A study of barge hull forms

HiSTORY

- The development of barge hull forms parallels the commercial exploitation of the inland rivers of the

United States. The first rafts of logs poled down the

Mississippi gave way to wooden barges lashed to steamboats as early as 1832. By the late seventies,

fleets of barges became common. With the

develop-men., of tnt iron and steel indu.tries the movement of coal became of increasing importance. The flat its, which had been too cheap to warrant return

.,tream, were replaced by more permanent types of

barges. In the decade 1910 to 1920, steel was intro-duced as a hull material, but the construction

meth-ods employed evolved barges which could carry little, due to excessive internal structure.

In the Rivers and Harbors Act of 1910, Congress authorized the Secretary of War to design and con-struct two experimental towboats together with a

suitable complement of barges for towing and deliver-ing supplies along the Mississippi and its tributaries. The Board appointed by the Chief of Engineers made a thorough study of all available design and operating information, and conducted a series of model and full scale trials of towboats and barges. The resulting pub

lîshed data constituted the first step in the

improve-mant of barge hull forms for river transportation.

River traffic was drastically reduced in 1914 and

1915; in 1918 much of the river tonnage was destroyed

or carried away by ice floes which filled the rivers. situatìon was greatly improved in the twenties the government sponsored programs for the

canal izatjjn of the Ohio and also established the

Fed-eral Bargc Line. These advances were followed by

A STUDY OF BARGE HULL FORMS

THE AUTHOR

,.s Director, Experimental Test Division, Reed Research, Inc. He received hv Bachelor of Science degree ni Naval Architecture and Marine Engineering from Webb Institute of Naval Architecture in 1942. He served with the

Consolidn ted Steel Corporation, ILS. Maritime Commission, ILS. Army

Trans-portation Corps, and the Navy Department prior to his employment with

Reed Research in 1954.

projects for the improvement of the Upper Missis-sippi, the Missouri, the Tennessee, and the illinois

Rivers.

About this time, forerunners of the modern

com-mon carrier barge line appeared. The improvements resulting from the studies of 1910 to 1915 began to

be put iiìto use. The Corps of .ngineers £owoat

Board was reorganized in 1928, and a complete

anal-ysis was made of the latest practice in water

trans-portation on the Mississippi and its tributaries. During the period between 1930 and 1940, barge operators and builders began to utilize model basins

for the improvement of individual barges and flo-tillas. With the increase in industrial activity in the

Gulf States, the movement up river of large cargoes

steadily increased and savings in barge resistance

became increasingly important.

As inland river barges improved, so did the barges employed in the harbors of the United States. These

barges, used for short hauls by alongside or astern

towing, evoked novel problems in resistance and di-rectional stability. Barges came into existence which

were especially designed for the movement of any number and variety of cargoes. Weatherproof

cov-ered barges, tank barges. merchandise carriers, au-tomobile carriers, car floats, and many other types were used in both commercial and military

opera-tions.

The entire inland and iritra-coastal waterway sys-tem, with dependable river stages and efficient tow-boats and barges is now an extremely important fac-tor in the nation's transportation system.

A.SN.E. Journal, Novemb.r I9S _7S1.

Technische Hogeschoot

HULL FORMS

_TAGGT

O

TRANSPORTATION CORPS BARGES

At the end of World War II, the Army Transpor-tation Corps was employing a heterogeneous col-lection of river, harbor, and seagoing barges which had been procured prior to and during the war. In the stress of wartime, little attention had been paid to the design of hull forms or even to the simplify-ing of structural design details.

To evaluate these barges in light of later day

re-quirements and modern design techniques, a series

of model tests was set up for both resistance and

directional stability measurements of the existing

designs. Each barge model was towed at three

differ-ent drafts, and trim was varied during directional

stability tests. This program included tests on a total of twelve barges. Seven of these were existing types; five were post-war designs. In this article the results

of tests on ten of these barges are presented. The

bow and stern profiles and body lines of these barges are £hown in Figures 1 through 11. Dimensions

giv-en are those of the model.

