View Full Version : U-Boat Targeting Wheel
10-21-2009, 07:15 PM
On p. 423 of Clay Blair's Hitler's U-Boat War: The Hunters, Blair writes that the rules and restrictions on U-Boats targeting ships during the first year of WWII were so complicated that the Kriegsmarine issued a special wheel device to sort out what could and couldn't be targeted.
Has anyone read or heard about this elsewhere? Does anyone have a photo or sample of one of these wheels? The Historian of the German Naval Association hasn't even heard of this.
10-21-2009, 11:29 PM
That would be the Kriegsmarine Glücksrad.
It was a circular device segmented into 8 sections with a rotating arrow affixed to the center.
The commander would spin the arrow with one good fling and it would point to a section when the arrow stopped whirling. Whatever option the arrow pointed at would determine the course of a pending attack situation.
the options which the arrow might stop on were:
1. Attack with the Deck Gun
2. Attack with torpedo while submerged
3. Attack with torpedo while surfaced
4. Let the ship pass by
5. Crash dive, go deep, go silent
6. Call the Luftwaffe
7. Be More Aggressive
8. Please ask again later
It was a very frustrating device to use as the arrow would often stop spinning between the options, forcing the commander to try again.
this cost valuable seconds in an attack situation.
Occasionally the option pointed to by the arrow once it stopped spinning wouldnt even apply to the given situation.
In February 1940, KaptLt. Johann Bernard, in command of U-101 had to spin the little arrow no less than 7 times before the arrow pointed to something vaguely appropriate to his situation.
strangely for the first 3 spins, it landed on "be more agressive", the 4th spin resulted in the arrow coming to rest upon the "Please ask again later" option.
After waiting approximately 7 agonizing minutes so that it would be "later", kaptLt. Bernard attempted to use the device a 5th time, this time it landed on "Call the Luftwaffe" however he was several hundred miles outside of any aircraft range.
On his 6th attempt the device frustratingly said "Please ask again later" once more.
The enfuriated commander dashed the Glücksrad upon the command room floor. this lodged the arrow on "Crash dive, go deep, go silent" therfore it was the only thing he was able to do for the remainder of the patrol.
as a result of the U-101 Glücksrad Incident, BdU collected up all of the Glücksrad devices and they were destroyed; commanders were told to take whatever actions they felt the situation demanded.
unfortunately not a single authentic example of the Glücksrad exists today
10-21-2009, 11:52 PM
An Artists conception of the Glücksrad device
10-22-2009, 05:10 AM
Very creative...well done :rotfl2::rotfl2::rotfl2:
10-22-2009, 06:23 AM
What kind of response is "Please try again later".
What is it, a freaking "8 ball".:o
Beyond Blair's book I have not run across a single reference to this item. I thought this was someone pulling his leg and discounted it as fake.
Thanks for bringing it up.
10-22-2009, 08:51 AM
GoldenRivet -- Bravo. That certainly made my morgen. :yeah::salute:
Rconch -- Someone sent me some pictures of a Widmann'sche Prisenscheibe wheel that appears to be a targeting wheel for neutral and friendly merchants. I've sent it to the Historian at the German Naval Association for his take on it since my German isn't good enough to read the details.
10-22-2009, 09:16 AM
please send me also a copy of them, I might be able to help determining what it is and how it works :up:
10-22-2009, 09:47 AM
Great follow up,:salute: look forward to hearing more about this.
Just can't come to grips about how obscure this thing was, that no one I have read, that I remember, ever mentioning this thing before.:damn:
I just can't imagine a commander or XO spinning a "wheel of fate" before sinking a ship.
10-22-2009, 11:48 AM
It is missing the 9th option... let Bernard decide. ;)
10-29-2009, 07:34 AM
The sender of the picture asked that I not share it; however, he can be reached at U-Boat.net.
I did get confirmation from the historian at the German Naval Association: after some resaerch I think, I can disclose the secret of the "Prisenscheibe" or "Prize dial". As the name suggests, it was a device not used for targeting, but a means to find out how to treat a enemy or neutral merchant vessel according to the prize rules of the German navy.
It was designed by a certain Widmann and consisted of a system of corresponding dials, similar to a circular slide rule, to help the commanders of uboats to find out rather quickly, how a foreign vessel had to be treated correctly, e.g. if a neutral merchant ship with a cargo of contraband could be sunk immediately, had to be captured or if it could continue it's voyage unharmed. Another feature was, that the dial gave information about the paragraph of the prize rules concerned.
Thus it was possible, to reduce the time for the examination of a merchant vessel to an abolute minimum.
You will find some information on the "Prisenscheibe" in the records of the Nuremberg Trial, 129th day, Mai 14., 1946, testimony of Fregattenkapitän Günther Hessler.
I hope, I was able to answer your questions.
FLOTTENRICHTER KRANZBUEHLER: Were- you given any information during your period of training on economic warfare according to the Prize Ordinance?
HESSLER: Yes. I was informed of it.
FLOTTENRICHTER KRANZBUEHLER: Was the so-called "prize disc" used which has just been submitted to you?
HESSLER: Yes, I was instructed about it.
FLOTTENRICHTERUEHLER: Will you tell the Tribunal briefly just what the purpose of this "prize disc" is?
HESSLER: It was a system of discs by means of which, through a simple mechanical process in a very short time one could ascertain how to deal with neutral and enemy merchant ships-whether, for instance, a neutral vessel carrying contraband could be sunk or captured, or whether it must be allowed to pass.
This disc has another great advantage in that it indicates at the same time the particular paragraph of the Prize Ordinance in which the case in question may be found. This made it possible to cut down the time required for the investigation of a merchant ship to a minimum.
FLOTTENRICHTER KRANZBUEHLER: That means that the disc was in the nature of a legal adviser to the commander?
FLOTTENRICHTER KRANZBUEHLER: I now submit this disc to the Tribunal as Exhibit Doenitz-95.
10-29-2009, 09:17 AM
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