3%-FATH0M LtilE RECOTI AREA ()F INTEREST VISUAL OBSERVATI()il

()FFSH()RE TIEARSHORE I F()RESH()REBACI(

SHORE I HII{TERLAI{OIcoastal terrain exits)

HIGH -,:11'l \

t i LEI{GTH r

t1----lBERM CREST

MEAI{ /1g$, -JWATER 3(}.F()OT

DEPTH

Figure 21. Typical beach profile.

Figure 22. Delermining gradient or per-centage of slope.

32

is expressed as a ratio of water depth to hori-zontal distance and is classified as:

Flat . Less than 1:120Mild. .....1:120to1:60Gentle .....1:60to1:30Moderate . . 1:30 to 1:15Steep . . More than 1:15

Backshore width is measured from the upperlimit of normal wave action inland to theextreme limit of storm wave action. The gra-dient and composition of the backshore areidentified in the same manner as those of theforeshore. Vegetation is often found growinghere since it is normally dry and acted upononly by storm waves.

Hinterland is the area extending 5 milesinland from the back of the beach (coastline).

Length is the distance along the beach at thewater's edge during high and low waterbetween the ends of the beach. Usable beach

_I

V

_lWhen using any distance for (H), use theformula:

%Stooe= f, xlOOBy always setting the horizontal (H) at 50, andmeasuring the vertical distance (V), theformula becomes:

% Slope = 2V

lh to hori-

han 1:12020 to 1:6060 to 1:3030 to 1:15than 1:15

the upperod to the, The gra-ghore areose ofthelgrowing:ted upon

' 5 milesoastline).

rch at thelw waterble beach

length is that length less those areas thatpresent obstacles to landing. Obstacles in-clude all natural and manmade obstaclesbetween the low-water line and the coastline.

Shape is classified as straight, concave, orconvex. The coastline is marked by the limitof normal storm wave action and is classifiedas cliff, dune, or plain.

BEACH SUBVEY REPOBTA beach survey report is a written report con-sisting of three sections. It may be accom-panied by sketches, overlays, annotatedcharts, photographs, exposed film, and soiland vegetation samples to clarify or amplifythe information contained in the report. Thethree sections are:

Heading. The heading contains the followinginformation, which the SFOB/FOB uses toevaluate the information in the rest of thereport.

o The DTG the report is submitted.o The identity of the element conductingthe survey.o The identity and location of the beachsurveyed:

Reference maps or charts used.Designation or code name of the beach.Six-digit coordinates of the beachflanks.Landmarks used for identification andtheir position relative to the center of thebeach.

o The DTGthe survey was completed.o The DTG the survey was started.o The datum plane used to determine theshoreline.r A brief description of the conditionsunder which the survey was conducted toinclude weather, visibility, and enemyinterference.o A list of items to be forwarded (e.g., bymessage pickup procedures).

Beach description. This section contains datato evaluate the suitability of a beach foramphibious operations. As such, it is the

body of the report and must be detailed andprecise. It includes-

o Beach length and configuration'o Usable beach length.o Beach interruptions and obstacles.o TyPe of coastline.o Foreshore description:

width.Gradient.Composition.

o Backshore description:width.Gradient.Composition.

o Vegetation.o Exits.

Observed enemy situation. The enemy situa'tion section contains all information aboutthe enemy that may have been collected dur'ing the beach survey. It includes a precisediscussion of all manmade objects on thebeach, regardless of whether or not suchobjects were obviously erected as part of abeach defense. The discussion of enemydefenses and activities is not limited to thosebccurring on the beach proper; it includes allsuch defenses and activities observed.

SURF OBSERVATIONFAVORABLE SU RF CHARACTE RISTICSEven though the actual surf characteristicsmay be unpredictable, the relative surf char'acteristics for two tentative landing areascan be predicted and the best one selectedbased on these predictions. The followingfactors tend to produce preferred conditions:

Nearshore shoals,ledges, and rough bottomcontours tend to break up wave patterns andmay reduce surf on the beach, but aredependent on water depth, gradient, andwave height.

Offshore islands tend to break up oceanswells and produce several patterns ofsmaller waves.

Swift currents flowing in the same direction

33

as the wave advance and the onshore windsmay reduce wave height.

A reef face or other abrupt break in the bot-tom may cause each wave to break up intosmaller waves.

A shallow gradient will cause waves to breakgradually (spilling breakers). The number ofbreaker lines and the distance from the beachwhere waves break depend on gradient andwave height.

