Canadian mine sweeper, Sea Keeper


Canadian mine sweeper, Sea Keeper



A mine hunter is a naval vessel that actively 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 neutralise 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 quiet electrical drive and usually have a wood, glass-reinforced plastic (GRP) 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 harbours. As manoeuvrability 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 naval warship designed to counter the threat posed by naval mines. Minesweepers keep waterways clear for shipping.


Although naval warfare has a long history, naval mines were not deployed until 1855 in the Crimean War. The first minesweepers date to that war and consisted of British rowboats trailing grapnels to snag the mines. Despite the use of mines in the American Civil War, there are no records of effective minesweeping being used. Officials in the Union Army attempted to create the first minesweeper but were plagued by flawed designs and abandoned the project.

Minesweeping technology picked up in the Russo-Japanese War, where aging torpedo boats were pressed into sweeping service in 1908 and more boats were purchased for the purpose the following year.
In Britain, naval leaders recognized before the outbreak of World War I that the development of sea mines was a threat to the nation's shipping and began efforts to counter the threat. Sir Arthur Wilson noted the real threat of the time was blockade aided by mines and not invasion. The function of the fishing fleet's trawlers with their trawl gear was recognized as having a natural connection with mine clearance and, among other things, trawlers were used to keep the English Channel clear of mines. 

A Trawler Section of the Royal Navy Reserve became the predecessor of the mine sweeping forces with specially designed ships and equipment to follow. These reserve Trawler Section fishermen and their trawlers were activated, supplied with mine gear, rifles, uniforms and pay as the first minesweepers. The dedicated, purpose-built minesweeper first appeared during World War I with the Flower-class minesweeping sloop. By the end of the War, naval mine technology had grown beyond the ability of minesweepers to detect and remove.

Minesweeping made significant advancements during World War II. Combatant nations quickly adapted ships to the task of minesweeping, including Australia's 35 civilian ships that became Auxiliary Minesweepers. Both Allied and Axis countries made heavy use of minesweepers throughout the war. Historian Gordon Williamson wrote that "Germany's minesweepers alone formed a massive proportion of its total strength, and are very much the unsung heroes of the Kriegsmarine." Naval mines remained a threat even after the war ended, and minesweeping crews were still active after VJ Day.

After the Second World War, allied countries worked on new classes of minesweepers ranging from 120 ton designs for clearing estuaries to 735 ton ocean going vessels. The United States Navy even used specialized Mechanized Landing Craft to sweep shallow harbors in and around North Korea.

As of June 2012, the U.S. Navy had four minesweepers deployed to the Persian Gulf to address regional instabilities.

Pinguin, German Navy ROV


Pinguin, German Navy ROV


Operation and requirements

Minesweepers are equipped with mechanical or influence sweeps to detonate 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, glass-reinforced plastic (GRP) 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, paravane) 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 through 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 neutralises 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. The first such ship was HMS Wilton, also the first warship to be constructed from glass-reinforced plastic.



Notable minesweepers

HNLMS Abraham Crijnssen – famous for her escape from Surabaya in 1942 disguised as a tropical island

HMS Bronington – formerly commanded by HRH Prince Charles, Prince of Wales

Calypso – research vessel of Jacques-Yves Cousteau; the ex-Royal Navy BYMS-class vessel J826

USS Hazard – museum ship at Omaha, Nebraska

HMS Wilton – the first combined MCMV and the first warship constructed from GRP. Now converted to a yacht club's club house and moored on the foreshore between Leigh-on-Sea and Westcliff in Essex, England

USS Lucid - The last surviving U.S. Navy MSO hull, it is in process of being restored as a museum.


A mine countermeasures vessel or MCMV is a type of naval ship designed for the location of and destruction of naval mines which combines the role of a minesweeper and minehunter in one hull. The term MCMV is also applied collectively to minehunters and minesweepers.





