Talk:Naval mine

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[edit] 16th Century Silly Putty?

I think this may be wrong!

[edit] Double paravane sweep?

I have never heard of this being used. It seems like it would make the risk far worse for the sweeper with no gain, compared to simply having a single paravane and twice the cabel length to cover the same area. When sweeping you either start on "safe" water and work your way into the minefield without ever exposing the sweeper, or if in a real hurry to clear a path, you sweep a single line through the minefield and then you keep the sweeper in water you know are clear while enlarging it. A double paravane sweep is a lot of extra work and no gain in both cases. It would also make it harder to cut the sweeper free, as the crew would have to remove several extra wires to clear the sweeper in the case of an attack.

-Pehrs

It was used. I haven't done enough reading to know the tech reasons why; AFAIK, it was to minimize the pressure wave on "clamshell" mine exploders. Trekphiler 10:10, 30 December 2005 (UTC)

[edit] The mining threat

The first actions of the naval campaign started the day that war was declared. Royal Navy vessels dredged up and cut German transatlantic communication cables, forcing the Germans to communicate to their interests in the Americas by less secure means for the rest of the war.

The U-boat fleet, which was to dominate so much of the battle of the Atlantic, was very small at the beginning of the war and much of the early action by German forces involved mining convoy routes and ports around Britain. Initially, contact mines were employed, which meant that a ship had to physically strike one of the mines in order to detonate it. Contact mines are usually suspended on the end of a cable just below the surface of the water and laid by ship or submarine. By the beginning of World War II most nations had also developed mines that could be dropped from aircraft, making it practicable to lay them in enemy harbours (although they simply floated on the surface). The use of dredging and nets was effective against this type of mine, but nonetheless was time-consuming, and involved the closing of harbors while it was completed.

"although they simply floated on the surface)" Not necessarily. Trekphiler 10:33, 30 December 2005 (UTC)

Into this arena came a new mine threat. Most contact mines leave holes in ship's hulls, but some ships surviving mine blasts were limping back to port with buckled plates, popped rivets, and broken backs. This appeared to be due to a new type of mine that was detonating at a distance from the ships, and doing the damage with the shockwave of the explosion.

These mines were devastating; often ships that had successfully run the gauntlet of the Atlantic crossing were destroyed entering freshly mineswept harbors on Britain's coast. More shipping was now being lost than could be replaced, and Churchill ordered that the recovery, intact, of one of these new mines was to be given highest priority.

Then the British experienced a stroke of luck in November 1939. A German mine was dropped from an aircraft laying mines onto mud flats in the Thames estuary, well above the waterline. As if this was not sufficiently good fortune, the land happened to belong to the army, and a base, including men and workshops were close at hand.

Experts were quickly dispatched from London to investigate the mine. They had some idea by this time that the mines used magnetic sensors, so they had everyone remove all metal, including their buttons, and made new tools out of non-magnetic brass. They then safed the mine and rushed it to labs at Portsmouth, where scientists discovered a new type of arming mechanism inside.

The arming mechanism had a sensitivity level that could be set, and the units on the scale were milligauss. Gauss is a measurement for the strength of a magnetic field, and so they knew why it went off before coming into contact with the ship. Using the detector from the mine, they were able to study the effect of a ship passing over it. A ship, or any large ferrous object passing through the earth's magnetic field will concentrate the field at that point. The detector from the mine measured this effect, and was designed to go off at the mid-point of the ship passing overhead.

From this crucial data, methods were developed to clear the mines. Early methods included the use of large electromagnets dragged behind ships, or on the undersides of low-flying aircraft (a number of older bombers like the Vickers Wellington were used for this purpose). However both of these methods had the disadvantage of "sweeping" only a small strip at a time. A better solution was found in the form of electrical cables dragged behind ships, passing a large current through the seawater. This induced a huge magnetic field and swept the entire area between the two ships. The older methods continued to be used in smaller areas; the Suez Canal continued to be swept by aircraft, for instance.

