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What if the Germans used u-boats as a supply vessels in Sealion

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  • What if the Germans used u-boats as a supply vessels in Sealion

    What if after the first wave of German landings of Sealion, which according to war game experiments could have succeeded were followed by the Germans taking some ports and then using part of their U-boat fleet to provide supplies for the troops?
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  • #2
    Not possible. The channel is too shallow for submarines. It also wouldn`t have been very practical. The Germans would have probably done better if they supplied the troops the regular way and protected them with aircraft while the submarines would patrol the entrances to the channel.

    Also, unlike in WW1, the Germans didn`t have any mercantile submarines to execute such action. And even if they did, they probably wouldn`t have been able to carry much supplies.
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    • #3
      the best what if for Sealion is in that book "Invasion"... cant' remember the author now. but in anycase, the book makes a good - if optimistic - case.

      see, the problem for Sealion is twofolds:

      1.how to bring troops to south England

      2.how to keep them from beeign cut off

      for 1. Germany could do it. it could amass enough sea lift to carry troops, etc. to at least 4-5 divisions (2 divisions in a first wave) as well as paradrop 2-3 divisions. Seelöwe planned for this.

      for 2. that's depends on 1.air superiority (ok, that the luftwaffe could do) and 2.prevent the Royal Navy to operate in the channel / dover-calais area. and that's difficult to say the least as the German navy would not stand a chance and be decimated in a few days, and the german luftwaffe while powerfull and Stukas able to sink ships, would find it hard to avoid light and heavy British forces to sink the flow of ships... so not easy at all - even if, I'll grant that, the Royal Navy would suffer enourmous losses (mines, U-boote, stukas, et.) but what's that when the survival of the nation is at stake.

      however should german forces actually land and manage to advance 20-50 kim inland, it is my personal opinion that british morale would collapse, jsut as the french did, churchill or not, stiff upper lip or not - but that can't be proven of course - and fortunately did not happen.
      "Freedom cannot exist without discipline, self-discipline, and rights cannot exist without duties. Those who do not observe their duties do not deserve their rights."--Oriana Fallaci

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      • #4
        I would imagine the amount of supplies that the whole U-boat fleet could carry- even if the Channel were deep enough- would be insignificant compared to the needs of a land force. Also, the loading and unloading would be incredibly slow, as access is limited to the few hatches penetrating the pressure hull.

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        • #5
          Originally posted by jthomas View Post
          I would imagine the amount of supplies that the whole U-boat fleet could carry- even if the Channel were deep enough- would be insignificant compared to the needs of a land force. Also, the loading and unloading would be incredibly slow, as access is limited to the few hatches penetrating the pressure hull.
          1) Let's assume germans dedicate half of their u-boat fleet to transport duty - that is 28 boats.
          2) Let's assume that u-boat can carry ~100 tons at least and make on average 1 cruise a day (to Portsmouth, Brighton, Bexhill or Dover)
          That totals to 2800 tons a day. According to Manstein's memoir's ,6th army needed 550 tons of supplies daily in order stay operational - so ~5 times more plus some additional supply by air + occasional ship passing the british blockade seems to be enough.

          As to the slower rate of unloading - maybe some external hermetic temporary cargo bins could be attached to the subs. (obviously the subs would not be used for military attacks while transporting)
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          • #6
            Originally posted by Tom Phoenix View Post
            Not possible. The channel is too shallow for submarines. It also wouldn`t have been very practical. The Germans would have probably done better if they supplied the troops the regular way and protected them with aircraft while the submarines would patrol the entrances to the channel.

            Also, unlike in WW1, the Germans didn`t have any mercantile submarines to execute such action. And even if they did, they probably wouldn`t have been able to carry much supplies.
            That is simply not true - the channel is at least 60 - 45 meter deep completely sufficient for the submarines to swim and even evade attacks by submerging to a certain extent. There were cases in the war when submarines were evading attacks by submerging even in 30m deep sea!
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            • #7
              Originally posted by leopold View Post
              2) Let's assume that u-boat can carry ~100 tons at least and make on average 1 cruise a day (to Portsmouth, Brighton, Bexhill or Dover)
              That is a gross over estimate of the supply carrying capacity of a German submarine. Have you ever seen how tiny German submarines of WWII are? Something like 2 tons is more reasonable. The bulk of the supplies is a more limiting factor.

