Reluctant Poster
Tech Sergeant
- 1,737
- Dec 6, 2006
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The idea that America won the war simply by building ships faster than the enemy could sink them is an argument with several large holes in it;But they did not stop more than 10% of the supplies, even though the ships they sank were capable of more than one trip. Read Hitler's U-Boat War by Clay Blair; he explains this. We did react to the U-boat success, built ships faster than they could sink them, and in 1944 were sinking something like 10 times the tonnage in U-boats that they were sinking in our ships. The Germans lost 500 U-boats in WWII, 10 times as many as the USN.
Not enough bombers. And not enough timeWhy didn't the British bomb the U boat pens while they were being built on West Coast of France? If they had bombed around the time the cement was poured it would have destroyed them.
The Pens are also as indestructible as a structure made by Man can be with 1940s bombing technology. They are still there in Lorient, too expensive to break up.Not enough bombers. And not enough time
The idea that America won the war simply by building ships faster than the enemy could sink them is an argument with several large holes in it;
1. In addition to losing ships you are losing cargo which must be replaced. In some instances the cargo is virtually irreplaceable. For example the planned expansion of the enormous refinery at Abadan was delayed on two separate occasions, each time by several months due to a U-boat sinking the ship carrying the equipment.
2. There was a world wide shortage of shipping throughout the entire was. If all you're new builds are going into the lifeline to Britain the other theaters are going without. The Bengal famine which claimed 2 to 3 million lives was blamed in part on the prioritization of shipping for war materials.
3. There was a shortage of tankers. Tankers are much harder to build than cargo ships. The Germans knew this and made them priority targets. Admiral King stupidly lost 50 priceless tankers in the first 6 months of the war which was 10% of the allied fleet. After that tankers were always in short supply. Without oil the whole show grinds to a halt.
4. When the Royal Navy defeated the U Boats in May 1943 the USN was able to cancel a large portion of their destroyer escort program. This freed shipyard capacity to build landing craft. The was a shortage of landing craft through the war. without the additional landing craft operations would have had to be postponed. I would guess that the advance thru the Pacific would have suffered.
5. People. War is actually fought by humans. Any organization consistently losing 10% of its strength falls to pieces pretty quickly. Everyone is a rookie. Efficiency plummets. Serving in the Merchant Marine was one of the most dangerous jobs in the war. I think only bomber crews and, ironically, U-boat crews had a higher mortality rate. Approximately 30,000 mariners died terrible deaths, blown to bits when you're ammunition cargo goes up, trapped below deck when your ore carrier sinks within a minute of being torpedoed, burned to death when your gasoline tanker catches fire, scalded by steam in the boiler room or simply freezing to death in the Atlantic watching the other ships sailing off because they can't stop for fear of suffering the same fate. I'm amazed that morale didn't crack as it was, but if the loss rate had continued I doubt you would find anyone willing to go on a suicide mission.
I believe the "turncoat" Frenchman who was in charge of the facility was assassinated by the Resistance. It turned out he was working for British intelligence.Why didn't the British bomb the U boat pens while they were being built on West Coast of France? If they had bombed around the time the cement was poured it would have destroyed them.
I've visited one in France, I agree they appear indestructible.The Pens are also as indestructible as a structure made by Man can be with 1940s bombing technology. They are still there in Lorient, too expensive to break up.
They did, but with such a small payload and so little subsequent bombing during construction that they didn't prevent their completion and after that there simply never was the consistent and focused effort to take them out/disrupt operations for good. The surrounding cities and civilian population took a heavy beating instead.Why didn't the British bomb the U boat pens while they were being built on West Coast of France? If they had bombed around the time the cement was poured it would have destroyed them.
SchnorkelUnless I am adding things up wrong the U-boats were sinking ships faster than they could be built in 1940 and 1941. The shipbuilders beat the U boats by about 17% in 1942 and it is probably true that it was in the last few months? Things may have been a bit on the iffy side at the end of 1942. Things looking better for the allies but not out of the woods yet, If Germans can get back to earlier success rates (or even close) then the surplus goes away.