MODEL TESTING BASINS

The eleven barge model tests reported in this

article were carried out in two model testing tanks. Barges C, E, I, and J were tested in the Naval Tank

at the University of Michigan. Barges A, B, D, F, G, and H were tested in Tank No. i at the Experimental Towing Tank, Stevens Institute of Technology.

me Naval Tank is 360' long by 22' wide by lo' deep. Models are towed under a carriage which

spans the basin and runs the full length of the basin along rails mounted atop the basin walls. The car-riage is propelled at constant speed by means of a traction motor mounted on the c'rriage.

Stevens Tank No. i is 100' long by 9' wide by 4.5' deep. Mode]s are towed from a dynamometer riding

on an overhead control rail. The dynamometer is

propelled by means of a continuous wire running

along the rail and around _{a motor driven pulley.} A direct current motor is used to accelerate the

model up to towing speed and an alternating current sychronous motor mounted on the same shaft is cut

in to tow the model at constant speed down the tank.

In the prediction of full scale resistance values, the model results from both tanks are equally

re-782 AS.N.E. JournaS. No,mb.r I9S

liable, in the prediction of full scale yaw character..

istics, however, the larger size tank and the _type

of carriage propulsion employed in the Naval_Tank permit the quantitative prediction of yaw; the

di-rectional stability results from the Stevens Tank _are

qualitative only. in the Naval Tank the model _can swing freely in full yaw amplitude throughout

sev-eral cycles. The smaller dimensions of Stevens Tank

No. i do not permit full swing of a badly yawing barge, and it is seldom that a model can complete

more than one and one-half cycles. Also, the cutting

in of the synchronous motor often gives an abrupt

acceleration to the model. If the model is not headed straight down the tank at this instant, the first swing is overemphasized. Thus, although the complete cor-rection of model yaw in this tank can be considered

indicative of full scale performance, uncorrected

yaw amplitude cannot be predicted with any degree of accuracy.

EXPANSION OF MODEL TEST RESULTS

The expansion of all model results covered in this

article has been in conformance with standards set forth by the Society of Naval Architects and 1arine Engineers in Bulletin i-2 of the Hydromechanics Sub-Committee. The Schoenherr Friction

Formu-lation was used for both model and full scale. A

constant addition of 0.0004 was made to the fric-tional resistance coefficient for roughness. Ail full

scale predictions are based on immersion in salt

water at 15° Centigrade.

For the purpose of comparing the results of the resistance tests of all eleven barges, the model re-sults have been expanded to a full scale waterline length cf 0O ieet, regardless f the length of the

original barge. Based on this length the dimensions

and principal hull form coefficients are given in

Ta-ble 1. Curves of total resistance are given in Figure

12.

FACTORS AFFEL. IING BARGE RESISTANCE

The original barge model testing program was so

planned that modifications could be accomplished on each barge form to improve resistance and yaw

char-acteristics. The program thus permitted a limited

study of those factors which influence performance.

TABLE I

Barge Dimensions, Ratios, an.cl Coefficients Based on loo foot Length

3

A B-1 B.2 C D E F C H 1 3 Length in Feet 10000 100.00 100.00 100.00 100.00 100.00 100. 00 100.00 100.00 100.00 100.00 Beam in Feet 19.91 28.41 32.56 2324 33.33 21.88 25. 66 18.82 27,05 27.38 27.74 Draft in Feet 4.48 6.89 2.96 6.97 4.69 5.47 5. 18 4.57 6.56 6.39 7.12 Displacement in tons, S.W. 212.70 488.6 236.8 421.3 430.0 283.2 325. 5 219.3 428.1 417.9 469.4 Length-to-Beam Ratio 5.022 3.250 3.071 4.303 3.000 4.570 3. 893 5.314 3.697 3.653 3.606 Beam-to-Draft Ratio 4.448 4.150 11.000 3.333 7.109 4.000 4. 953 4.119 4.125 4.286 3.839 Displacement Length Ratio 212.7 488.6 236.8 421.3 430.0 283.2 325. 5 219.3 428.1 417.9 469.4 Block Coefficient 0.835 0.872 0.859 0.909 0.961 0.826 0. 357 0.890 0.844 0.835 0.831 Prismatic Coefficient 0.847 0.900 0.922 0.911 0.961 0.850 0. 914 0.896 0.846 0.851 0.848 Maximum Section Coefficient 0.986 0.969 0.932 0.998 1.000 0.972 0. 937 0.996 0.998 0.981 0.9S0 Waterplane Coefficient 0.921 0.988 0.991 0.991 1.000 0.925 1. 000 0.976 0.950 0.982 0.981 Vertical Prismatic Coefficient 3.907 0.883 3.866 0.917 0.961 0.893 0. 857 0.914 0.889 0.850 0.847

e 37 c.21r 0 $SO' e e 0O!'_1 o

Figure 1. Bow and stern profiles and body lines of Barge A. This 210'x40'x9' seagoing barge was in active service during World War il. lt is representative of seagoing barges employed in commercial service, but with more complicated Íorebody lines. Ingall's patented pyramid type skegs were used to correct yaw.

