''Avenger''-class mine countermeasures ships are a class of 14 ships constructed for the

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

from 1987 to 1994, designed to clear mines from vital

waterways A waterway is any navigable body of water. Broad distinctions are useful to avoid ambiguity, and disambiguation will be of varying importance depending on the nuance of the equivalent word in other languages. A first distinction is necessary ...

. The ships have the hull designator MCM. The ''Avenger''-class ships are being replaced by the ''Freedom'' and s, as well as other MCM platforms, which use various

unmanned An uncrewed vehicle or unmanned vehicle is a vehicle without a person on board. Uncrewed vehicles can either be under telerobotic control—remote controlled or remote guided vehicles—or they can be autonomously controlled—autonomous vehicl ...

air, surface, and undersea vehicles to detect and destroy naval mines at a standoff distance.

History

Background

In the early 1980s, the U.S. Navy began development of a new

mine countermeasures A naval mine is a self-contained explosive device placed in water to damage or destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, any v ...

(MCM) force, which included two new classes of ships and minesweeping helicopters. The vital importance of a state-of-the-art mine countermeasures force was strongly underscored in the

Persian Gulf The Persian Gulf ( fa, خلیج فارس, translit=xalij-e fârs, lit=Gulf of Fars, ), sometimes called the ( ar, اَلْخَلِيْجُ ٱلْعَرَبِيُّ, Al-Khalīj al-ˁArabī), is a mediterranean sea in Western Asia. The bod ...

during the eight years of the

Iran–Iraq War The Iran–Iraq War was an armed conflict between Iran and Ba'athist Iraq, Iraq that lasted from September 1980 to August 1988. It began with the Iraqi invasion of Iran and lasted for almost eight years, until the acceptance of United Nations S ...

, and in Operations Desert Shield and

Desert Storm The Gulf War was a 1990–1991 armed campaign waged by a 35-country military coalition in response to the Iraqi invasion of Kuwait. Spearheaded by the United States, the coalition's efforts against Iraq were carried out in two key phases: ...

in 1990 and 1991 when ''Avenger'' and ''Guardian'' conducted MCM operations. ''Avenger''-class ships are designed as mine hunter-killers capable of finding, classifying, and destroying moored and bottom mines. The last three MCM ships were purchased in 1990, bringing the total to 14 fully deployable, oceangoing ''Avenger''-class ships. These ships use

sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on o ...

and video systems, cable cutters and a mine-detonating device that can be released and detonated by remote control. They are also capable of conventional sweeping measures.

Operations

As of 2012, eight ''Avenger''s were forward-based: four at

Sasebo is a core city located in Nagasaki Prefecture, Japan. It is also the second largest city in Nagasaki Prefecture, after its capital, Nagasaki. On 1 June 2019, the city had an estimated population of 247,739 and a population density of 581 persons p ...

, Japan with standing crews, and four at

Manama Manama ( ar, المنامة ', Bahrani pronunciation: ) is the capital and largest city of Bahrain, with an approximate population of 200,000 people as of 2020. Long an important trading center in the Persian Gulf, Manama is home to a very di ...

, Bahrain, with ten ships' companies on rotational deployments. In March 2012, the USN announced plans to deploy another four MCMs to Bahrain to counter potential Iranian threats to mine the Strait of Hormuz reflecting increasing tensions between the United States and Iran over the latter's nuclear program.

Design

Hull

The hulls of the ''Avenger''-class ships are constructed of

wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin ...

with an external coating of

fiberglass Fiberglass (American English) or fibreglass ( Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clo ...

. The wood used is

oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...

, Douglas fir and

Nootka Cypress ''Callitropsis nootkatensis'', formerly known as ''Cupressus nootkatensis'' ( syn. ''Xanthocyparis nootkatensis'') is a species of trees in the cypress family native to the coastal regions of northwestern North America. This species goes by many ...

because of their flexibility, strength and low weight. This construction allows the hull to withstand a nearby blast from a mine, and also gives the ship a low magnetic signature.

Mine countermeasures systems

The ships use AN/SLQ-48 remotely operated mine disposal system supplied by Alliant Techsystems (ATK) and the EX116 Mod 0

remotely operated vehicle A remotely operated underwater vehicle (technically ROUV or just ROV) is a tethered underwater mobile device, commonly called ''underwater robot''. Definition This meaning is different from remote control vehicles operating on land or in the a ...

