MK 57 Submarine-laid ASW Mine

The MK-57 is a 2,000-pound submarine-laid moored mine designed for use against high-speed and
deep-water submarines. It contains 360 pounds of HBX-3 and utilizes a total-field magnometer-type
magnetic influence firing device. Consisting of a fiberglass case and a cast-steel anchor the Mk 57 is
designed for launching from the standard 21-inch torpedo tube. Upon deployment, the mine sinks to the
bottom of the water where the case/anchor separation and the mid-freeing sequences take place as in the
Mk 56 mine. However, case depth for the Mk 57 is determined by a cable-measuring device in the anchor.
When the preset depth has been determined, an electrical signal is sent to an explosive device which
locks the cable to prevent further payout. If the mine becomes buried in bottom sediment, a slow-burning
propellant in the anchor is ignited, which frees the mine from the bottom. Scuttling features are the same
as those of the Mk 56. If the hydrostat fails, or if the mine becomes separated from its mooring cable, the
mine will fill with water automatically and neutralize itself to prevent detection and possible hazards to
friendly ships.
LENGTH: 121-1/16 inches
DIAMETER: 21 inches
WEIGHT: 2059 pounds