Newly under development is a Mine Hunter based on the SWASSH hydrographic survey vessel built on a SolarNavigator platform called the Dragonfly. This alloy/composite vessel has low acoustic transmission, also reducing the fluid pressure generated by traditional hulls.


This autonomous vessel comes into its own where persistent monitoring is necessary. Being unmanned, the ship may map and survey potential minefield areas 365 days a year with no fuel or crew costs, representing a significant reduction in operating costs. Two or more vessels may monitor different potential conflict areas at the same time with just one shore based monitoring computer operator. Areas may be mapped into a database for strategic planning.








The SeaFox mine hunting system developed by Atlas Elektronik incorporates a remotely controlled surveillance system and autonomous ‘hunter’. The SeaFox I underwater surveillance vehicle is used for target identification and mine hunting. The system was employed recently to clear sea mines along the Libyan coast during the naval blockade on Libya.

The ‘mobile SeaFox’ (SeaFox C), an expendable fiber-optic guided vehicle that autonomously guides itself to predesignated targets, destroying sea mines by activating a large shaped charge. The system can fit on any ship, with minimal configuration.

This fibre-optic guided, one shot mine disposal vehicle SeaFox C is used for semi-autonomous disposal of naval mines and other ordnance found at sea. It is able to automatically relocate previously acquired positions of underwater objects within minutes with an integrated homing sonar. After relocating, these objects can be identified using the onboard CCTV camera and destroyed by the use of a built-in, large caliber shaped charge. SeaFox I is a reusable vehicle for identification and training in the application field of mine hunting. In this vehicle the SeaFox C warhead is replaced by ballast weight. It is deployable from a wide range of carrier platforms, including dedicated MCM vessels, surface combatants, craft of opportunity, rubber boats and helicopters. Ten navies have now decided to operate the SeaFox, making it the most successful mine disposal system in the world.


Based on a wide range of sensors and sophisticated algorithms the SNAV team is developing a system for the Dragonfly mine hunter to measure: magnetic, electric, pressure, acoustic, and seismic pressure signatures for real combat conditions to identify the most advanced naval mines being made today, typically: cylindrical, conical shaped and moored naval mines; triaxial magnetic. Once the targets are acquired they are logged, then systematically eliminated, which can be by ROV placed MILA-6C smart computer-controlled, time-fuzzed underwater limpet mines or other demolition charges.


U.S. intelligence agencies reported that North Korea was secretly developing underwater nuclear torpedoes and mines. This was according to a newsletter run by dissident North Koreans. The report was published by the Korean newsletter NK Chisigan Yondae, or NK Intellectual Solidarity.

The U.S. Navy once had nuclear torpedoes and mines, as did the Soviet navy, and China’s military also has discussed the use of nuclear torpedoes in its military writings as recently as 2006. A “secret” Wikileaks cable dated September 26, 2008 added credibility to the report.

The idea of nuclear sea mines is not a new idea, there are several Chinese articles that have discussed the nuclear sea mine capability over the last decade. In China’s Underseas Sentries, a Winter 07 Underwater Magazine article by Andrew Erickson, Ph.D., Lyle Goldstein, Ph.D., & William Murray, the Chinese discussion is mentioned:

Submarines have attracted particular attention as a deployment platform for rising mines. An article by Dalian Naval Academy researchers suggests significant PLAN interest in SLMMs. A researcher at Institute 705 advocates acquisition of an encapsulated torpedo mine, similar to the Cold War-era U.S. Captor mine, which could be laid in very deep waters to attack passing submarines. Mine belts—external conformal containers designed to carry and release large numbers of mines—can be fitted to submarines in order to bolster their otherwise limited payloads.


One article emphasizes that the Soviet navy developed a “mine laying module capable of carrying 50 sea mines on either side of the submarine” and states, “For the past few years related PLA experts have expressed pronounced interest in submarine mine belts…. The PLA very probably has already developed submarine mine belts.” Another source notes, however, that “submarines built after World War II rarely carry mines externally.”

