A minehunter is a naval vessel that seeks, detects, and destroys individual naval mines. Minesweepers, on the other hand, clear mined areas as a whole, without prior detection of mines. A vessel that combines both of these roles is known as a mine countermeasures vessel (MCMV).
A minehunter uses an imaging sonar to detect and classify targets and then sends out divers or remotely operated vehicles to inspect and neutralize the threat, often using small charges that are detonated remotely.
As minehunters will often be operating in close proximity to mines, they are designed so as to reduce their own acoustic and magnetic signatures, two common forms of trigger for mines. For example, they are often soundproofed by mounting machinery on shock absorbers or by using the quiet electrical drive, low magnetic electric motors and usually have a wood, fiberglass, or non-ferrous metal hull, or are degaussed to reduce magnetic signature.
Minehunters are generally small, shallow-draught vessels, as they are often called upon to work in enclosed bodies of water such as shipping channels or harbors. As maneuverability in such areas is critical the Voith-Schneider cycloidal propulsor is commonly used, allowing the engine thrust to be transmitted in any direction. A number of modern vessels use catamaran hulls to provide a large, stable working platform with minimal underwater contact; this reduces draught whilst lowering acoustic transmission and reducing the fluid pressure generated by the moving hull that may otherwise detonate mines with a hydraulic pressure trigger.
A minesweeper is a small warship designed to remove or detonate naval mines. Using various mechanisms intended to counter the threat posed by naval mines, minesweepers keep waterways clear for safe shipping.
Minesweepers are equipped with mechanical or electrical devices, known as “sweeps”, for disabling mines. The modern minesweeper is designed to reduce the chances of it detonating mines itself; it is soundproofed to reduce its acoustic signature and often constructed using wood, fiberglass or non-ferrous metal, or is degaussed to reduce its magnetic signature.
Mechanical sweeps are devices designed to cut the anchoring cables of moored mines, and preferably attach a tag to help the subsequent localization and neutralization. They are towed behind the minesweeper, and use a towed body (e.g. oropesa) to maintain the sweep at the desired depth and position. Influence sweeps are equipment, often towed, that emulate a particular ship signature, thereby causing a mine to detonate. The most common such sweeps are magnetic and acoustic generators.
There are two modes of operating an influence sweep: MSM (mine setting mode) and TSM (target simulation mode or target setting mode). MSM sweeping is founded on intelligence on a given type of mine, and produces the output required for detonation of this mine. If such intelligence is unavailable, the TSM sweeping instead reproduces the influence of the friendly ship that is about to transit the area. TSM sweeping thus clears mines directed at this ship without knowledge of the mines. However, mines directed at other ships might remain.
The minesweeper differs from a minehunter; the minehunter actively detects and neutralizes individual mines. Minesweepers are in many cases complementary to minehunters, depending on the operation and the environment; a minesweeper is, in particular, better suited to clearing open-water areas with large numbers of mines. Both kinds of ships are collectively called mine countermeasure vessels (MCMV), a term also applied to a vessel that combines both roles.
Check out Naval Library App to find out the specifications of all mine warfare vessels.