A submarine trench in the nearshore or fore-shore area generally reduces waveheight. Submarine canyons in offshore areashave no effect. In rare instances, trenches inthe nearshore/foreshore areas cause surfre-inforcement.

UNFAVOBABTE SURF CHARACTERTS.TtcsThe least desirable surf conditions existwhen several breaker lines are present orwhen a single breaker line spills directly ontothe beach. The following factors tend to pro-duce undesirable surf conditions:

A steep bottom will cause waves to breakclose to or directly onto the beach. The breakof the wave will be followed by a violentshoreward rush of water if the wave is higherthanSor4feet.

A sandbar parallel to the beach may causewaves to peak up or break, depending on thewater depth over the bar. (The sandbar willhave no effect if the depth of the water overthe sandbar exceeds twice the wave height.)A single breaker line may form over a sand-bar while another breaker line forms close toor on the beach. Multiple breaker lines mayexist with or without the presence of a sand-bar. Sandbars are frequently found offsandybeaches exposed to wave action.

Kelp and dense seaweed on the surface of theforeshore and nearshore sea approach willsignificantly impede small boat,/swimmerprogress. These areas should be avoided ifpossible.

34

All waves will break when the water depth isless than the wave height. About half of allwaves will break when the water depth isbetween one and two times the wave height.Very few waves will ever break in waterdeeper than twice the wave height, althoughthe wave crests will tend to peak up distinctlyat this point.

suRF REPORT (SURFREP)One of the most critical and highly variableitems of information required by the com-manders of the SFOB/FOB is the surf condi-tions on beach landing sites. Surf forecastscan be made if the nature of the offshorewaves is known or can be accurately pre-dicted and charts of the inshore bottom areavailable. Another way to collect this infor-mation is to make a recon to observe the surf.Surf observation requires only one person, awatch with a second hand, a pencil, andpaper.

Select a vantage point as close to the shore-line and as near to the center of the BLS aspossible.

Make observations only on that portion ofthe surf zone that lies directly in front (sea-ward) of the vantage point.

Observe the surf for a 10-minute period.

Record each breaker as it occurs. Record onlythe outermost breaker occurring along yourline of sight when two or more waves breaksimultaneously.

Record significant breaker height to nearesthalf meter. Significant breaker height isthe average height of the highest one third ofall the breakers observed during the period.

Record maximum breaker height to nearesthalf meter. Maximum breaker height isthe height of the largest, single breakerobserved during the period.

Record breaker period to nearest halfsecond.Breaker period is the time in secondsbetween breakers. It is computed by dividing600 seconds (10 minutes) by the total number

lepth islf of allepth isheight.I waterthoughrtinctly

ariablele com-f condi-,reCaStS

rffshorerly pre-mm are.s infor-he surf.)rson, ail, and

e shore-BLS as

rtion ofnt (sea-

od.

rrd onlyng your:s break

nearesteight is,third ofperiod.

nearesteight isbreaker

lsecond.gecondsilividingnumber

of breakers observed during the period.

Record number of breakers by type as indi'cated below:

o Spilling (Letter Code A). The wavebecomes unstable at the crest and formswhite water at the crest. The white water(foam) expands slowly down the front faceof the breaker. Breaking action is mild.o Plunging (Letter Code B). The wavecrest advances so much faster than thebase of the wave that it falls almost intothe trough with a violent action. Theresulting foam appears almost instantlyover the complete front. At times, air iscaught in the breaker as it tumbles for-ward, creating a tYPe of exPlosion.o Surging (Letter Code C)' The wave cresttends to advance faster than the base ofthe wave, suggesting the formation of aplunging breaker. However, just beforebreaking comPletelY, the wave baseadvances faster than the crest and theplunging is arrested' These are generallyfound at steep gradients.

Breaker angle,/direction is the acuteangle (in degrees) formed between thebreaker lines and the shoreline, expressed tothe nearest 5 degrees. The breaker direction isthe direction towards which the breaker ismoving, expressed as R (right) or L (left) ofthe observer.

Littoral drift (inshore current) is thespeed of the current moving generally par-allel and adjacent to the shoreline expressedto nearest one-tenth knot. This number is fol-lowed by the letter R (right) or the letter L(left) to indicate the set (direction) of this cur-rent. This set is the direction towards whichthe current is flowing, as seen by theobserver.

