TABLE OF CONTENTS

United States Fleet Anti-Submarine Instructions

Part IV - Surface Craft

Page
4000 GENERAL AND COMMAND RELATIONS 4-1 -- 4-3
  4010 Convoy Instructions 4-1
    4011 Convoys Under U.S. Control 4-1
  4020 Instructions Governing United States Escort and Support Groups 4-1
    4021 Convoy Commodore 4-1
    4022 Escort Commander 4-1
    4023 Support Group Commander 4-1
  4030 Escort Group and Support Group Joint Operations 4-1
    4031 Command Instructions 4-1
    4032 Cooperation Required 4-1
  4040 Carrier with Escort Group 4-1
  4050 Control of Air Operations 4-2
  4060 Command of Combined Escort and Convoy 4-2
    4061 Convoy of Naval Ships 4-2
    4062 Convoy of Mixed Naval and Mercantile Ships 4-2
    4063 Scheduled Convoys 4-2
    4064 Designation of Convoy Command 4-2
  4070 Reports from Escort Commanders 4-2
    4071 Dispatch Reports 4-2
    4072 Essential Voyage Repair Reports 4-2
    4073 Written Reports 4-3
4100 CONDUCT OF SCREEN (ESCORT COMMANDER) 4-3 -- 4-6
  4110 Mission 4-3
  4120 Means of Locating Enemy Submarines 4-3
    4121 Daily Enemy Submarine Estimates 4-3
    4122 Ship Based HF/DF 4-4
    4123 Ship Based MF/DF 4-4
    4124 Radar 4-4
    4125 Visual Sighting 4-4
    4126 Sonar 4-4
  4130 Enemy Tactics 4-4
  4140 Storm Procedures 4-4
  4150 Discussion of the Escort Commander's Problem 4-4
  4160 Training 4-5
  4170 Fueling at Sea 4-6
4200 CONDUCT OF THE SCREEN (SURFACE ESCORTS) 4-6 -- 4-9
  4210 Station Keying 4-6
    4211 Patrolling Station 4-6
    4212 Zigzagging 4-6
    4213 Change of Course 4-6
    4214 Equalizing Stations 4-6
    4215 Rejoining 4-6
  4220 Investigation - Visit and Search 4-7
  4230 Rescue of Survivors 4-8
  4240 Screening a Disabled Ship 4-8
  4250 Stragglers 4-8
  4260 Convoy Discipline 4-8
  4270 Sweeps 4-8
    4274 Types of Sweeps 4-9
4300 SCREENING DISPOSITIONS (SURFACE CRAFT) 4-9 -- 4-27
  4310 Airships in Joint Operations 4-9
  4320 Airship Use of Sono-Buoy 4-10
  4330 Tactics for MAD 4-10
    4331 Pickets 4-10
    4332 Escorts Stationed Astern 4-10
    4333 When Night Surfaced Attacks are Probable 4-11
    4334 Poor Sonar Conditions 4-11
    4335 Poor Visibility 4-11
    4336 Patrolling Stations 4-11
  4340 Use of Tables for Stationing of Escorts 4-11

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Table of Contents - Part IV (Continued)

Page
  4350 Anti-Aircraft Dispositions 4-11
    4355 Dispositions for Torpedo Boat Defense 4-12
  4360 Diagrams 4-13
    4360-1 Diagram #1 - Probability of Hitting Curves 4-13
    4360-2 Diagram #2 - Typical Sonar Coverage Plan 4-14
    4360-3 Diagram #3 - Typical Contact Probability Curves 4-15
    4360-4 Diagram #4 - Increase of Limiting Approach Angle for 14 1/2 Knot Zigzagging Convoy 4-16
    4360-5 Diagram #5 - Typical Picket Dispositions 4-17
    4360-6 Diagram #6 - Typical Escort Dispositions 4-18
    4360-7 Diagram #7 - Typical Escort Dispositions 4-19
  4370 Tables for Stationing Escorts 4-20
  4380 Patrol Plan Tables 4-26
4400 COUNTER-ACTION PLANS 4-27 -- 4-29
  4410 Value of Counter-Action 4-27
  4420 Type of Counter-Action 4-27
  4430 Typical Day and Night Plans 4-27
  4440 When Direction of Attack is Immediately Known 4-27
  4450 Diagram #8 - Operation "Bingo" (Night) 4-28
  4460 Diagram #9 - Operation "Zombie" (Day) 4-29

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United States Fleet Anti-Submarine Instructions

Part IV

SURFACE CRAFT

4000 GENERAL AND COMMAND RELATIONS.

  1. Convoy Instructions.

    1. These instructions in this publication are applicable to the escort of convoys in the military and trade convoy systems under United States control.

  1. Instructions Governing United States Escort and Support Groups.

    1. The Convoy Commodore is the officer, Naval or Merchant, designated to command the convoy. He is responsible for the internal arrangements of the convoy including the assignment of stations to ships in the convoy, for the issue of instructions and regulations for the convoy, and is always responsible for the safe navigation of the convoyed ships. Under normal conditions the Convoy Commodore will control the convoy tactically in accordance with standard instructions for convoys and such additional instructions as he may receive from competent authority.

    2. The Escort Commander is the Senior Naval Officer of the Escort. The Escort Commander is responsible for the proper disposition of the escorts for the defense of the convoy, subject to instructions received from higher authority and the enforcement of such instructions given to the convoy as related to the defense of the convoy. Evasive alterations of course by the convoy when exigencies of the situation warrant are ordered by the Escort Commander, after consultation with Convoy Commodore if practicable.

    3. The Support Group Commander is the Senior Naval Officer of the Support Group.

  1. When an Escort Group and a Support Group operate together, the following instructions are applicable:

    1. A support group consisting of a carrier with screen, or of anti-submarine ships only, or both, may be placed under the command of the Escort Commander of a convoy, or the Commander Support Group may coordinate his operations with those of the Escort Commander as directed by their common senior.

    2. The Commander Support Group and the Escort Commander will keep each other informed of their operations. The Escort Commander will cooperate in such matters as in fueling ships of the support group and providing a protected station in the convoy for the carrier when flying is impossible.

  1. When an aircraft carrier is included in an Escort Group operating in direct communication, visual or voice radio, with a convoy, the Carrier Commander shall exercise control of his aircraft and any shore-based aircraft in meeting the requirements of the Escort Commander. When the carrier is operating beyond this distance, the aircraft that are sent to the convoy as escort shall be in the same status as land-based aircraft operating when no carrier is present. In acting on information and requests of the Escort Commander it should be borne in mind that the object of air support is to render assistance to the Escort Commander, and that he bears full responsibility for the safety of the convoy.

