Easy to Lay, Hard to Sweep

The mere ex­is­tence of mines poses psy­cho­log­i­cal threat to prac­ti­cally stop maritime op­er­a­tions and thus deny ac­cess to a de­sired area at sea. A mine doesn’t have to ac­tu­ally ex­plode to achieve its mis­sion of ac­cess de­nial.

SP's NavalForces - - MINE SWEEPING - Rear Ad­mi­ral (Retd) Dr S. Kul­shrestha

The United States and Great Bri­tain had de­ployed nearly 72,000 mines dur­ing World War I against Ger­many to en­force a block­ade of the North Sea and to counter the Ger­man U-boats. The US de­ployed nearly 12,000 mines dur­ing Op­er­a­tion Star­va­tion in Ja­panese coastal wa­ters be­tween March and Au­gust 1945. These were air-de­ploy­able, ad­vanced influence ground mines that were much eas­ier to de­ploy in offensive min­ing. Mines have been used in con­flicts rang­ing from Korea, Falk­lands to Gulf wars and have in­flicted ma­jor ca­su­al­ties.

The naval mine is a rel­a­tively cheap, easy to em­ploy, highly ef­fec­tive weapon that af­fords weaker navies the abil­ity to op­pose larger, more tech­no­log­i­cally ad­vanced ad­ver­saries. The mere ex­is­tence of mines poses psy­cho­log­i­cal threat to prac­ti­cally stop maritime op­er­a­tions and thus deny ac­cess to a de­sired area at sea. Thus, a mine doesn’t have to ac­tu­ally ex­plode to achieve its mis­sion of ac­cess de­nial. North Kore­ans were able to de­ter and de­lay the ar­rival of US Marines suf­fi­ciently to es­cape safely, by min­ing Won­san Har­bour in Oc­to­ber of 1950 with about 3,000 mines.

Mine tech­nol­ogy has kept a step ahead of the ships de­signs for low acous­tic and magnetic sig­na­tures and many coun­tries are en­gaged in de­vel­op­ment and pro­duc­tion of naval mines. Non-metal­lic cas­ings, ane­choic coat­ings, mod­ern elec­tron­ics and fi­nally rea­son­able costs have made mines a weapon of choice for poor and rich nations alike. It is es­ti­mated that about 20 coun­tries ex­port mines while about 30 pro­duce them. Swe­den, Rus­sia, China and Italy are the lead­ing ex­porters. Mine MN 103 Manta from SEI SpA of Italy is one of the most ex­ported mines in the world with about 5,000 Man­tas in in­ven­to­ries throughout the world.

Clas­si­fi­ca­tion, Lay­ing of Mines and Ac­tu­a­tion Meth­ods

Mines are clas­si­fied based upon their depth of op­er­a­tion, meth­ods of de­ploy­ment or the way they are ac­tu­ated. The ver­sa­til­ity of de­ploy­ment can be gauged by the fact that mines can be laid by ma­jor­ity of sur­face craft, sub­marines, crafts of op­por­tu­nity and air­craft/he­li­copters. Mines have been used by coun­tries and non-state ac­tors alike with dan­ger­ous ef­fects and thus continue to pose a cred­i­ble threat to navies as well as mer­chant marine.

Types of mines are based upon the depth at which they are de­ployed. As per the US Naval Mine War­fare Plan, the un­der­wa­ter bat­tle space has been di­vided into five depth zones: deep wa­ter (deeper than 300 feet), shal­low wa­ter (40-300 feet), very shal­low wa­ter (10-40 feet), the surf zone (from the beach to 10 feet) and the craft land­ing zone (the ac­tual beach). Mines are of three ba­sic types namely, float­ing or drift­ing mines, moored or buoy­ant mines and bot­tom or ground mines.

Drift­ing mines float on sur­face and are dif­fi­cult to de­tect and iden­tify be­cause of fac­tors like vis­i­bil­ity, sea state and marine growth, etc. Moored mines are teth­ered mines us­ing an­chor­ing ca­bles to ad­just their depths. These can be contact- or in­flu­enced-based mines. Bot­tom mines are most dif­fi­cult to lo­cate as they can also get buried un­der sed­i­ment layer which can­not be pen­e­trated by nor­mal sonars.