Speed in knots may be determined by throw'ing a stick into the current and observing thedistance it travels in 1 minute. Divide thisdistance by 100; e.g., if the stick traveled 250feet, the current speed is 2.5 knots.

Lines of breakers is the number of well'

defined breaker lines in the surf zone' It isfollowed by the width of the surf zone to near-est meter. The width is the distance from theoutermost breaker to the extreme uprush ofwater on the beach'

Remarks. Include special factors that couldaffect the above report; e.g., strong winds,restricted visibility. (If none, omit this item inthe report.)

NOTE: The term RIGHT or LEFT of theobserver always refers to the BLS as theobserver would view it from the sea'The types of hydrographic survey- -are

dis-

"o.""aln detaii in NAVEDTRA 38013, US

Nu"ut Special Warfare Training Handbook'On" of t-he simpler types is the day combatrecon. (See figure 23.) This type of recon can

be conducted more rapidly and will exposethe s*immers less to enemy shortfire than

olh", typ"" of recon, however,'it provides theleast accurate information'

The day combat recon is scheduled so thatthe delivery craft can drop the swimmers assoon as there is enough light to identify thebeach. In this way the swimmers can reachthe beach and return before the averageman's working day begins' This type reconrequires-

o A person in charge, pickup man, cartog-

"uph"r, and two swimmers for everY 25

meters of beach to be surveYed'

o Appropriate cast and recovery and cartog'

"upfrv equipment and one slate, leadline,

and pencil Per swim Pair'

Procedure:

-, . One pair, usually the pair in the center,is designated guide Pair.

o The swimmer pairs are dropped in thewater 25 meters apart in a line parallel toand 500 meters from the water's edge'

o Using the guide pair as a reference point'pairs maintain a 25-meter interval duringthe recon.

35

CE-E

CECf-.

-.-.

-.-t

Cf-.CE.

Figure 23. Day combat reconnaissance.

o Upon signal from the guide pair, theswimmers move toward the U"acfr. iffr"guide pair may use a compass to assist inswimming a predetermined course to andfrom the beach or it may guide on adesignated object on the beach-.)o When the leadline man in each pairreaches a point where he estimates thedepth is 2t feet(usually the depth at whichrecordings are first made), hL lowers hisline.

o When the leadline touches the bottom,the leadline man notifies his buddy (therecorder) who signals the guide p.i, tostop.

o The leadline man records the depth onhis slate.

o The guide pair estimates the distance to

the high water mark and signals all pairsto take a sounding.

o From this point on, soundings are takenevery 25 meters in to the beach. Whenevera swim pair reaches an 1g-, 12-or 6-footsounding, it also takes a bottom sample.o At the water's edge all pairs shift left127/2 meterc with each pair recording thebeach gradient and any other significantforeshore, backshore, or hinterLnd fea_tures in its area.o When the shift left has been completed,all pairs swim back out to sea, iakingsoundings as before and still guiding onthe guide pair.

o On command from the guide, theswimmers form a line parallel to the beachwith each man 2b meters apart for the

36

I pairs

taken)never6-footrple.

left 72rg the6cantI fea-

leted,rkingrg on

, thercachr the

pickup. To do this, one man from the centerpair remains stationary, and all othersswim towards the flanks. If anothermethod of pickup is to be used, the pickupline formation will be changed accord-ingly.

Key points. One pair is designated before-hand to take a surf observation (SUROB)rather than take soundings during the recon.

If the recon is to be accurate, it is imperativethat the swimmer pairs maintain the properinterval and that all pairs follow tha guidethroughout the recon. Another technique toadd accuracy is to have a third swimmer witha 25-meter line accompany the guide pair; hecan swim ahead to where the next soundingshould be taken. This can also help verify theguide's initial distance estimate.When making a dive during a combat recon,care must be taken to prevent fins fromsplashing water. To do this, the diver force-fully brings his arms up from his side, palmsupward, to thrust himself straight down.When he is several feet below the surface, heexecutes a jackknife dive and commences hisunderwater swim.

Swimmers should be careful to avoid detec-tion from the beach. They should avoid allow-ing the sun to reflect off the face mask, hold-ing the line or slate above water when sound-ing or recording, proceeding into too shallowwater, and raising the body out of the waterwhen close to the beach.

