Speed of laying a minefield in enemy waters

[Steve Crandell]

I'm guessing all of their locations were revealed to the Japanese as part of the surrender of Singapore.

[Byron Angel]

Thanks for your data Byron. Yes, it seems logical to chart accurately a mine field, nobody knows when an own force has to pass thru it. Anyway, did not mines have a life time? Did not the war treaties oblige its adherents to set their mines so they would become harmless after a set time?

Regards

Hi Marcelo,
That might have been a clause in the Hague Convention (I profess no qualifications in that arena), but in no case that I am aware of did any WW1/WW2 sea mines possess any "self neutralization" feature. All the mines laid in the North Sea in WW1 were swept up (well, most were). Great numbers of mine were sewn in the Baltic in both wars and around the Japanese Home Islands in WW2 as well. There are still unswept (and some drifting) mines lurking at sea.

To give an idea of the scale of things, I don't think I would be far off in guesstimating that 100,000+ mines were laid in the North Sea alone in WW1. Back in my international chemical trading days (early 1980s), I worked with a Dutch bulk charter broker from Amsterdam. He told me that they were STILL doing regular precautionary sweeps of the main channels serving the big seaports like Antwerp and Rotterdam - drifting mines were considered a legitimate problem.

Byron

[marcelo_malara]

Hi Byron. There is a somewhat ambiguous article in the 1907 Convention.


When anchored automatic contact mines are employed, every possible precaution must be taken for the security of peaceful shipping.

The belligerents undertake to do their utmost to render these mines harmless within a limited time, and, should they cease to be under surveillance...

https://avalon.law.yale.edu/20th_century/hague08.asp

[OpanaPointer]

Thanks, Byron, my inner chaos demands I forget "n't" when it would cause the most confusion.

And, just for fun. https://en.wikipedia.org/wiki/North_Sea_Mine_Barrage

[Byron Angel]

Thanks, Byron, my inner chaos demands I forget "n't" when it would cause the most confusion.

And, just for fun. https://en.wikipedia.org/wiki/North_Sea_Mine_Barrage

Thanks OpanaPointer,
The Wiki entry was actually useful and interesting! Not always the case.

B

[Byron Angel]

Just remembered and located another reference document in my chaotic filing system -

O.U. 5243
INSTRUCTIONS FOR TACTICAL AND STRATEGIC EXERCISES
Carried out on Tables or Boards
January 1921
Admiralty Naval Staff, Tactical Section

Appendix VI - Mining and Minesweeping

POINTS TO BE OBSERVED (Page 37)
A minefield must start at a safe distance from those previously laid in the vicinity.
[ii] Minelayers must return to harbor to embark another outfir of mines.
[iii] Speed of minelaying. The actual minimum working interval (in time) between successive mines laid from the same rail is 12 seconds.
For A.W. minelayers other than C.M.B.'s a speed of 15 knots should not generally be exceeded on account of the stern wave introducing errors in depth taking; for the same reason the state of the sea must be taken into account, errors of depth equal to half the height of a wave may be expected. A table of time intervals for various speeds is given in Torpedo Manual, Vol. 1, Part II.
Submarines ar 3elimited to a speed of 5 knots whilst laying, to ensure the mines clearing the hull on release.
C.M.B.,s usually lay in groups and stop engines before laying.
[iv] Mines are inoperative till one hour after laying.
[v] The minefield efficiency of all contact mining systems is affected:-
- (i) Nearly always by rise and fall of tide, and
- (ii) frequently by the strength of current.
[vi] Minelayers cannot lay mines under the following weather conditions:-
A wind of force 7 or more from any direction, or a sea of force 5 or more on the quarter. These figures should be reduced by 25 percent when destroyer minelayers are employed.

FWIW.

Byron

[OpanaPointer]

Thanks, Byron, my inner chaos demands I forget "n't" when it would cause the most confusion.

And, just for fun. https://en.wikipedia.org/wiki/North_Sea_Mine_Barrage

Thanks OpanaPointer,
The Wiki entry was actually useful and interesting! Not always the case.

B

Until we examine a wiki page we don't know how good it is. Just like everything else in the unverse.

[OpanaPointer]

Well Byron, we are speaking of offensive (ie in enemy waters) mine laying, friendly ships would not be supposed to be around. Anyway I agree, 40 knots is about 20 m/s, surely a bottom mine would have no problem being tossed at such a speed, but a moored mine is out of the question, the water is like concrete at that speed.

Regards

Why do you differentiate between them? Just for clarification.

Defensive mine fields have to be traversed. You chart them carefully. Offensive mines should never have a pattern, it just makes the enemies clearing efforts easier.

[marcelo_malara]

Just for that reason, an offensive mine field, located near an enemy port, is not normally sailed by friendly ships.

[OpanaPointer]

Just for that reason, an offensive mine field, located near an enemy port, is not normally sailed by friendly ships.

I'm not sure anyone implied that.

[marcelo_malara]

Well, no, but machinery is costly, in money, space onboard, consumption, nobody would design and build a high speed mine layer if it was not intended for offensive operations, in which velocity in transit would be paramount.

[wadinga]

Hi Marcelo,

We should remember there were many neutral vessels which might have been trading with either or even both sides. Before they were invaded in WWII Holland, Norway, Denmark and Greece all had ships ploughing the seas and Sweden and Spain did throughout. Many minefields were publicised to funnel neutral traffic so it could be more-easily searched for war aiding materials (contraband). Until they entered the war, even Russia, Japan and the USA were neutrals with their ships trading with Europe and expecting the warring nations to respect their safety. The Hague provisions attempted to regulate mining to protect non-belligerents going about their lawful business on the sea, but mines are automaton weapons which can't differentiate and many neutral vessels were sunk by mines.

the RN frequently used converted merchant ships with high capacity for defensive fields and destroyers and specialist designs like the Abdiels for fast in/out missions in enemy-controlled waters. The RAF and Luftwaffe dropped lots of mines, primarily magnetic, in shallow waters the RN and Kriegsmarine could not reach.

All the best

wadinga

[OpanaPointer]

Well, no, but machinery is costly, in money, space onboard, consumption, nobody would design and build a high speed mine layer if it was not intended for offensive operations, in which velocity in transit would be paramount.

Other than getting to a proposed barrage area and getting back again for the next mission. Slow minelayers wouldn't be great threat.

[Fatboy Coxy]

I just did manage to locate one of my references, "Endless Story - Being an Account of the Work of the Destroyers, Flotilla-Leaders, Torpedo-Boats and Patrol Boats in the Great War" by Captain Taprell Dorling, RN. Chapter XXIV - "The Twentieth Flotilla" covers his service in said Flotilla as captain of HMS Telemachus . 20th Flotilla was often employed in the last year of the war on mine-laying expeditions in the German Bight. Telemachus could carry 40 x "H mines". She was capable of 30+ knots, but mine-laying speed was 12 knots. The mission described in the a/m book referenced laying interval of "150 ft" (50 yards).

H mines ?, does this simply suggest Hertz horn mines, as apposed to a particular mark?

I don't think the destroyers could carry some of the mines, owing to their size and so were somewhat limited to what they could lay, I don't know if that applied to the Abdiels.

regards
Fatboy Coxy

[Fatboy Coxy]

I know fatboy Coxy is always interested in South East Asia activities.

Uh oh nailed me

Regards
Fatboy Coxy