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  1. When a carrier is operating with either an Escort Group or a Support Group, the Commanding Officer of the carrier will control all air operations, including fighter cover, in accordance with the general requirements of the Escort or Support Group Commander.

  1. Command of Combined Escort and Convoy.

    1. In a task force, group, or unit organized as an escorted convoy, and composed entirely of naval ships, the senior officer of the task organizations, unless otherwise ordered by competent authority, commands both convoy and escort.

    2. In a task force, group, or unit, other than a regular scheduled mercantile convoy, organized as an escorted convoy, and composed of mixed naval and mercantile ships in the convoy, the senior officer of the task organization, unless otherwise ordered by competent authority, commands both convoy and escort.

    3. In a regularly scheduled mercantile convoy, the Escort Commander commands both convoy and escort even though there may be present in a ship in the convoy an officer senior to him, except that Task Force Commanders responsible for convoys may designate the Convoy Commodore to command both convoy and escort when in their judgment the Escort Commander is not qualified to assume this responsibility.

    4. The Fleet Commander exercising coordinating supervision over a task force, group, or unit organized as an escorted convoy may designate any officer in the Task Organization to command both convoy and escort without regard to seniority, but the provisions of 4061, 4062, and 4063 above, govern unless specifically altered by the Fleet Commander concerned.

  1. Reports From Escort Commanders.

    1. The dispatch reports listed below will be made by Escort Commanders of Trans-Oceanic Convoys to the operational authority concerned only when radio security permits unless the operational authority specifically directs otherwise.

      2. SUBJECT OF REPORT
      1. D/F bearing of submarine when bearing is first sighting report or would clarify situation.
      2. Suggested rendezvous for scattered convoy. (Include appropriate routing authorities as information addressees.)
      3. When situation demands and security permits or whenever radio silence is broken, Escort Commanders report position, course and speed.
      4. Report of encounter with submarine.
      5. Attacks by enemy aircraft.
      6. Reports of number of survivors, ship sinkings, or damage.
      7. Weather reports - when radio silence is broken.
      8. Names of stragglers with suggested rendezvous - if over 48 hours, or if diversion is made after straggling - when breaking radio silence.
      9. When detaching sections or ships, report time, position, course and speed of convoy and of sections or ships detached.
        Addressees shall be kept to a minimum in all cases. Addressees whose immediate knowledge of the substance of the report is not considered essential, shall not be included. Operational authorities are responsible for passing reports from escorts at sea to other interested authorities. (See Part VII.)

    2. In addition to the reports listed in Article 4071, Escort Commanders may, under the same restrictions as to radio security, transmit to the SEA FRONTIER COMMANDER of port of entry (for relay to appropriate shipping authorities and CominCh C&R) information as to essential voyage repairs to ships in the convoy when such advance knowledge will materially assist in planning by shipping authorities and hence, reduce turn around.

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    1. Written reports from U. S. escorts of submarine sightings, attacks and escort operations shall be made as directed by Fleet and Force Commanders.

4100 CONDUCT OF SCREEN (ESCORT COMMANDER).

  1. Mission - The safe and timely arrival of the convoy at its destination is the primary mission of the Escort Commander - normally accomplished by destruction or evasion of the enemy.

  1. Means of determining the location of enemy submarines are:
    Daily enemy submarine estimates.
    Ship based HF/DF.
    Ship based MF/DF.
    Aircraft reports.
    Surface borne Radar.
    Visual.
    Sonar.

    1. Daily Enemy Submarine Estimates - Positions obtained by HF/DF shore net plus reports of sightings, sonar or radar contacts and sinkings provide the best information as to the general location of submarines and are used as a basis for the daily enemy submarine estimates promulgated by the Commander in Chief, United States Fleet, and the Admiralty.

    2. Ship Based HF/DF.

      1. The information available from ship based HF/DF, is dependent on the type of equipment and the skill of the operating personnel. To obtain a fix when two or more HF/DF ships are present requires a high degree of training. The Escort Commander should train his group in this work in order to utilize this equipment to the best advantage.

      2. A single HF/DF bearing is of varying degree of value. Ship borne HF/DF equipment can normally distinguish between a ground and a sky wave. Under normal conditions the ground wave does not extend over 50 miles. If the HF/DF ship is doubtful as to whether the bearing is on a near submarine, the reported bearing should be weighed with other information on hand in deciding whether or not to investigate the bearing. If it is definitely from a near submarine the Escort Commander should normally order a sweep by a surface escort or plane. Sweeps predicted on HF/DF bearings should extend to the distance prescribed by the Escort Commander either by doctrine or by instructions on the spot. (See Article 4270.)

      3. Under the following circumstances a full measure of investigation should be accorded whether it be conducted by aircraft, surface craft or both:

        1. When bearing is taken on the sighting report.

        2. When information has been received from a shore station that the first sighting report has been made only recently.

        3. In general, on any bearing or bearings of a near submarine, when it is deemed that an attack by submarines is not imminent and, therefore, the forces to be engaged in investigating can be reasonably spared.

      4. When homing activities by the submarine have existed over a period of time sufficient to have effected concentration and an attack is considered imminent, the decision to use surface craft for investigation should be carefully weighed. Knowing that submarine pack attacks usually occur at night, the time of day and the visibility are important factors entering into the decision as to surface craft investigation.

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    1. Ship Based MF/DF - Submarines may use MF for homing other submarines. MF should be monitored and provision made for obtaining and plotting such bearings. Action should be taken as in the preceding article. Since powerful shore transmitters on these frequencies are often heard at sea, it is desirable that the transmissions be definitely identified as submarines before "alerting" the MF plotting organization.

    2. Radar - (See Article 1320).

    3. Visual Sighting - The importance of lookouts has not been diminished by the advent of HF/DF, radar, sonar and aircraft.

    4. Sonar - (See Part I).

  1. Enemy Tactics - Characteristics of enemy submarines are contained in ONI 220 (Revised) - German and Japanese Submarines and Their Equipment. Information on current enemy tactics in published in U. S. Fleet Anti-Submarine Bulletin.

  1. Storm Procedure.

    1. The object of a storm procedure is to reduce scattering during a storm, and to expedite reforming after the storm.

    2. In order to reduce scattering it is sometimes necessary to reduce speed and turn to a favorable course for riding out the storm. This should be done prior to the time the ships of the convoy commence this maneuver independently, with masters taking matters into their own hands. Though it is desirable to maintain course and speed as long as possible, this should not be carried to the point of endangering ships of the convoy.

    3. In order to maintain control it is advisable to devote efforts to prevent straggling in width, as it is much easier to round up stragglers along the track. This can be done by having an escort lead each wing and the center column, with one or more escorts astern to ride herd on stragglers. The remaining escorts close in on each flank to keep the convoy from spreading.