During every recon, the most thorough photo-graphic coverage possible should be obtained.The areas to be covered are:

Offshore to hinterland panoramas (seefigure21). From both the left and right flanks of thebeach, standing at the water,s edge, takepanoramas of 10% overlapping views begin-ning offshore and sweeping inshore. Showthe approaches, 1eefs, waterlines, the fulllength of the beach, full width of the beach,and beach gradient.

Backshore and hinterland panoramas. From

the scarp at the center of the beach, take apanorama of the backshore and hinterland,ridges, escarpments, vegetation, and obsta-cles.

Beach exfts. Obtain medium views and close-ups emphasizing location, surrounding fea-tures, access, and trafficability. Take viewsfrom the beach facing inland and from thehigh ground inland facing seaward.Hinterland. Show vegetation, soil and rocktypes, trafficability indications such aswheel tracks and swamp areas, obstacles,habitation, roads, and defenses or defenda-ble positions.

Miscellaneous. Show conditions or obstaclesthat will assist in identifying the materialcomposition and trafficability of the beach.Take complete coverage (including closeups)of any features encroaching on or limitingthe usefulness ofthe landing areas, such ashazards to approach and barriers to egress.Include personnel or familiar objects in pho-tos whenever possible to assist interpreter indetermining measurements. Whenever pos-sible, obtain photographs of underwaterobstacles. Pictures taken at night should betaken with infrared film and flash, and per-sonnel should be trained in their use.Recording. As eaeh photo is taken, make anentry on the Beach Survey Photo Data Sheet(figure 24). Be sure to include every phototaken-even the mistakes and blanks.When a person has been included in a pictureto show the relative size ofbeach features, besure to include the person's height on thePhoto Data Sheet.

There are three steps to be taken before sub-mitting negatives of beach photographs to acommand that requests them:

1. With each set of beach photographs, sub-mit a chart of the beach with markings indi-cating the locations from which the photoswere taken.

2. Print on each negative the national intel-ligence survey (NIS) number (or name) of the

37

b.each and the exposure number of the nega-tive.

3. Submit a Photo Data Record with the nega_tive. (See suggested format, figure 25.)Marking the swimmer,s slate. Each swimmershould mark off his slate prior to a recon sothat all he has to do while in the water is fill inthe blanks. See figure 26 for the different

markings used for the various recons.When time permits, a post-recon question_naire should be filled out by each swimmerpair immediately after a combat recon. Thisallows the swimmers to submit more detailedinformation and gives the cartographer morelegible writing from which to work. See sug-gested format post recon questionnaire at endof chapter (figure 27).

NOTE: All data on top ofthis sheet is to be printedin india ink on the be_ginning of each rollof film.

BEACH

PHOTOGMPHER

UDT- DET-DATE

TIIYE STARTED--IIMEEXPOSURE# DATT & TIME COI]

COUNTRY

CAMERA

FI LTl S IZE

FOCAL LENGTH

FINISHED- ROLL#

Figure 24. Sample beach survey photo data sheet.

PHOTO DATA RECORD

UI'ICLASSIFIED

PH0T0GRAPHER: FINCH, F. E., Qt4Z, USN, UDT _ it DET ,,C,,F0CAL LENGTH: 6,, NEGATIVES: 4 x 5

BEACH PHOIOS OF ,,I]S BEACH 22, UTOPIAUTOP IA

2

NIS BEACH 22

EXIT AT LEFT FLANK

031800T JUNE 1956

UTOP I A

3

NIS BEACH 22

UTOP IA

4

NIS BEACH 22

EXIT AT RIGHT FLANK

031800r JUNE 1956

UTOP I A

5

NIS BEACH 22

UNCLASSIFIED

BEACH CENTER LOOKING INLAND CLOSEUP OF TANK TRAPN,TE TANK TRA, rr,i FR0NT ;|,s5iltsrflE i5l3'OF TREI RIGHT SIDE031800T JUNE 1956

DESCRIPTION OF

38

Figure 25. Suggested format photo data record.

PAIR#

NAMES:

DEPTH(FT )

DIST(IN)

DIST(ouT) COMMENTS

23

45

67Rg

l0

12l3l4l5l6

1.

ueetion-rimmerrn. ThisletailedermoreSee sug-e at end

Front

PERPENDICULAR ADMIN, IBS &SUBMERGED

Back

DAY COMBAT

SWIMMER NO:YARD MARKER:

NAMES:

LN DEPTH LN DEPTH COMMENTS

2 142 t54 l6

17

l9

t0 Z

12 24

PARALLEL ADMIN & NIGHT COMBAT

format various slate markings.

