When classified according to the position they assume in the water, mines fall into three categories: bottom, moored, and drifting:

• Bottom mines are most effective in comparatively shallow waters. A large negative buoyancy (tendency to sink) brings the bottom mine to rest on the ocean floor and keeps it there. In very deep waters, surface vessels may pass over certain bottom mines without actuating their firing mechanisms or, in the event of an actuation, without suffering much damage. Of course, a bottom mine planted in deep water is still effective against nearby submarines. The international community also refers to bottom mines as "ground mines."

• Moored mines are used for deepwater plants and are effective against submarines and surface ships. The explosive charge and firing mechanism in a moored mine are housed in a positive-buoyancy case, i.e., one that tends to float. A cable, attached to an anchor on the sea bottom, holds the case at a predetermined depth below the surface. Moored mines are sometimes also called "volume mines."

• Drifting mines float freely at or near the surface of the water. They have no anchoring devices. Even though the Hague Convention of 1907 outlawed the use of drifting mines, they have since been used during periods of sea conflict. Drifting mines are no longer in the U.S. Navy’s mine stockpile.

When classified according to the method by which they are delivered, mines again fall into three categories: aircraft-laid, submarine-laid, and surface-laid:

• Aircraft-laid mines are normally employed in offensive operations and are dropped from aircraft in the manner of a bomb. These mines must be specially configured for air delivery. Aircraft provide the capability for replenishing minefields over an extended period of time and area without danger from previously laid mines. Aircraft are also capable of mining enemy-held inland waterways.

It wasn’t until World War II that aircraft successfully planted mines, and it was then that it became readily apparent that there were many advantages of air delivery. This was demonstrated by the number of mining campaigns of that war, the most notable of which was the strategic blockade of the harbors of Japan, a campaign briefly recounted at the beginning of this publication. In short, aircraft can lay mines quickly, in great quantity, and over large areas. Moreover, aircraft are the only vehicles capable of replenishing a large minefield without danger from the submerged field itself. Also, they can lay mines in shallow bodies of water, including rivers and harbors that cannot be readily or safely transited by submarines or surface ship minelayers.

Most air-laid mines use some sort of flight gear to decrease their water‑impact velocity and to provide stability in the air.  This usually consists of a parachute pack and release gear that function as follows: when released from the aircraft, the active portions of the flight gear (as an example, the fins and/or parachute) deploy at a safe distance away from the aircraft.  Flight gear may also include an aerodynamic nose fairing to reduce drag as the mine is carried externally on the aircraft.  As the mine strikes the water, the flight gear may be broken off by impact with the water, or release gear frees the mine case from the flight gear after the mine submerges to a given depth.  At that point, the flight gear and mine then sink to the bottom free from each other. 

Almost any aircraft that normally carries bombs (Navy, Air Force, or Marines) can also lay mines.  Like bombs, air-laid mines are equipped with arming wires that maintain the mines in a safe condition until they are released from the aircraft.  However, at the instant a mine is released from the aircraft’s bomb rack, the arming wires are withdrawn, leaving the mine with the potential to arm.  On the other hand, should it become necessary to jettison the mine in a safe condition, the pilot actuates remote solenoids that allow the arming wires to fall intact with the mine, rendering it safe. 

Submarine-laid mines normally used in offensive operations are specially configured mines that are launched from the torpedo tubes of submarines.  Tactically, the number of mines that a submarine can carry may be considered a disadvantage, but the secrecy with which a submarine can deliver mines to an enemy port or operating area at great distances from friendly bases provides an overwhelming tactical advantage.

When secrecy is paramount, the submarine is the preferred mine-laying vehicle. Although submarines can carry mines great distances from friendly sea ports, they are not conducive to carrying very large payloads. Nonetheless, it is interesting to note that although the torpedo was widely considered to be the primary weapon utilized by the submarine during World War II, many missions undertaken by submarines of the Seventh Fleet involved the laying of mines. Throughout the war, submarines planted a total of 576 mines, resulting in 27 ships sunk and 27 damaged, or approximately one ship sunk or damaged per each 10 mines planted!

• Surface laying is the most economical method of delivery because of the greater number of mines that can be carried by the delivery vehicle. But, there are highly unacceptable constraints that favor the utilization of air or sub-surface delivery. For example, enemy control of the sea area, the requirement for surreptitious delivery, or the need to replenish an existing minefield all limit the feasibility of surface laid mines in most situations. It should be noted that by using appropriate modifications, aircraft-laid mines (less flight gear) and submarine-laid mines may also be planted by surface craft in support of E&T missions.

