Mines in the RJW period

[mbv]

In the torpedo thread Jim Cobb asked about the mines in use by both sides during the RJW. At the time I didn't have much info. but just noticed a small section in Steam, Steel & Shellfire: The Steam Warship 1815-1905 edited by R. Gardiner (Conway Maritime Press, 1992). Here is the info. ....................

The Japanese used a spherical mine with 72lb (33kg), or possibly larger, picric acid charge, and an internal battery powered firing circuit completed by movement of a pendulum. This type of mine blew up the Petropavlovsk and damaged several major ships, while an un-moored drifting version sank Navarin at Tsushima.

Russian mines were of truncated conical or later spherical shape with Hertz Horns. The latter, invented in 1868, were a development of the Jacobi type used by the Russians in the Crimean War (a well caulked wooden keg with coned ends and five fuses). In the Hertz Horn type a glass tube contained battery electrolyte which activated an internal battery and fired the mine when the tube was broken by hull contact with the mine.

Charges in Russian mines were 66lb (30kg) in M1877, 72lb (33kg) in M1888, c125lb (57kg) in M1893 and M1898. All were gun-cotton. Hatsuse and Yashima were sunk on the same day by the Hertz Horn type mines.

Most moored mines of the 1880s and later used the plummet depth taking method of deployment. In this British invention the mine floated on the surface while the sinker descended with a plummet and wire of length equal to the desired depth of the mine. On the plummet striking the bottom, a pawl and ratchet locked the mooring wire drum in the sinker which dragged the mine down to the desired depth of deployment.

The only relevant volume on mines in the bibliography of the above book is J.S. Cowie Mines, Minelayers and Minelaying (London 1949).

Another recent reprint you may like to read is:

John Townsend Bucknill, Submarine Mines and Torpedoes as Applied to Harbour Defence (1889)
Paperback 263 pages (February 2005)
Publisher: Naval and Military Press
ISBN: 1845740262

[Bullethead]

an un-moored drifting version sank Navarin at Tsushima.

This is the only example I know of where this tactic not only worked, but was actually used. Back in those days, there was almost as great a fear of a retiring enemy fleet spewing a sea of mines in its wake for the pursuers to trip over as there was of torpedoboats. This fear of mines laid during battle persisted into WW1, and worried Jellicoe considerably. But it seems to me that it would have had very little chance of success, and only worked against Navarrin due to special circumstances.

Most moored mines of the 1880s and later used the plummet depth taking method of deployment. In this British invention the mine floated on the surface while the sinker descended with a plummet and wire of length equal to the desired depth of the mine. On the plummet striking the bottom, a pawl and ratchet locked the mooring wire drum in the sinker which dragged the mine down to the desired depth of deployment.

This sure seems overly complicated. By WW1, the Germans (at least) were using a much simpler system that worked on the opposite principle. Their mines consisted of the mine itself, which was buoyant, an anchor, and a cable between them. The whole assembly sank to the bottom when laid, but the mine was held in the anchor by blocks of salt. When these dissolved, the mine floated up to the end of the cable, which held it at the desired depth below the surface. You'd think this system would have been invented first, or at least would have quickly come into use.