110

The English Channel is too shallow in many places to be safe for U-Boats. The operating depth for the Type VII submarine was up to 230 meters, while the English Channel is only 45 meters deep in many places. In a confined channel such as this a U-Boat's only defence against air and surface attack is to dive quickly, to an unpredictable (but deep) depth. ...


110

SHORT ANSWER The short answer is that this was considered by the British to be the simplest and most economical way of disposing of the German U-boat fleet. The decision to sink the U-boats rather than salvage or divide them up among the ‘Big Three’ (the UK, the US, the Soviet Union) was part of the Potsdam Agreement (August 1945). It was agreed that the ...


55

In addition to the other answers, WWII submarines were primarily surface vessels which could submerge for combat. They had very limited speed, visibility, and battery range underwater. The batteries took a long time to recharge, and they had to be on the surface for it. Limited visibility made it difficult to spot their prey. Limited speed limited their ...


47

The options that submarines had were, in practice, limited to sinking Allied shipping and leaving the area as quickly as possible to avoid detection. U-boats had a disadvantage compared to destroyers (not to mention airplanes) when it came to speed, especially when submerged. They were also poorly equipped to fight surface warships as their deck guns were no ...


41

1) Things have changed with the advent of nuclear-powered submarines since the 1960's, but WW2 submarines were small - and had a small crew. Even the largest U-boats, the Type VII and it's cousins, were only 67m (220 ft) long, and with a deck only about 10 feet wide for most of the length. They are quite a bit smaller than even the smallest destroyers, and ...


35

To prevent torpedoes from becoming a navigational hazard in the event of a miss the 1907 Hague Convention VIII had a section on mines. Once a torpedo was out of fuel it was buoyant. Therefore any torpedo that missed its mark (which was a lot!) would become a random and deadly hazard to navigation. The easiest solution to this was to detonate the torps at ...


35

Other answers have explained why basing the U-boats in the English Channel was a poor idea for the Germans. Here's what actually happened: In spring 1944, most of the U-boats were based in the ports of the Bay of Biscay, where they had easier access to the North Atlantic than they would had they been based in the Channel ports. On June 6th, all seaworthy U-...


34

According to a 1999 article by Mark A. Bradley in Proceedings, the U.S. Naval Institute's professional journal ("Why They Called the Scorpion "Scrapiron," July 1998), on May 20, 1968, the Scorpion was ordered to intercept a Soviet flotilla near the Azores that included one Echo-II-class nuclear-propelled submarine, a submarine rescue vessel, two ...


33

Not a "hard" answer, but more than a comment. The German Type VIIC was the most common type of U-boat, but with limited range and endurance. Its fuel bunkers could keep the diesels going for 20-35 days non-stop at a speed of 10-12 knots (own calculation, using the various "range X at speed Y" data points given here and here). The Type IXC/40 would, by the ...


33

The general answer, "It's easier to sink than capture," has already been given. Now consider the specifics. In the early stages of the war: In two words - "Prize crew". Having captured a ship, it is necessary to plant on it a sufficiently large crew to either operate it by themselves or to oversee the original crew and keep them in line. This means the ...


30

Before I retired, I was an electrical engineer and rode a number of submarines in order to test sonar systems that my company had installed. Normally we stayed on board for the entire trip which was usually 4-5 days. On one occasion, a supercharger on one of the two engines literally exploded. The submarine had to immediately surface and we proceeded to ...


28

In wartime lookouts were sometimes deliberately left on deck when the submarine came under attack and crash-dived. One such incident was the German submarine U-68 : Suddenly, the siren was sounded for a crash dive. The survivor helped secure the 3.7 cm. gun and then noticed that one of the gunners had been wounded. He struggled forward with the wounded ...


22

The reason is simple: nobody wants an uncontrolled explosive device floating around. You yourself, or someone else, other then your enemy may later accidentally hit it. For the same reasons all anti-aircraft shells explode at the end of their trajectory: who knows what they may hit on the ground.


21

The allies blockaded Germany in WW2. Even if the Kriegsmarine could capture ships (and Orangesandlemons's answer correctly explains that this was unlikely) - there was no way to actually bring them to German ports. The British navy would just re-capture/sink them on the way.


