Surface Warships Against Submarines

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of

than the cost of providing an additional platform

forces in planning the time, place, and nature of their aggressive action.

In his report as Chief of Naval Operations in 1977, Admiral James Holloway wrote that “Sea con­trol is the fundamental function of the U. S. Navy and connotes control of designated air, surface, and subsurface areas. It does not require simultaneous control over all international waters, but is selective and exercised only where and when needed. Sea con­trol is achieved by the engagement and destruction of hostile aircraft, ships, and submarines at sea or by the deterrence of hostile actions through the threat of destruction.”

Moreover, Admiral Holloway says, naval forces in­volved in sea control efforts “must assure the security of those sea lines of communication between the United States and its overseas-deployed forces, be­tween the United States and its allies, and the lines of sea commerce linking the United States and its allies with the sources of the world’s critical raw ma­terials, particularly energy, upon which the economic survival of the free world depends.”

According to Admiral Holloway, fleet readiness and modernization are the main responsibilities of the U.S. Navy. Readiness is the capability to carry out any assigned role in prompt response to orders. Modernization is the continuous replacement of old ships and equipment in the fleet with new. The former CNO further said that “shipbuilding is the most complex and demanding [part of fleet mod­ernization] because [of] the long life and high initial cost of a ship. . . . Therefore, the most careful plan­ning is required to insure that a ship will be a useful investment over its programmed lifetime. Because of the unique investment considerations involved in fleet modernization, new ships must produce a force structure which at all times retains the warfighting balance to cope with coordinated air, surface, and submarine threats in any theater.”

If we could produce the optimum system for a long-term defense posture, that would appear to be both efficient and economical. But because systems of fixed characteristics will not be adequate for long against potential aggressors who have the option of time, place, and form of aggression, in reality it would be neither efficient nor economical. The mod­ernization of the fleet must, therefore, include the flexibility to adapt changing technologies to mini­mize the attractiveness of new options to a potential aggressor.

The case for surface warships as an essential ele­ment of sea control is based on the perceived charac­teristics of such ships which include the facts that:

► They have the mobility to reach distant locations on short notice without negotiation for base or access rights;

►  They provide a viable and authoritative represen­tation of national interest;

►  They can remain on station for extended periods in widely dispersed areas under almost all environmental conditions even without local base support;

►  They have some ability to perform a wide range of tasks;

►  They possess communications and command and control systems capable of supporting a wide range of activities;

►  Most are highly adaptable to modernization.

The concern expressed by Western analysts over

the extensive expansion and modernization of the Soviet Navy’s big-ship surface fleet offers ample evi­dence that modern surface warships provide at least a perception of capability. So long as nations depend upon merchant ships for the transportation of their resources and industrial products, the use of surface warships to attack or defend them will remain an option open to planners. The question is not whether surface ships should be included in the sea control force, but what realistic requirements for surface war­fare systems are.

The potential threat to shipping and to friendly control of the sea obviously includes surface and air forces as well as submarines. 'To survive in an opera­tional environment that presents a constant threat of attack from any one or a combination of these re­quires the “warfighting balance” called for by Ad­miral Holloway. No “platform” can do it all. The submarine can offer no help to other ships under at­tack by aircraft or small, high speed, shallow draft missile boats such as hydrofoils or surface effect craft- Aircraft lack both the endurance of ships and their ready access to more ammunition in a magazine' though when operating from a ship these short­comings can be alleviated. For the foreseeable future' surface warships will continue to be necessary to the power who would control the sea.

When the need for surface warships is accepted, ⁰ role for them in antisubmarine warfare follows easily- If surface ships can provide some defense against a particular threat, it appears unwise to do without that defense because some other platform might pt°' vide the defense more effectively. It is particularly unwise if that other platform cannot be relied on ^t0 be available at all times and under all circumstances- The cost of providing and maintaining such defensi^ve power in an existing surface ship, usually much l^esS different type, must be weighed against the risk ^t0

tual events in such warfare. However, there are sev­eral principles which are not only relevant but im­portant in any analysis of maritime warfare, regard­less of the state of technology. These are the princi­ples of the objective, of flexibility, of coordination, and of preparedness. World War II provides illustra­tions of each:

►  The objective. It must be assumed that any war begun by a major aggressor against the United States will have some objective beyond the sinking of mer­chant ships or the defeat of naval forces by sub­marines. If the objective warrants a war, it will most probably warrant its continuation, even if the forces initially engaged on one side or the other were to be defeated. The opposing forces in the battles of the Atlantic in both world wars went through a series of tactical and technical initiatives (convoys were coun­tered by wolf packs, which were countered by aircraft and support groups; submarines attacking on the sur­face at night were countered by radar, which was countered by radar detection devices, and so on) in spite of devastating losses, until the German nation submitted. In neither war was the submarine threat eliminated until the very end. On 11 November 1918, a U-boat building program of over 200 sub­marines was well under way and, had Germany not been forced to surrender in May 1945, the produc­tion of type XXI and XXIII U-boats would have pre­sented a radically more dangerous threat to Allied shipping than the Type VII and Type IX U-boats which had been mastered in 1943. On the other hand, the Allies were always successful eventually in finding a counter to new initiatives by the U-boat command, and the combined forces of the Allied navies were able to keep open the lines of communi­cation despite each new submarine threat.

►  Flexibility. An aggressor can be expected to apply whatever technology and tactics are available. Unless a war ends quickly, there will be time to change tac­tics and adopt new technology to meet newly-evident needs. Several times during the second Battle of the Atlantic the advantage shifted from the submarine to the antisubmarine forces, and back, following the implementation of a new doctrine or a technical ini­tiative by the losing side.

►  Coordination. After extensive analysis the Royal Navy credits World War I U-boats with sinking no more than seven ships from air-escorted convoys. Al­though aircraft sank no submarines during that war, it was their presence around convoys that kept most U-boats from attacking. In the next war twenty ships were sunk from air-escorted convoys, more than in the first war, but still not many. In both wars the U-boats were devastating to independently routed ships, to ships in weakly escorted convoys, and ^t0 those unsupported by aircraft. The much publicize hunter-killer operations by escort carrier task groups were successful when they were directed by intelh' gence or surveillance sources from headquarters ashore to a high probability area. Except when nt- tacking unescorted shipping, the U-boats were most successful when operating in coordination with one another and with aircraft under direction of ^£h^e U-boat command ashore.

► Preparedness. Even though it had been engag^e^ against the U-boats in the mid-Atlantic for months before Pearl Harbor, in 1942 the U. S. Navy ^waS poorly prepared for the U-boat offensive off our own East Coast. There were many reasons for this, not the least of which was lack of any established policy °^r any plans for implementation of a policy upon com' mencement of hostilities in American waters. Unless the United States is prepared for the full range ⁰ potential submarine threats, a brief, concentrated ef­fort might well succeed in achieving the aggressors objective before the defense forces can react eff^eC' tively. As we have seen, it took nearly twenty y^eafS of peacetime development and tactical experimenta­tion before the Type XXI equivalent was considere potentially in hand. During the succeeding fift^eetl years, all or nearly all ASW technology has been 4' rected at the nuclear submarine threat, with a resul­tant reduction in our capability to meet the challen£^e of the advanced diesel-electric submarine. Vastly ^irn' proved, with high capacity, long-endurance ba^c" teries, the modern diesel-electric submarine cannot be countered with the systems and tactics optimize for the nuclear threat. Reportedly, recent advances ^1,1 active sonar have made it effective against diesel electric submarines when used properly.

The Submarine s Vulnerabilities

As a basis for developing antisubmarine requi^re ments and policy, the potential enemy submarine should be examined for its vulnerabilities as well ‘^lS for its capabilities. One way to do this is to examine the operational constraints imposed on the potenti* threat by the nature of its probable and possible m^|S sions.

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At all times, submarines can be considered to n in one of four operational phases, each of which i*¹¹ poses constraints and limitations on a submarine, o knowledge of the effect of these constraints and lm¹¹ tations on the operating characteristics of each tyP^e of submarine will provide guidance for both AS^ planners and ASW operators. The first phase inclu4^eS

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| ^e submarines’ building, and their upkeep, refit, ‘tout, training, and local exercises in their home P^ort or advanced base area. The local waters are under friendly control and to penetrate them an ^enemy would need to mount a major strike. The marines are constrained by the nature of the area

°ncerned about enemy action.