    4. The task for storm procedure should be made clear to each escort according to station assignment.

  1. Discussion of the Escort Commander's Problem.

    1. The Escort Commander's problem is usually complicated by a lack of sufficient and definite information upon which to formulate his plans. The degree of his success can be measured by his ability to take proper offensive action upon receipt of the first information that a submarine is near. The daily submarine estimate may place the convoy in an area infested with submarines, but it does not follow that submarines have contacted the convoy. It is not to be assumed, because a sweep has failed to contact submarines, that the sweep has been of no value. Sweeps may force down a submarine in a position to sight the convoy, thus causing periods of submergence which will favor opportunities to "shake off" a possible shadower.

    2. If the Escort Commander can hold down the first submarine or submarines which sight the convoy he can usually retain the initiative. Escorts used offensively early in the game are more effective than when used later defensively in the face of attack. Indications which are considered worth intensive investigation and extra fuel expenditures are:

      1. A sighting by aircraft in the vicinity of the convoy. The distance at which an investigation is practicable will be determined by -
        Bearing from convoy.
        Speed of convoy.
        Number of escorts available.

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      1. Notification or interception of a sighting report by submarines.

      2. HF/DF bearing from a ship of the convoy or an escort corroborated by report from shore authorities.

      3. HF/DF bearings from a ship of the convoy or an escort reported as near. (See Article 4122.)

      4. MF/DF bearings recognized as submarines. (See Article 4123.)

      5. Any radar contact.

    1. The Escort Commander must at all times review the evidence available, to determine whether he is concerned with one or more than one submarine. As soon as more than one are in contact with the convoy his decisions become more difficult. The relative value of escorts used offensively and defensively may then change.

    2. It is doctrine that if an A/S ship is in contact with a submarine she shall remain with it until the submarine is destroyed. When during daylight, there are strong indications that only one submarine is in the vicinity, it is good doctrine to continue the search for a long period. If the search is well conducted, the submarine will have difficulty in gaining sufficient distance to surface and close the convoy without being sighted. During low visibility the situation changes in that a submarine may surface without detection at a relatively short distance from the hunting escorts unless they are equipped with efficient radar.

    3. In general terms it is considered that normally if a contact is not regained within two hours in daylight or within one hour at night, the probability of regaining contact is so reduced that the escort will be of more value in screening the convoy. The factors involved - likelihood of attack, number of escorts available, sonar conditions, hours of daylight remaining, etc., are variable. Therefore, none of the foregoing should be considered as restricting the Escort Commander in this important matter. The absence of as escort from the screen is almost always of such importance that, lacking instructions given on the spot, a clear understanding should exist between the Escort Commander and his commanding officers. It is therefore strongly recommended that instructions be issued in advance to all escorts covering this point.

    4. Whenever the current situation requires modification of his doctrine along these lines the Escort Commander should so inform his commanding officers before losing visual or very high frequency voice communications.

    5. Information To Be Obtained Prior To Departure - Escort Commanders and commanding officers of escort ships should obtain prior to sailing the latest intelligence on the following:

      1. Enemy activities.

      2. Location of enemy submarines.

      3. Mined or danger areas along the scheduled route and areas of possible diversion.

      4. Hydrographic information.

      5. Location and time of probable meeting or passing other convoys, or friendly ships liable to be encountered enroute.

      6. Latest wreck charts and data.

      7. Full information on times and methods of receiving position, course and speed, and situation reports.

  1. Training - Experience has shown that a well organized, well trained escort group led by an aggressive Escort Commander is generally a match for enemy submarines. Experience has also shown that the accomplishments are much less if the escort is made up as a group of ships which not previously trained and operated together. The Escort Commander is completely responsible for the training and performance of his group. He must be intimately familiar with each ship of his unit, its capabilities and limitations. He should know the personalities and capabilities of the commanding officers, and so indoctrinate his group that at sea the group will function efficiently with a minimum of orders. When attacks develop, counter measures should be immediate and automatic. This can be achieved only if the escorts are positively trained as a team.

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  1. Fueling At Sea - (See Fueling at Sea Instructions U. S. Fleet, CominCh P-2 and "NavShips 633 - Fueling Escort Vessels at Sea from Merchant Tankers".

    1. On long voyages advantage should be taken of every opportunity to fuel the escorts. Escorts should be refueled even if the slightest doubt exists as to their ability to complete the voyage without refueling. Under some circumstances refueling after only two days' steaming is wise. There have been cases where this was not done, and later developments such as weather conditions, the submarine situation, etc., prevented the operation during the remainder of the voyage.

    2. Escorts should be familiar with both alongside and the astern methods of refueling. The astern method permits of refueling operations in rougher seas than does the alongside method.

    3. Whenever practicable on voyages where refueling operations are contemplated, the Escort Commander should take special precautions to insure material readiness of the escort oilers.

4200 CONDUCT OF THE SCREEN (SURFACE ESCORTS).

  1. Station Keeping.

    1. Patrolling Station: (See Articles 1200 and 4336)

      1. Escorts shall patrol stations for the dual purpose of preventing the submarine from penetrating the screen by a planned approach, and of providing for the escort's own safety from torpedo fire. Therefore, patrolling should be done erratically, taking care to avoid wake interference from adjacent escorts.

      2. Escorts should normally maintain a speed of at least 2 knots in excess of convoy speed and not less than 12 knots if escorts are capable of that speed.

      3. Normally escorts should continue patrolling their station at night and during low visibility. If an escort under these conditions is unable to maintain station by intermittent use of radar or sonar, it is advisable to close the convoy periodically.

    2. Zigzagging: (See Article 1200)

      1. Zigzagging for slow convoys (speed less than approximately 12 knots) with a broad front is considered to be ineffective in avoiding attack of submarine as well as having the serious disadvantage in the loss of distance made good, and may result in confusion and straggling.

      2. Zigzagging is considered to be effective and should be prescribed for high-speed convoys and slow convoys of relatively small numbers of ships in which the front is fairly narrow. Escorts conform in general to the zigzag courses of the convoy, but their stations remain relative to the base course.

    3. Change of Course:

      1. On execution of a change in convoy course escorts take station relative to the new course without signal.

      2. When a course change is scheduled to be executed, escorts should anticipate the maneuver with due regard to affording the best protection as to both old and new courses.

    4. Equalizing Stations - Escorts should equalize stations as necessary due to absence of an escort for any reason. If an escort is to be absent for a considerable period of time, the Escort Commander should reassign stations to the remaining escorts.

