How to avoid overestimation of ASDIC?

[HJ Tulp]

The ASDIC device was developed because of the serious difficulties the Royal Navy had in curtailing the German submarine problem during WWI. ASDIC didn't get operational until after the war however and the First Battle of the Atlantic was mainly won through the implementation of the convoy system. Regardless of that the ASDIC was seen the premier detection device that would win the Second Battle of the Atlantic before it even started. The Royal Navy assessed ASDIC's chances of detecting a submarine at 80%. All these lessons turned out to be wrong when the war started.

This way of thinking influenced the Royal Navy Interbellum doctrine in two ways:
1. It learned that further research in anti-submarine doctrine wasn't needed.
2. It learned that submarines would be far less useful in the next war and directly influenced it's designs.

This way of thinking wasn't limited to the Royal Navy. It also influenced German thinking with some saying that modern detection devices made the submarine obsolete or otherwise only viable in a massed or combined arms approach. Also made part of the case for the adoption of surface raiders. In fact, when the Royal Netherlands Navy first started exercising with ASDIC equipped vessels in 1941 it still send shockwaves through it's submarine division.

How can this overestimation of ASDIC be prevented? In the Royal Navy, the Kriegsmarine or even the Koninklijke Marine? Why did every navy that started using ASDIC (or something like that) overestimated it's effectiveness?

 

[Finbarr the Fair]

My guess is that they were fixated on the idea that submarines would need to stay submerged to attack merchant vessels as well as warships. They didn't consider the possibility that, given the slow speed of convoys, surface attacks at night would prove a serious problem that reduced ASDIC's effectiveness. Other developments that affected the Battle of the Atlantic were yhe Wolfpack tactics, long range aircraft guiding the packs to convoys as would breaking the UKs merchant shipping code.

More realistic exercises, both map and with real ships and submarines, in the early 1930s might have shown up the flaws in reliance on ASDIC.

 

[Pangur]

My guess is that they were fixated on the idea that submarines would need to stay submerged to attack merchant vessels as well as warships. They didn't consider the possibility that, given the slow speed of convoys, surface attacks at night would prove a serious problem that reduced ASDIC's effectiveness. Other developments that affected the Battle of the Atlantic were yhe Wolfpack tactics, long range aircraft guiding the packs to convoys as would breaking the UKs merchant shipping code.

More realistic exercises, both map and with real ships and submarines, in the early 1930s might have shown up the flaws in reliance on ASDIC.

Related question, when it comes to exercises how much leay way is given to the sides?

 

[El Pip]

Related question, when it comes to exercises how much leay way is given to the sides?

And of course what is the actual purpose of the exercise? As early as the 1920s the Admiralty are discussing deliberately over-stating the capabilities of ASDIC to deter anyone from building submarines and there is a realisation that public statements must match what is seen at sea. I would not be surprised if this leaked through into the exercises which were setup to give a result that supported that effort.

On it's own terms this deception plan somewhat worked. Donitz's memoirs claim British "propaganda" on ASDIC was believed by everyone from U-boat crews to Hitler and he was always battling against it. He was not helped by the fact that German intelligence entirely failed to gather any useful information on the real capabilities of ASDIC or the fact that Germany had gone flat out researching passive listening (good for U-boats) and done nothing on active sets like ASDIC, so they had no set of their own to compare the claims to. Above all the British deception campaign was very much pushing at an open door, much of the KM didn't want U-boats as they were a distraction from 'proper' capital ships; it is always easier to trick someone into believing something they already want to be true.

If the Admiralty are honest about ASDIC I think you would get more research and effort on anti-sub tactics, but you'd also get a bit more worry by politicians and the general public and of course Germany would built a lot, lot more U-boats because the Admiralty has just admitted they have no real counter to them. You can sketch out a TL where this means Coastal Command gets more priority (maybe even transferred along with the FAA), ahead firing depth charges get invented early (the tech is simple enough) and late war tactics get invented early. Or of course none of that happens and instead it's broadly the OTL RN but facing a massive U-boat fleet as early as 1939. Without the benefit of the hindsight I can absolutely see why the RN didn't risk the later option.

 

[HJ Tulp]

On it's own terms this deception plan somewhat worked. Donitz's memoirs claim British "propaganda" on ASDIC was believed by everyone from U-boat crews to Hitler and he was always battling against it. He was not helped by the fact that German intelligence entirely failed to gather any useful information on the real capabilities of ASDIC or the fact that Germany had gone flat out researching passive listening (good for U-boats) and done nothing on active sets like ASDIC, so they had no set of their own to compare the claims to.

Didn't the Germans develop an ASDIC-like detection device in the S-Gerät? What effect -if any - did that have on German comprehension of submarines flaws and strenghts?

Above all the British deception campaign was very much pushing at an open door, much of the KM didn't want U-boats as they were a distraction from 'proper' capital ships; it is always easier to trick someone into believing something they already want to be true.

Can we really say it's a a deception campaign if the active party is unaware that it's claims aren't true? With regards to the rest of the quoted part I think you are very right. Here is what I found in Military Innovation in the Interwar Period:

A small band of antisubmarine officers at Portland were the only ones to know that nine times out of ten, submarines were able to avoid detection by asdic and to penetrate destroyer screens. They were also well aware that the asdic echo was usually smothered by the transmission during the critical final 500 yards of approach and that asdic's effective range of one kilometer measured poorly against the passive hydrophones of sub￾marines, which ranged effectively up to ten kilometers. Yet ignorance provided security. Admiral Sir Manley Power put it simply: "The sad truth is
that much of the navy disliked and feared submarines and was all too inclined to think that if they shut their eyes, the bogeyman would go away."49 In short most of the British naval planners still shared Admiral Arthur K. Wilson's denunciation of the submarine in 1902 as "underhanded, unfair, and damned unEnglish."

 

[El Pip]

Didn't the Germans develop an ASDIC-like detection device in the S-Gerät? What effect -if any - did that have on German comprehension of submarines flaws and strenghts?

It was only deployed fairly late in the war and I believe development only started after the war had begun. By that point I think the practical lessons from wartime experience were probably more important. One of which was that for their purposes an active device did more harm than good as it gave away the location of the U-boat so the S-Gerat was never popular.

Can we really say it's a a deception campaign if the active party is unaware that it's claims aren't true?

At a basic level the Admiralty can believe the device is say 60% effective and think that's 'good enough' to win a war of attrition, but still launch a deception campaign based on it being completely 100% effective to try and avoid that war at all.

I also think it's important to remember the technology was developing all the time, in the 1920s even the Admiralty didn't think ASDIC was much good but were deliberately over-stating the capability to try and influence others into not building submarines. But by the 1930s there was a much wider deployment of sets and the sets had gotten better, not just longer range but things like control from the bridge and the automatic range recorder, so there was a believe the technology had to some extent caught up with the earlier claims. Of course that wasn't the case, but it wasn't a completely unreasonable position as late 1930s ASDIC was far more effective than the WW1 era sets.

Fundamentally the Admiralty funded a dedicated ASW research facility throughout the entire inter-war, kept developing and refining the tech, and ran regular ASW exercises, even if those exercises were more about maximising training than tactical innovation. It was far from perfect and mistakes were made, but it was also very much not shutting their eyes and ignoring it so I think I disagree with the quoted section.