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

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  • leopold
    replied
    Yes, my supply figures were intended for the first wave. (~100 000 troops)
    hence the required 3000 tons per day.

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  • Andy H
    replied
    The only figure that comes close to yours is an intial 4500 being landed in the first wave. After that we get figures anywhere from 50-75,000 horses landing on the following waves.

    Now we have a figure somewhere between 500-750tons per day, and that's a big chunk of your stated 3000tons. Obviously some could be offset by natural grazing, but its still a headache to supply, and what a fire risk on a submarine.

    Regards
    Last edited by Andy H; 11 Mar 07, 22:20.

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  • Andy H
    replied
    Your figures concerning the horses a wrong, and I haven't got time at the moment, but I'll get back to you later today with the actual figures. Also its not the weight that's the problem but the size of actual food bails. A 10kg bail of hay takes up a lot more room than a 10kg box of nails for example.

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  • leopold
    replied
    Originally posted by Andy H View Post
    Well I've come across some rather far fetched ideas and 'facts' concerning Seelowe in my time but this one sits at the top.

    Just because a nation has X submarines in commision, doesn't then mean that X submarines are available for operations. The Germans in there proposed invasion plans, had to utilize U-Boats from the training schools. Some of those boats couldn't even dive because of problems with there rubber seals. There was also a rubber shortage at this time due to the other priorities for Seelowe. Others had worn engines that precluded them reaching anything near there proposed speeds.

    Somebody mentioned using Italian submarines Well anybody who knows anything about Italian submarines (available historically) will realise how silly this proposal was.

    I've skimmed through many of the pages but has anybody mentioned how fodder for the horses was to be transported in the U-Boats?

    Regards
    Historically there were supposed to be around 5000 horses in Sealion, each horse eats ~10 kg a day so the daily supply for them would be 50 tons - relatively insignificant compared to the 3000 tons a day overall requirement.

    As to the rest of your arguments - I've addressed the subs availability issue from the start by defining that there would be ~50% - 70% of the available uboats used.
    As to the italian subs - why not? They would not have to engage.
    Besides there were some good successes of italian subs against the british so I wouldn't dismiss a 25 subs fleet just like that.
    But finally as I said - I have a better 'what if' idea in which the u-boat supply may be part of - maybe I'll post a separate thread if I have some time.

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  • Andy H
    replied
    Well I've come across some rather far fetched ideas and 'facts' concerning Seelowe in my time but this one sits at the top.

    Just because a nation has X submarines in commision, doesn't then mean that X submarines are available for operations. The Germans in there proposed invasion plans, had to utilize U-Boats from the training schools. Some of those boats couldn't even dive because of problems with there rubber seals. There was also a rubber shortage at this time due to the other priorities for Seelowe. Others had worn engines that precluded them reaching anything near there proposed speeds.

    Somebody mentioned using Italian submarines Well anybody who knows anything about Italian submarines (available historically) will realise how silly this proposal was.

    I've skimmed through many of the pages but has anybody mentioned how fodder for the horses was to be transported in the U-Boats?

    Regards

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  • leopold
    replied
    I have some additional ideas about the Sealion, which (theoretically in the 'what if' universe) could have made it much more viable.
    So solving only the supply with the u-boats is too small part of the whole.
    I guess if someone here disagreed we'd have to agree to disagree...

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  • robcraufurd
    replied
    Originally posted by leopold View Post
    Torpedoes are quite hydrodynamic - actually much more than deck guns (for instance)
    Ah, so you're just strapping the thing to the U-Boat, then when you arrive at the coast getting a couple of lads to cut it loose and dump it in the water. A procedure that'll take time, assuming of course they don't open the hatch and find it's broken loose on the trip over.

    That's why I suggested a switch - it will allow the speed to be adjusted to diver's convenience.
    If it's just a switch, then the first time the poor bugger switches it on he's probably going to fall off as the thing races away- smooth, wet metal, remember? You'd need some sort of throttle system, the installing of which would take a lot of time, considering that if the entire thing isn't waterproof it'll simply short out.

