A moored, contact mine laid by surface craft. Two types of this mine are known to exist and both are deginated by the Japanese "Mark 6". Only the "Mark 6, Model 1" has been recovered. The "Mark 6, Model 2" has been reported from intelligence sources. The depth of water in which the mine may be laid is not known, although a case depth of 82' and a mooring cable length of 3360' has been reported for the "Mark 6, Model 2". Its use has been limited, although specimens were recovered on Kwajalein and Guam.

The characteristics of the mine are as follows:

Case

Shape – Spherical, 41".4 in diameter.

Color – Black.

Material – Steel.

Charge – Mark 6, Model 1 - 478 lbs. block-fitted Shimose.

Mark 6, Model 2 - 440 lbs. (Type 88) explosive.

Total Weight – Mark 6, Model 1 - 1000 lbs.

Mark 6 Model 2 - 903 lbs.

External Fittings

Horns – Four, electrochemical, 90° apart around the upper hemisphere.

Cover Plate – 17".4 in diameter in the top center of the case, secured by 16 bolts.

Arming Switch Mechanism – 5".2 in diameter, in the center of the cover plate.

Lifting Lugs – Three, around upper hemisphere, 120° apart.

Mooring Bridle – On the lower hemisphere, consisting of five 15" lengths of chain, four of which are attached to the support legs, and one to the mooring spindle.

Mooring Spindle Housing – 5".6 in diameter, in the bottom center of the case.

Support Legs – Four, around the lower hemisphere, 90° apart.

Mooring Cable – 6 - 10 mm (0".24 - 0".39) diameter.

Operation

No details of the anchor nor the depth-taking mechanism are known. Shortly after the mine is launched tension on the mooring chain closes the mooring safety switch. Disso-lution of a soluble plug allows the spring-loaded arming switch to close, arming the mine.

The mine fires when one of the horns is bent sufficiently to brask its glass vial, allo-wing electrolyte to run into the battery cup and generate sufficient current to fire the detonator.

Safety Precautions

The mooring safety switch is designed to open and disarm the mine when tension is removed from the mooring spindle. This feature, however, is not dependable.

Figure 20 – Cross section of mine type JH.

Figure 21 – Mine type JH.

Figure 22 – Type JH floating.