While these methods were useful for clearing mines from local ports, they were of little or no use for enemy controlled areas. These were typically visited by warships only, and the majority of the fleet then underwent a massive de-gaussing process, where their magnetic fields were reduced to such a degree that it was no longer "noticed" by the mines. This started in late 1939, and by 1940 British warships were largely immune for the few months at a time until they once again built up a field. Many of the boats that sailed to Dunkirk were de-gaussed in a marathon four-day effort by hard-pressed de-gaussing stations.

The Germans had also developed a pressure-activated mine and planned to deploy it as well, but they saved it for later use when it became clear the British had beaten the magnetic system. They were then sown across likely invasion areas off the coast of France. This system had the disadvantage of requiring a periodic resetting of the trigger mechanism, so they were attached to chains and cables so they could be pulled to the surface and reset. Unlike the contact mine, however, in this case the mine lay on the ocean floor, and the cable ran to a float on the surface.

In 1944 General Erwin Rommel timed the resetting so that the mines would be at their best effectiveness during late April and into May - the best time for an allied invasion of France during the early summer. In June they were getting past the point of effectiveness and he ordered them pulled in for maintenance. The allies launched D-Day on June 6th, and the mines could not be replaced until it was too late.

The "clamshell" mines were considered usweepable, & the Germans were afraid to lay them for fear the Brits would counter with their own, which the Germans couldn't sweep (N knowing the Brits couldn't sweep them, either). They'd have been exceedingly useful had they been laid when built, instead of going into storage just days before Neptune went ashore... Trekphiler 10:33, 30 December 2005 (UTC)

[edit] Minesweeping

This article has more details about minesweepers and minehunters than the actual articles about minesweepers and minehunters. Maybe we should move the information, and have the countermeasures section be shortened. - LtNOWIS 18:29, 31 Oct 2004 (UTC)

[edit] Mine models

This page contains information on a variety of different mines. Perhaps this information should be broken out into individual pages for each significant mine model? Further; a top page listing the various models, including foreign models. I suggest this because the M-08 mine appears in a few pages regarding Operation Praying Mantis and the ships involved, and it seems appropriate to make such a page (I'm about to do this). Mine warfare is an often overlooked aspect of naval warfare, yet it is responsible for casualties to more USN ships than any other weapon type since World War II. It seems appropriate that more effort should be devoted to this area of naval weapons, and thus more breakout of the information into appropriate subpages. --Durin 22:14, 8 Apr 2005 (UTC)

[edit] US Navy ships hit

Since World War II, mines have damaged or sunk 14 U.S. Navy ships, while air and missile attacks have damaged only four.

I moved this line just now from the intro paragraph down to the "Mines and the USA" section, where it's more appropriate. Still, the line begs for mroe data. How many of the 14 incidents were accidents? How many were actually targeted at US Navy ships? Without that piece of data, the line is bereft of meaning. Tempshill 18:12, 23 September 2005 (UTC)

[edit] Rewrite

The article said this:

"=== Distance mines ===
Influence mines do not need physical contact with the ship to detonate. The earliest ones were moored mines used in the American Civil war and detonated electrically by observers on the shore. These were seen as superior to contact mines because they only deprived the waterway to the enemy. Distance mines use several kinds of instruments to detect if an enemy is nearby, most frequently a combination of acoustic, magnetic and pressure sensors. More exotic solutions also exist, such as optical shadows or electro potential sensors. These are modern mines and frequently cost many times more than contact mines. Still, they are very cheap compared to other anti-ship weapons and can be deployed in large numbers.
"====Remotely controlled mines ====
"Frequently used in combination with coastal artillery and hydrophones the remote controlled mines can be in place even in peacetime, which is a huge advantage when it comes to blocking important shipping routes to defend harbours. The mines are usually modified distance mines and can be turned into "normal" mines with a switch (which prevents the enemy from simply capturing the controlling station and deactivating the mines), detonated by hand or be allowed to detonate on their own.
"These mines usually weighed 200 kg, including 80 kg of explosives (TNT or hexatonal).
"====Floating distance mines ====
"The floating distance mine is the backbone of any mine system today. They are deployed everywhere the water is too deep for bottom distance mines. Usually equipped with magnetic or acoustic sensors, a floating distance mine is effective against most kinds of ships. A floating distance mine usually has a lifetime of more than 10 years, some of them almost unlimited. The floating mines are limited by the fact that they have to float, so they cannot carry unlimited amount of explosives. More than 150 kg is simply a waste of money, as the mine gets too large to handle and the extra explosives do not add much to the mine's effectiveness.
"These mines usually weighed 200 kg, including 80 kg of explosives (hexatonal)
"====Bottom distance mines ====
"Bottom distance mines are used when the water is no more than 60 meters deep or when mining for submarines down to around 200 meters. They are much harder to detect and clear, and they can carry a much larger payload than a floating mine. Bottom mines also use pressure sensitive instruments, which are less sensitive to sweeping than any other type.
"These mines usually weighed 150-1500kg, including 125-1400kg of explosives (hexatonal)