The second phase is the transit between the base ^a and the objective area. Constraints on the sub- mes during this phase include routing, speed, r need to remain covert, requirements to com- d_e ⁿ'^{Cate w}fih the shore or with other forces, and the bme of enemy control of the transit area.

^e third phase is the patrol or time spent in the *°n area before beginning the objectives of the the ^<T^rnent- Constraints during this phase include _t|^n^SU^^rnar'^nes’ need to remain covert, communica- f ^Instructions, requirements to get into position the execution of the objectives, and the level of ^ ASW effort.

^e fourth phase is the engagement with the y as directed by the operation order. The sub- min'⁰⁰⁵ °^i^ect'^{ves w}‘d range from reconnaissance, _eva ^ln&’ delivery of saboteurs or agents, and survivor ation, to attacks on military or mercantile ship- i Constraints in this phase are primarily those "’hi li ^ ^ct^rcumstances of the engagement,

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_a<jj. ^{Ic an}d electromagnetic warfare techniques in

^ ^ltlon to “normal” ASW efforts. Other restrictions

y arise from the need to communicate for down-

missile guidance or for a coordinated attack.

_ter.^rnar*^ne fire control and weapon system charac-

_arij ^lcs affect their movement, relative positioning,

exposure to hostile sensors and weapons.

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capability can have any of three possible effects on the production and operation of a potential oppo­nent’s submarine force. The latter may be deterred from planned aggressive action, it may be encouraged to proceed as is, or it may be challenged to develop new capabilities. Whatever, it is impor­tant to understand what the effect actually is.

In order to perceive the strength, skill, and pur­pose of the foe as accurately as possible, intelligence must be collected and analyzed. The full range of the potential enemy’s submarine capabilities to harm one’s own interests must be compared with the con­straints upon and vulnerabilities of that threat. This will provide guidance as to the foe’s probable reac­tions to the ASW capabilities he perceives us to have.

The major ASW role of surface warships is the pro­tection of military and mercantile shipping against the submarine in its fourth, or engagement, phase of operations. Only if surface warships are plentiful are they likely to be ordered to pursue submarines operating in their patrol or transit phases.

So far, hunter-killer tactics have been successful only when the Huk forces are directed to intercept submarines as a result of advance information on their intended movements. Even with such informa­tion, the ability of surface ships to cover a patrol or transit area depends upon the ability of their sensors

to ¹/'^10na^ ^escorts. The number will vary according ^e speed advantage while leaping and the area of ^rage while searching. Again, any increased sus-

1 'bility to detection of the escorts due to high­^sPeed 1              i-i

^legs must be offset by counter detection and

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capability when the escorts are in the search

■ ^e speed of advance for a convoy or naval force _$ub^U ° ^*^{e near} the upper limit at which the anti- tfarine systems of the escort forces are effective. _t ^{ntt t}b*s will vary with the environmental condi- ^ns over a long route, it follows that the transit _c ^6e should vary accordingly, rather than remain th^nSCant Should reliable intelligence indicate that . C IS little          ir\7 nf cnhmarines

ittle probability of submarines being present transit area, speed may be increased to ^rnum. In favorable environments it may be pos- ^t0 maintain protected lanes within which ship- g can proceed at its maximum speed.

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ⁿ°ise has been a major issue in determining ti_0[^^{Ce s}h'P requirements in recent years. High self­simultaneously announces one’s presence and fate ^{S Slrn}fl^ar noises from submarines. Surface war- ^ers had become so accustomed to machinery ^{e a}nd active sonar sounds that the old “that’s the

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^ ^1C is syndrome was hard to break. Additionally, silencing of propulsion systems involves high design, production, and buffering. How-

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ever, the elimination of noise can mean removing or reducing its cause, which is likely to be an ineffi­ciency in the machinery. The net cost of a quiet ship might be far less than that of a noisy one on a life cycle basis. Since this is a relatively new issue for surface ships, convincing statistics from operational experience in realistic situations have not been devel­oped.