Disturbingly, there is some discussion of a theoretical nature in Chinese naval analyses concerning arming sea mines with tactical nuclear weapons. One such analysis, in the context of discussing Russian MIW, notes that nuclear sea mines could sink adversary nuclear submarines from a range of 2000 meters…. A second article finds that a nuclear payload is one logical method to increase the destructive power of sea mines, while a third analysis argues that nuclear MIW is especially promising for future deep-water ASW operations. It concludes: “At this time, various countries are actively researching this extremely powerful nuclear-armed sea mine.”43 An article in the July 2006 issue of Modern Navy (Dangdai Haijun), published by the PLA Navy itself, in the context of discussing potential future PLA Navy use of sea mines, also notes the potential combat value of nuclear-armed sea mines. While there is no direct evidence of the existence of such naval tactical nuclear weapons programs in China, these articles do perhaps suggest the need to closely monitor any Chinese efforts in this direction.

The question is, Is North Korea a signatory of the 1971 Seabed Treaty? Perhaps North Korea don't take such things seriously, but use of a nuclear sea mine would be a clear violation.

In the focus of the Iranian nuclear program, we have never seen where a red line was crossed in regards to an Iranian nuclear program, but if someone in Seoul has decided North Korea has crossed that red line with the North Korean nuclear program, that might help explain why the Obama administration seems to be committed to the new South Korean led strategy in dealing with North Korea, even if supporting that strategy takes the Korean Peninsula to the brink of war.


WWII Mine Hunters



U.S. military enters new generation of sea mine warfare, By JON RABIROFF - Stars and Stripes May 9, 2011

CHINHAE NAVAL BASE, South Korea — For many, a sea mine brings to mind the image of a rusted, seaweed-covered World War II relic bobbing in the surf toward the hull of an unsuspecting ship.

In conversations about modern warfare tactics and weaponry, the subject of sea mines gets lost in all the talk about satellite surveillance, stealth aircraft and high-tech artillery.

But those in the business of sea mine countermeasures want the world to understand that they are not manning any sort of museum wing of the U.S. military. In fact, they say, sea mines are more dangerous than ever and could be a key warfare component for countries and terrorist groups in future conflicts around the world.

“We ignore mines at our own peril,” said Scott Truver, one of the United States’ leading experts on sea mine warfare. “Mine warfare is not usually a priority until a (mine) goes off.”

To address the very real threat, the U.S. will replace its fleet of 14 minesweepers over the next 15 years with multifunction vessels, including 24 that can be outfitted to find and eliminate surface and underwater explosives.

“There is a new generation of mines … that will cause us much more time and effort trying to find them,” said Capt. Robert Lineberry, commander of U.S. Mine Countermeasures Squadron 7 based in Sasebo, Japan. “It’s not just this little round spikey thing. Now they have mines that will bury, they have mines that don’t look like mines — they might look like seaweed or rocks or whatever. It’s a big challenge.”

Not ‘low-tech’

Those who know best say seaborne explosives should never be too far from the minds of U.S. military officials. Consider:


-Of the 19 U.S. Navy ships sunk or seriously damaged since World War II, 15 were the victims of sea mines.

-China has reportedly prepared to deploy 80,000 sea mines to help it claim control of the seas during any potential conflict.

-North Korea is reportedly developing nuclear sea mines with an eye toward neutralizing the naval supremacy of the U.S. and other countries in the event of a conflict.

“(Sea) mines are just as much of a threat today as they have ever been … so the importance of having a credible counter-mine capability is just as important for the U.S. Navy and our allies,” said Paul Ryan, president of the Mine Warfare Association in California, a group whose mission is “to continue to advocate for a robust mine warfare capability.”

“To think that mine warfare is low-tech is wrong. Mines can be very sophisticated and have capabilities that can create problems for the United States Navy,” said Truver, who has assisted in the development of Navy and Marine strategy papers on mine warfare over the past two decades. “If we are intent on going into harm’s way, one of the most effective ways to harm us is mines.”

