Seelöwe - German & British mining operations

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LWD
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Re: Seelöwe - German & British mining operations

#61

Post by LWD » 25 Mar 2013, 16:15

Juha Tompuri wrote: Yes, but the text (and the understanding) comes from a non-navy person, and nothing by so far presented fact backs up his claims.
Nothing contradicts them either. Of course one problem may be that more is being read into them than is justified. Thus the problem may be with us to some extent as well.
LWD wrote: ???? It's clearly not speculation. I was simply pointing out that we have no idea what percentage of the mines would break their cables in the period indicated. Since some WWII minefields lasted well after the war it clearly wasn't 100%. In the context it seems implies that periodic reseeding of the fields would be necessary. Furthermore it's not clear if that number was a general rule of thumb or applied specifially to the conditions in the channel. This isn't speculation is recognizing the limits of the information presented.
Do you believe in the speculation that it would be possible that up to/more than 50% of the mines laid would have been torn loose at the time frame mentioned?
As I mentioned the first time this was brought up I was rather surprised how soon this was a problem. As I see it there are 3 possibilities:
1) The above is incorrect or misleading.
2) The above applies in particular to German mines of the time layed in the Channel. One of the other sources I linked noted a number of problems with the German mines of the time and an account I've read of laying the North Sea Barrage in WWI indicated significant mine losses (via premature detonations) during the laying process. The currents and bottom conditions in the Channel might also cause more problems than normal.
3) It was more generally applicable to mine fields of that period.
As for what the percent losses are we can make some estimates based on the fact that such fields were still considered hazards post war in some circumstances. If the loss rate were 50% per week in 6 months less than 1 mine in 1,000,000 would be left. If it was 50% every 2 weeks it would be 1 in 1,000 for 6 months or 1,000,000 for a year. Clearly there would be no post war hazard from such fields. Even 50% in 6 months would leave only 1 in 1,000 after 5 years. So if it's generally applicable we are talking about the earliest possible time for a few mines breaking away. This still tends to suggest 3 is not correct.
It's hard to say anything more about 2 I simplly don't know enough about it.
As for 1 the KM from what I've read did not want to attempt Sea Lion at the same time they didn't want to say no to Hitler. Now this and what follows can readily be called speculation. I have seen documents, indeed one I've linked in this thread I beleive, where the KM complains that they are behind schedule in their mine sweeping due to lack of LW support. Stating that they are short on mines for the use intended would be verifyable and seems to be verafied (although I haven't seen any numbers on captured French mines that might be used). Accentuating this by implying that mines breaking away are more of a problem than it really is could be another ploy to discourage Sea Lion without coming right out and saying "it's a bad idea". The Heer didn't seem all that thrilled with the prospect either so wouldn't be inclined to challenge this.
LWD wrote:It's certainly not as good of data as I would like but at this point it is all we have. If you have more one way or another please present it.
I really haven't seen any facts that backs up the claim that Channel and the neighbouring waters were full of floating mines every now and then during the war.
We are unfortunatly left at least at this point with the above statement. How accurate it is or even exactly what it means are far from clear. On the other hand the numbers of mines that Sea Lion projected using were never laided in the waters they planned on using them so the floating mine problem you suggest never really had a chance to form. Although I believe I have read of a number of ships hitting floating mines during the war and after. Of course during the war it's not always easy to tell if it was a floating mine, a layed mine, or even a torpedo. I would love it if we could get a document that goes into more detail on this and/or someone with knowledge in the area to post here.

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Re: Seelöwe - German & British mining operations

#62

Post by LWD » 25 Mar 2013, 16:37

Urmel wrote:...I don't really see how the question of minefield deterioration matters. If the Germans still need the minefields after 8 days they have a whole world of other problems. ...
Actually rather the opposite is true. If you look back through this thread you will find that there are some pretty solid arguments for it takeing the Germans at least that long to lay the fields. Furthermore I think the time table for the landing of just the first wave invisioned it taking several days then there was a second wave. Indeed if you look at
http://www.da.mod.uk/colleges/jscsc/jsc ... on-sealion
there is a pdf document linked
http://www.da.mod.uk/colleges/jscsc/jsc ... ngland.pdf
On page 18 of that doucment it mentions spreading the second wave over 4 or 5 echelons each taking a couple of days. Then on page 47 it mentions the mineing operations were to be undertaken from D-8 to D-2.


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Re: Seelöwe - German & British mining operations

#63

Post by LWD » 25 Mar 2013, 17:01

The document I just linked in the post above:
http://www.da.mod.uk/colleges/jscsc/jsc ... ngland.pdf
Has a fair amount of relevant info that has not previously been mentioned.
For instance on page 47 it mentions that the miiens will be between 100 and 180 feet apart. It also mentions that the Germans had gathered 6,000 mines and 800 dummies.