Surface ships have an advantage over equally noisy (or equally quiet) submarines in terms of detection by passive acoustic sensors, for unlike a submarine, a percentage of their self-noise can be vented to the atmosphere and some more may be trapped in near­surface propagation, depending on oceanographic conditions, at shallower depths than the submarine’s sensors.

Flow noise, caused by the movement of a ship or a towed body through the water, also contributes to

detection and sensor efficiency equations. It can be reduced significantly by improving the shape and smoothness of wetted surfaces. The addition of rub­ber windows to surface ship sonar domes has im­proved passive detection greatly.

The coating of a hull with long chain polymers can further reduce flow noise by decreasing friction. How to do this is still under examination. It may soon be practical for increasing efficiencies in liquid piping systems as well as for propulsion.

Special attention to reduction gear and propulsion shaft alignment, shock mounting, shaft alignment of pumps, generators, converters, and other internal systems, and the design, pitch, and cleanliness of propellers are well worth the time and expense they take. The cleaning of underwater surfaces has become much more practical than before now that we have diver-operated cleaning gear. The potential all these provide for winning advantages in combat far out­weighs their cost if the alternative is inadequate ASW system effectiveness.

Transient noises produced by systems that work regularly, but at intervals of from several seconds to several minutes, often provide alerting signals and classification clues to a passive listening system and should be minimized. These systems include steering gear and stabilizers. A routine operation on board most warships, paint chipping, can be heard at great distances underwater and the source of the noise is easily recognized as a naval ship. This works both ways: Surface ship systems can hear and identify the noises made by a submarine’s steering, depth con­trol, and periscope systems.

Finally, it is important to remember that a ship’s radiated noise signature is not what its own sensors measure unless those sensors are capable of conduct­ing a complete signature survey.

Sonar

Perhaps the most heated debate in surface ASW circles in the past ten years has been over the em­ployment of sonar in the active mode. Proponents of

We still don’t know as much about our variable depth sonars' capabilities as we might. Even so, it is clear that under certain circumstances it is the best sonar we have, especially against quiet electric-drive submarines, a type with which the Soviet Navy is well supplied. This is the SQS-35 at the stern of the Francis Hammond (FF 1067). VDS is carried by thirty-five of the 46 Knox class frigates, the eight modernized Forrest Sherman class destroyers, and the research ship Glover (AGFF 1).

active sonar once went so far as to attempt dictating to operational commanders that sonar must be active at all times when at sea. Such a dictatorial policy f°^r a radar system would not be accepted by a typ^e commander, but such was the degree of emotion with sonar that the effort was made. The proponents of passive sonar held that active sonar should never be used in a search mode because of its beaconing effect.

There is a time for the use of sonar in each mode and it is the operational commander who must set the doctrine, based on the operational circumstances- To establish adequate doctrine, his staff must under­stand fully the nature of the threat, the operating characteristics of the available sonars, and the environmental conditions. The following factors ap­ply:

►  Active sonar is a beacon, as is any regular erm^s' sion from a point source of acoustic or electromag­netic energy.

^ Just as in radar search, a submarine or other 1^|S' tening platform can detect active sonar emissions at ^a much greater range under most conditions than the active sonar will receive an echo from the submarine-

►  Submarines can make a range estimation from >ⁿ" tercepted sonar transmissions.

►  Because the sonar is intentionally at higher power- its transmissions will be detected at greater range⁵ than other noises emitted from a surface ship at t‘^,e same frequency.

►  Submarines are alerted to the presence of AS^xV ships and of the probability of a high value targ^et under escort by the transmission of sonar.

j The detection of a submarine by active sonar is Tu ^nt’^ent upon many factors in a complex equation

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^ese include sound propagation conditions within

encompassing both the submarine and the ship, the power and frequency of the sonar, the P n and aspect of the submarine and her size and and¹^ ^re^^ect*^on characteristics, the surface weather ^sea state, the operating efficiency of the sonar, ^{n r}he capability of the detection and classification

system.