In what perhaps could be considered a nod toward to the sea mine threats posed by China and North Korea, four of the U.S. Navy’s 14 minesweepers are forward-deployed and based in Japan, and two of them — the USS Avenger and USS Guardian — participated in this year’s massive Foal Eagle military exercise in South Korea in March along with a number of other mine-countermeasure units from the U.S. and South Korea.

While in South Korea for the exercise, Lt. Cmdr. Patrick German, commanding officer of the USS Avenger, said developing sea mine countermeasures is constantly evolving because of advances in the technology of the weapons.

“There are mines that can actually pinpoint the size and shape of a ship in the water as it’s passing by at various speeds,” he said. “The technology out there is incredible. If they are doing (what they’re doing) with an iPhone, what do you think they’re doing with weapons?”

Lt. Cmdr. Zach Aperauch, the officer-in-charge of Helicopter Mine Countermeasures Squadron 14, Det. 1, based on Pohang, South Korea, said he and his counterparts are members of “an unappreciated community” in the U.S. military.

“A lot of people don’t understand how prevalent (sea mine warfare) is (and) the versatility it affords,” he said. “It’s a weapon … that’s always going to be used in the future.

“Obviously today the (execution) of the national military strategy is for the Navy to operate in a littoral environment, and to be able to project power ashore,” he said. “So, elimination of the mine threat is critical to that mission being successful.”

‘A terrible thing that waits’




According to the Navy’s 2009 report, “21st Century U.S. Navy Mine Warfare; Ensuring Global Access and Commerce,” there are more than a quarter-million sea mines in the inventories of 50 navies around the world. More than 300 kinds of sea mines are produced by 30 countries.

“These figures are for sea mines, proper,” the report said. “They do not include underwater improvised explosive devices, which can be fashioned from fuel bladders, 50-gallon drums, and even discarded refrigerators.”

Sea mines not only come in all shapes and sizes, but they can be deployed from aircraft, ships, pleasure boats, submarines, and even pickups crossing bridges, the report said. Some rest on the ocean floor, some are designed to float freely, while others are moored by chains or other means at or below the surface of the water.

Once in place, it said, “a mine is a terrible thing that waits.”

Mines detonate when they are struck by a target or set off by remote. Influence mines, according to the report, can be fitted with magnetic, acoustic, seismic and pressure sensors that can detect a ship’s approach, determine what kind of vessel it is and the most effective time to detonate.

Along with the variety of mines and methods, there are many ways to search for and neutralize them from the air, the surface of the sea and underwater.

“It’s a cat-and-mouse game,” said Chief Petty Officer David Fuhrman, a mineman on the USS Avenger. “They build something. We try to build something better to find it. We find it and then they build something to counteract what we have to find it.”

As part of that “game,” the U.S. Navy’s 14 Avenger-class minesweepers are designed to sometimes be invisible to the sea mine sensors that set off the explosives, while at other times they are equipped to act like a passing aircraft carrier or nuclear submarine.

Some mines are set to explode in response to changes in magnetic and acoustic fields, so the U.S. minesweepers all have hulls made of wood, glass-reinforced plastic or a combination of the two, Truver said. The amount of metal allowed on board is also tightly regulated.

“We try to match the magnetic field of the earth, so we are masked by the earth’s magnetic field,” Fuhrman said. “Almost everything that’s on this ship … is non-magnetic. The engines are non-magnetic, all the way down to the grill in the galley is non-magnetic.

“We’re not allowed to use wire coat hangers,” he said. “If everybody on board brought 10 hangers, we’d kill our magnetic signature and we could actually set off a mine.”

Sonar is the primary way potential mines are identified in the water when the Navy is hunting for explosives, according to the 2009 report, but explosive ordnance disposal divers, marine mammals, video cameras on mine neutralization vehicles and laser systems can also be used.