39

CURRENT

OUTSIDE SURF ZONET-DIR -VEL -KTINSIDE SURF ZONE: DIR VEL KT

SU RF

TYPE: %SPILL %PLUNGE %SURGEANGLEJfFROM-AV HT:

-FT MAX HT-FT

PERIOD:

-SEC

LINES IN SURF ZONE-WIDTH OF SURF ZONE

BOTTOM COMPOSITIONi FATH2 FATH3 FATH

BEACH

COMPOSITIONSHAPE

GRAD I ENT_l !OBSTAC L ES

EXITSMISC

PAI R#

NAMES:

DI ST(YDs)

LANE LANE LANE .ANF

D I NFO U INFO D INFO INFO

255075

t00125150I75?oo2252502/5300

Figure 26. Suggested

POST-R ECON NAISSANCE OUESTION NAI R E(S uggested Format)

Swimmer Pair No.

Names:

Date

Condition of sea from drop point to surf line: Calm (less than 1 ft)_Smooth (1-2 ft)_Slight (2-3 ftl_Moderate (3-5 ft)_Rough (5 ft and up)_Current outside breaker line: Direction Velocity in knots.Distance from first breaker line to high water marker (HWM)_yards.Type of breakers: Spilling_Mixed_plunging_None_.Average height of breakers_ft.Maximum height of breakers_ft.Period in minutes between series of high breakers_.Number of lines of breakers:

Distance from HWM to breaker lines: 1-!_3 4_yards.Time interval between breakers: sec.Breaker angle with respect to beach: O,uartering_parallel_.Current inside breaker line: Direction_ Velocity_ KnotsType of bottom at 1 fathom curve:

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

40

Rip tides present: Yes_No_.Sandbars present: Yes_ No_.composition of beach A. sand-shells-pebbles_Lava_Rock_

B. Veryfine_Fine_Medium_Large_.17. Shape of beach: Straight_Curved_Cusped_Other_.18. Trafficability: How deep impression did you make in sandl_.

(Specify how impression made:_.)19. Obstacles underwater (describe number, type, size, location, depth of water over,and estimate amount of explosive required to demolish):

A. NaturalB. Manmade

20. Obstacles on beach (describe type,number, size, and location, and estimate amount ofexplosive to demolish):

A. NaturalB. Manmade

Figure 27, Suggested format post reconnaissance questionnaire.

,l_.n knots.

s.

er over,

22.

23.

24.

21 . lntelligence data:A. Was there any indication of enemy activity on beach: Yes-No-

B. Tracks on beach: Yes-No TyPeC. Gun emplacements: Yes-No-TYPeD. Personnel: Sentries: Yes-No-TypeE. Tanks: Yes_No_.F. Other comments

Exits from beach: A. Personnel B. Vehicles

Does the area appear to be mined: Yes,Sounding and distance from HWM:

ln-sounding Distance Out-Sounding Distance

25. Draw beach profile as beach looked to you with approximate location of prominentlandmarks.

No

,Ount Of

Figure 27. (Continued) 41

CHAPTER 4

This chapter provides guidance in the use ofboats to transport combat units on inland water-ways, lakes, rivers, canals, and delta areas. Thetactics and techniques discussed appty to theuse of the MARS and nonmilitary craft such assampans, kayaks, junks, and other local smaltcraft.

Small boats may be used to support SF opera-tions. The principles and tactics of smaliboathandling and crew drill are similar and gen_

erally may be applied to many differentoperations.

PLAN NING CONSIDE RATIONS

SF detachment commanders participate inthe early planning for all u*phibiou"- op"ru-tions. On receipt of the initial infiltrationorder, the SF commander will coordinatewith amphibious support elements on theplan of execution. The plan will includeavailability and type of boat to be used,departure time, embarkation and debarka-tion sites, communications, and rehearsalplans.

SF detachment commanders who plan andconduct small boat operations musiconsiderthe boat as a means of transportation and not

42

as an armed fighting vehicle. Boat patrols orboat-transported security elements will haltfrequently to observe or scout the river bank.In some instances these elements may berequired to fight from small boats, Thismight occur in reaction to an ambush, sur_priseenemy activity, pursuit of enemy boats,or when operating in swamps or floodedareas where debarkation is impractical.

Detachment commanders must analyze allthe advantages and limitations in operatingsmall boats.