Between Pages 48 and 49 there is a map with what I take to be the minefields indicated.

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Re: Seelöwe - German & British mining operations

#64

Post by phylo_roadking » 25 Mar 2013, 21:03

It's perhaps worth noting that BOTH flanks fo the Channel Narrows were to be protected by mines - the Portland-Griz nez line AND the northern end of the Narrows!

Leaving aside the question of how many mines were available - ANY number of mines breaking free from the KM's Northern "barrage" would drift INTO the sea lines being used by the invasion flotillas and subsequent logistics bridge because of the prevailing north-south currents in the Channel!

No matter if its 8 or 80 mines a week breaking free - the Germans wouldn't want those drifting into their convoys!
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Re: Seelöwe - German & British mining operations

#65

Post by Juha Tompuri » 25 Mar 2013, 21:08

Urmel wrote:
Juha Tompuri wrote:
Urmel wrote:One could argue it is speculation that Blumentritt was clueless about the question of naval mining operations just because he was an army officer. He was on the staff planning the operation.
http://forum.axishistory.com/viewtopic. ... 0#p1779213
No one (before) here has claimed General Blumentritt being clueless.


Regards, Juha
You're the one who says basing a statement on naval matters on him is pure speculation because he's not a naval officer, not me. Shrug.
Nope again.
Urmel wrote:I don't really see how the question of minefield deterioration matters.
It's question of reliability of the sources presented here.

Urmel wrote:The best way of figuring out whether there was anything real to this question would presumably be to look at British mining operations to block the channel to submarines - was re-seeding on a bi-weekly/monthly/whatever basis needed to keep them intact?
Yes, in addition to the similar German and French sources, those would be most welcomed.
Urmel wrote:I doubt it, but I don't know.
I highly doubt the "mine replacing" info there too.

Regards, Juha

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Re: Seelöwe - German & British mining operations

#66

Post by Juha Tompuri » 25 Mar 2013, 21:32

LWD wrote:
Juha Tompuri wrote: Yes, but the text (and the understanding) comes from a non-navy person, and nothing by so far presented fact backs up his claims.
Nothing contradicts them either.
That the mines were not breaking loose (at any meaningful numbers)?
Well if something was not a problem, it might not have been mentioned.
If it was a problem, where are the other mentions of it?
LWD wrote: So if it's generally applicable we are talking about the earliest possible time for a few mines breaking away.
Seems to be so.
LWD wrote:
Juha wrote:
LWD wrote:It's certainly not as good of data as I would like but at this point it is all we have. If you have more one way or another please present it.
I really haven't seen any facts that backs up the claim that Channel and the neighbouring waters were full of floating mines every now and then during the war.
We are unfortunatly left at least at this point with the above statement. How accurate it is or even exactly what it means are far from clear. On the other hand the numbers of mines that Sea Lion projected using were never laided in the waters they planned on using them so the floating mine problem you suggest never really had a chance to form.
I think that there were enough mines laid by the allies too, that if the mines breaking free would have been a serious problem, it would have been recognized and reported.

Regards, Juha

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Re: Seelöwe - German & British mining operations

#67

Post by Juha Tompuri » 25 Mar 2013, 21:35

Thank you for sharing it.
Seems to be interesting.

Regards, Juha

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Re: Seelöwe - German & British mining operations

#68

Post by LWD » 26 Mar 2013, 15:53

Juha Tompuri wrote: ... I think that there were enough mines laid by the allies too, that if the mines breaking free would have been a serious problem, it would have been recognized and reported.
Perhaps. If the mines breaking free was a significant problem due to local conditions in the part of the channel the Germans wanted to lay their mines then that would not be the case. There are also reports of floating mines being a problem it's not clear how much of one though. The problem is we have this one statement which is by implication backed by naval authorities. However it raises more questions than it answers. Perhaps part of the problem would be that it was a simplified response/rational to the mine fields not being as effective as some might wish. Note that
http://www.lexpev.nl/downloads/germanun ... es1946.pdf
mentions a number of problems with German mines of the period including:
page 16 referring to EMC type mines
" In 1940 8th horn removed ... devise actuated in heavy seas" Unfortunately not clear when in 1940
"... upper antenna abandoned in 1941 ... excessive numbers that broke loose in rough waters"
ON page 22 it explains the dummys. EMG type mines floated only partially submerged and thus were visible as were the dummys.
page 23
"By 1940 the Germans had realized that thier standard-type base plates for moored mines had two serious short comings:
1. In deep water hydrostatic pressure sometimes prevented arming ...
2. In shallow water, rough seas caused excessive arming and disarming, frequently wore out the spindle-mechanism membranes."
Unfortunately it doesn't mention whne the modified base plates were available, however other sections mention the low priority given to mine R&D.
So it does look like there were a number of problems that could limit the effectiveness of the German minefields and