Divers can be brought in to detonate, disable or recover sea mines, according to Lt. Michael Bailey, an underwater mine countermeasures officer with MCMRON 7.

“That was a big lesson learned from the war on the ground in Afghanistan … to understand what the enemy is throwing at us and then we can better counter it,” he said.

‘A necessary tool’

Truver said less than one percent of the U.S. Navy’s budget goes toward mine warfare, with $1.54 billion earmarked for that purpose in the proposed 2012 budget.

“Given the pressures on the budget, this is the best we’re going to get,” Truver said.

“Mine warfare – it’s an insurance policy,” Ryan said. “How much emphasis do you want to put on it to deter the bad guys?”

Plans call for the Avenger-class minesweepers now in operation to be replaced over the next 15 years by multifunction Littoral Combat Ships, 24 of which will be capable of being outfitted to carry out mine countermeasures in addition to other tasks.

The MH-53E helicopters being used for mine countermeasures will be replaced with the more up-to-date MH-60S helicopters.

Lineberry said the new ships, “will have different modules on board that will allow the Navy much more flexibility in its war-fighting in the future,” and the new helicopters will employ “several different systems that will be decades newer than we are using today.”

Mine countermeasures, he said, “are a big and growing business for the United States Navy right now.”










This ominous sight is the unmistakable outline of a mine – discovered on the seabed outside one of the Mediterranean’s busiest harbours by the experts of HMS Ledbury, who helped blow it to kingdom come.

The Portsmouth-based minehunter was on patrol with a NATO task group off the Sardinian capital Cagliari when her world-beating sonar picked up a contact on the seabed.

That prompted Ledbury’s team to launch their remote-controlled robot mine disposal system, Seafox, which beamed back a live video feed to the warship’s operation rooms.

Seafox is used both to identify objects – and also dispose of them courtesy of the explosive charges it carries.

In this instance, however, there was so much marine growth on the mine that it needed a first-hand inspection from Ledbury’s specialist mine clearance divers.

AB Diver Josh Spibey and the ship’s executive officer, Lt Sean ‘Central’ Heaton, donned gear and went down 43 metres (141ft) to the seabed. Their inspection confirmed the device was a wartime German GY* buoyant contact mine.

The mine was designed to be anchored to the seabed, float just below the surface and detonate if struck by the hull of an unsuspecting passing vessel, blowing them apart with up to 335kg (738lb) of high explosives.

The mine had long since broken away from its mooring and sunk to the floor of the Mediterranean – but it still posed a threat to fishermen or other vessels if it had been moved in rough seas.

Because the mine was inside Italian territorial waters, permission had to be sought from the Italian authorities to destroy it; Ledbury marked the mine with a buoy and went into the port of Cagliari for a planned weekend visit while a decision was made.

Authority was given and early on Monday morning Ledbury sailed and met up with an Italian bomb disposal unit at the buoy.

Ledbury’s dive team, working with their Italian counterparts, placed 4lb (1.8kg) packs of plastic explosives on the mine and following some help by the Italian Coastguard to shepherd a few local fishermen and yachts out of the area, the combined operation resulted in the detonation of a third of a tonne of explosives.

Because the mine lay so far below the surface, the water pressure suppressed the majority of the explosion – but an impressive shockwave was seen and the sea boiled as the 70 year old mine blew a large crater in the sea floor, throwing sand and mud up into the crystal clear waters of the Mediterranean.

“The discovery and disposal of this mine has demonstrated once again the professionalism and effectiveness of the Royal Navy’s mine countermeasure capability,” said Lt Cdr Tony Williams, Ledbury’s Commanding Officer.

“I am immensely proud of the efforts of my team and this is a fitting culmination to a challenging deployment for Ledbury working with our NATO partners.”

This success came on the last period of planned minehunting operations for Ledbury and her crew – the ship has been working with NATO’s SNMCMG2 mine countermeasure group in the Med since the beginning of the year alongside Turkish, Spanish, Italian and German counterparts. Ledbury’s due home at the end of the month.