    5. Rejoining - When rejoining the convoy, escorts should steer deceptive courses and use high speed. If conditions permit, the ship rejoining should so announce on voice frequency as soon as radar contact is established in order to obviate reports of contacts for their escorts.

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  1. Investigation - Visit and Search.

    1. When a strange ship or object is sighted, the sighting escort should:

      1. Head for the contact at high speed, using deceptive maneuvers while maintaining a collision course as the mean closing course.

      2. Start preliminary identification early and outside of point blank range.

      3. Have guns and torpedo batteries trained on target, ready for instant use. The fire control and torpedo control problems should be solved while standing in.

      4. If challenge is not answered correctly or ship is otherwise suspected, proceed with investigation, visit and search. Whatever the method, keep the initiative; keep the upper hand; proceed positively and quickly.

      5. Normally, any ship encountered should be immediately directed to take a course which will keep the ship from sighting or closing the convoy.

    2. Each escort should have thoroughly instructed boarding parties and prize crews ready for immediate action. Each escort should also have a table of useful international signals for eliciting all desirable information in the shortest time. If identification signals and appearance are proper it will normally be unnecessary to take further action. The following procedure is suggested for an escort examining a suspicious ship:

      1. Hoist international signal to ship to heave to. If she refuses to comply, fire a shot across her bow. If she still refuses, treat her as an enemy ship.

      2. If the ship has stopped (investigating ship should keep end-on and close to a position about a mile from her, preferably ahead, to minimize the danger of torpedo fire, but keep gun and torpedo batteries bearing so as to be ready in case she opens fire, or her enemy character is established.

      3. If it is decided to board, a boat should be lowered and the ship ordered to close it.

      4. Investigating ship should not remain stopped in waters where submarines may be operating, but should keep good way on after the boat in the water.

      5. If, upon approach of the boarding boat, the crew attempt to abandon ship, they should be driven back on board. If ship refuses to allow boarding party on board, warning should be sent that unless resistance ceases the ship will be machine-gunned.

      6. Boarding officer should, as soon as character of ship is definitely established as friendly, unfriendly or suspicious, immediately communicate with own ship by pre-arranged signal. If character is definitely friendly the presumption may be made that submarines are not operating in vicinity and time can be saved by running down to pick up the boat. If character is undetermined or definitely enemy, ship should be made to tow boat clear of area.

      7. As soon as possible the Captain should be warned that his ship will be sunk if he permits any radio transmissions to be made.

      8. When examining a ship at night, searchlights should be used as little as possible. It may be preferable to delay boarding until daylight.

      9. The possibility of submarines operating with a merchant-man should always be considered.

    3. Procedure when a second ship is available to act in support:

      1. Supporting ship should patrol about 6000 yards on the beam of the strange ship and be ready to open fire immediately.

      2. Supporting ship should open fire immediately if the investigating ship so requests, or if investigating ship appears to need assistance.

      3. Supporting ship should maintain a suitable position for opening fire until investigating ship is well clear.

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  1. Rescue of Survivors:

    1. The destruction of a submarine and continued protection of the screened units from immediate attack take precedence over rescue of survivors. A contact shall never be broken off to pick up survivors. When the approximate position of a submarine is known, search shall not be terminated to rescue survivors until convoy is clear of danger area and possibility of making contact is remote. When counter action operations by the escort group are doctrine immediately following a torpedoing, rescue of survivors will take place on completion of these operations or as indicated in the plan. Subject to the above every effort shall be made to rescue survivors.

    2. The nearest escort to the sunken or damaged ship should carry out the rescue operations. Adjacent escort circle and conduct sonar search during rescue operations. If a specially fitted rescue ship or other ship of convoy undertakes the rescue, the nearest escort institutes maximum effective sonar screen around operation. The above measures will be varied in accordance with orders issued by the Escort Commander.

  1. Screening a Disabled Ship.

    1. Some Escort Commanders have included in their operation plans the requirement of dropping depth charges at random on a circumference not closer than 2000 yards from the vicinity of rescue operations. This is supposedly intended for morale effect on the submarine. Such practice is held to be not only wasteful, but of possible assistance to the submerged submarine in its attempts either to clear the area or for further attack on a still floating ship.

    2. With only one escort available - conduct an alternately expanding and contracting retiring search from 2000 to 4000 yards about the disabled vessel.

    3. With two or more escorts available - sector patrols should be used.

  1. Stragglers.

    1. Do not hesitate to order stragglers to close up or to lead then back into formation if necessary. During fog or low visibility escorts in the rear should close up to insure stragglers are detected early and led back to the formation.

    2. Unless otherwise ordered by the Escort Commander, or unless pursuing an enemy contact at the time, the nearest escort should screen a straggler or disabled ship and make a report to the Escort Commander. Information given shall include position from convoy, maximum speed, reason for falling out and time required to remedy defects.

  1. Convoy Discipline.

    1. The escorts must assist the Convoy Commodore in maintaining convoy discipline by reporting ships which smoke, show lights, get out of position, use their radio, pump bilges, or dump garbage in daylight. Warning such ships will normally be done via the Convoy Commodore, but due to poor signal equipment on many merchant ships, it may be necessary for an escort to go within hail of such ships and pass the warning. In situations requiring immediate action, such as showing lights at night, the escort must act directly using such measures as are necessary.

  1. Sweeps.

    1. In escort of convoy operations the general objective of sweeps is to prevent submarines from tracking the convoy.

    2. In connection with sweeps by surface ships or aircraft the primary consideration should be "at what distance, under the existing circumstances, can the submarine track?" It is known that submarines track a convoy, sometimes for days, while the submarine group is being assembled for "pack" attack.

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    1. In escort of convoy operations the general objective of sweeps is to prevent submarines from tracking the convoy.

    2. Types of Sweeps:

      1. Routine sweeps made at irregular intervals to detect or drive down possible shadowing submarines.

      2. Sweeps or investigation based on radio intelligence to detect and keep down submarines which are attempting to send radio reports and homing signals.

      3. Protracted sweeps to hold down submarines in order that evading action can be taken by the convoy when there is a degree of certainty of the presence of submarines in the vicinity, though directions are not known.

      4. Radar sweeps in low visibility for any of the purposes stated above.

      5. Continuous sweeps to extreme visibility distance by escorts stationed on the flanks.

    3. Type (A) sweeps should be made when visibility is fair to excellent, fuel expenditure permits, and there is no definite information of a submarine being present. Since the object is to sight a submarine, high speed should be used in order to provide an element of surprise. This type of sweep is effective at any time.