21

An anecdotal addition to the excellent points in the existing answer: At the end of WWII, my mother was discharged from the ATS before my father was discharged from the army, so she got a job as bookkeeper to a scrap metal merchant operating near the base where they were stationed. Her boss was the winning bidder on a contract to scrap some damaged, ...


18

When German Raiders Did Use Captured Ships In addition to the other answers, there were a few examples of German raiders sending captured ships back early in the war. These were auxiliary cruisers, fast, long ranged merchantmen fitted with enough hidden weapons to overpower lone merchant ships. If they encountered a warship they'd disguise themselves as a ...


16

An underwater explosion creates turbulence in the water, creates bubbles, and perhaps mixes waters of varying temperatures or salinities, all of which affect the refraction of sound in water. For ASDIC to work best the water should be homogeneous, with laminar flow only.


14

By 1944, US submarines were very experienced and had ironed out their problems with their equipment. They had been conducting an extremely successful offensive campaign against Japanese shipping since the beginning of 1942, and unlike German U-boats, had not taken heavy losses and so gained in experience. They had fixed the flaws in the Mark 14 torpedo ...


14

WWII submarines making a journey of any length would run on diesels on the surface during the day, if there were reasonable odds of not being sighted. Rapid ("crash") diving was a very important tactic for them, and the ability to do it quickly was an important factor in both sub design and crew training. If they were travelling through a contested area ...


14

Why yes, indeed. I count, fast and dirty, at least 37 Japanese destroyers sunk by US submarines in WW2. A good place to look is the Joint Army Navy Assessment Committee though it requires a little perseverance. At least 9 US destroyers or destroyer escorts were sunk by German submarines and at least 8 sunk by Japanese submarines (including midgets and ...


13

Your expectation "does that not mean that any echos should die down more quickly" is largely inaccurate for that portion of the explosive energy directed vertically, or near vertically. Precisely because sound travels so much faster in water than air, and that water is much denser than air, the transmission coefficient from water to air for sound is very ...


13

Yes. There was some controversy about that. But it was low-key and even time-delayed for a fait-accompli. The government would have been restricted to make such a deal, and violated it in secret. The press found out anyway. 'Twas one-time-only', as they promised then until the next deal of that kind came along. If it was in public debate, then at that time a ...


12

The first submarine was developed by Cornelis Drebbel, a Dutchman, in 1620. The first submarine that went into action was the Turtle, developed by David Bushnell in 1776. It went in action, but never sank a ship. The first submarine to do that was the Hunley in 1864. (With the loss of the submarine, and its entire crew). The first modern submarine that ...


11

Submarines are most effective against unarmed merchantmen, preferably on the open sea with few or no escort vessels, and fewer aircraft in the general area. The English Channel was "covered" by the greatest concentration of Allied warships and aircraft. An all-out battle in the confines of the English Channel would not have allowed the subs sufficient (...


11

You are really talking not about seaworthiness, but about stability. "Together with the Hague Visby Rules, the common law provides that the concept of "seaworthiness" covers: the ship, its equipment and supplies, the crew, the vessel's suitability for the particular cargo and its suitability for the particular voyage or for particular ports". If the physics ...


10

The old naval term 'hulk' is applied to vessels that are no longer in sea service but still perform some support role in port. So in the case of a "battery charging hulk", it's used to provide additional battery charging facilities for the other diesel-electric submarines. In most cases, hulks are stripped of any items that are not essential to their new ...


10

How do you imagine that's gonna to happen? You are talking about convoys, not single and unarmed merchant ships etc. which have been in fact captured by German raiders like Schwern answered in detail. A British convoy is surrounded by destroyers/frigates and several columns of ships transporting goods, the most valuable (most volume and expensive cargo) in ...


9

For very practical reasons, these pure leisure activities did not take place close to enemy shores, or in climates that were just too uninviting. Close to the "Golden West" of American targets airplanes would be just much too quick to approach and the highest latitudes just too cold and often just too windy to be of any joy. But the crews did try to enjoy ...


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