    I said OK, not sterling success.
    The british did OK in the evacuation - nobody disputes that. Which leads to questioning would they be equally effective in evacuating themselves to Canada? - if need arises...
    Somehow, I doubt the need would have arisen.

    The extra practise comes from the Kanelkampf - 70000 tons of shipping sunk.
    The limited success that the Kanalkampf enjoys is, in part, due to the fact that the British see the attacks as harassment and refuse to commit in strength. However, the Luftwaffe don't exactly cover themselves in glory: 33 merchant ships in a month?

    Look at the attack on convoy CW9. 20 merchant ships set off: 2 are sunk by E-Boats, one collides with another and sinks and ten reach harbour. To achieve the destruction of seven colliers, the Luftwaffe loses 31 planes, including 15 Stukas: the RAF lose 19, including a Blenheim bomber.

    But I allready addressed that - if RN destroyers are ambushing at some point the Germans would know it and deploy at another point where there are no destroyers. If RN decide to take all the shoreline they'd be streched too thin and can be attacked at some point.
    How would the Germans know where the destroyers are going to be? They haven't broken British codes, and naval radar isn't going to tell them what type of ship they're looking at. It'll be guesswork at best, with whatever information might get through the tangled bureaucratic organisation being second-hand and out-of-date. Also, just because the Germans plan an 80-mine invasion doesn't mean that they're going to establish themselves effectively along its full length. They'll have a handful of available beaches for resupply, which the RN and RAF will be attacking almost continually.

    If the destroyer is searching for a sub in the Dover area it would be raining a heavy caliber shells in the tens of meters proximity of the ship's hull.
    It would be a matter of time before any destroyer captain stubborn or suicidal enough to stay there long enough would get a nice direct hit.
    "Tens of metres"? "Raining" shells, considering time to reload and train on a target doing around 30 knots? I think you're being a bit optimistic. Remember how ineffective they are against merchant shipping. The continual lack of success would probably lead to an order to stop wasting ammunition after a while, reserving their shells for slower-moving battleships.

    Couple of such occasions and the any destroyer fleet would be withdrawn from the straits.
    So the invasion of Britain is going on, and the Royal Navy's destroyers are sat out of range, doing nothing. There's no point keeping your ships nice and shiny while your country is being invaded and occupied.

    Remember that the british couldn't even know that the u-boats are so important for the supply. They would concentrate their efforts against surface transports.
    The destroyers are going to be patrolling the Channel. They'll be using ASDIC at least intermittently, otherwise they might fall prey to a sneak attack. Sooner or later, they're going to force one of the boats to the surface, or snap the cable when destroying one and allow the cargo to float up, or the RAF or intelligence operatives will spot the unloading procedure. This isn't going to remain a secret forever.

    The amunition for the Calais based Naval guns wasn't an issue at all.
    When you're firing at the occasional convoy, perhaps. When you're almost continually shelling fast-moving destroyers, sooner or later the ammunition is going to run out. Manufacturing heavy naval shells is taking resources- fuses, steel, propellant- away from lighter artillery. Considering how slowly the German economy picks up the slack when the Russian campaign starts to bite hard, I'd be concerned about this.

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  • leopold
    replied
    Originally posted by robcraufurd View Post
    With all the attendant problems of acoustic signature, drag, et cetera.
    Torpedoes are quite hydrodynamic - actually much more than deck guns (for instance)

    Originally posted by robcraufurd View Post
    These torpedoes travel at 30 knots. It's the equivalent of clinging on to a moving car. Furthermore, Italian manned torpedoes are drastically different from normal torpedoes.
    That's why I suggested a switch - it will allow the speed to be adjusted to diver's convenience.