    4. Type (B) sweeps should be made on knowledge or radio activity by submarines in the vicinity. If the direction is known, the escort should sweep along the bearing relative to the convoy since it is assumed the transmitting submarine is on the approximate course and speed of the convoy. The escort should remain in the most probable area over a relatively long period in order to hold down the submarine while the convoy moves on. If the direction of the transmission is unknown as might be the case when the radio listening watch hears the transmissions but no bearing is obtained by the radio direction finder two escorts should be detailed, each to sweep one side of the convoy.

    5. Type (C) sweeps are difficult. The actual position of the submarine is indeterminate. Information, probably from sources ashore, as at hand to the effect that the convoy is being shadowed of the convoy is in an area of considerable submarine activity. The best opportunity for evasion exists when the submarine can be held down until well astern of the convoy in late daylight hours. A submerged submarine will drop aft at some speed between the convoy speed plus submarine speed and the convoy speed minus submarine speed dependent on what course the submarine takes. In an average case, if the submarine were 20 miles on the bow of a 10 knot convoy, it would have to be held down for five hours in order to be thirty miles astern of the convoy. Sweeps by surface escorts for the purpose of enabling the convoy to evade should be commenced 6 to 10 hours before dark, should commence from ahead and draw slowly aft until dark when the sweeping escorts should rejoin by deceptive courses.

    6. Type (D) sweeps may be ordered at any time during low visibility conditions. During such sweeps the sweeping ships should be at general quarters ready to use all weapons.

    7. Type (E) sweeps are carried out by escorts whose stations are at visibility distance on the flanks. The sweeps should extend from broad on the bows to the quarters of the convoy.

4300 SCREENING DISPOSITIONS (SURFACE CRAFT).

  1. The Anti-Submarine screening dispositions included herein are to be used as a guide to assist the Escort Commander in stationing his escorts. These dispositions take into account the following considerations:

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    1. Torpedo Danger Zone. The torpedo danger zone about a convoy is determined by constructing Probability of Hitting Curves. (See Diagram #1.)

    2. Submerged Approach Area. In order that a submerged submarine may reach a firing position in the torpedo danger zone the approach must be initiated in a limited area called the submerged approach area. To determine the submerged approach area, limiting approach lines are drawn tangent to the torpedo danger zone and are inclined outward at an angle whose sine is the ratio of the submarine's assumed speed to convoy speed. (See Diagram #1.)

    3. The submerged approach area shown in Diagram #1 is for a non-zigzagging convoy. If the convoy zigzags, the torpedo danger zone and the submerged approach area increase. (See Diagram #4). The submerged approach area for a zigzagging convoy is determined by increasing the inclination of the limiting approach lines to the base course by an angle whose cosine is the ratio of the speed made good along the base course to the convoy speed.

    4. Typical Sonar Coverage Plan. To evaluate the effectiveness of the sonar screen, a study was made of various patrol and zigzag plans using the standard echo search plan. Diagram #2 shows a typical sonar coverage plan in which the search is centered on the base course. Convoy speed was assumed to be 15 knots with the escort zigzagging at 17 knots, keying interval 2000 yards. While this diagram holds for only one set of conditions, it is presented to show the coverage obtained for a typical zigzag plan. The contact probability for the zigzag plan shown in Diagram #2 is shown by the solid line in Diagram #3. The dotted line shows the contact probability for the echo search plan centered on the bow of a ship patrolling at 12 knots (convoy speed 8 knots).

    5. It is assumed all escorts have adequate sonar gear and surface search detection radar.

    6. In some cases the dispositions are a compromise between requirements of defensive screening and of offensive action against a submarine that may have obtained a firing position inside the torpedo danger zone of convoy.

    7. With an insufficient number of escorts to make a reasonably tight sonar screen, escorts are stationed to emphasize the most favorable firing positions for the submarine.

  1. The escort dispositions in the tables apply to average speed (6 to 12 knots) non-zigzagging convoys. For higher speeds, the stations do not differ appreciably as an inspection of Diagram #1 indicates. However, for an appreciable increase in speed the Escort Commander may move the screening line further ahead. For zigzagging convoys the wider screening line required to cover the increased limiting approach area should be considered.

  2. Other Factors in Stationing of Escorts.

    1. If more than 6 escorts are available for small convoys or more than 8 for large convoys, the Escort Commander should, with due regard to visibility, consider stationing pickets at some 12,000 to 18,000 yards distant in an outer screen, in order to gain advantage of defense in depth. Experience has demonstrated that pickets are valuable in the interception of surfaced submarines, investigation of surface ships, to divert neutral ships, and to give the Escort Commander timely warning of pending dangers. Stationing of pickets depends upon weather, visibility, and the prevailing tactical situation. Typical picket dispositions are shown in Diagram #5. As a rule it is desirable that, so far as the fuel situation permits, pickets should make wide sweeps in their sectors with a view to covering as large an area as possible and not indicating to the enemy the position of the convoy. Pickets stationed down moon should cover the full convoy as silhouetted by the moon in order to contact any submarine approaching from this favorable attack position.

    2. One or more escorts stationed astern of the convoy have proven useful in preventing straggling and in maintaining convoy discipline. Such escorts are in a position to frustrate an attack from astern and to take counter-action against a submarine that may have penetrated the sonar screen. Particular cognizance should be taken that these escorts have efficient surface search radars.

[4-10]

    1. If night surface attacks are probable, the Escort Commander should consider stationing additional escorts on the quarters of convoys, particularly those making slow speeds.

    2. When sonar conditions are poor, consideration should be given to drawing escorts closer together to form a tighter sonar screen.

    3. In low visibility during daylight, it may be advisable to take night stations.

    4. Patrolling Stations. (See Article 4211.) In some cases of day stationing it may be found that escorts are sufficient in number to permit their sonar beams to overlap. In such cases, the Escort Commander may wish to preserve the sonar screen intact and may, therefore, consider the proposition of causing the escorts to change course simultaneously in carrying out the patrol of their stations. For convenience in this connection, three tables of patrol plans are provided. These appear after the screening disposition tables.

  1. Use of Tables for Stationing of Escorts.

    1. For ready reference, diagrams #6 and #7 showing typical station assignments with varying number of escorts are included. While these diagrams apply to specific cases, the positions of the escorts in relation to one another do not change materially with variation of the number of columns in the convoy.

    2. Tables #1 to #6 following these diagrams give recommended stations of the escorts for convoys of various sizes. These tables describe the station of the escort by nearing and distance from the reference column of the convoy. For escorts ahead and on the bows and flanks, the bearing and distance are from the leading ship of the reference column. For escorts stationed astern it is assumed all columns contain the same number of ships and bearing and distance are from the theoretical last ship in column. As an example, with a three column convoy with five escorts, (night):

      1. Escort #1 bears 015°; distant 3000 yards from leading ship in column #3.

      2. Escort #3 bears 080°; distant 3500 yards from leading ship in column #3.

      3. Escort #5 bears 180°; distant 2000 yards from theoretical last ship in column #2.

    3. Tables are provided for convoys arranged in 1, 3, 6, 9, 12, and 15 columns. For a convoy arranged in a different number of columns, the Escort Commander should use the nearest applicable table and slightly the stations to conform to the new front.

