Why Doenitz did not understand that the allied had detected HF/DF and broken enigma codes?

The argument for the importance of Ultra is that its critical impact on the Atlantic Campaign was limited to a few critical months of 1941-42, when there was not enough escorts to protect most of the convoys, nor RAF willing to lend sufficient aircrafts to combat the threat. In other words, Ultra aided GB at a time when avoiding contact was the only effective measure to prevent losses.

 

A further addendum to my comment is that in war, all efforts are time-critical. Doenitz was not incompetent, but he proved less competent in the pursuit of better techniques and technology than his adversaries who conceived from the get-go the integration of which was paramount.

 

Upss the allies actually detected the Metox: Osprey - Vanguard kriegsmarine U -boats ... page 21.

 

Metox was a crude German ESM device that was used by surfaced U-boats to detect early Allied airborne metric wave length radars. The set was produced in France and the antenna a crude wooden cross with copper wire for an antenna on it. The antenna got the name "Biscay cross" by U-boat crews. As a early warning set it was dispised and mistrusted by most crews.

 

Germany's population was 80 million, Britain's, 50 million. Germany's steel production capacity was twice Britain's. Germany's machine tool stock was 3 time Britain's. Germany's industrial capacity wasn't only slightly higher, it was more like two times higher.

Britain had a larger shipyard capacity, but that could be reversed in a few years of infrastructure buildup. The United States had 140 million people, 4 times Britain's steel production, 3 times the coal production and 3 times the machine tool stock. They had a smaller fleet than Britain's in 1940, but by 1945, the US had build several times the shipping tonnage that Britain produced (according to wikipedia, Britain made 6 million tons of shipping tonnage during the war while the US made 33 million tons). However, we have to assume that the USSR doesn't exists for Germany to do a naval buildup of comparable proportions.

 

I can add that a Bismark class battleship cost 200 million reichmarks while an U-boat cost 2.5 million reichmarks. Considering the other semi-useless surface vessels, canceling these things and redirecting the resources to the navy, they could have well over 200 extra u-boats operating by 1940-41. In 1942, O-boats sank 6 million tons of allied shipping, or 500,000 tons per month. If the Germans managed to achieve and surpass this rate of sinkings in 1939, by 1942 UK would be without a merchant fleet, as their initial merchant fleet had 16 million tons in 1939 (another source that I have put UK's merchant fleet in 20 million tons).

 

You're still trying to compare apples to oranges. The U.S. was able to outbuild Britain during WWII because the U.S. had a very large shipbuilding industry to begin with. Shipyards are quite large and complicated. Germany was unlikely to build enough new ones in a period of a few years to compete with England for several reasons:

They are geographically constrained to good ports, of which Germany has very few

They require a very specialized skill set which will take time to expand

They are very complicated facilities with significant physical plants that will have a relatively long lead time, even if sites and workforce are available.

The U.S. was able to expand much more significantly since none of these constraints affected the U.S. to a similar degree. There were many many good sites which could be expanded. There were many workers that could train new ones. The effort to expand capacity was already well under way when the U.S. entered the war.

How much steel, coal, or even factory goods a country can produce has very little impact. China today produces lots of all of these things, but has a much smaller shipbuilding industry than several countries whose economies are smaller. (England and Japan being two significant examples.) They simply don't have the tradition of it and there just aren't that many good sites.

 

As I read in the Osprey´s U-boat ... Metox device emits a signal detectable by the British H2S radar. (same source)

 

Even if Raeder and the other 'big ship' men had been in favour of building 300 U-boats before the war they still wouldn't have been built, Hitler would have not allowed it.
Building this many U-boats would threaten only one nation, Britain, and seeing that in the period leading up to WW2 Hitler was hopeful that Britain would stay out of the war, building these boats would have been against his political strategy

 

But Britain also had access to the rest of the empire, a large fleet, and numerous shipyards. For instance I believe at the end of the war Canada had the third largest fleet in the world. However Germany is taking on the entire commonwealth so all the production, resources, and population don't just come from the British Isles.

That is by no means certain. When do you start canceling things and when do you start building them up. Then there's the question of how Britain reacts to all this.

That's a pretty big if.

 

Germans had their skills also, so...

Other German Cryptanalytic Successes.

In addition to Naval Cipher #3 and #5, the following systems are known to have been read by the German naval Communication intelligence organization:


Various British Naval and Air codes (low grade): including COFOX, MEDOX, FOXO, LOXO, SYKO, Air Force code and Aircraft Movement code.

U.S. Hagelin: A Hagelin reencryption of 26 September 1943 was read by the Germans. The compromise was noted by the British from their reading of German Mediterranean traffic.

Anglo-French.

Merchant signals: Supplied with the books from merchant shipping abandoned or sunk, the enemy had no difficulty with Mersigs.

Russian: aircraft reporting system, weather system, and low grade naval traffic