    Originally posted by robcraufurd View Post
    OK results? Over a third of a million troops are evacuated from the pocket- a pocket that Goering pledged to exterminate with air power. Hardly a sterling success. Where exactly does the extra practice and tactical development come from, between May and September 1940? Are the Luftwaffe not slightly busy fighting the Battle of Britain, rather than developing effective anti-ship tactics?
    I said OK, not sterling success.
    The british did OK in the evacuation - nobody disputes that. Which leads to questioning would they be equally effective in evacuating themselves to Canada? - if need arises...
    The extra practise comes from the Kanelkampf - 70000 tons of shipping sunk.


    Originally posted by robcraufurd View Post
    Doesn't matter. The U-Boats have to come right up to the British shoreline, which means that the destroyers can essentially wait for them wherever they like.
    But I allready addressed that - if RN destroyers are ambushing at some point the Germans would know it and deploy at another point where there are no destroyers. If RN decide to take all the shoreline they'd be streched too thin and can be attacked at some point.

    Originally posted by robcraufurd View Post
    How do you compromise its ability to patrol for subs? It's not even worth opening fire on the destroyer, because you know that unless the first shot is a dead-on hit it's just going to move away. All you're doing is wasting ammunition- ammunition which could have been better used across the Channel, were there a way of getting it there.
    If the destroyer is searching for a sub in the Dover area it would be raining a heavy caliber shells in the tens of meters proximity of the ship's hull.
    It would be a matter of time before any destroyer captain stubborn or suicidal enough to stay there long enough would get a nice direct hit.
    Couple of such occasions and the any destroyer fleet would be withdrawn from the straits.
    Remember that the british couldn't even know that the u-boats are so important for the supply. They would concentrate their efforts against surface transports.

    The amunition for the Calais based Naval guns wasn't an issue at all.

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  • robcraufurd
    replied
    Originally posted by leopold View Post
    Obvioulsy the torpedo will not be fired through the tube - allthough theoreticaly there could be some hook mechanism installed in front of the tube, but I think the best and simplest way would have been to attach the torpedo to the deck and to surface briefly in order to shoot it.
    With all the attendant problems of acoustic signature, drag, et cetera.

    As to the possibility of manning it - since those were battery powered torpedoes they could have external switch installed and some handles for the guy to grasp (if italians did it , why not the germans) - so that willl be a short (15 minute ) trip to the shore where the guy will anchore the rope and await some assistance from shore party.
    These torpedoes travel at 30 knots. It's the equivalent of clinging on to a moving car. Furthermore, Italian manned torpedoes are drastically different from normal torpedoes.

    They were , but don't forget that for the LW pilots this was somewhat unexpected mission that they weren't prepared for and they still got OK results. The whole RAF also was summoned with the sole purpose of interfering.
    By the time of the invasion those bomber pilots had much more experience and better tactics in ship attacks.
    OK results? Over a third of a million troops are evacuated from the pocket- a pocket that Goering pledged to exterminate with air power. Hardly a sterling success. Where exactly does the extra practice and tactical development come from, between May and September 1940? Are the Luftwaffe not slightly busy fighting the Battle of Britain, rather than developing effective anti-ship tactics?

    Actually detecting them at that time was a problem. Even during the day the first successful detection of a sub was in december 1940 and I strongly suspect that they simply saw it from above and then suddenly thought : wow! it's on the radar too!
    And you don't think that the fact that there aren't any U-Boats in the Channel at this point had anything to do with the length of time for a successful detection? Furthermore, as I said, the radar is ineffective within close range: what you're describing simply could not happen.

    It also was constantly giving false echoes from the sea and shore ... no wonder that the first actual night detection happened at the end of 1941.
    First SUCCESSFUL night ATTACK. Not just a detection: U-451 sunk near Tangiers with one survivor.

    As to the collaboration with the destroyers .. theoretically it's possible - on practise I couldn't dig up any evidence of any successful operations of that kind prior to 1941
    Oddly enough, I can't find any evidence of successful amphibious operations using canal barges. I guess theoretically it's possible...