_tio^Pass-^{e s}°nar can detect submarines by a combina- k°ⁿ of direct path, convergence zone, and bottom- ^unce propagation at great ranges, depending on noise characteristics of the submarine and the _are^ano§^raphic conditions. Potentially, surface ships ^as effective passive sonar platforms as are sub­marines.

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any other passive system, there are signif-

^^ar>r advantages 'to collecting tactical intelligence Jq⁰¹ P^ass‘^ve sonar, not least of which is that one _Sq ^eSp^{1 c} without alerting an enemy that he is doing tha ^aSSIVe systems provide more classification clues _su^an active ranging systems; as many clues as a tio ^tT'^{aririe s} noises provide. Using time, relative mo- det ^an<^ ^ray'P^ath analysis, the range to a passively _r ^ette<^ ^tar8^et can be calculated with sufficient accu- _Ca^ that LAMPS or any other available ASW aircraft

^e positioned to localize the submarine and at­^tack her.

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coma^{aCy m 1CSS} time than passive sonar does, given

contrast, active sonar provides ranges of greater

t, and also provides greater tracking accuracy. te_rr)^VeVer’ ^^ecause °h the short ranges of active sys- ' within many environmental conditions, a

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^speed submarine can break contact by maneu-

® ^and using decoys or false targets. Despite such _ter^^rtS’ *ⁿ conjunction with aircraft-deployed sys- ’ the surface passive-active combination can i ^ain contact on an evasive submarine while con-

p^tlri8 attacks on her. ^activ^CC1UenCy *^{S 3n} *^mP^ortant consideration in both _Vjj^^{c an}d passive systems. While low frequency pro- fiten ^^{reater ran}8^e ‘ⁿ active systems, high fre- _sjpj ^cy Provides the greater accuracy and better clas- f_r ^Catl0r>. Because active acoustic weapons use high b_and^ency> passive sensors should cover the high Pp, , ^S ^^{or se}lf-defense alert as well as the lower bands

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_artl^. marine noises of uniform intensity below the -t background noise can be detected by ad- rep_et- • ^sonar processing because of their regular or *^{tlVe na}ture and their directionality, compared ca„ i ^t*^le taodomness of the background noise, which ^atl U: filtered.

Both active and passive sonar systems can be towed effectively by surface ships, with the towing depth and tow length controlled to best advantage for the existing environmental conditions. Towing places the receiving sensors far from the ship, un­masked by the noises of the ship’s wake or structure. Towing and maneuvering problems are minimal.

A towed linear array provides a wide acoustic aper­ture for the detection of very low frequency sound propagate over long range via convergence and bottom-bounce paths.

Development of a tactical doctrine for variable depth sonar has suffered from lack of operational evi­dence stemming from restrictions imposed during exercises for reasons of submarine safety. When it was introduced, VDS was so respected that a Com- SubLant assistant chief of staff for operations com­mented that it was the capability he would least like to see a potential enemy install. Under the strong near-surface layers predominant in many ocean areas during the summer months, it is the only active sur­face ship sonar with short- to medium-range capabil­ity. It augments passive systems and can be used to advantage where there is a threat from quiet electric-drive submarines.

Towed passive sonars, capable of providing in­formation for vectored attack against enemy sub­marines without warning, not only place consider­able mental strain on the crews of those submarines, but they also make more difficult for them the achievement of fire control solutions.

Weapon Systems

The characteristics of ASW weapons are essentially the same no matter what the platform, whether sur­face, subsurface, or air. Therefore, any assignment of ASW roles to one or another of these based on weapons capability stems primarily from the method of delivery. The submarine is limited to a swimout or rocket-delivered weapon. The first takes a long time to get there when fired at a long range, and the launching noise of the second may alert the target.

The surface ship can vector an aircraft to attack over the full area of her power to detect and localize and can, in a tight spot, employ either swimout or rocket delivered weapons. While submarines can also vector an aircraft attack, they do so at a sacrifice of their operational freedom and their flexibility to ma­neuver at their optimum tracking depths.

Because she has little chance of delivering a sur­prise attack at short range, the surface ship should always endeavor to attack at maximum range, thus minimizing the danger of a counterattack. Surface ships can carry a greater number of ASW weapons

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than either submarines or aircraft, and they can re­load at sea.