              Loading and unloading of the supplies down the tiny submarine hatches is very time consuming. Your subs won't make 1 trip per day.

              The British ports will not be in any kind of workable order (block ships and pre-planned demolitions) . You will have anchored subs, wallowing in the surf, transfering supplies to barges and little boats for the run to shore. Very difficult and time consuming.

              The subs will be very vulnerable to british aircraft and light naval units while on the surface.

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              • #8
                Why? Why not use the U-Boats for the job they were designed for- cutting off British trade- and use regular merchant ships to transport cargoes- the job they were designed to do? It's like using the King Tigers as resupply vehicles for the Battle of the Bulge. If you're really concerned about protecting your supply line from air or sea attack, it would make more sense to pour funds into more effective methods of camouflage, or perhaps to upgrade engines, than to use U-Boats.

                If, however, the decision was made, then you could get around the small capacity issue by towing loads, packed into waterproof crates and given just the right amount of buoyancy. Of course, it'd ruin the acoustic camouflage of the submarine- a little like towing a giant target behind you- not to mention slowing it down to a crawl. Not saying it's practical, but if it's a choice between finding a solution and being sent to Belsen, that's what I'd suggest.
                Fere libenter homines id quod volunt credunt

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                • #9
                  Originally posted by AdrianE View Post
                  That is a gross over estimate of the supply carrying capacity of a German submarine. Have you ever seen how tiny German submarines of WWII are? Something like 2 tons is more reasonable. The bulk of the supplies is a more limiting factor.

                  Loading and unloading of the supplies down the tiny submarine hatches is very time consuming. Your subs won't make 1 trip per day.

                  The British ports will not be in any kind of workable order (block ships and pre-planned demolitions) . You will have anchored subs, wallowing in the surf, transfering supplies to barges and little boats for the run to shore. Very difficult and time consuming.

                  The subs will be very vulnerable to british aircraft and light naval units while on the surface.
                  Well, why don't we look on the facts?
                  1) The german VIIB 'workhorse' submarine has displacement: surfaced 753 tons, submerged 857 tons , so it has reserve buyoance of 100 tons.
                  2) In addition to that it carries ~100 tons of fuel for 16000km range. but since it needs only less than 1000km for the cross channel trip that gives another ~90tons to spare.
                  3) Also it can do without ~14 tons of torpedoes+2.5 tons of deck gun shells and some additional crew supplies (food for long patrols ~10 tons or more)
                  Which gives a total close to 200 tons. I say - let's be conservative and make it 100. But 2tons ??? That's less than the schnaps supply for the crew!
                  As to the problems with the tiny hatches - read my previous post, it offers a simple solution - the cargo can be in a extarnaly attached to the hull and pressurized bays (maybe even towed after the sub and released if there's danger)
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                  • #10
                    Originally posted by robcraufurd View Post
                    Why? Why not use the U-Boats for the job they were designed for- cutting off British trade- and use regular merchant ships to transport cargoes- the job they were designed to do? It's like using the King Tigers as resupply vehicles for the Battle of the Bulge. If you're really concerned about protecting your supply line from air or sea attack, it would make more sense to pour funds into more effective methods of camouflage, or perhaps to upgrade engines, than to use U-Boats.
                    .
                    The whole idea is that there was no time for engine upgrade or fancy camouflage - but ony to do the invasion in 1940 ASAP with whatever is available.
                    All previously done research that I read about points to the fact, that allthough the first invasion wave could pass the channel successfully the following supply ships would be decimated and cuted off by the RN and RAF and that couldn't be helped agains nor by the LW nor by Kriegsmarine.
                    The comparison with the King Tigers is completely unappropriate since the tigers were using armour and not stealth.
                    Originally posted by robcraufurd View Post
                    If, however, the decision was made, then you could get around the small capacity issue by towing loads, packed into waterproof crates and given just the right amount of buoyancy. Of course, it'd ruin the acoustic camouflage of the submarine- a little like towing a giant target behind you- not to mention slowing it down to a crawl. Not saying it's practical, but if it's a choice between finding a solution and being sent to Belsen, that's what I'd suggest.
                    That seems like a good adjustment - besides the acoustic camouflage becomes important only when some RN destroyer comes close enough and at that point the cargo can be released so the sub swims to safety.
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                    • #11
                      Originally posted by leopold View Post
                      The whole idea is that there was no time for engine upgrade or fancy camouflage - but ony to do the invasion in 1940 ASAP with whatever is available.
                      In that case: standard merchant ships. They're not perfect, but they're a hell of a lot better than U-Boats.