(ROV) mine neutralization system supplied by ATK and

Raytheon Raytheon Technologies Corporation is an American multinational aerospace and defense conglomerate headquartered in Arlington, Virginia. It is one of the largest aerospace and defense manufacturers in the world by revenue and market capitali ...

. The AN/SLQ-48 detects, locates, classifies, and neutralizes moored mines and mines resting on the seabed. The vehicle uses high-frequency, high-resolution sonar,

low light level television Low light level television (LLLTV) is a type of electronic sensing device, usually a CCD camera sensitive to wavelengths above the normal "visible" (0.4 to 0.7 micrometre) wavelengths, and into the short-wave Infrared - usually to about 1.0 to 1.1 ...

(LLLTV), cable cutters, and explosive charges to detect and dispose of mines, while remaining tethered to the vessel by a cable and under control of the vessel. The ATK/Raytheon ROV is a similar system, but has a tether cable, and also carries cable cutters for dealing with tethered or moored mines, and explosive charges to detonate the mines.

Sensor systems

The ships employ the AN/SQQ-32 advanced minehunting and classification

from Raytheon and

Thales Underwater Systems Thales Underwater Systems or TUS (formerly Thomson Sintra ASM, Thomson CSF DASM and then Thomson Marconi Sonar) is a subsidiary of the French defense electronics specialist Thales Group. It was created in 2001 and belongs to its naval division. It ...

(formerly Thomson Marconi Sonar). The system has two sonars fitted in a small submersible pod towed under the ship. When not deployed the submersible is housed in a trunk below the deck of the ship. The sonars are a Raytheon search and detection sonar and a Thales high-resolution, high-frequency, target-classification sonar. The deployment and retrieval system for the submersible was designed by the Charles Stark Draper Laboratory in Massachusetts. The ''Avenger'' class employ the AN/SPS-55 surface-search and navigation

radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, we ...

supplied by Cardion, Inc. of New York. The ships have been equipped with

CMC Electronics CMC Electronics Inc. (french: CMC Électronique) is a Canadian avionics manufacturer. The company's main manufacturing facility is located in Montreal, Quebec with additional facilities located in Ottawa, Ontario and Sugar Grove, Illinois. His ...

LN66 or Raytheon AN/SPS-66 navigation radars, but are slated to be upgraded with the AN/SPS-73.

Propulsion

The ''Avenger''-class ships are equipped with four Waukesha-Pearce

diesel engine The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-ca ...

s (MCM 1 and 2) or Isotta-Fraschini ID 36SS6V diesel engines (remainder), which are designed to have very low magnetic and

acoustic signature The term acoustic signature is used to describe a combination of acoustic emissions of sound emitters, such as those of ships and submarines. In addition, aircraft, machinery, and living animals can be described as having their own characteristic ...

s. Each engine develops 600 horsepower (447.4 kW) (combined 1.79 MW) sustained power, providing a cruising speed of with

controllable pitch propeller In marine propulsion, a variable-pitch propeller is a type of propeller with blades that can be rotated around their long axis to change the blade pitch. Reversible propellers—those where the pitch can be set to negative values—can al ...

s. For stationkeeping the ship uses two Hansome electric motors rated at 294 kW. Precision maneuvering capability is provided by a 257 kW Omnithruster

hydrojet A pump-jet, hydrojet, or water jet is a marine system that produces a jet of water for propulsion. The mechanical arrangement may be a ducted propeller (axial-flow pump), a centrifugal pump, or a mixed flow pump which is a combination of both ...

(powered by Solar (Caterpillar Inc) Magnetic Marine Gas Turbine Generator).

Ships

Gallery

Image:USS Sentry (MCM-3);11120302.jpg, USS ''Sentry'' and USS ''Kingfisher'' Image:USS guardian H.jpg, USS ''Guardian'' Image:USS Gladiator MCM-11.jpg, USS ''Gladiator'' in the Persian Gulf

References

Notes

Sources

United States Navy Fact File: Mine Countermeasures Ships – MCMNaval-Technology.com: Avenger Class Mine Countermeasures Vessel
*

External links

* ttp://www.globalsecurity.org/military/systems/ship/mcm-1-gallery.htm Globalsecurity.org: Photo gallery {{Avenger class mine countermeasures ship Mine warfare vessel classes Naval ships of the United States