Size

Over the years warships have been growing in re­sponse to demands for better endurance, sustained speed, weapon suites, habitability, sensors, and command systems: All factors that must be weighed in determining the best size for any new ship. The threshold at which the survival of an escort ship be­comes a concern in deciding whether to pursue a threat she was designed to counter is where the size and value of the ship must be cut, and this can only be done before she is built.

The ability to perform at least one important mis­sion is essential to justify a ship’s construction or her continued operation. A multi-mission capability ob­viously justifies greater size than an ability to per­form only one. The ability to replenish at sea is a possible trade-off for reduced endurance or payload. Reduced manning and increased automation will lessen concern over a ship’s survivability. When the survival of the force is its own first priority, its mis­sion objectives are at high risk.

Command and Control

All escort type warships should have sufficient C³ facilities to permit continuity of mission control within a force or escort group should any one ship be lost, damaged, or detached. Specially configured command ships are easily identified and will proba­bly be priority targets. To communicate as seldom as possible, especially before battle, while in combat is not only cost effective, but also an important consid­eration to survival in an electronic warfare environ­ment.

Oceanography and Tactics

Besides ship characteristics, oceanographic and tac­tical considerations are the key factors in the determi­nation of roles for surface ships. Many ocean areas present acoustical environments so favorable to sub­marines that they should be avoided by shipping un­less blockades can be established to keep the sub­marines out. On the other hand, the environment can also be entirely favorable to ASW units. Where the bottom is very irregular, the water is not espe­cially deep, and there is a good deal of biological noise, submarines can fairly easily escape detection. Of course, they are also likely to find it hard to de­tect the enemy. In deep water where both bottom bounce and convergence zone propagation are possi­ble, detection probability by surface ships rriay in­crease to nearly 100 percent, especially against larg^e nuclear submarines. The tactical trade-offs com­manders must consider are obvious.

Oceanography

Knowledge of the oceanographic environment within which any ASW mission is to be conducted >^s essential to its accomplishment. U. S. submarine of­ficers were indoctrinated in the basics of ray p^at^ analysis during World War II through the adven­tures of Sammy Submarine. Sammy was a cartoon character who depicted effectively the reasons for fr^e' quent dives to make bathythermograph traces ^anc^ how to employ the information, primarily in avoid­ing detection. Technology and techniques have ad­vanced considerably to where the submariner of today is confident he can measure, analyze, and use ocean­ographic information to his advantage in search, de­tection, tracking, and attack, as well as in evasion' Surface officers require similar expertise to counter a well directed threat. Happily, various schools no" offer them the necessary knowledge.

Depending on the environment, surface ships’ p^aS' sive sonar systems can detect submarines many md^eS away. Long detection ranges are achievable wheⁿ multiple convergence-zone propagation is present' Normally, single convergence-zone ranges vary fr^0,T1 15 to 35 miles, depending on the area. The con­vergence zone is an annulus about the sound sourc^c where sound waves converge near the surface aft^e^ normal refraction towards the bottom and reverse refraction upwards. The process may be repeate many times depending on the sound pressure le^ve and frequency of the source, providing annuli at suC' cessive ranges of about 30, 60, and 90 miles and on to several more zones. It requires very deep water aⁿ is dependent on the temperature structure of ^£h^e water column. The “wall” of the annulus is thi°’ which results in a narrow tracking zone of abor^,t eight to ten percent of the range. The detecting u^n,r must be alert 'to obtain track solution on a submarine’ early and maneuver to remain at the convergent range while positioning a follow-up system such ^aS LAMPS. If the detecting ship can maneuver freely may be able to prolong the tracking until the LAMP-⁴’’ or another aircraft, arrives and gains contact.

