Difference between revisions of "Type II Mine (DE)"

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Latest revision as of 09:07, 14 July 2019

Type II Mine[1]

The German Type II Mine was suitable for use from minelayers. This article is based, initially, on a British report on German mines from July, 1917.[2]

Type II Mine
Weight 710 lbs.
Casing 0.2 in. welded steel
Trigger five impact horns, one being on top
Charge 290 lbs. wet gun cotton
Primer 12 oz. of unknown type
Detonator 90 gr. fulminate of mercury
Buoyancy 320 lbs.
Height 46 in.
Diameter 31.5 in.

The charge was built up of hexagonal discs of 12 ounces weight packed in a hard wood medium. The primer was held in a drawn brass casing suitable to last at least 6 months in seawater by British estimates. It was of a substance more volatile than dry gun cotton and considerably smaller than that in the Type I mine.

Action of Laying and Detonation

German mines of Type I through V worked in the same manner. The mine and sinker went to the bottom together. After 10 or 20 minutes, a soluble plug dissolved to release the mine, which rose under its own buoyancy, trailing the tethering cable behind. When the hydrostatic depth gear in the mine determines that its proper depth has been attained, it fired to grip the mooring cable. After this, the depth gear and grip would be locked to prevent ratcheting upward with a rising tide. The British felt the depth gear was reliable and accurate.

When a contact horn was struck and bent, a glass tube of acid would break, and its contents would flow to a bichromate battery to energise it, causing the detonator to fire. This action was instantaneous.

Type II, Small

There was a smaller variant of this model for use by above-water minelayers, possibly only used in the Baltic. The Russians had recovered some and shared their discovery with the British.

Type II Small, Mine
Weight 324 lbs.
Charge 54 lbs. hexanite
Buoyancy
Height 37 in.
Diameter 25 in.

Some of the Baltic mines laid by surface minelayers had horn extensions to increase their sensitivity.

Footnotes

  1. German Navy: Part IV, Section 3. Torpedoes, Mines, Etc.. Plate 27.
  2. German Navy: Part IV, Section 3. Torpedoes, Mines, Etc.. pp. 18-26, Plates 26, 27, 28, 32, 34, 35, 37.

Bibliography

  • Admiralty (July, 1917). German Navy: Part IV, Section 3. Torpedoes, Mines, Etc. (C.B. 1182) The National Archives. ADM 186/228.