  1. Anti-Aircraft Dispositions.

    1. Should air attack become a primary threat, escorts should close the convoy forming a screen equally spaced at 2,000 - 3,000 yards in daytime (3,000 - 4,000 yards, night) from the nearest ship of the convoy. (Diagram paragraph 4357). Escorts should use speed available and maneuver as necessary to:

      1. Bring maximum gunfire to bear.

      2. Remain in assigned sector.

      3. Take evasive action.

    2. The screen should be divided into four sectors as shown in diagram, with Sector Commanders in tactical control for purposes of:

      1. Control of barrage fore for their sector.

      2. Assigning of radar guards.

      3. Laying of smoke screens.

      Consideration should be given to radar, armament and smoke-making ability in stationing of individual escorts.

[4-11]

    1. Convoy ships should fire only at visible targets having due regard for safety of other vessels. Convoy vessels should not fire at night due to danger of revealing their position to attacking aircraft.

    2. Should air attack become imminent the convoy should be enveloped by smoke. The escort sectors in the direction of the relative wind should be maneuvered expeditiously to accomplish full smoke coverage of the convoy prior to attack.

  1. Dispositions for Torpedo Boat Defense.

    1. Should torpedo boat attack become a threat, escorts should form screen equally spaced and about 4,000 yards from nearest ship in convoy. One escort in each sector should take station as radar picket in about the center of the assigned sector, 8,000 yards from the screen. All vessels should be on their guard against floating mines which are sometimes dropped by Torpedo Boats.

    2.  
Anti-aircraft Dispositions

[4-12]

  1. Diagrams:
    2. 4360-1
Diagram No. 1

      Assumptions Made:

      1. Convoy not zigzagging.

      2. Probability of hits by only the center torpedo of a spread.

      3. Torpedo speed 30 knots; range 5000 yards.

      4. Interval 1000 yards; distance 500 yards; ship length 400 feet.

      5. Torpedoes aimed for greatest probability of hits rather than at selected targets.

      6. Torpedoes fored from ranges in the neighborhood of 1000 yards are subject to these errors:
        7. Target course +/- 10°
        Target speed +/- 1 knot
        Aiming +/- 2°

      7. Corresponding errors with shots fired from 3000 to 5000 yards are:
        8. Target course +/- 15°
        Target speed +/- 2 knot
        Aiming +/- 2°

[4-13]

      4360-2

Diagram No. 2

[4-14]

      4360-3

Diagram No. 3

[4-15]

      4360-4

Diagram No. 4

[4-16]

      4360-5

Diagram No. 5

[4-17]

      4360-6

Diagram No. 6

[4-18]

      4360-7

Diagram No. 7

[4-19]

  1. Tables for Stationing Escorts:

    1.  

      TABLE 1 - 3 SHIPS IN COLUMN

      STATION No. ----- DAY ----- ----- NIGHT -----
      RELATIVE
      BEARING      		 DISTANCE RELATIVE
      BEARING      		 DISTANCE
      7 ESCORTS        
      1 000 3000 030 3000
      2 320 3500 330 3000
      3 040 3500 070 4000
      4 290 4500 290 4000
      5 070 4500 100 5000
      6 270 5500 260 5000
      7 090 5500 180 2000
      6 ESCORTS        
      1 020 3000 000 2500
      2 340 3000 300 3000
      3 060 4000 060 3000
      4 300 4000 260 4000
      5 090 5000 100 4000
      6 270 5000 180 2000
      5 ESCORTS        
      1 000 2500 045 2000
      2 310 3000 315 2000
      3 050 3000 090 3500
      4 280 4500 270 3500
      5 080 4500 180 2000
      4 ESCORTS        
      1 030 2500 000 1500
      2 330 2500 290 2500
      3 080 4000 070 2500
      4 280 4000 180 2000
      3 ESCORTS        
      1 000 1500 000 1500
      2 280 2500 280 2000
      3 080 2500 080 2000
      2 ESCORTS        
      1 060 2000 060 2000
      2 300 2000 300 2000
      1 ESCORT        
      1 000 2000 000 1500

[4-20]

    1.  

      TABLE 2 - 3 COLUMN CONVOY

      STATION No. ----- DAY ----- ----- NIGHT -----
      REFERENCE
      COLUMN      		 RELATIVE
      BEARING      		 DISTANCE REFERENCE
      COLUMN      		 RELATIVE
      BEARING      		 DISTANCE
      7 ESCORTS            
      1 3 010 4000 3 010 4000
      2 1 350 4000 1 350 4000
      3 3 055 4000 3 055 4000
      4 1 305 4000 1 305 4000
      5 3 090 5500 3 090 5500
      6 1 270 5500 1 270 5500
      7 2 180 3000 2 180 2000
      6 ESCORTS            
      1 3 010 4000 2 000 3500
      2 1 350 4000 1 325 4000
      3 3 055 4500 3 035 4000
      4 1 305 4500 1 280 5000
      5 3 090 5500 3 080 5000
      6 1 270 5500 2 180 2000
      5 ESCORTS            
      1 2 000 4000 3 015 3000
      2 1 315 4000 1 345 3000
      3 3 045 4000 3 080 3500
      4 1 270 5000 1 280 3500
      5 3 090 5000 2 180 2000
      4 ESCORTS            
      1 3 015 4000 2 000 3000
      2 1 345 4000 1 285 2500
      3 3 075 4000 3 075 2500
      4 1 285 4000 2 180 2000
      3 ESCORTS            
      1 2 000 3000 2 000 2500
      2 1 300 3000 1 260 2500
      3 3 060 3000 3 100 2500

[4-21]

    1.  