Mines can be ac­tu­ated by contact, influence and by re­mote or a com­bi­na­tion thereof. With mod­u­lar tar­get de­tec­tion de­vice (TDD) up­grade kits, the older contact mines can be eas­ily up­graded to ac­tu­ate by influence meth­ods. The influence needed for ac­tu­a­tion could be pres­sure, acous­tic or magnetic or a de­sired com­bi­na­tion. In ad­di­tion, ship coun­ters and anti-mine counter sys­tems are also be­ing in­cor­po­rated in to the mines to make them much more po­tent and lethal.

Coun­ter­ing the Threat Posed by Mines

Mine coun­ter­mea­sure op­er­a­tions (MCM) are of offensive and de­fen­sive types. While the offensive MCM in­volves de­struc­tion of ad­ver­saries’ mines in stor­age or pre­vent­ing him from min­ing the wa­ters, the de­fen­sive MCM comes in to play af­ter the mines have been laid. A fun­da­men­tal con­stituent for suc­cess­ful MCM op­er­a­tions of both types is ac­tion­able in­tel­li­gence, sur­veil­lance and re­con­nais­sance (ISR).

De­fen­sive MCM is fur­ther sub­di­vided into ac­tive and pas­sive types. The pas­sive type in­volves min­imis­ing ships sig­na­tures as well as avoid­ing mines by ac­cu­rately lo­cal­is­ing them. Ac­tive MCM on the other hand utilises mine hunt­ing and mine sweep­ing sys­tems to avoid and/or neu­tralise the mines and carve out a safe pas­sage for the fleet ships. Neu­tral­i­sa­tion in­volves

The naval mine is a rel­a­tively cheap, easy to em­ploy, highly ef­fec­tive weapon that af­fords weaker navies the abil­ity to op­pose larger, more tech­no­log­i­cally ad­vanced ad­ver­saries

sweep­ing the wa­ter body (with influence or me­chan­i­cal sweeps) with sur­face, air or sub­sur­face as­sets.

Re­motely Op­er­ated Ve­hi­cles

Re­motely op­er­ated ve­hi­cles (ROVs) are the most com­monly used ve­hi­cles in MCM. ROVs are teth­ered ve­hi­cles con­nected by an um­bil­i­cal ca­ble to the mother ship. They of­fer a ma­ture tech­nol­ogy for mine iden­ti­fi­ca­tion and neu­tral­i­sa­tion. The um­bil­i­cal pro­vides both power and real time data trans­mis­sion and con­trol fa­cil­ity.

The PAP sys­tem de­vel­oped by ECA of France is one of the old­est ROVs used in MCM. The cur­rent ver­sion, PAP Mark 5 with fi­bre-op­tic um­bil­i­cal and 130 kg ex­plo­sive charge pay­load ca­pa­bil­ity can op­er­ate up to six kts speed, and up to a depth of 300 me­tres. Some of the other well known sys­tems in­clude the Ea­gle se­ries of ve­hi­cles, de­vel­oped by Bo­fors Un­der­wa­ter Sys­tems AB. The Ea­gle se­ries has the abil­ity to op­er­ate in any ori­en­ta­tion, in­clud­ing up­side down and its ex­ten­si­ble ma­nip­u­la­tor arm is used to place a charge next to a mine while main­tain­ing a safe stand­off dis­tance. The newer ver­sions, Dou­ble Ea­gle and Dou­ble Ea­gle Mk II, are much larger, with cor­re­spond­ing in­creases in depth and speed.

The mine iden­ti­fi­ca­tion and neu­tral­i­sa­tion (MIN) sys­tem has been de­vel­oped and pro­duced by Ale­nia Elsag Sis­temi Navali and Riva Caizoni of Italy. It can iden­tify and neu­tralise both moored and bot­tom mines. Its power pack is a closed-cir­cuit oleo pneu­matic ac­cu­mu­la­tor to min­imise the noise and magnetic pro­file. Raytheon’s ROV, AN/SLQ-48(V) mine neu­tral­i­sa­tion sys­tem (MNS), used by the US Navy uses a con­ven­tional elec­tro-me­chan­i­cal ca­ble; the ve­hi­cle can reach a speed of six kts, while car­ry­ing two ca­ble cut­ters and a bomblet. Also avail­able is a pack­age that com­bines bomblet with a ca­ble grab­bing ca­pa­bil­ity for the de­struc­tion of moored mines. It has a low light TV, high res­o­lu­tion sonar and is man­u­fac­tured as per mil­i­tary stan­dards.