Operations

L

Mrefferent

\PTER 4

ttions

;rols orLll halt'bank.ray be. Thish, sur-boats,loodedil.

rze allrating

ADVANTAGESSpeed. Motor-powered boats available to SFdetachments can attain speeds up to 50kilometers per hour. Even at slower speeds,boat-transported forces can move morequickly in areas with dense waterway sys-tems than foot troops in armored personnelcarriers.

Range. Fuel efficiency for a MARS is 3 to 11kilometers per gallon depending on the loadcarried.

Obstacles. Traveled waterways are usuallyfree ofobstacles, and shallow draft boats cannormally maneuver around any obstaclesencountered. In dense jungles and coastalareas, waterways often constitute the onlysatisfactory routes of surface movement.Obstacles such as fallen trees, traps, mines,and other natural or manmade obstacles willslow movement considerably.

Boat capacity. Units moving by boat can carryfar more weapons and equipment than footelements. In planning boat operations, com-manders must insure that adequate meansare available to move and use equipmenteffectively after troops debark. Troops shouldtake only equipment they can manpack if noother means for moving equipment are avail-able.

LIMITATIONSCanalized movement. Boats are confined towaterways. Movement may be restricted byheavy volume of water traffic. Boats can,however, be carried for short distances over-land.

Concealment and cover. Some waterways,especially wide waterways normally used ascommunication routes, are devoid of coverand concealment. Boats can be seen and eas-ily fired upon in daylight. This may limitboat operations to night movement, or boatsmay have to travel close to the banks whereshadows and overhead branches aid conceal-ment.

Noise. The noise of outboard motors reducesthe degree of surprise and secrecy. For opera-

tions such as ambushes, raids, and infiltra-tions, required secrecy and surprise may beobtained by rowing indigenous rivercraft.

Landing requirement. Boats must go to or nearthe shore to unload troops in shallow water oron land. This limits the reaction time of theforce in surprise situations such asambushes. Often there are no convenientlanding sites.

The MARS offers the SF operational detach-ment (SFOD; "O" a swift and relativelysilent means to transport a split detachmentfrom a distant water dropoff point to its BLSand to return to a designated pickup point.The use of the MARS should be considered fordelivering personnel to the BLS under thefollowing conditions:

o There is no threat from enemy air orcoastal defense systems.o The tide, current, and wind conditionsmay cause swimmer fatigue and naviga-tional errors.o The large amount of equipment neededto conduct the mission precludes swim-ming bundles to the BLS. (See appendix Cfor a complete planning checklist.)

Further aspects concerning the operationaluse of the MARS may be found in TM 5-1940-276-70. Using inflatable assault boats forinfiltration requires detailed planning andpreparation. Personnel must have a thoroughknowledge of small boat handling tech-niques, boat team assignments, and specificduties. Extensive rehearsals should be con-ducted during the preinfiltration preparationphase and even during the movement to drop-off point phase if time and situation permit.

SPECIAL CONSIDERATIONSBoat operations are basically the same asother operations that use special means toincrease speed of movement (trucks, heli-copters). Backward planning techniques areused. Commanders should avoid basing ihegeneral scheme of maneuver on availablewater routes. Boats are intended to increase,

43

not restrict, the range of choice available.Detachment commanders should consider:

INTETLIGENCETerrain intelligence is especially importantto the detachment commander when he isplanning small boat operations. He shouldcarefully analyze the waterway net, espe-cially in an enemy-dominated area where thepattern of canals and streams may be alteredto suit the enemy and to confuse opposingforces. He should use aerial photographsextensively to get a detailed picture ofdrain-age patterns, new canals, obstacles, andrecent changes not shown on maps. photos orphotomaps are desirable for determininglocation during movement because of thedifficulty in measuring distance traveled onwater.

Personnel supplement this informationwhile moving on the waterways by recordingactual conditions. They record obstacles, pos-sible ambush sites, current speed, water piantgrowth, amount of tidal effect, and other fac-tors that may influence boat operations.In analyzing the enemy situation, a detach-ment commander should carefully considerthe water avenues available to the enemyforce. He should give special attention tolocating and neutralizing boat resources,especially powered craft that can be used byenemy units. From his analysis and informa-tion concerning the waterway, he can effectoperations to position friendly units to blockall water routes available to the enemy.

COMMUNTCAT!ONSFor security, communication between boatsmust be minimal. The entire operation,including immediate action drills, should beplanned so that radio communication be-tween boats is unnecessary. One way toavoid the need for radio communication is touse a follow-the-lead-boat-and-do-as-it-doesplan. Boat teams should stay within sight ofeach other so that they can use arm and handsignals.