                      All previously done research that I read about points to the fact, that allthough the first invasion wave could pass the channel successfully the following supply ships would be decimated and cuted off by the RN and RAF and that couldn't be helped agains nor by the LW nor by Kriegsmarine.
                      In this case, you simply have to bite the bullet, build up convoys and hope you don't lose too many ships on the way over. If you use your U-Boats to help protect the convoys, it hinders the Royal Navy far more than if they're just ploughing a furrow up and down the Channel, laden with whatever supplies you can manage to get into the boat.

                      The comparison with the King Tigers is completely unappropriate since the tigers were using armour and not stealth.
                      In both cases, you're taking a perfectly good piece of equipment and entirely wasting it by refusing to use it for the purpose it was meant for.

                      That seems like a good adjustment - besides the acoustic camouflage becomes important only when some RN destroyer comes close enough and at that point the cargo can be released so the sub swims to safety.
                      With the tiny amount of cargo you're going to be able to carry using the U-Boat method, I don't think you're going to want to release any of it.

                      Can I recommend something? Go out- tonight, tomorrow, whenever you get the change- and buy a copy of the film Das Boot. Go home, get a pencil and a piece of paper, and watch it. Make sure to make a note every time you see a space where they could put some cargo. Let us know the results, won't you?
                      Fere libenter homines id quod volunt credunt

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                      • #12
                        Originally posted by robcraufurd View Post
                        In that case: standard merchant ships. They're not perfect, but they're a hell of a lot better than U-Boats.
                        No they are not.
                        According to the wargames played by the british royal military academy they would have led to disaster for the germans.

                        Originally posted by robcraufurd View Post
                        In this case, you simply have to bite the bullet, build up convoys and hope you don't lose too many ships on the way over. If you use your U-Boats to help protect the convoys, it hinders the Royal Navy far more than if they're just ploughing a furrow up and down the Channel, laden with whatever supplies you can manage to get into the boat.
                        Absolutely not. This is complete joke. Submarines were created to attack convoys,not to protect them. They would have been decimated by the RN in the shallow waters of the channel. Only by evading the surface warships they could have survived.

                        Originally posted by robcraufurd View Post
                        In both cases, you're taking a perfectly good piece of equipment and entirely wasting it by refusing to use it for the purpose it was meant for.
                        The purpose of any war equipment is first of all to help win the war!
                        If we listen to your argument the germans shouldn't have used AA projectors to blind infantry in Poland, nor 88 AA guns to shrek Matildas in France, nor should have Romel placed a perfectly good fighter engines in trucks to simulate attacking tanks!

                        Can I recommend something? Read some books on WWII! You can probably find some under the "History" section.