KNIFEFISH ROV UUV - Navy Will Give Nearsighted Minehunter Robotic Glasses

The Navy is building a fleet of mine-hunting ships that investigators say aren’t all that hot at finding mines. So in the coming years, those ships are going to get drone supplements to dive deep below the sea to spot the underwater weapons. Think of ‘em as pairs of robotic glasses.

This is a scale model of the Navy’s newest drone sub, called the Knifefish. Manufactured by General Dynamics, the Navy unveiled it for the first time on Monday at its annual Sea Air Space convention just outside Washington, D.C.

The Knifefish — named after a real fish that emits an electric field — will be a 19-foot robot with a 21-inch diameter that launches from a Littoral Combat Ship (LCS), the new Navy ship built to fight close to shore. The robot is basically a solution to a chief LCS vulnerability discovered by the Pentagon’s top weapons tester: although one of its missions is hunting mines, its chief mine-spotting systems are “deficient” for exactly that task.

Enter the Knifefish. Starting in roughly 2015, according to General Dynamics, each LCS will be able to launch two Knifefish modules, with the primary task of finding mines buried in the sea floor. It’s an autonomous robot: sailors aboard an LCS will program the Knifefish’s navigation systems with instructions on where to swim ahead of launching it. It can swim for 16 hours at a time.

But the chief asset of the Knifefish’s autonomy isn’t navigation, it’s analysis. It uses a set of low-frequency wideband frequencies to spot a mine that gives off a resonance “very near” that of the particular mine it’s hunting, says Capt. Duane Ashton, the Navy’s program manager for unmanned maritime systems. That “allows you to fingerprint the object being looked at,” instead of having a human sailor spending hours discovering and cataloging the types of mines he or she encounters — something Ashton calls a “significant game-changer.”

The Knifefish won’t neutralize mines that it finds, though — it just relays data back to the mothership about the mines’ location. That, at least, may take some of the pressure off the LCS’ other mine-spotting systems, the AN/AQS-20A Sonar Mine Detecting Set and the Airborne Laser Mine Detection System, neither of which have impressed Pentagon testers.

But the Knifefish won’t transmit that data in real time. It’ll store up to 12 terabytes of data collected by its acoustic sensor package. Data recovery will have to occur after the Knifefish swims back up to its LCS parent. Which might be a problem, since the LCS can’t survive a blast from any mines it doesn’t detect.

“We’re talking about a large amount of data, terabytes of data,” Ashton explains, adding that the Navy doesn’t believe it needs real-time data reporting right now, although it might reevaluate after the first Knifefish missions. The robots should arrive in the fleet not long after the first of two LCSes are permanently stationed in Singapore.

The Knifefish is also a step toward diversifying the Navy’s robotic portfolio. Successive Navy chiefs have been keen to build underwater robots that can swim across entire oceans, but the propulsion and fuel systems necessary aren’t technologically mature yet. The Knifefish is decidedly not a long-range robot sub, although General Dynamics and the Navy won’t say specifically how fast it can swim or how far it’s expected to patrol.

Still, the Navy has yet to fully explain what a vulnerable LCS is supposed to do while it waits for its mine-hunting robots to swim back to mama. How the Knifefish performs “will help determine the tactics, techniques and procedures” for the LCS, Ashton says. But if the Knifefish turns out not to be able to see very well, the Navy’s newest ship might be dead in the water.




The U.S. Navy’s Knifefish UUV is a cutting-edge mine hunter, with the ability to find and identify mines, even the most challenging undersea environments. Knifefish is the new Surface Mine Countermeasure (SMCM) Unmanned Undersea Vehicle (UUV), built by General Dynamics Advanced Information Systems of Mcleansville, NC, based upon a Bluefin-21 vehicle from Bluefin Robotics. The systems helps the Navy’s meet an urgent requirement to reliably detect and identify buried mines in high-clutter environments. 