44

SUPPLY AND MATNTENANCEThe gasoline supply in a UWOA must becarefully planned, since outboard motors con-sume a high rate of fuel. Most motors requireconstant and proper maintenance to insuredependable performance. Commandersshould consider the need for extra mainte-nance personnel in operational areas. Spareparts and extra motors may be carried onoperations conducted away from the mainguerrilla base.

ORGANIZATIONThe detachment commander should remainflexible in organizing small boat elements.The mission in the objective area may dictatethe size of force required, force composition,amount of equipment, order of boats in thewater movement, and number of boatsrequired.

OTHER CONSIDERATIONSSmall boats give SF units the additionaladvantages of flexibility and mobility.Powered craft give SF units a load-carryingcapability, maneuverability, and speed. Acommander can employ these craft in sup-port of civic action projects, environmentalimprovement programs, and when required,counterguerrilla and recovery operations.Powered craft permit the SF unit to bringsuperior fire power to bear against an insur-gent force operating in predominantly waterareas.

Small boats/powered craft can also be usedfor-Medical evacuation. Small boats provide arelatively fast means of evacuating casual-ties. When boat evacuation is planned, aidstations may be located for convenient accessto waterways. Landing sites should be pre-pared to facilitate unloading casualties.Movement of supplies. The methods of mov-ing supplies may be primarily by water whenoperating in remote areas and during adverseweather conditions. Small boats and indi-genous craft may be used to transport sup-

rust be0r8 con-require,insureandersnainte-. Spareried one main

remainrments.dictatersition,in theboats

tslitionalt.

Erylngeed. Ain sup-mentalquired,ons.

r bringr insur-l water

rc used

vide a:asual-ad, aidaccessbe pre-i8.

f mov-rwhendverseI indi-rt sup-

plies and equipment from the transport craftto storage sites or distribution points in theUWOA. Small craft may also be used totransport high tonnage supplies to caches ormission support sites (MSSs) for use in guer-rilla operations.

Resources control measures. Small boats usedon patrols have the speed to overtake andinspect local rivercraft used in daily com-merce or by the insurgent. Internal defenseand development (IDAD) forces may usesmall boats to police waterways and searchfor suspected craft as part of a resources con-trol campaign. Boats can tie up in critical

TACTICS ANDParamilitary and other local forces organ-ized and trained by SF detachments may berequired to conduct interdiction operations.They can conduct small boat supported oper-ations such as patrols, ambushes, raids, andriver crossings.

RECON NAISSANCE PATROLSRecon patrols normally use atleasttwo boatsthat furnish mutual support. There are threebasic movements that a recon patrol canuse-

Successive bounding overwatch (figure 2B).The boats in the patrol keep their relativeposition in the boat column. Boat number onemoves ahead while boat number two debarksits troops to observe. When boat number onereaches a secure position, troops debark andobserve until boat number two moves up totake over this position.

Alternate bounding overwatch (f igure 2g). Thetwo boats alternate as lead craft on eachbound. This method, although more rapidthan successive bounds, does not permit per-sonnel in the second craft to carefully observethe area forward of the lead craft before theypass the halted lead craft.

Traveling overwatch. All boats move at a mod-erate speed, maintaining boat position and

areas, allowing the unit to establish check-points in conjunction with local agencies.

Various types of small boats may be used toperform the missions and tactics describedabove. Guerrilla and conventional forcesshould receive training on small boat han-dling. Local boats may be used for infiltra-tion and disguised movements. When boatsare so used, they are operated in accordancewith local practice and custom;obvious mil-itary formations and boat tactics are avoided.When units use local boats, they must per-form maintenance to insure that boats canperform their mission.

TECHNIOUES

security by careful observation. The leadingboat stops to investigate dangerous areaswith the remaining craft maintaining theirpositions. This is the fastest but least securemethod of movement.

The techniques described above apply to bothguerrilla units and foreign internal defense(FID) forces when conducting waterborneoperations. Advance guard and flank guardsalso assist in march security.

AMBUSHESIn planning ambushes the commandershould consider the waiting time at theambush site. Changes in the tide affect waterlevels, and water flow may change direction.At ebb tide boats may be stranded or with-drawal routes may become too shallow. Theambush must be planned to anticipate thesechanges in water level.