                        Originally posted by robcraufurd View Post
                        With the tiny amount of cargo you're going to be able to carry using the U-Boat method, I don't think you're going to want to release any of it.
                        ?
                        I allready answered to the amount issue. Do me a favor and roll back your browser.
                        Originally posted by robcraufurd View Post
                        Can I recommend something? Go out- tonight, tomorrow, whenever you get the change- and buy a copy of the film Das Boot. Go home, get a pencil and a piece of paper, and watch it. Make sure to make a note every time you see a space where they could put some cargo. Let us know the results, won't you?
                        I've seen that movie, and again, roll back the browser, this time to your own post in which you propose solution to your own question.- Is it cold in Yorkshire? Are you using liquer to warm up?!?
                        If you believe, you receive.
                        If you doubt, you go without.

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                        • #13
                          Originally posted by leopold View Post
                          No they are not.
                          According to the wargames played by the british royal military academy they would have led to disaster for the germans.
                          Did the RMA ever play wargames in which the Germans used U-Boats? No? I wonder why. Merchant ships are designed to carry cargo from port to port: they are built for bulk transit. U-Boats are designed for sinking ships: they're small and relatively quick, and- most importantly- they're sealed tubes. What about the turnaround time? For the pitiful amount of cargo you deliver, you'd have to spend so much time recharging batteries and refilling air tanks that it'd hardly seem worth it.

                          Absolutely not. This is complete joke. Submarines were created to attack convoys,not to protect them. They would have been decimated by the RN in the shallow waters of the channel. Only by evading the surface warships they could have survived.
                          At least with my method, they might cause enough damage and chaos to give a convoy time to get through. If the U-Boats are just moving cargo, the Royal Navy will simply sweep the Channel clear. Or haven't you quite decided whether the Channel is dangerous or not? If not, may I remind you that there's a quite impressive indicator loop system in the Channel that would make life interesting for these slow-moving freighters of yours.

                          The purpose of any war equipment is first of all to help win the war!
                          If we listen to your argument the germans shouldn't have used AA projectors to blind infantry in Poland, nor 88 AA guns to shrek Matildas in France, nor should have Romel placed a perfectly good fighter engines in trucks to simulate attacking tanks!
                          Each of these, however, happened to be well-designed for their secondary purpose. Had you suggested using U-Boats to land spies on the coast, this would have been a reasonable use of them. Bulk cargo transit is not a realistic alternative use: like using an 88 to open your bottle, or a searchlight as a bedside lamp.

                          I've seen that movie,
                          So you watched Das Boot, the story of 40 men packed together like rats, living in claustrophobic conditions, breathing air rank with the sweat of their comrades, and thought, "I bet that ship could carry at least two hundred tons of cargo."

                          and again, roll back the browser, this time to your own post in which you propose solution to your own question.
                          I suggested that alternative because I felt sorry for you, coming on here every day and see the ideas which you've clearly spent so much time on being smacked around like a squash ball. I consider my alternative utterly impractical for a number of reasons. A U-Boat doing a maximum of 7 knots underwater will find it almost impossible to tow a cargo. Tides in the Channel would, in all likelihood, create a situation much like when a caravan gets caught in high cross-winds. The risk of the chain by which the cargo is connected to the submarine becoming ensnared in the propellor is too high.

                          Is it cold in Yorkshire? Are you using liquer to warm up?!?
                          So far, your two contributions to this forum have been a bridge across the Channel and U-Boats carrying supplies. If there's one of us drinking here, it sure as hell isn't me.
                          Fere libenter homines id quod volunt credunt

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                          • #14
                            Another Waste of Resources...

                            The U-boats could never have kept an invasion force supplied - they simply could not carry enough. The 100 tons figure per u-boat is ludicrous. They may have been able to carry the weight, but that amount of supplies could never have been fitted into a u-boat. The idea of strapping them externally is also ridiculous. You now have to waterproof all the supplies, and the vessel would have become less streamlined meaning it would be slower and make more noise. A blind man with a hearing impediment could have located them and caught them in his row boat!!

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                            • #15
                              Originally posted by robcraufurd View Post
                              Did the RMA ever play wargames in which the Germans used U-Boats? No? I wonder why.
                              Exactly, if they did the results of the wargame might have been different.