The initial SMCM UUV System being acquired by the Navy includes a pair of Knifefish UUVs, along with launch and recovery and support equipment, as well as the advanced sonar payload provided by the General Dynamics Team. The plan is for each of the littoral combat ship (LCS) mine countermeasures (MCM) mission packages to contain one Knifefish system, with two of the lithium-ion battery-powered UUVs, as well as associated launch and recovery equipment, a support container, spare parts and support equipment. The system is designed for use with LCS, but it can also be used from vessels of opportunity. The Knifefish system recently passed its preliminary design review.

LCS is a relatively small, fast, agile surface combatant designed to address anti-access in the littoral or coastal regions of the world. The ship can be reconfigured with modularized mission packages for one of three focused mission: anti-submarine warfare, MIW and anti-submarine warfare.

The ship itself—referred to as the seaframe—has core capabilities including navigation; command, control, communications, intelligence, surveillance, launching and retrieving boats, aircraft and unmanned vehicles, and weapons for self-defense. The LCS MIW Mission package will carry systems to search, identify, and neutralize mines in the water column from the near surface, bottom, and the water column. The LCS mission package is comprised of modularized mission systems and support equipment; mission specialists; and support aircraft and crews. As systems are upgraded, or new ones become available, it will be possible to upgrade the mission package without making extensive modifications to the ship.

Knifefish employs a low-frequency broadband synthetic aperture side-scanning sonar to look for mines that are in the water column, or “proud” mines that are resting on the sea floor or partially buried.

“The Knifefish does not use acoustic imagery like most sonars. The Knifefish Low Frequency Broadband (LFBB) sonar is better able to find buried mines and resolve mine contacts from non-mines in high clutter environments than acoustic imagery sonars,” said Capt. Duane Ashton, a program manager for unmanned maritime systems with the Program Executive Office for the LCS. “Knifefish provides capability that we don’t have with UUVs today,”

Currently, the Knifefish must be recovered and its data processed and compared against the mine threat library is stored onboard LCS. The database allows Knifefish to identify just about any kind of mine-like object it could encounter, including virtually all known types of sea mines. Each reflection from an active transmission has unique characteristics that can be identified and classified. The system will compare any objects it locates with the database. “It knows what an anchor or a refrigerator looks like, and can rule them out” Ashton says. “And it knows with a high degree of certainly when it has found a mine-like object.”

The library will be updated as new threat mines are deployed. “A future product improvement will allow the UUV to perform the mine identification processing on board the vehicle,” Ashton says.

If the LCS mine warfare mission specialists determine that a mine has been located, classified and identified, the mine can be plotted and avoided, or destroyed by using the Airborne Mine Neutralization System or EOD divers. 
Each UUV will search its preprogrammed area independently for up to 16 hours, but both can operate simultaneously if desired, Ashton says. 

When underway on a mission, the vehicle periodically provides the mission specialists on the LCS host platform with its GPS position and “wellness” update,” by means of a satellite link and a small antenna. The UUVs do not communicate with each other.

After each mission, Knifefish is designed to be turned around quickly so it can get back in the water for the next assignment, said Tom mason, General Dynamics Advanced Information Systems program manager for Knifefish. “The UUV will have a subsystem called the Removable Data Storage Module (RDSM) which will contain all of the data recorded by the mission. The RDSM will be taken from the UUV and downloaded to shipboard processors for post mission analysis. While the UUV is executing the next mission, the previous mission batteries are recharged and the RDSM prepared for reuse. To support this requirement, both the RDSM and batteries can be swapped out with ready spares.”

Knifefish is 22 ft. long, 21-in. in diameter, and it weighs 1,700 lbs.

The SMCM UUV started as a Science and Technology (S&T) program run by the Office of Naval Research, has transitioned to an acquisition program. The investment in S&T has paid off. Ashton says ONR helped develop the prototype being used for testing while the Engineering Development Manufacturing (EDM) systems are being developed. EDM system testing will be followed by developmental testing, and finally operational testing. 