    You are assuming that somehow u-boats attract german shells, while destroyers repell them.. how did that happen?
    If they aim at the destroyer using radar and miss it, what is the probability of hitting precisely a object 64x5 meter in 1-2 km radius of it?
    It's zero for all practical purposes.
    Since the chance of hitting the destroyer is zero for all pratical purposes, I'd say that both the destroyer and the U-Boat have roughly the same chance of taking damage from this indiscriminate shelling. A destroyer struck by a shell has a chance of surviving: a submerged U-Boat may not be so lucky.

    My guess is that the destroyer will not come chasing u-boat more than the middle of the channel - if at all.
    Those naval guns become exponentialy more precise the closer you get.
    Doesn't matter. The U-Boats have to come right up to the British shoreline, which means that the destroyers can essentially wait for them wherever they like.

    I agree that even with radar assistance it was very dificult to hit a fast moving ship 30 km away ... but to drive it off the area and compromise it's ability to efectively patrol for subs is entirely different matter...
    How do you compromise its ability to patrol for subs? It's not even worth opening fire on the destroyer, because you know that unless the first shot is a dead-on hit it's just going to move away. All you're doing is wasting ammunition- ammunition which could have been better used across the Channel, were there a way of getting it there.

    It's not like the channel is in the other side of the world! These bombers are actually crossing it when they go to missions.
    Why not drop by and say hello? (At least drop something ...)
    Scene: The base of II Fliegerkorps, Sturzkampfgeschwader 1, in the Pas de Calais. September 30th, 1940
    Oberst Schulze is at his desk as Leutnant Schmidt enters, escorted by two military policemen.

    SCHULZE: Leutnant Schmidt, you appear to have returned rather sooner than I expected.
    SCHMIDT: Ja, Herr Oberst.
    SCHULZE: Shouldn't you be bombing British artillery positions around Ashford?
    SCHMIDT: You see, Herr Oberst, I was crossing the Channel on my way to perform the mission when I spotted a British destroyer. So I swooped down on it, and I dropped my bombs, and strafed it with my cannon- although I couldn't get too close, mind, since its flak guns were firing at me.
    SCHULZE: And did you sink it?
    SCHMIDT: Well, there was quite a lot of flak, and the sun was in my eyes...
    SCHULZE: So you didn't sink it.
    SCHMIDT: Well, no.
    [pause]
    SCHMIDT: But I scared them pretty well. This one guy seemed rather red in the face- I think he might have been having a heart attack...
    SCHULZE: So what happened then?
    SCHMIDT: Well, I'd used up all my bombs on the destroyer, and there didn't seem much point wasting petrol, so I came back.
    SCHULZE: I see.
    Schulze shuffles papers on his desk
    SCHULZE: Ordinarily, the procedure for this would be relatively simple: Court-martial for disobeying orders, followed by military prison. However, it appears that the rest of your flight was intercepted by Spitfires over Hythe and downed, which incidentally makes you our last remaining pilot: I am, therefore, promoting you. Congratulations, Oberleutnant Schmidt.
    SCHMIDT: Thank you, sir.
    SCHULZE: And now, I am instructed to give you a top-secret mission that will end the war. You shall fly, under the cover of the Britisher radar, to London, where you will avoid the flak and barrage balloons and drop a bomb on Ten Downing Street. Thus, the arch-imperialist Churchill will perish, and the cowardly Britishers will sue for peace.
    SCHMIDT: Heil Hitler!
    The curtain falls

    BTW italians did provide some planes and pilots to the battle of britain effort... can't remember the numbers.
    There's a reason they're not remembered. They drop about 54 tons of bombs during the whole thing, frequently flying so high that the AA guns don't even bother to open fire. Their fighters are biplanes, with open cockpits that allow the pilots to catch frostbite. Those who are captured don't seem particularly unhappy about it, and I don't blame them.