During World War II, surface craft were used primarily for defensive mining operations, i.e., defending friendly harbors and waters from clandestine penetration by enemy submarines. Planting was usually done from specially designed minelayers or from certain other surface craft adapted to perform this important role. Throughout the war, thousands of these mines were laid just outside Chesapeake Bay, around Cape Hatteras, and around Key West to protect our shipping against the enemy. Large minefields were also laid in the Atlantic off the coasts of Trinidad and North Africa and in the Mediterranean off the coast of Sicily. Although there is no record of any of the enemy’s vessels being sunk or damaged in the Navy’s defensive minefields, neither is there any record of the enemy’s ships passing through them. Perhaps the simple knowledge that these fields existed prevented any attempts being made, thus proving the adage that mines work well even when they don’t work at all!

When classified according to their use, mines fall into two categories: Service and E&T:

• Service mines are explosive weapons for use against wartime targets, sometimes loosely referred to as "warshots" or "all-up rounds." They consist of an explosive-loaded case, fully functional target detecting and firing mechanisms, and all necessary ancillary components.
• E&T mines may be any one of a number of expendable or reusable configurations used primarily for training and Fleet exercises. Inert-loaded or empty cases are used, but small explosive devices and/or pyrotechnics essential to the realism of the training or exercise may be contained in some configurations to release flares or surface floats. Most E&T mines are recovered from the water for refurbishment and eventual reuse. Recovery is enhanced by installing a small acoustic sonar transmitter (delayed output is possible) within or on the mine so that Navy divers or the Marine Mammal System (MMS) Mk 5 (trained sea lion) can acoustically ascertain the mine’s exact bottom location. The six types of E&T mines are described in the following paragraphs. Note that only the last four mine types are planted in the water.
• Handling mines are used to train aircraft and submarine crews in the techniques of mine handling and loading. They are never planted. The mine’s case is inert loaded to simulate the Service mine’s weight and center of gravity (CG). Externally, the case is fitted with nonfunctional flight gear (when emulating an air-laid mine) and all components necessary to fully interface with the intended delivery platform. Handling mines contain no low-level explosive devices. Handling mines are painted bronze to help distinguish their specific training function.
• Shop mines are used to provide general mine familiarization and instruction for developing proficiency in mine assembly and testing. The mine consists of an inert-loaded or empty Service-configured mine case with all inert mine components necessary to assemble the mine to any approved Service configuration. Shop mines are obviously not planted in the water and are painted blue to help distinguish their specific training function.
• Laying mines are used in training aircraft and submarine crews in the techniques of planting mine fields. The laying mine consists of a standard inert-loaded mine case without the internal components normally used for mine detection and actuation. However, the mine case is ballasted to compensate for the absence of its internal components. This ballasting serves to simulate weight and CG characteristics identical to those of Service mines. When used for training aircraft crews, the laying mine is equipped with standard flight gear which functions the very same as in Service mines. Laying mines are usually painted either white with orange stripes or orange with white stripes. This helps make them more visible in the water.
  
• Mechanical sweep mines (Mines Mk 6) serve as the Navy’s moored E&T mine shapes. They are inert shapes used for developing proficiency in our MCM minesweeping operations against moored mines. The spherical mine case is painted either white with orange stripes or orange with white stripes for international requirements and to help make it more visible. The mine’s anchor is left black.
• Hunting mines are used by MCM personnel to help develop their mine hunting skills and techniques. Since the purpose of a hunting mine is only to provide a generic planted shape to locate, any inert mine shape (developmental or foreign as well) may be used to serve this purpose. Hunting mines are normally planted by surface ships, since costly mine delivery by air or submarine is unnecessary. Hunting mines are normally painted either white with orange stripes or orange with white stripes to help make them more visible.
• Actuation mines are used in influence MCM training. This type mine is inert loaded to simulate Service mine weight and CG characteristics. It is configured with the very same components required to configure a Service mine (excluding those explosive devices associated with the explosive train). When influenced by a target signal (sensing of a proper magnetic, pressure, acoustic and/or seismic signature), the actuation mine responds by releasing a pyrotechnic signal (colored smoke) which simulates mine detonation. It may also release a tethered float after a preset delay to aid in its bottom location and recovery. Actuation mines are normally painted either white with orange stripes or orange with white stripes to help make them more visible.

Given the preceding information on mine position, delivery, and use categories, the table below is provided to acquaint the reader with the mines the U.S. Navy still plants for Service requirements. Note that only six mine types currently serve the U.S. Navy’s Service commitments worldwide.

The table below is meant to acquaint the reader with the fifteen mines the U.S. Navy still plants for E&T requirements. All mines listed in both tables (Service and E&T) are illustrated and described in detail in Section 8 of this publication.

* Note that the two Versatile Exercise Mine (VEM) Mk 74 and 75 assets listed are
specially constructed simulator training devices designed to be representative of
foreign threat mines. As such, they do not have U.S. Navy Service mine
counterparts. They are described on pages 8-13 and 8-14 respectively.

A Hunting Mine Mk 36 Is Prepared For Refurbishment

Hunting Mine Mk 36 Is Loaded Into a Water Blaster To Remove Old Paint and Corrosion