Carbonit Mine

The German Carbonit Mines were made by the Carbonit Company of Hamburg. This article is based, initially, on a British report on German mines from July, 1917.

Carbonit Mine
Weight	836 lbs.
Casing	0.2 in. welded steel
Detonator	2 Tetryl detonators in parallel
Primer	2.2 lbs. of lightly compressed T.N.T.
Charge	220 lbs. of cast T.N.T.
Buoyancy	240 lbs.
Height on rails	over 6 feet high
Diameter	–
Sinker weight	660 lbs. (330 more can be added)
Mooring wire	330 feet of 1.25-in wire, breaking strain 4.5 tons

Firing was done by four volt batteries at a current of 0.1 ampere or more.

It would sink to the bottom with its sinker and rise about 15-20 minutes later when a soluble plug dissolved.

The sinker was an iron plate with rollers to engage a mine rail on the hosting vessel.

Trials in H.M.S. Vernon

In a tideway trial, a two knot tide was found to cause the mine to sink just 6 inches with 37 feet of mooring wire out — a better depth-keeping than British mines. This mine had 40 pounds more buoyancy than British weapons. The horns proved very good at triggering on Vindictive, as the mine rolled as the ship passed alongside. The mine passed a six day endurance test easily, and two withstood a counter-mining test of 220 pounds of T.N.T. exploded 45 yards from them in 15 feet of water.

Fish Type

These mines were unusual in that their wire spool was in the sinker, not in the mine body. The mine was placed into a cradle on the sinker just before deploying.

Carbonit "Fish Type" Mine
Weight	lbs.
Casing	0.2 in. welded steel?
Triggers	four horns
Detonator
Primer
Charge	200 kgs. T.N.T.
Buoyancy
Height
Diameter	–
Sinker weight
Mooring wire

Bibliography

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