Ground effect cargo planes to avoid the U-boat threat?

I wonder about this. The battle of the Denmark Strait list that Bismarck/PE had heard pow and hood before spotting them?
Also, the Germans were stated to use hydrophones to avoid torpedo attacks. Did the Germans have better passive sonar?

The RN had the best sonar in the world in 1939, they'd spent a lot of time and money on it. Their hydrophones were good, but not as good as the Germans

Germany invested in better hydrophones. This was sensible, as they wanted U-boats to hear the noise of a convoy from as far away as possible. Their sonar wasn't good.

Better hydrophones would have been useful to the RN, but not nearly as important as better sonar. There's only so much money around.
 
The RN had the best sonar in the world in 1939, they'd spent a lot of time and money on it. Their hydrophones were good, but not as good as the Germans

Germany invested in better hydrophones. This was sensible, as they wanted U-boats to hear the noise of a convoy from as far away as possible. Their sonar wasn't good.

Better hydrophones would have been useful to the RN, but not nearly as important as better sonar. There's only so much money around.
Thanks, that explained the superficially apparent discrepancy
 
I wonder about this. The battle of the Denmark Strait list that Bismarck/PE had heard pow and hood before spotting them?
Also, the Germans were stated to use hydrophones to avoid torpedo attacks. Did the Germans have better passive sonar?
Prinz Eugen had what I have seen described as the best passive SONAR system in the world at the time, with the implication that it was better even than other KM vessels. Something I have wondered about...
 
The water flow and turbulence past a U-boat is far different from that around a sonar dome.


These were warships as well as
Source?
because as ex-RN, I highly distrust this


All NATO sonars were high frequency sonars and slowly devolving to lower & lower frequency as greater range was demanded. Target acquiring was still critical which still demands frequency in thousands of hertz. For the Germans the GHG was for long range detection and I gather ultra low frequency of few hundred hertz and behaves differently.
 
These were warships as well as



All NATO sonars were high frequency sonars and slowly devolving to lower & lower frequency as greater range was demanded. Target acquiring was still critical which still demands frequency in thousands of hertz. For the Germans the GHG was for long range detection and I gather ultra low frequency of few hundred hertz and behaves differently.

OK, first of all we are talking WW2 here, not what was done in NATO 20 years later.
NATO sonars were certainly NOT all high frequency. Lower frequency was a change brought in as they reached the limiting factor for sonar power (which is you boil the water in the sonar dome...) and better knowledge of sound propagation, an attempt to get better long range detection in the further convergence zones. There are issues in both high,medium and low frequency sonars, which was why A/S ships carried at least two, and often all 3 types.

And you still havent cited anything as I asked.
 
http://www.cdvandt.org/GHG1996.pdf

Can't vouch for the author but the paper looks comprehensive enough.

To use the GHG effectively the German subs had to come to a dead stop (diesel) or <3 kns. Late war developments (1943 onwards) mitigated this somewhat.

If submarines are having difficulties then how on earth is a warship at 20 kns going to function?

Interesting paper, it goes into the theory of why the Germans were using hull-mounting hydrophones.

The main issue for a WW2 U-boat is that there is a lot of turbulent flow around the boat when moving - they weren't very streamlined (by modern standards). Their propellors were also more noisy and more subject to cavitation noise.
That is why they had to slow down. Not a huge issue, as the main reason for the system was to find groups (convoys) of ships, and until you find one, there isn't a need for speed. Its rather similar to the sprint/drift system used by a modern A/S vessel with a tail, and for similar reasons (although the modern ship of course has way more capable audio processing ability).

I assume the fitment to raiders was for similar reasons - to detect a convoy target, and possibly also to stay away from warships.
 
O'HARA GERMAN FLEET AT WAR 1939-1945,

Covers incident with Franz Kohlauf sinking HMS Charybdis in a night torpedo strike. He detected the RN group @ 20-30km with GHG while escorting a convoy.

During the Bismarck battle Prince Engen GHG unit was used several times to locate @ 40km while maneuvering against the britsih @ speed.
 
O'HARA GERMAN FLEET AT WAR 1939-1945,

Covers incident with Franz Kohlauf sinking HMS Charybdis in a night torpedo strike. He detected the RN group @ 20-30km with GHG while escorting a convoy.

During the Bismarck battle Prince Engen GHG unit was used several times to locate @ 40km while maneuvering against the britsih @ speed.

You keep quoting stuff that has nothing to do with the original point, which is how many of these were done by a ship (or U-boat) moving at over 20kt.
That is the question you keep not answering.
Can you quote the relevant sections from the book? I'm not going to buy it just to see if you are correct.

I am dubious about the Prinz Eugen claim. There was no need to locate the British at 40km during the Bismark battle, they were already closer then this and in visual and radar contact.
So when exactly did this happen, and why?
 
O'HARA GERMAN FLEET AT WAR 1939-1945,

Covers incident with Franz Kohlauf sinking HMS Charybdis in a night torpedo strike. He detected the RN group @ 20-30km with GHG while escorting a convoy.

During the Bismarck battle Prince Engen GHG unit was used several times to locate @ 40km while maneuvering against the britsih @ speed.

If you read the diaries / logs from the Prinz Eugen you'll recognize that whilst the GHG could detect sounds at relatively high speeds (15 kns was regarded as the maximum speed at which it could operate) it also delivered as many false reports as it did true ones. At least three times a report was made of torpedoes heading for the PE. In fact it would appear that for surface warships the primary purpose of GHG was to make the ship aware of torpedoes at short to medium range.

It is not a location finding device - merely direction finding. Now if you are a submarine tracking a convoy thats not a big problem. But if you are trying to locate warships then its quite possible that you'll get a visual by the time you can triangulate the position of the ships.
 
As I said GHG required a experten to use effectively and it was developed for long range detection of convoys -not the exact location. The sound baring could be used to dispatch seaplanes to find the convoy etc, but they often got updates from B-Dienst which appears to have detected 1/2 of all convoys in the North Atlantic 1941-43.

As a rule direction finding increased chances of locating a target.

The 15-20 knots figures for GHG were discussed on warship-1 com by German posters some time ago. However the links were a hard drive ago. I would recommend posters go ask them, maybe some regular posters can link the discussions in question.
 
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