This is a false grouping of command detonated & influence mines. I'm rewriting.

It also says this:

"===Active mine===
"An active mine is a mine that moves on its own when it is deployed. Usually submarines deploy active mines and they have the form of a torpedo. That way the mine can be deployed deep inside an enemy harbour."

This is the same as the CAPTOR system described as a separate type above in the article. I'm rewriting that, too. Trekphiler 09:57, 30 December 2005 (UTC)

[edit] FIDO

It may've been called a mine for security, or perhaps conceal that it was a torpedo from the Bureau of Ordnance, which controlled torpedo production & would have taken the project over... (So perhaps for security there, too...). Trekphiler 10:03, 30 December 2005 (UTC)

[edit] Delete

I deleted this:

"(which is the area where the enlisted traditionally sleep and explains why enlisted are far more likely to die in a mine detonation than officers.)"

It isn't always true enlisted sleep forward; enlisted tend to outnumber officers, which would also account for it; & merchant ships, the most common vic of mines, tend not to have enlisted...

I deleted this, too:

"but also a deeply flawed operation."

It may well have been; keep your opinions to yourself. Trekphiler 10:12, 30 December 2005 (UTC)

[edit] Bias

There's a strong bias toward U.S. weapons, here. No mention of the pioneering work by Frank E. Smith (later Sir Frank), RN, inventing the magnetic mine in 1917, nor the German WW2 "clamshell" acoustic-magnetic (combined-trigger) mine (considered unsweepable at the time), nor (tho U.S.) the "destructor" improvised mines used in 'nam. And the description of mine warfare could use help; something should be said to submarine minelaying against Japan, the WW1 "mine barrage" across the North Sea, & the "destructor" campaign in 'nam. This is a bit bigger than I want to take on, but if somebody else does, I'll throw in my two or three cents' worth to try & keep it clear & honest. Trekphiler 10:27, 30 December 2005 (UTC)

[edit] Mine warfare

There's also something that should be said about Nimitz. He didn't use offensive mining against Japanese bases; instead, he placed subs on close blockade duty, taking them off the firing line against merchant shipping... Trekphiler 10:36, 30 December 2005 (UTC) Since most of these harbours would have been out of range of aircraft how would he have deployed mines there without risking ships? Also subs can easily change location to follow the enemy, mines, once laid cannot.217.7.209.108 12:58, 28 February 2007 (UTC)

[edit] Underwater Explosion Effects

Hello all. I would like to ask a more precise definition about underwater explosion effects. In this article http://www.navweaps.com/index_tech/tech-026.htm I found a very interesting explanation about contact underwater explosion. The author Nathan Okun explains how a contact explosion can be really devastating for the ship hull. In this Wikipedia's article I read otherwise that contact mine "just" creates a hole in the ship. Moreover Nathan Okun doesn't mention the resonating effect of a distant explosion neither he describes it as the most shattering effect for the ship structure. Sorry my english and Thank You Luca —The preceding unsigned comment was added by AgenteOrange (talk • contribs) 08:39, 18 March 2007 (UTC).

[edit] Repetition

IMHO the 'Daisy-chained mine' concept explained amongst the 'Unusual mines' is mentioned before: in the third paragraph of 'Floating contact mines' in the section 'Types'.