Knifefish LCS developmental testing will occur in FY15, he says. Operational testing will occur in FY16, and Knifefish could be operational by FY 2017. 

General Dynamics Advanced Information Systems is the prime contractor and systems engineering lead, responsible for payload and mission module integration. The vehicle is provided by Bluefin Robotics. Ultra Electronics Ocean Systems is providing the low frequency broadband (LFBB) synthetic aperture sonar processing, with design and system engineering support from the Applied Research Laboratory of Penn State University (APL/PSU).

The Naval Sea Systems Command is the contracting activity for the prime contract with General Dynamics Advanced Information Systems.



Knifefish mock up mine hunting ROV, UUV





According to Baltic militaries, an estimated 80,000 unexploded mines remain in the Baltic, mostly laid by Nazi Germany and the Soviet Union during World War II. Only a few are located during regular sweeping operations.

In addition, some 40,000 tonnes of chemical weapons were dumped in the sea after the war, according the Helsinki Commission which groups Baltic nations.

Around 2,000 tonnes of chemical weapons remain in Lithuanian territorial waters said Klevas Tubys, head of its naval data department.

On board the Suduvis, another Lithuanian mine-sweepers, in total darkness, five navy members scan the depths on-screen.

A sonar device on the prow picks up objects some 30 metres (100 feet) below.

Sergeant Aivaras Rimkus has learned to read the points of light on his display, picking out mines.

"A sonar signal sent back by a mine is very strong, and the point of light flashes brightly on screen," he told reporters after having finished his duty.

Most of the time, however, the discovery needs to be confirmed by a robot equipped with a camera.

"We've found all kinds of things down there. Even refrigerators," said Rimkus, grinning.

If the object is indeed a mine, the robot places an explosive on it which is set off remotely from the vessel.

A total of 160 square kilometres (99 square miles) were swept in Operation Open Spirit, and seven mines were neutralised.

"Since international mine-sweeping operations began in 1997, a total of 143 mines have been discovered," said Lithuanian military spokesman, Antanas Brencius.

Lithuania's military resources would be over-stretched if it carried out such operations alone.

The nation of 3.3 million built its forces from scratch after breaking free from the crumbling Soviet Union in 1990.

The Red Army only left the region in 1994, and Lithuania plus formerly Soviet-ruled neighbours Estonia and Latvia joined NATO and the European Union in 2004.

The Suduvis did not locate any mines this year. But for its commander, Lieutenant Rimantas Preimantas, that was good news.

"Not finding anything is actually positive, because it means the zone is clean," he explained.

Further north, in Estonian waters, vessels involved in a 2009 operation found 64 unexploded mines.

Lithuania's President Dalia Grybauskaite has announced plans for a formal appeal before the United Nations for more help to solve the problem.







Technical details of German Second World War sea mines

'Stonefish' – a British influence mine

Development of Minewarfare

List of various mine types

Description of mines used by the United States

Henry Norton Sulivan: a depiction of early Naval Mine

Belgian-Netherlands Naval Mine Warfare School, NATO Center of Excellence

W.L.Clowes in 1855

Popular Science, March 1940, Can Mines Conqueror Sea Power

Popular Science, November 1943, Mine Killers at Work

"Fighting The Submarine Mine – How Navies Combat A Deadly Sea Weapon" October 1941

"Mines Are Dirty Tricks" , February 1951

UK National Archives leaflet on Royal Navy research and development

Wartime use of Leigh Park House

History of HMS Vernon












The Dragonfly autonomous mine hunter-killer can search all day 355 days a year without fuel or crew. Using an onboard ROV it can destroy any mines it finds remotely or log them for later demolition. Expressions of interest are invited for delivery in 2014/15 - confidentiality assured. Of the 19 US Navy ships destroyed since WWII, 15 were by mines. Countermeasures are essential even in times of peace. Effective countermeasures keep the peace. 





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