                              Originally posted by robcraufurd View Post
                              Merchant ships are designed to carry cargo from port to port: they are built for bulk transit. U-Boats are designed for sinking ships: they're small and relatively quick, and- most importantly- they're sealed tubes. What about the turnaround time? For the pitiful amount of cargo you deliver, you'd have to spend so much time recharging batteries and refilling air tanks that it'd hardly seem worth it.
                              The average crossing distance of the channel is ~120km, the VIIB's surface speed is ~30km/h, let's say it is slowed down by the cargo to 20km/h, lets say it needs to get submerged third of the way to avoid unpleasant destroyer siluets - that is still less than 10 hour trip one way. Add 2 hours to unload (mind you that the cargo may be towed as you offered) that's a one trip per 24 hours. And I have used only half of the submarine fleet.(28 boats)

                              Originally posted by robcraufurd View Post
                              At least with my method, they might cause enough damage and chaos to give a convoy time to get through.
                              Yes, damage they can cause, but not enough, according to the wargames. Do that browser rollbacking again!

                              Originally posted by robcraufurd View Post
                              If the U-Boats are just moving cargo, the Royal Navy will simply sweep the Channel clear.
                              Or haven't you quite decided whether the Channel is dangerous or not? If not, may I remind you that there's a quite impressive indicator loop system in the Channel that would make life interesting for these slow-moving freighters of yours.
                              Yeah right, the RN was quite often unable to find u-boats in the immediate surroundings of the allied convoys at that point - to speak about sweeping clear tens of thousands of square kilometers at that point is ridiculous.
                              The u-boats were vulnerable if confronting warships directly - in such case the Channel is definetly dangerous for them.
                              In case of them evading confrontation it's relatively safe - as proven by many cases of u-boats patrolling the channel with enormous Allied superiority.

                              Originally posted by robcraufurd View Post
                              Each of these, however, happened to be well-designed for their secondary purpose. Had you suggested using U-Boats to land spies on the coast, this would have been a reasonable use of them. Bulk cargo transit is not a realistic alternative use: like using an 88 to open your bottle, or a searchlight as a bedside lamp.
                              Many of the human inventions were done by using something designed for one purpose in another context by adapting it.
                              If you cannot accept the facts it only shows some type of internal limitation inside your brain hardware.

                              Originally posted by robcraufurd View Post
                              So you watched Das Boot, the story of 40 men packed together like rats, living in claustrophobic conditions, breathing air rank with the sweat of their comrades, and thought, "I bet that ship could carry at least two hundred tons of cargo."
                              I watched 'Das Boot', and I thought : "these u-boats were tough." I also thought " These sailors sure knew how to improvise"
                              I also watched a documentary movie about project "Prüfstand XII" - I suggest you faimiliarize youself with it and keep in mind that the target was to cross the Atlantic and I am talking only about the channel.

                              Originally posted by robcraufurd View Post
                              I suggested that alternative because I felt sorry for you, coming on here every day and see the ideas which you've clearly spent so much time on being smacked around like a squash ball.
                              If so, than you made a good suggestion for completely inadequate reason.
                              However don't feel too proud of yourself yet. - the suggestion has been around for several decades.

                              Originally posted by robcraufurd View Post
                              I consider my alternative utterly impractical for a number of reasons. A U-Boat doing a maximum of 7 knots underwater will find it almost impossible to tow a cargo. Tides in the Channel would, in all likelihood, create a situation much like when a caravan gets caught in high cross-winds. The risk of the chain by which the cargo is connected to the submarine becoming ensnared in the propellor is too high.
                              Again, these problems were addressed in "Prüfstand XII" and found manageble in much tougher situation of the atlantic.

                              Originally posted by robcraufurd View Post
                              So far, your two contributions to this forum have been a bridge across the Channel and U-Boats carrying supplies. If there's one of us drinking here, it sure as hell isn't me.
                              So far, there were several hundred reads of my 2 threads, so the issue may be interesting to someone else even if you disagree.
                              If you believe, you receive.
                              If you doubt, you go without.

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