Un­manned Un­der­wa­ter Ve­hi­cles

Since the UUVs have evolved from the rugged and re­li­able ROVs, de­sign­ers of UUVs have in­cor­po­rated sys­tems de­vel­oped for com­mer­cial, sci­en­tific and MCM pur­poses. Au­ton­o­mous un­der­wa­ter ve­hi­cles (AUVs) are emerg­ing as a ma­jor plat­form for the mine de­tec­tion and clas­si­fi­ca­tion tasks. While de­signed to op­er­ate in­de­pen­dent of con­tin­ual hu­man con­trol, many of these do have some com­mu­ni­ca­tion link used for the trans­mis­sion of data, but not for di­rect com­mands and con­trol. With no hard tether, an AUV can cover far greater ranges than an ROV, pro­vid­ing a much greater stand­off ca­pa­bil­ity for manned plat­forms. The dis­ad­van­tage, of course, is that the ve­hi­cle must be able to op­er­ate in­de­pen­dently for ex­tended pe­ri­ods of time. Data is of­ten col­lected and stored on the ve­hi­cle, and there may be a sig­nif­i­cant time de­lay be­fore it is avail­able for pro­cess­ing and ac­tion by the hu­man in the loop. In some cases, fi­bre-op­tic or acous­tic

­com­mu­ni­ca­tion links may be used to pro­vide some data back to the host plat­form dur­ing the mis­sion. Some of the UUVs are de­scribed in sub­se­quent para­graphs.

Alis­ter man­u­fac­tured by ECA weighs up to 960 kg de­pend­ing on sen­sor suite and can op­er­ate at depths of up to 300 me­tres. It has a top speed of 8 kts and en­durance of 12-20 hr. The K-Ster UUV, a 50-kg minekiller, com­pletes the com­pany’s range.

Kongs­berg of Nor­way’s Hu­gin AUV fam­ily com­prises mod­els with di­am­e­ters of 0.75 to one me­tre, which can be equipped with sen­sors and op­er­ate in semi-au­ton­o­mous or au­ton­o­mous modes. The Hu­gin 1000 has 24-hour en­durance and a fourkt. cruis­ing speed, while the Hu­gin 3000 runs for 60 hours. They also man­u­fac­ture the re­mote en­vi­ron­men­tal mea­sur­ing units (Re­mus) AUV fam­ily of UUVs. This in­cludes the Re­mus 100, with a weight of 37 kg, 19-cm in di­am­e­ter and oper­at­ing depth of 100 me­tres with 22-hour en­durance. It can main­tain a speed of five kts for eight hours. The Re­mus 600 is 3.25 me­tres long, 32.4 cm in di­am­e­ter and car­ries a range of sen­sors due to its mod­u­lar de­sign. It weighs 240 kg, can be con­fig­ured to op­er­ate at 600, 1,500 or 3,000 me­tres. It has an en­durance of 60-hour and top speed of five kts. The Re­mus 6000 can go up to 6,000 me­tres and has an en­durance of 22 hour at 862 kg weight.

At­las Elek­tronik’s AUVs in­clude the SeaOt­ter Mk. II and deep-div­ing Sea Ot­ter Mk. II D. The for­mer is for MCM, ISR (in­clud­ing on the sur­face) and rapid en­vi­ron­men- tal as­sess­ment (REA) mis­sions. Its mod­u­lar de­sign per­mits dif­fer­ent pay­loads. Sea Ot­ter Mk II weighs 1,000 kg, is 3.45 me­tres long, and has 24 hours en­durance and top speed of eight kts.

Saab’s mod­u­lar AUV62-MR for mine re­con­nais­sance is cylin­dri­cal, four, seven or ten me­tres long, with a 53 cm di­am­e­ter, and weighs 600-1,500 kg. It op­er­ates au­tonomously at 500 me­tres. With a top speed of more than 20 kts, the ve­hi­cle cov­ers 20 sq km per hr in REA mis­sions.

UUVs de­ployed by the US Navy in­clude Archer­fish by BAE Sys­tems, a sin­gle-shot mine killer with a scan­ning sonar, di­rect­e­den­ergy war­head, and twin propul­sors that al­low it to hover be­sides a tar­get for re­mote video iden­ti­fi­ca­tion. It can be dropped from he­li­copters or launched from sur­face ships and UUVs. The most mod­ern sys­tem is the Lock­heed Martin AN/WLD-1(RMS) which is a diesel-pow­ered, ra­dio-con­trolled, semi-sub­mersible mine hunter. It is seven me­tres long, weighs 5.8 tonnes and has a top speed of 16 kts. The re­mote mine hunt­ing sys­tem (RMS) pro­vides the pri­mary mine re­con­nais­sance ca­pa­bil­ity in the US Navy’s lit­toral com­bat ship (LCS) mine coun­ter­mea­sures (MCM) mis­sion pack­age.

