Today's mines are designed for deployment against many types of ships to achieve a variety of results. However, to meet the challenges of the missions that they may be called upon to perform, mines are becoming increasingly complex. Moreover, the number of these missions is so large that no one mine can serve all purposes. Therefore, the Navy stockpiles many types of mines with the necessary built-in versatilities to provide the options needed for a wide array of missions.

As previously mentioned, all mines discussed in this training manual are sea mines; i.e., those mines that are placed in deep or shallow waters, coastal areas, harbor entrances, rivers, canals, and estuaries. Sea mines also include destructors, which are general-purpose bombs containing influence-firing mechanisms.

Some mines with small explosive charges are designed only for use against riverboats and wooden vessels of small displacement. Some mines with large charges can destroy or damage most capital ships. Still, other mines are intended primarily for use against submarines.

Although mines are becoming increasingly complex (largely because of the intelligence built into their firing systems), the same technology that has made mines more complex in some ways has made them simpler in others. For example, the newer mines have features which make assembly, testing, and stowing much easier and safer than was possible with the older, less-complex mines.

The advantages of mines over other weapons include the following characteristics:

9 Mines lie in wait for the enemy without accepting a return threat.

0 Mines can win battles passively by influencing the enemy to retire without attacking.

Mines can be successful in confining ships to a certain area where they can be attacked by other means.

* Mines can cause ships to take longer alternate routes.

Mines are a continuous menace to enemy morale.

Mines can attack targets that human controllers cannot see or hear.

Mine effectiveness is measurable in delays caused to enemy operations.

* Mines can cause the enemy to expend effort and material on countermeasures that otherwise are not productive and would not be necessary.

0 Mines are cost-effective in that their targets are very valuable. The cost to the enemy when a target is destroyed is often far greater than the combined cost of the mines and the laying of those mines.

MINE TYPES

When mines are classified according to the position they assume in the water, they fall into three categories: (1) bottom mines, (2) moored mines, and (3) drifting mines.

BOTTOM MINES

Bottom mines are most effective in comparatively shallow waters. A large negative buoyancy brings the bottom mine to rest on the ocean floor and keeps it there. In very deep waters, surface vessels may pass over the mine without actuating its firing mechanisms or, in the event of an actuation, without suffering much damage. Bottom mines planted in deep water are still effective against submarines.

MOORED MINES

Moored mines are used for deep-water planting and are effective against submarines and surface ships. The explosive charge and the 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.

DRIFTING MINES

Drifting mines float freely at or near the surface. They have no anchoring devices, and their buoyancy is approximately neutral. The use of drifting mines was limited by the Hague Convention of 1907 and are no longer in the U.S. Navy's stockpile of mines.