The Allied introduction of new sensors and weapons means they keep the tactical initiative and the increase number of escorts just push that further.
The Germans failed to keep up the technical pace fell and behind quickly. A few extra AA guns or 20 tons more fuel oil is not really changing things by very much. They sat on the schnorkel for several years. They failed to enlarge the internal size of the boats for far too long and used those ridiculous deck storage tubes for reloads, which were pretty much useless in the North Atlantic, especially in winter. They kept a rather slow submerged speed, Under 8kts for the Type VII while the British T and U/V could make 9 and the S class could do 10kts. In a given amount of time (say 15 minutes) a boat that can do 10 kts has over 50% more "area" to disappear into than an 8 kt boat.
Please note I am not talking about new hull forms or type XXI subs.
The outcome of the Battle of the Atlantic was a lot harder to call in 1941 and most of 1942. Nov 1942 being a high point for the U-boats with 126 ships (802,160 tons) sunk. the next month saw the sinkings drop to about 1/2.
There is a difference between what we know now and what they knew then. Just a few really bad months in row would have meant real trouble but the Germans were not able to put 3 or more (or even two?) high scoring months together.
Schnorkel
The Germans weren't the only ones to sit on the Schnorkel and do nothing. Britain knew about it from at least late 1941 when the Dutch subs started to operate from Singapore and then Ceylon under British Command (see O-19 & O-20), if not from May 1940 when Dutch forces started arring in Britain. And the RN had apparently studied "underwater battery charging" pre-war. It was raised again in late 1942 when the A class were being designed. It was dropped on the ground that "submerged dieseling" had no operational value to British submarines "presumably because neither the German nor the Jpanese had effective airborne sea search radars to threaten submarines at night. Late in the war the the idea was revived, and plans were made for depot ships in the Far East to fit snorkels ('snorts' in British parlance) if necessary." (Friedman "British Submarines in Two World Wars")
And the Schnorkel had a major problem - it slowed the deployment speed of a U-boat from a decent surface cruising speed to a 6 knot at most crawl. So U-boats could spend less time in the operational area.
The Schnorchel - Technical pages - German U-boats of WWII - Kriegsmarine - uboat.net
The U-boat War in World War Two (Kriegsmarine, 1939-1945) and World War One (Kaiserliche Marine, 1914-1918) and the Allied efforts to counter the threat. Over 40.000 pages on the officers, the boats, technology and the Allied efforts to counter the U-boat threat.www.uboat.net
Underwater speed
First a correction. The only British S class with an underwater speed of 10 knots were the 12 pre-war built subs, completed 1934-38. The wartime boats of this class, ordered from Jan 1940 and completed from March 1942) could only do 9 knots submerged. And they could only run at that speed for 1.25 hours which only gets you about 11 miles away from your target before you have to surface to recharge your batteries, thereby making yourself a sitting target. And that assumes that you had a fully charged battery to begin with, which was unlikely given a submerged approach if the attack is in daylight. The RN were however happy to see that underwater speed reduced to 8 knots in the A class of 1943.
S class submerged endurance 120 nm @ 3 knots.
T class (1943 spec) 126 nm @2.25 knots
U class 120 nm @ 2 knots.
A US Gato could run underwater for 48 hours on a full battery charge. But that was at a speed of only 2 knots = 96 nm
Underwater speed was not nearly as important in WW2 as you seem to believe. All navies preferred to sneak away at low speed and increasing depth if necessary to remain undetected. That way they might be able to come back for a second bite at the cherry. A dived sub could not generally outrun a surface escort in most sea conditions. One reason why the RN escort classes had a minimum speed of 16 knots at the start of WW2, increasing later. Also a sub of that era travelling fast underwater generated a lot of noise, rendering it more detectable on ASDIC / Sonar. And running at high underwater speeds burned through the available battery power VERY fast (see above for the S class).
