFF-DUFF.
     
  2. Jan7

    Jan7 Member

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    Dig in Welcome to the National Security Agency - NSA/CSS about these matters and you will could test this.




    Jan.
     
  3. lwd

    lwd Ace

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    I'm not sure exactly what you are trying to say. A link to the NSA home page doesn't exactly illustrate anything. On the other hand one can look at pages like:
    uboat.net - Fighting the U-boats - Technical pages
    and see how important HUFF DUFF was. As for the code breaking it becomes a question of how much it helped and when. It seems to have in general been more useful at the strategic rather than the tactical level.
     
  4. Jan7

    Jan7 Member

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    :eek:Excuse me, Lwd, follow these links: Search Enigma in NSA/CSS Web page





    Jan.
     
  5. brndirt1

    brndirt1 Saddle Tramp

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    This site has some info on METOX:

    Goto:

    uboat.net - Technical pages

    It shows the flaws in the system as well.
     
  6. lwd

    lwd Ace

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    Do you have a good reference? Ie a particular document and if it's long a location in it? I looked through the first page of results and found nothing to support your position. As such this was hardly more helpful than giving the home page.
     
  7. Carronade

    Carronade Ace

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    I have a question for you guys. Much before the war, the british had developed a technology called [ASDET - Anti Submarine echo detectors], was the technology a failure? Else, how could the U boats have been so successful?[/QUOTE]

    This brings up a couple of good points. Whether or not something is successful is not a straight yes-or-no question. Asdic (derived from Anti Submarine Detection Investigation Committee, the body responsible for its development) was a big step forward; prior to that the only underwater detection devices were hydrophones, listening for noise from the submarine itself. Asdic put out an active sonic ping which reflected from the target.

    Ironically the success of asdic led to an exagerrated expectation that the submarine problem had been licked. It was considered that say two asdic-equipped escorts could provide adequate protection to a convoy or major warship. However it had its limitations. Early asdic sent out a narrow 'pencil' beam, maybe 5 degrees wide, and the operator had to manually turn it to scan one 5 degree sector at a time. It was highly dependent on operator skill and water conditions; in particular, cold-water layers called thermoclines could shelter submarines beneath them (note, this is a quick-and-easy explanation of a complex topic).

    Moreover the U-boats developed a simple counter to Britain's underwater detection device - attacking on the surface! At night of course, when the low silhouette and small conning tower were hard to spot. One oddity about WWII submarines is that they spent most of their time and conducted their most successful attacks on the surface. The U-boats' "happy time" occurred before the development of effective radar, and radar on both ships and antisubmarine aircraft was largely responsible for turning the tide of the Battle of the Atlantic.

    The other big submarine campaign of WWII was ours against the Japanese, but this time the subs were the ones with radar, and again the most successful attacks were carried out at night on the surface.
     
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  8. Spaniard

    Spaniard New Member

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    I remember reading some UBoats went up to 800' Max also depending what Type.

    At a 1000' that must of been one hell of a Ride! They used to take a string and attach it to both sides of the Sub.
    as the string drooped they would see how much the sub had compressed.

    See this link Type VIIC/41 - German U-boat Types of WWII - uboat.net
     
  9. T. A. Gardner

    T. A. Gardner Genuine Chief

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    ASDIC or, SONAR or, several other names was developed by not only the British but the US, French, Japanese and, Germans prior to the outbreak of the war. There were several different methods of producing the sound including quartz crystal, rochelle salt crystal, and magnetostriction.
    Anyway, sonar systems of this period were typically "searchlight" types. That is they produced a conical beam of sound typically about 11 degrees or so in angle. The operator would scan a sector, shift the facing of the ocillator (the thing that produces the sound) and scan again. This was a rather slow process and accomplished manually. A paper recorder would aid in tracking any target discovered.
    These sonars could pick up a submarine at about two to six thousand yards in typical conditions. Depending on the sonar dome (or lack thereof) the searching ship could move at between 10 and 20 knots with 10 to 15 being typical and effectively search.
    By late war the Allies had begun to develop and install scanning sonars on their ships. These were either a searchlight type that could scan automatically or one that was omni-directional and could discriminate on return signals as modern sonars do.

    A major reason U-boats were initially successful was that they could operate on the surface. This allowed them to have a speed competitive with that of the escorts they faced. Helping this was the shortage of escort ships Britain had.
    With the advent of radar, long range partol aircraft, and more escorts the U-boats were forced to submerge more or just stay submerged (snorkel) to survive. This alone greatly reduced their effectiveness.
    In most cases sonar wasn't the sensor that found U-boats initially. It was generally radar or radio direction finding (HF/DF). From these sensor detections an escort or two could proceed to the location and then begin to search for the U-boat with sonar. Often the object of such operations wasn't to per se sink the submarine but rather simply force it to remain submerged while the convoy sailed away.
    Once the convoy was a safe distance away from the contact the escorts could quickly steam to catch up again. The U-boat would then have to surface and very carefully to avoid detection work very hard to get ahead of the convoy to try and set up another attack. If it got detected on radar doing this it was subject to another round of being forced to submerge and wait out the escorts that came to attack it.
     
  10. efestos

    efestos Member

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    In may 1940 The german caught many Ducht submarines with a primitive kind of Schnorchel. They tested this invention for not many time and removed the snorkels from the submarines!

    In august 1941 a Wickers wellington with his ASW radar land in an Axis airport... (the Kriegsmarine wasn´t informed till December).

    In MHO, It should have become evident that the surface ataks would end sooner or later. (It was later. GB prefered to bomb cities than give priority to the ASW radars) Dönitz didn't realized of that untill the "Black may" 1943.

    The speed of a U - boote decreased dramtically when it was submerged. But just removing the guns the maximun sped increased in 4 knots!

    This is a matter of a What IF?.

    My questions : Could the ASW radars detect an snorkel? The air carried radars too? AT what distance?
     
  11. Jan7

    Jan7 Member

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    Shortly: Yes. These are a questions very complex to explain in few lines, because this distance is determined for the power and the wavelength of the radar equipment and the antenna dessign. I suggest you the lecture of this book "The Secret War by Brian Johnson". Basically, with a minor wavelength -frequency elevated-, the energy of radar reflects in the surfaces wich dimensions are similar at this wave length.
    Also, I attach at my post a couple of my Favourites about radar themes, who explain, very well than me these questions.









    Jan.
     

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