The RMS ad­dresses a crit­i­cal mine war­fare gap—us­ing un­manned, off board sys­tems to de­tect, clas­sify, lo­calise and iden­tify bot­tom and moored mines in lit­toral re­gions—with­out putting sailors or ships in the mine­field. It uses an un­manned, au­ton­o­mous re­mote multi-mis­sion ve­hi­cle (RMMV) that tows an ad­vanced vari­able depth sen­sor (AQS-20A) that sup­ports mine hunt­ing sen­sors. RMS searches an area five times faster and at less than 1/10th the cost of older sys­tems. The RMMV can op­er­ate at great dis­tances (over the hori­zon) with 24-hour en­durance. Fu­elled for long en­durance, the RMMV’s 370 hp Cummins diesel marine engine and high-ef­fi­ciency propul­sor can drive the seven-me­tre-long ve­hi­cle at speeds ex­ceed­ing 16 kts. A stream­lined snorkel/mast—the ve­hi­cle’s only vis­i­ble fea­ture above the wa­ter­line— draws air into the engine, and pro­vides a plat­form for RF an­ten­nas and an ob­sta­cle avoid­ance sys­tem.

Real-time com­mand and con­trol of the RMMV—in­clud­ing op­er­a­tional sta­tus—are re­layed to the host ship via one of two en­crypted data com­mu­ni­ca­tions modes. For close-in (line of sight) mine hunt­ing, a high data rate RF link sends back con­tin­u­ous VDS sonar data and cam­era video. When over the hori­zon, a lower RF band­width sends snip­pets of sonar data and video im­agery. Dur­ing its mine re­con­nais­sance mis­sion, the RMMV de­ploys and tows a ver­sion of the AN/AQS-20 mine hunt­ing vari­able depth sen­sor—de­signed to de­tect, clas­sify, lo­calise and iden­tify

Mine coun­ter­mea­sure op­er­a­tions are of offensive and de­fen­sive types

bot­tom and moored mines. The AN/AQS20A car­ries port and star­board side-look sonars, a for­ward-look sonar, a gap-filler sonar, and a vol­ume-search sonar or an elec­tro-op­ti­cal iden­ti­fi­ca­tion sen­sor for mine iden­ti­fi­ca­tion.

Fu­ture Trends in AUV Tech­nol­ogy

The AUVs op­er­ate in highly un­cer­tain un­der­wa­ter en­vi­ron­ment where nav­i­ga­tion in­for­ma­tion from satel­lites is not di­rectly avail­able. While oper­at­ing un­der strong cur­rents or other un­der­wa­ter dis­tur­bances AUVs re­quire ex­ter­nal ref­er­ences for main­tain­ing ac­cu­rate nav­i­ga­tion. Cur­rently AUVs use dead reck­on­ing, INS and acous­tic sys­tems, which are prone to po­si­tional drift over ex­tended mis­sion pe­ri­ods. Geo­phys­i­cal meth­ods util­is­ing in­for­ma­tion from AUV’s lo­cal en­vi­ron­ment of­fer the best so­lu­tion. This would re­quire tech­no­log­i­cal ad­vance­ments in fea­ture ex­trac­tion from sonar data and mod­el­ling of un­der­wa­ter dy­namic en­vi­ron­ments.

Ad­vances in AUV propul­sion and ma­noeu­vring tech­nol­ogy have been at­tained in ar­eas of the bi­ol­ogy in­spired high lift un­steady hy­dro­dy­nam­ics, ar­ti­fi­cial mus­cle tech­nol­ogy and neu­ro­science based con­trol. These can im­prove AUV’s low speed ma­noeu­vring ca­pa­bil­i­ties in­clud­ing hov­er­ing, small ra­dius turn­ing, sink­ing and pre­ci­sion sta­tion keep­ing.

Mine, the poor na­tion’s weapon is easy to be laid, but very dif­fi­cult to sweep, re­quir­ing her­culean ef­forts in both cost and time.

Pho­to­graphS: Lock­heed Martin, Saab Group

Re­mote Mine­hunt­ing Sys­tem (RMS)

AUV62-MR, AUV Sys­tem for Mine Re­con­nais­sance

Newspapers in English

Newspapers from India

© PressReader. All rights reserved.