Type XXI
The purpose of the latger battery capacity and higher underwater speed of a Type XXI as the Germans saw it when it was being developed, was not to increase the max speed to allow escape after an attack, but to increase the underwater cruising speed, so reducing the transit times to the operating areas, and only surfacing if the weather was too bad to Schnorkel. Some comparitive date from Showell's "Hitler's 'Wonder' Boats". Type IXC v Type XXI Speed / range
Surface fast - 18.3knots / 5000 nautical miles v 15.6 knots / 5,100nm
Surface cruising - 10 knots / 13,450 nm v 10 knots / 15,500 nm
Submerged max - 7.3 knots v 17 knots
Submerged fast - 4 knots / 63 nm v 10 knots / 110 nm
Submerged cruising - 2 knots / 128nm v 5 knots / 340 nm.
This way they reckoned a Type XXI could travel 160 nm submerged each day at 7 knots with 4 hours schnorkelling and runnning the diesels burning just 2 tons of fuel while crossing the really dangerous Bay of Biscay. It could then cruise at 10 knots burning just 3.5 tons per day.
A Type IXC would need 12 days to travel submerged from Lorient 720 nm to 20 degrees west and 38 days on the surface to travel the 3,800 miles from 20 degrees west to Panama. A Type XXI would reduce that to 5 and 23 days respectively.
There were a number of technological innovations that helped aircraft sink or even just scare away U-boats.
First and most importantly, microwave radar, which could even spot U-boats in the dead of night and enable attacks under circumstances in which the U-boats could not spot the aircraft.
Second, better depth charges. Early in the war US depth charges could not be set to go off shallow enough to damage a U-boat that had only just submerged.
Third, the air dropped acoustic homing torpedo, which sank a U-boat on its very first action, also giving the USN the honor of being the very first military to use guided missiles in combat. The effort had the substantial additional benefit of showing the USN that there were people who could design, develop, and build torpedoes a hell of a lot better than those idiots at the USN-operated RI torpedo Factory.
Air-launched unguided rockets were useful as well, since they provided airplanes with a "broadside" comparable to a large warship. First successful use was by a RN Swordfish aircraft.
Magnetic Anomaly Detection gear enabled U-boats to be detected and attacked while they were still submerged. Some aircraft were fitted with rocket-propelled depth charges that fired so that the rockets slowed the bombs and enabled them to hit where the aircraft had been rather than in front of it, therefore closer to where the MAD gear had spotted it.
The USN's BAT radar guided fire and forget missile originally was designed to attack U-boats but by the time it became available the threat in the Atlantic had ended and so it was switched to attacking Japanese surface ships in the Pacific.
Not enough bombers, not enough powerful bombs, good flak, not enough good aiming by night.Why didn't the British bomb the U boat pens while they were being built on West Coast of France? If they had bombed around the time the cement was poured it would have destroyed them.
Both points had been proven in WW I. Just on a somewhat smaller scale.the more air patrols U-boats had to face in transit from their bases to the North Atlantic the more efficiency reductions, range also matters as the further offshore the U-boats were pushed reduced their efficiency, but patrolling the open ocean looking for U-boats without aids like code breaking is a waste, making convoys safer much better but again it is remarkable how few ships were lost from convoys in both absolute and percentage of loss terms until the second half of 1942.
Underwater speed was not nearly as important in WW2 as you seem to believe. All navies preferred to sneak away at low speed and increasing depth if necessary to remain undetected. That way they might be able to come back for a second bite at the cherry. A dived sub could not generally outrun a surface escort in most sea conditions. One reason why the RN escort classes had a minimum speed of 16 knots at the start of WW2, increasing later. Also a sub of that era travelling fast underwater generated a lot of noise, rendering it more detectable on ASDIC / Sonar. And running at high underwater speeds burned through the available battery power VERY fast (see above for the S class).