      TABLE 3 - 6 COLUMN CONVOY

      STATION No. ----- DAY ----- ----- NIGHT -----
      REFERENCE
      COLUMN      		 RELATIVE
      BEARING      		 DISTANCE REFERENCE
      COLUMN      		 RELATIVE
      BEARING      		 DISTANCE
      8 ESCORTS            
      1 3 007 4000 5 004 3500
      2 1 350 4000 2 356 3500
      3 6 010 4000 6 045 3500
      4 1 310 4000 1 315 3500
      5 6 050 4000 6 090 5000
      6 1 275 5500 1 270 5000
      7 6 085 5500 6 160 3000
      8 3 171 3000 1 200 3000
      7 ESCORTS            
      1 5 004 4000 5 004 3500
      2 2 356 4000 2 356 3500
      3 6 040 4000 6 045 3500
      4 1 320 4000 1 315 3500
      5 6 080 5000 6 090 5000
      6 1 280 5000 1 270 5000
      7 3 171 3000 3 171 3000
      6 ESCORTS            
      1 5 004 4000 3 008 3500
      2 2 356 4000 1 330 3000
      3 6 040 4000 6 030 3000
      4 1 320 4000 1 270 4000
      5 6 090 5000 6 090 4000
      6 1 270 5000 3 171 3000
      5 ESCORTS            
      1 3 007 4000 6 351 3000
      2 1 330 3500 1 009 3000
      3 6 030 3500 6 080 3000
      4 1 270 4000 1 280 3000
      5 6 090 4000 3 171 3000
      4 ESCORTS            
      1 6 351 3000 3 009 3000
      2 1 009 3000 1 285 2500
      3 6 080 3000 6 075 2500
      4 1 280 3000 3 171 3000

[4-22]

    1.  

      TABLE 4 - 9 COLUMN CONVOY

      STATION No. ----- DAY ----- ----- NIGHT -----
      REFERENCE
      COLUMN      		 RELATIVE
      BEARING      		 DISTANCE REFERENCE
      COLUMN      		 RELATIVE
      BEARING      		 DISTANCE
      9 ESCORTS            
      1 7 353 4000 5 000 3500
      2 3 007 4000 1 008 3500
      3 9 010 4000 9 352 3500
      4 1 350 4000 1 310 3500
      5 9 055 4000 9 050 3500
      6 1 305 4000 1 260 5000
      7 9 090 5500 9 100 5000
      8 1 270 5500 1 180 3000
      9 5 180 3000 9 180 3000
      8 ESCORTS            
      1 5 000 4000 7 000 3500
      2 1 007 4000 3 000 3500
      3 9 353 4000 9 035 3000
      4 1 315 4000 1 325 3000
      5 9 045 4000 9 090 4000
      6 1 270 5000 1 270 4000
      7 9 090 5000 9 180 3000
      8 5 180 3000 1 180 3000
      7 ESCORTS            
      1 7 000 4000 7 000 3500
      2 3 000 4000 3 000 3500
      3 9 035 3500 9 035 3000
      4 1 325 3500 1 325 3000
      5 9 090 4000 9 090 4000
      6 1 270 4000 1 270 4000
      7 5 180 3000 5 180 3000
      6 ESCORTS            
      1 7 000 4000 5 000 4000
      2 3 000 4000 1 340 3500
      3 9 030 3500 9 020 3500
      4 1 330 3500 1 270 4000
      5 9 090 4000 9 090 4000
      6 1 270 4000 5 180 3000
      5 ESCORTS            
      1 5 000 4000 9 000 4000
      2 1 340 4000 1 000 4000
      3 9 020 4000 9 090 4000
      4 1 270 4000 1 270 4000
      5 9 090 4000 5 180 3000

[4-23]

    1.  

      TABLE 5 - 12 COLUMN CONVOY

      STATION No. ----- DAY ----- ----- NIGHT -----
      REFERENCE
      COLUMN      		 RELATIVE
      BEARING      		 DISTANCE REFERENCE
      COLUMN      		 RELATIVE
      BEARING      		 DISTANCE
      10 ESCORTS            
      1 9 353 4000 9 353 3500
      2 4 007 4000 4 007 3500
      3 12 000 4000 12 000 3500
      4 1 000 4000 1 000 3500
      5 12 050 4000 12 050 3500
      6 1 310 4000 1 310 5000
      7 12 090 5500 12 090 5000
      8 1 270 5500 1 270 3000
      9 11 180 3000 12 180 3000
      10 2 180 3000 1 180 3000
      9 ESCORTS            
      1 9 353 4000 6 007 3500
      2 4 007 4000 2 000 3500
      3 12 000 4000 11 000 3500
      4 1 000 4000 1 320 3500
      5 12 050 4000 12 040 3500
      6 1 310 4000 1 270 5000
      7 12 090 5500 12 090 5000
      8 1 270 5500 1 180 3000
      9 6 171 3000 12 180 3000
      8 ESCORTS            
      1 6 007 4000 9 000 3500
      2 2 000 4000 4 000 3500
      3 11 000 4000 12 030 3000
      4 1 320 4000 1 330 3000
      5 12 040 4000 12 090 4000
      6 1 275 5500 1 270 4000
      7 12 085 5500 12 180 3000
      8 6 171 3000 1 180 3000
      7 ESCORTS            
      1 9 000 4000 6 007 3500
      2 4 000 4000 1 000 3500
      3 12 030 4000 12 000 3000
      4 1 330 4000 1 270 3000
      5 12 090 5000 12 090 4000
      6 1 270 5000 1 180 4000
      7 6 171 3000 12 180 3000
      6 ESCORTS            
      1 6 007 4000 6 007 4000
      2 1 000 4000 1 000 3500
      3 12 000 4000 12 000 3500
      4 1 270 4000 1 270 4000
      5 12 090 4000 12 090 4000
      6 6 171 3000 6 171 3000
      5 ESCORTS            
      1 6 007 4000 10 000 4000
      2 1 000 4000 3 000 4000
      3 12 000 4000 12 090 4000
      4 1 270 4500 1 270 4000
      5 12 090 4500 6 171 3000

[4-24]

    1.  