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Re: Seelöwe - German & British mining operations

#69

Post by Juha Tompuri » 26 Mar 2013, 21:42

LWD wrote:
Juha Tompuri wrote: ... I think that there were enough mines laid by the allies too, that if the mines breaking free would have been a serious problem, it would have been recognized and reported.
Perhaps. If the mines breaking free was a significant problem due to local conditions in the part of the channel the Germans wanted to lay their mines then that would not be the case.
There were enough mines laid that if there would have been any meaningful problem of mass mine breaking away, we would have reports mentioning it.
LWD wrote: The problem is we have this one statement which is by implication backed by naval authorities
As earlier mentioned, that is speculation.
LWD wrote:ON page 22 it explains the dummys. EMG type mines floated only partially submerged and thus were visible as were the dummys.
No, the mines itself were (there) well under the surface.


Regards, Juha

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Re: Seelöwe - German & British mining operations

#70

Post by phylo_roadking » 26 Mar 2013, 22:13

ON page 22 it explains the dummys. EMG type mines floated only partially submerged and thus were visible as were the dummys.
No, the mines itself were (there) well under the surface.
http://www.navweaps.com/Weapons/WAMGER_Mines.htm
EMG
Moored surface mine developed from EMC and introduced in 1941. Later withdrawn as it was impossible to render completely safe. Used four Hertz horns and mooring depth was 98 fathoms (180 m).
http://www.ibiblio.org/hyperwar/USN/ref ... -Mines.pdf
Since the EMG mine floated slightly above the water surface, minefields utilizing this assembly were easily detected and avoided. To make this apparent disadvantage inure to their own benefit, the Germans developed a dummy EMG which consisted merely of the normnal float and amchor, and a 325-foot length of mooring cable. These dummies were laid in separate fields or togethe with EMGs. They were designated "Simulacker fur EMG".
Regarding the breakaway rate of mines...it might be worth finding out exactly which of the various classes of German sea mines available in 1940 were intended for use in the Sealion barriers...and if any of them were the "shallow" types intended for German coastal waters or the Baltic...
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Re: Seelöwe - German & British mining operations

#71

Post by Juha Tompuri » 26 Mar 2013, 23:49

phylo_roadking wrote:
ON page 22 it explains the dummys. EMG type mines floated only partially submerged and thus were visible as were the dummys.
No, the mines itself were (there) well under the surface.
http://www.navweaps.com/Weapons/WAMGER_Mines.htm
EMG
Moored surface mine developed from EMC and introduced in 1941. Later withdrawn as it was impossible to render completely safe. Used four Hertz horns and mooring depth was 98 fathoms (180 m).
The year mentioned seems to be a bit out of the topic era, and perhaps the "surface mine" mention at that webpage there means the difference of bottom mines, or just containing some mistake, as it contradicts to the LWD posted (official) info.
phylo_roadking wrote: http://www.ibiblio.org/hyperwar/USN/ref ... -Mines.pdf
Since the EMG mine floated slightly above the water surface, minefields utilizing this assembly were easily detected and avoided. To make this apparent disadvantage inure to their own benefit, the Germans developed a dummy EMG which consisted merely of the normnal float and amchor, and a 325-foot length of mooring cable. These dummies were laid in separate fields or togethe with EMGs. They were designated "Simulacker fur EMG".
That quote is not from the website mentioned, and also sadly does not correspond to reality.

Regards, Juha

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Re: Seelöwe - German & British mining operations

#72

Post by phylo_roadking » 27 Mar 2013, 00:09

Since the EMG mine floated slightly above the water surface, minefields utilizing this assembly were easily detected and avoided. To make this apparent disadvantage inure to their own benefit, the Germans developed a dummy EMG which consisted merely of the normnal float and amchor, and a 325-foot length of mooring cable. These dummies were laid in separate fields or togethe with EMGs. They were designated "Simulacker fur EMG".
That quote is not from the website mentioned, and also sadly does not correspond to reality.
It is indeed a paragraph from page 22 of the article/publication that link takes you to http://www.ibiblio.org/hyperwar/USN/ref ... -Mines.pdf
Moored surface mine developed from EMC and introduced in 1941. Later withdrawn as it was impossible to render completely safe. Used four Hertz horns and mooring depth was 98 fathoms (180 m).
The year mentioned seems to be a bit out of the topic era,
...as it contradicts to the LWD posted (official) info.
Looking again at page 22 of http://www.ibiblio.org/hyperwar/USN/ref ... -Mines.pdf , the EMG was designed in 1940. Looking at navwar it was first used in 1941...and back at http://www.ibiblio.org/hyperwar/USN/ref ... -Mines.pdf it was used until 1943.