In small boat operations certain techniquesmay be used to enhance the chance of suc-cess. Motors may be switched off beforereaching the target area and paddles or polesused to propel the boats the remaining dis-tance. Boats may be allowed to drift to theirposition at the ambush site. Outboard motorsshould be ready for immediate use in event ofpremature enemy contact.

45

@cnrw oF BoAT #20ESERVES AilD C0VERSB()AT #I AS BOAT #IMOVES F()RWARD.

@aolr #r sELEcTS lEtyP0stTt0r{, M0vEs T0 tIC()VERED BY BOAT #2.

@cnrw or sorr *iOBSERVES, SIGIIATSB()AT #2 FORWARDIF CLEAR.BOAT #2 ASSUMES LOCATIONOF BOAT #I.

Figure 28. Successive bounding overwatch.

The commander may assume that theambush force is under constant surveillanceen route to its target area. He may thereforeleave a small security force near the boatswhen the ambush force halts to dismount,observe, or reconnoiter specific areas. Hemay also use the security force when boatsare concealed some distance from the selectedambush site and the ambush force moves byfoot to the site. The security force will set anambush in the vicinity of the debarkationpoint where the boats are concealed. Thistechnique helps if an enemy reaction forceattempts to flank and cut off the mainambush force from its transportation.

Whether the ambush is laid to cover a road,trail, or waterway, the main force will nor-mally debark and take up concealed posi-tions. Boat crewmen acting as a security ele-

46

ment will remain concealed in or near theircamouflaged boats during occupation of theambush site.

RAIDSIn planning a raid employing waterborneforces, the detachment commander mustanalyze the enemy situation carefully. Hemay use boats to move troops to the objectivearea, position blocking forces, position crew-served weapons teams, and secure his rearand flanks.

His elements may debark and approach thetarget on foot if the objective is some distancefrom the shore. This technique permits a thor-ough search of the area. It also enables theelementto fire and maneuver faster and moreeffectively in the event of premature contact,since the troops have debarked and are incombat formations.

@cnew oF BoAT #2OBSERVES AXD Cl)VERSBOAT #I AS B(]AT #1

@ eolr #2 sELEcTs rEwP0srTt0il T0 c0vERB(]AT #I AS BOAT #IM()VES FORWARO.

M()VES F()RWARD.

@cnew oF BoAT #r0BSERVES, SlGl{ALS @aBoAT #2 FoRI{ARD @IF CLEAR.

Figure 29. Alternate bounding overwatch.

ar theirn of the

:rborner must.lly. HerjectiveIn CfeW-ris rear

ach theistancel a thor-lles therd morenntact,. are in

Amphibious assault tactics may be usedwhen the objective or target is near the bankor shore. The assault force may use motor-driven boats to storm directly into the objec-tive area. The stormingtactics should only beused when surprise can be achieved andwhen the waterway and landing site arecompatible to high.boat speeds that permitfast landings and evasive actions. The com-mander, however, should consider insertinga support element on land ahead of theassault force to deliver fire in case the assaultforce is prematurely detected.

Smoke may be used to cover the friendlywithdrawal when withdrawing from a raidtarget. Ambushtacties may be used against apursuing enemy.

A diversionary attack by land may permittrained indigenous units to approach and

enter the target area using SCUBA and placeunderwater charges to destroy selected facili-ties when targets are relatively close to riverbanks or canals and the enemy has concen-trated his security in this area against boatattack.

RIVER CROSSINGSRiver crossing techniques are found in FM 90-13.

BOAT TRAVELING FORMATIONSThe criteria for selecting boat formations forwaterborne forces are the same as for select-ing combat formations for land forces. Thecommander must consider control, security,flexibility, reaction time, observation, andfields of fire. The width of the waterway maydictate the type of formation. Formationsthat will retain unit integrity should be used

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NARROW STREAM

DISTANCE BETWEEN BOATELEMENTS DEPENDS UPON

LIKELIHOOD OF ENEMYCONTACT AND ABILITY TO

SUPPORT EACH OTHER

ELEMENT

Figure 30. Boat traveling formations onstreams,

and should be based upon the likelihood ofenemy contact. Where a waterway is narrow,the leading platoon or element may haveboats on each side of the waterway for mu-tual support. If a quick landing is required,the boats are in position to land quickly on

48

either side. The unit following should also beintact and operate as a unit. Immediateaction drills for boat crews and units consist-ing of two or more boat crews should beplanned and rehearsed (figure 30).