Bottom-bounce propagation can occur in ^an^ depth of water and depends on bottom slope and r^e flectivity. It can most practically be used where th^L bottom-reflected sound wave returns to the surface ^at a range greater than that of the direct-path prop^aF³ tion of sound from the source. It may exist with con vergence, providing range determination fr^orn

An SH-2D Lamps 1 from the cruiser William H. Standley <CG 32) overflies a surfaced Soviet Foxtrot class electric-drive submarine, with an old Gearing class destroyer beyond. When this photo was taken seven years ago, Lamps was a scarce article. That hasn’t changed. In spite of its virtues, there is nothing to suggest that it will become a common item in the future. Without Lamps, U. S. surface ships cannot attack a submerged antagonist more than five miles distant. Those without Asroc cannot do that well.

_0f^{U t}'~P^ath analysis. The existence of bottom-bounce convergence-zone propagation can be predicted high probability from climatology and ^fWronrnental forecasts.

^ ceanographic conditions may be reasonably sta-

ove ^Wlt^'^{n an} operating area but certainly will vary

tio ^{f 3 S}^'PP*ⁿ£ ^or task group transit route. In addi-

the^{0 t0} k°^ttorn characteristics and thermal structure,

tic j^^r°^^a^^^e biological and current factors (both ver-

^ ^and horizontal) are important considerations.

_a P^ath analysis is important in the use of both

f ^{e a}°d passive systems. The sonic return or echo

active contact with a submarine follows the sam_e ^    .

noi P^roP^agation paths as do the submarine’s self- de ^ernissi°ns. There is some directionality to each _Su^^enc^ⁿg on the range, depth, and aspect of the marine and the specific nature and location of the

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pl_a^^nvironrn^ental data are essential inputs to tactical _are”ⁿⁱⁿg and the selection of routes and operating _r ^aS ^^ven if there is little or no freedom to select av ^W'^C^ ^^avorable ASW factors, the information is f₀ ^at>. ^{e t0 a}'^ '^{n t}b^e determination of convoy escort in ^ITlat'^{ons an}d naval force dispositions, or for justify- j ® ³⁽Jditional supporting elements in those waters st favorable to a safe transit, in , ^0rt'^range predictions can provide timely warn- _re^g Probable changes in the environment that may _0D^qU,re modification to protective formations or to gating procedures.

teal observations are required for refinement of range predictions and, for maximum tracking ^^acy> are always preferable when in contact with

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orrectly programmed, the ray path analyzer and and ^S^^stems are particularly useful to strategic _Su ^tactical planning. Planners who vary the as- _env-^x submarine and sensor depths along with the _tj₁ej^lr°^nrnental variables will be prepared to exercise options to meet the most probable tactics of _rriar. ^aching submarines. On contact with a sub- _r& ^ne’ ^tbe analyzers are useful in determining her ^ge’ depth, and probable movements. They are

particularly useful in support of localization with passive sonobuoys.

One of the submarine’s major advantages is her ability to operate at the best search or tracking depth consistent with the environmental conditions. Now, with towed systems the surface warship has gained a similar capability, and without sacrificing her ability to perform her other missions. Moreover, submarines operating deeper than at periscope depth, whether in an ASW or an anti-surface role, are unable to employ EW sensors, whereas the surface warship continually retains the use of all her passive sensors, and always has the option to use her active sensors.

Tactics

Patrol or Escort? Many operators consider escort to be defensive and dull, and hunter-killer patrol to be aggressive and glamorous. This idea has been voiced ever since U-boats commenced unrestricted warfare on shipping in the first World War. It has always been wrong. The fact is that all antisubmarine opera­tions are dull and exhausting until contact with an enemy is made. Then they become hectic, often brutal, contests of wits and technology. Peacetime exercises, where contacts are forced to provide train­ing and in which nobody gets hurt, produce unrealis­tic expectations of warfare. Convoying could be termed offensive submarine hunting using cargo ships as bait, but that also would be wrong. The objective of convoying is the safe and timely arrival of the cargoes in the escorted ships. Convoying is an offensive operation directed at achieving a national objective. A percentage of those submarines operat­ing at sea will manage to reach shipping lanes and attack the ships. Shipping requires and deserves all the protection necessary and available to escort it through submarine threat areas with a reasonable ex­pectation of safe arrival. There is no point in sailing ships if they have no chance of delivering their car­goes.

Attrition of submarines before, during, and after attacks on shipping should remain an operational ob­jective but should not be pursued at the cost of the