After that...it was replaced by the UMA/K assembly http://www.dtic.mil/dtic/tr/fulltext/u2/a953446.pdf
The German UMA/K mine assembly was designed and developed in late 1942 to defend the sea approaches to Northern Europe from Allied attack. It replaced the EMG mine assembly which was considered unsatisfactory for the defense of such waters...
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Re: Seelöwe - German & British mining operations

#73

Post by phylo_roadking » 27 Mar 2013, 00:32

Incidently - according to John P. Campbell in his Dieppe Revisited: A Documentary Investigation, p.105...when discussing the German discussions of a mine barrier in the Channel later, in 1942...
The whole scheme would have to be improvised, since mines were in short supply, and the Channle presented special problems, what with its shallow water, strong tides and currents and shifting seabed. Moored mines were rendered ineffective on a rising tide by the strong "dip" caused by the flow of water. No german moored mine had been designed for such conditions, except perhaps the EMG specifically designed for Sealion, and those that could be pressed into use had never before been used operationally on such a scale. They had no disarming device in case they broke loose from their cables; and drifting mines would endanger German shipping moving along the swept channel inshore of the barrier.
He ALSO notes (p.106) that when the barrier was laid, later in the year, comprising 4,124 EMC, EMG and KMA/Ks...three German ships were sunk within 24 hours by strays that broke free from the barrier in storms in October.
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Re: Seelöwe - German & British mining operations

#74

Post by phylo_roadking » 27 Mar 2013, 01:59

Also, I'd like to return to something in Bronsky's initial post in this thread...
Total of all planned German minefields was about 5,600 mines. The total German stockpile of mines included roughly 4,000 EMGs, a smaller number of EMC and EMD mines (similar characteristics), and some 4,000 UMA submarine-laid anti-submarine contact mines. No fields using the latter mines were planned.

Source for the German mines: Schenck, pp.330ish
This isn't actually correct; the stockpile for Sealion didn't "include" 4,000 EMGs according to Schenk - IIRC he actually said that 4,000 EMGs "were to be produced" I.E. just like the MFPs, the prefabricated jetties they tried out on Alderney, etc., they weren't going to be ready for the September 1940 date...I.E. the Sealion plans were for 4,000 EMGs to be available...

...which was, I presume, why they were "first introduced" in 1941.
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Re: Seelöwe - German & British mining operations

#75

Post by Juha Tompuri » 27 Mar 2013, 08:29

phylo_roadking wrote:
Since the EMG mine floated slightly above the water surface, minefields utilizing this assembly were easily detected and avoided. To make this apparent disadvantage inure to their own benefit, the Germans developed a dummy EMG which consisted merely of the normnal float and amchor, and a 325-foot length of mooring cable. These dummies were laid in separate fields or togethe with EMGs. They were designated "Simulacker fur EMG".
That quote is not from the website mentioned, and also sadly does not correspond to reality.
It is indeed a paragraph from page 22 of the article/publication that link takes you to http://www.ibiblio.org/hyperwar/USN/ref ... -Mines.pdf
No it is not.
That quote is a mixture of facts and fiction.
Re-reading or looking at the drawing (#20) at page 40 might be in place.
Juha wrote: the mines itself were (there) well under the surface.
phylo_roadking wrote:
Moored surface mine developed from EMC and introduced in 1941. Later withdrawn as it was impossible to render completely safe. Used four Hertz horns and mooring depth was 98 fathoms (180 m).
The year mentioned seems to be a bit out of the topic era,
...as it contradicts to the LWD posted (official) info.
Looking again at page 22 of http://www.ibiblio.org/hyperwar/USN/ref ... -Mines.pdf , the EMG was designed in 1940. Looking at navwar it was first used in 1941...and back at http://www.ibiblio.org/hyperwar/USN/ref ... -Mines.pdf it was used until 1943.

After that...it was replaced by the UMA/K assembly http://www.dtic.mil/dtic/tr/fulltext/u2/a953446.pdf
The German UMA/K mine assembly was designed and developed in late 1942 to defend the sea approaches to Northern Europe from Allied attack. It replaced the EMG mine assembly which was considered unsatisfactory for the defense of such waters...
Yes, when the EMG was operational, the Seelöwe was not actual anymore.

Regards, Juha

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