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  • leopold
    replied
    Originally posted by robcraufurd View Post
    It might be nice to have, were there a way of attaching a cable to the torpedo. You can only attach it before the torpedo's fired, so you have two choices: take the cable up through the sub to fix it to the cargo, in which case you've just neatly tied the sub into the chain, or have someone crawl out through the torpedo tube and clamber across the sub's hull. In either case, the torpedo will probably just float off the beach as the tide goes out, and the Germans will be left searching for nothing. As for manned torpedoes, I suspect they may well be slightly different to the torpedoes U-Boats were made to fire.
    Obvioulsy the torpedo will not be fired through the tube - allthough theoreticaly there could be some hook mechanism installed in front of the tube, but I think the best and simplest way would have been to attach the torpedo to the deck and to surface briefly in order to shoot it.
    As to the possibility of manning it - since those were battery powered torpedoes they could have external switch installed and some handles for the guy to grasp (if italians did it , why not the germans) - so that willl be a short (15 minute ) trip to the shore where the guy will anchore the rope and await some assistance from shore party.


    Originally posted by robcraufurd View Post
    Wow, that's a real achievement. Oh, wait. How many of those ships sunk are close to the shore, without room to manoeuvre? In fact, aren't all these ships busy supporting an evacuation?
    They were , but don't forget that for the LW pilots this was somewhat unexpected mission that they weren't prepared for and they still got OK results. The whole RAF also was summoned with the sole purpose of interfering.
    By the time of the invasion those bomber pilots had much more experience and better tactics in ship attacks.

    Originally posted by robcraufurd View Post
    No, the first successful night ATTACK is on the 21st. Detecting them's not a problem, but since the radar doesn't work within a few miles of the target, spotting them once you're close in is much harder. Of course, when you've got destroyer patrols within such close proximity, Coastal Command can just pass the information they gather on to the Royal Navy.
    Actually detecting them at that time was a problem. Even during the day the first successful detection of a sub was in december 1940 and I strongly suspect that they simply saw it from above and then suddenly thought : wow! it's on the radar too!
    Until the magnetron was widely used the u-boat detection by airborne radar was not reliable. Even when detecting something the position was with 1 mile error - how good is that.
    It means that it can detect a sub only if there are no ships at least a mile around it.
    It also was constantly giving false echoes from the sea and shore ... no wonder that the first actual night detection happened at the end of 1941.

    As to the collaboration with the destroyers .. theoretically it's possible - on practise I couldn't dig up any evidence of any successful operations of that kind prior to 1941

    Originally posted by robcraufurd View Post
    This sub is presumably within visual range, since you think ASDIC is useless. Do you think visual range for spotting the sub is greater than the margin of error for the naval guns or German artillery? If the sub's heading for the French coast, you better hope that the coastal artillery doesn't under-shoot, since an 1800lb projectile could really ruin a U-boat's day.
    You are assuming that somehow u-boats attract german shells, while destroyers repell them.. how did that happen?
    If they aim at the destroyer using radar and miss it, what is the probability of hitting precisely a object 64x5 meter in 1-2 km radius of it?
    It's zero for all practical purposes.
    My guess is that the destroyer will not come chasing u-boat more than the middle of the channel - if at all.
    Those naval guns become exponentialy more precise the closer you get.

    Originally posted by robcraufurd View Post
    What air bombing? Seriously, where are all these spare planes coming from? Are the Italians supplying them, as well as all their submarines?
    It's not like the channel is in the other side of the world! These bombers are actually crossing it when they go to missions.
    Why not drop by and say hello? (At least drop something ...)
    BTW italians did provide some planes and pilots to the battle of britain effort... can't remember the numbers.