      TABLE 6 - 15 COLUMN CONVOY

      STATION No. ----- DAY ----- ----- NIGHT -----
      REFERENCE
      COLUMN      		 RELATIVE
      BEARING      		 DISTANCE REFERENCE
      COLUMN      		 RELATIVE
      BEARING      		 DISTANCE
      11 ESCORTS            
      1 8 000 4000 8 000 4000
      2 4 007 4000 4 007 4000
      3 12 353 4000 12 353 4000
      4 1 000 4000 1 000 4000
      5 15 000 4000 15 000 4000
      6 1 305 4000 1 305 4000
      7 15 055 4000 15 055 4000
      8 1 265 5500 1 265 5500
      9 15 095 5500 15 095 5500
      10 5 180 3000 1 180 3000
      11 11 180 3000 15 180 3000
      10 ESCORTS            
      1 10 000 4000 10 004 4000
      2 6 000 4000 6 356 4000
      3 14 000 4000 15 000 4000
      4 2 000 4000 1 000 4000
      5 15 040 4000 15 060 4500
      6 1 320 4000 1 360 4500
      7 15 085 5500 15 100 5500
      8 1 275 5500 1 260 5500
      9 11 180 3000 15 180 3000
      10 5 180 3000 1 180 3000
      9 ESCORTS            
      1 10 000 4000 8 000 4000
      2 6 000 4000 3 000 4000
      3 14 000 4000 13 000 4000
      4 2 000 4000 1 320 3500
      5 15 040 4000 15 040 3500
      6 1 320 4000 1 255 5000
      7 15 085 5500 15 105 5000
      8 1 275 5500 1 180 3000
      9 8 180 3000 15 180 3000
      8 ESCORTS            
      1 8 000 4000 11 000 4000
      2 3 007 4000 5 000 4000
      3 13 353 4000 15 025 4000
      4 1 325 4000 1 335 4000
      5 15 035 4000 15 090 5500
      6 1 275 5500 1 270 5500
      7 15 085 5500 15 180 3000
      8 8 180 3000 1 180 3000
      7 ESCORTS            
      1 11 000 4000 8 000 4000
      2 5 000 4000 1 000 4000
      3 15 020 4000 15 000 4000
      4 1 340 4000 1 270 5000
      5 15 090 5500 15 090 5000
      6 1 270 5500 1 180 3000
      7 8 180 3000 15 180 3000
      6 ESCORTS            
      1 8 000 4000 8 000 4000
      2 1 000 4000 1 000 4000
      3 15 000 4000 15 000 4000
      4 1 270 4500 1 270 4500
      5 15 090 4500 15 090 4500
      6 8 180 3000 8 180 3000
      5 ESCORTS            
      1 8 000 4000 12 000 4000
      2 1 000 4000 4 000 4000
      3 15 000 4000 15 090 4500
      4 1 270 4500 1 270 4500
      5 15 090 4500 8 180 3000

[4-25]

  1. PATROL PLAN TABLES. (See Article 4336.)

    1. These plans are computed for a tactical diameter of 1000 yards.

PATROL PLAN 1

SPEED OF CONVOY 8 KNOTS - SPEED OF ESCORT 12 KNOTS

TIME CHANGE COURSE TO TOTAL COURSE
00 47 left 47 left
04 117 right 70 right
10 140 left 70 left
16 70 right base course
19 78 right 78 right
23 123 left 45 left
27 45 right base course
30 check-on station on base course
31 74 left 74 left
33 133 right 59 right
37 121 left 62 left
41 138 right 76 right
48 56 left 20 right
52 102 left 82 left
56 82 right base course

 

    1.  

PATROL PLAN 2

SPEED OF CONVOY 9 KNOTS - SPEED OF ESCORT 12 KNOTS

TIME CHANGE COURSE TO TOTAL COURSE
00 None base course
01 51 left 51 left
04 121 right 70 right
08 79 left 9 left
12 64 right 55 right
15 81 left 26 left
20 43 left 69 left
23 117 right 48 right
28 48 left base course
30 check-on station on base course
31 48 right 48 right
35 112 left 64 left
40 91 right 27 right
45 97 left 70 left
50 80 right 10 right
54 30 right 40 right
58 40 left base course

[4-26]

    1.  

PATROL PLAN 3

SPEED OF CONVOY 10 KNOTS - SPEED OF ESCORT 12 KNOTS

TIME CHANGE COURSE TO TOTAL COURSE
00 None base course
01 29 right 29 right
05 86 left 57 left
09 47 right 10 left
13 63 right 53 right
18 100 left 47 left
24 80 right 33 right
27 33 left base course
30 check-on station on base course
31 38 left 38 left
35 82 right 44 right
39 69 left 25 left
42 71 right 46 right
47 96 left 50 left
51 79 right 29 right
55 61 left 32 left
58 32 right base course

 

4400 COUNTER-ACTION PLANS.

  1. While the primary objective of escort dispositions is to intercept and thus prevent them gaining favorable attack positions, there is always the possibility that a submarine will penetrate the screen. Study of submarine attacks on convoys shows that counter-action on the part of escorts in the form of a simple prearranged plan increases the probability of detecting the submarine and consequently tends to discourage further attacks.

  1. The decision as to what counter-action should be taken rests with the Escort Commander. Considerations such as the presence of other submarines in the area or imminent air attack may render any counter-action other than broad sweeps impracticable. Suggested counter-action plans included herein are designed primarily for a situation in which it is unlikely that a second attack will be launched while the counter-action is being considered.

  1. One typical night and one typical day counter-action plan are shown in diagrams #8 and #9. These plans are based mainly on the assumption that a submerged attack was made or that the submarine submerged immediately after the attack. The possibility of surfaced attacks under poor radar conditions and the possibility of the submarine escaping on the surface when escorts are incapable of making high speed should be borne in mind. Escort Commanders should prepare their own plans and specifically designate escorts who are to participate in order that counter-action be immediate and with a minimum of orders.

  1. It is important that the direction from which the attack was made be ascertained as soon as possible. Lacking other evidence, the quickest way of obtaining this information is for the nearest escort to close the torpedoed ship at high speed. If the direction from which the attack was launched can be determined with certainty immediately, the Escort Commander should consider conducting a search only on the side from which the attack was made.

[4-27]

  1.  

 

Diagram No. 8

    ACTION ON PART OF ESCORT SEEING TORPEDOING - Fire two white rockets or roman candles (if torpedoed ship has not already done so) and advise Escort Commander.

    ESCORT COMMANDER - Orders "BINGO." Designate escort to screen rescue ship while rescue operations are conducted.

    ACTION ON PART OF ESCORTS PARTICIPATING IN COUNTER-ACTIONS - At "BINGO" increase speed to maximum consistent with good sonar searching and carry out plan indicated in diagram. Escorts 6 and 8 and 5 and 7 should adjust speed so that they are formed on line while conducting the search. Nearest stern escort (9) conduct operation "OBSERVANT" about torpedoed ship until contact is made or as directed by Escort Commander. Remaining stern escort (10) conduct box search as shown in diagram.

    Escorts remaining with convoy equalize stations to provide maximum protection.

[4-28]

  1.  

 

Diagram No. 9

    ESCORT COMMANDER - Orders "ZOMBIE." Designate escort to screen while rescue operations are being conducted. (It may be advisable that an additional escort stationed ahead be designated to pass directly through the convoy for this purpose.

    ACTION ON PART OF ESCORTS PARTICIPATING IN COUNTER-ACTIONS - At "ZOMBIE" increase speed to maximum consistent with good sonar searching and carry out plan indicated in diagram. All escorts except escort carrying out operation "OBSERVANT" maintain position in line while conducting search.

    Escorts remaining with convoy equalize stations to provide maximum protection.

[4-29]

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