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  • leopold
    replied
    Ok.
    I did some research as to the availability of 1m thick pipes at the time we are talking about.
    Since I couldn't dig up precise historical data of the production of 1m wide pipes during WWII I had to do some indirect assumptions:
    Today the total steel production of Europe (yearly) is :
    186Mton
    out of that 30 Mton is in the form of various pipes
    out of these 10% are big pipes (more than 40 cm wide) so I assume that ~5% are more than 1 meter wide. ==> there are 1.5 Mton of these produced today yearly.
    That totals to ~0.8% of the total steel production in europe.
    My assumption is that the ratio of amount steel / big pipes stayed more or less the same since the war. (If someone has more accurate data please share..)
    After the Germany occupied France the total steel production of all it's occupied teritory was ~40Mton from which 0.8% would be 320000 tons of steel in 1 meter pipes.
    That is 876 tons per day. Given our previous calculation of 4.5ton steel pipe = 11 ton cargo that gives us 2141 ton of cargo carried in tubes per day.
    However since there were more than 2 months of preparation and probably some available stock of pipes + some higher priority could be placed in big pipe producing factories the 3000 ton figure per day sounds completely realistic (at least for the first 3-4 months of the invasion)

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  • leopold
    replied
    Originally posted by robcraufurd View Post
    Like I said, look at Operation Cerberus. The South Foreland battery- 3 miles northeast of Dover, where the Channel's at its narrowest, opens fire at a fleet travelling at around 27 knots. Said fleet consists of the Scharnhorst, Gneisenau, Prinz Eugen and six destroyers- far larger than any anti-submarine patrol. The radar system on the guns has been upgraded, but out of 33 shots none hit their target.

    Radar-directed coastal artillery is of little use against capital ships, and of even less against destroyers. The only example of a ship being sunk by any form of coastal artillery that I've found is the Blucher in the Norway campaign, but that's at point-blank range against a ship that's barely moving.
    .... continued ... I agree that even with radar assistance it was very dificult to hit a fast moving ship 30 km away ... but to drive it off the area and compromise it's ability to efectively patrol for subs is entirely different matter...

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  • leopold
    replied
    Originally posted by robcraufurd View Post
    Like I said, look at Operation Cerberus. The South Foreland battery- 3 miles northeast of Dover, where the Channel's at its narrowest, opens fire at a fleet travelling at around 27 knots. Said fleet consists of the Scharnhorst, Gneisenau, Prinz Eugen and six destroyers- far larger than any anti-submarine patrol. The radar system on the guns has been upgraded, but out of 33 shots none hit their target.

    Radar-directed coastal artillery is of little use against capital ships, and of even less against destroyers. The only example of a ship being sunk by any form of coastal artillery that I've found is the Blucher in the Norway campaign, but that's at point-blank range against a ship that's barely moving.
    Hmm, you are telling that story only partially - this operation took many weeks of preparation on the german side, during which the germans gradually increased the power of their radar jammers - thus making the english radars useless. Also the ships passed at maximum speed as close to the French side as possible - they weren't circling around poking the water with asdic at 15 knots.
    The english guy responsible for the radars (forgot the name ) was suspicious of something 'fishy' prior to the operation ,but his superiors ignored him..

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  • robcraufurd
    replied
    Originally posted by leopold View Post
    Was there any artillery shooting from the french coast in that simulation? (I'm currenlty looking for this game so meanwhile your comments will be appreciated)
    How would it affect this balance considering that it was radar directed?
    How some additional english coast based artillery could have affected it?
    Like I said, look at Operation Cerberus. The South Foreland battery- 3 miles northeast of Dover, where the Channel's at its narrowest, opens fire at a fleet travelling at around 27 knots. Said fleet consists of the Scharnhorst, Gneisenau, Prinz Eugen and six destroyers- far larger than any anti-submarine patrol. The radar system on the guns has been upgraded, but out of 33 shots none hit their target.

    Radar-directed coastal artillery is of little use against capital ships, and of even less against destroyers. The only example of a ship being sunk by any form of coastal artillery that I've found is the Blucher in the Norway campaign, but that's at point-blank range against a ship that's barely moving.

    Leave a comment:


  • Carl Schwamberg
    replied
    Purist...I've lost my faith. You posted a statement without properly reserching & bullet proofing it first! Proof or not on this I'll have to be sckeptical of everything you post now.

    Another idol shattered....

    Leave a comment:

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