The experimentation undertaken on Barge B in-cluded construction of three sets of additional bow and stern rake ends. These rake ends had parabolic profiles. The sectional area curves of all three sets

were identical. The profile areas, however, were

va-ried, with the sectional area retained by varying the fuilness of individual sections. The profile area co-,jlcients, i.e., the ratio of profile area to the

circum-scribing rectangle, were designed with values of

0.67, 0.75, and 0.83 for the three sets of rake ends. Regardless of what combination of rake ends was

used, the resistance results at all speeds were

iden-tical. These tests led to the preliminary conclusion that the shape and slope of the rake profiles are im-portant from a resistance standpoint only insofar as

they affect the sectional area curve.

This conclusion was further supported by the

re-suits of tests on bow modifications made on Barge D

in this model it was found that little improvement resulted from a careful fairing of the forward rake end when the original sectional area curve was

re-tained.

tITJ*NC! IOfNTICAL LfSS SK(S

Several years ago at the University of _Michigan,

Professor H. C. Sadler carried out a series of

experi-ments to determine the optimum rake_{end slope for}

barges. He concluded that a slope of 3O at the

water-line was the most desirable. When his results are

reanalyzed and the sectional area curves of his mod-e:s are studied, it_{appears that the model with the 3Q0}

rake angle has the fairest _{sectional area curve.} Another factor which was studied in the

Trans-portation Corps tests _{was rake end length. Barge D,}

which initially had the shortest rake ends of the 734 A.S.N.E. JounaI, Noembe 95e

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Figure 2. Bow and stern profiles and body lines of Barge B-1. This 120x33'x8' harbor barge was produced in large numbers during World War Il and resembles barges commercially employed in similar service._{A single centerline skeg is provided for} directional stability.

models tested, was altered to provide a progressively

longer bow rake end. Test results indicated a de-crease in resistance as the rake end was lengthened,

as would be expected. There appears to be an op-tirnum rake end length when resistance is compared

with displacement tonnage. A series of tests at the University of Michigan established the optimum length of the forward rake end _{to be 25} of the length overall. It was also found that the after rake end could be of the _{same form as the forward rake,}

but with the after end _{cut off to reduce the after}

HULL FORMS

ENTUA,,Ct IQE.Pfl'ICAI. LESS SXLS

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rake length to 85% of the forward rake length. Testing a series of barge models at three different drafts offered an opportunity to evaluate the gross effect of draft on resistance. For each barge model the ratio of the resistance at shallow draft to the

re-cctance at maximum draft was plotted against

L)ed. The resulting curves indicated little variation with speed for each draft. Therefore, for each draft, an average resistance ratio was obtained. The plot

E Figure 3. Bow and stern profiles and body lines of Barge B-2. These lines represent the sanie barge depicted in Fgure 2. They have been redrawn on the basis of the 3'-O" waterline used for shallow draft tests.

of resistance ratio versus draft ratio for all barges

tested is given in Figure 13.

It can be seen from this plot that, from 50% to

100% load draft, the resistance is directly propor-tional to the draft. Below 50% draft the resistance ratio rises above the line of direct proportionality.

These results indicate that for similar types of barges

the resistance will vary as the iinear dimensions of

the cross section.

A.S.N.E. Jouriai, Noer,b.( IPSÓ ₇₈₅

J I 1.0 H as s 20 L '5,04Y 'C 6H rl4H

FORMS

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786 A.S N E. JounôI. Nc.nber iS&

FACTORS AFFECTING THE YAWING OF BARGES Directional stability, or the ability of a barge to follow a straight course behind a towing vessel, is

an extremely important factor in the operation of

tugs and barges. A yawing barge is a danger to

nav-igation and to the towing vessel. The veering of a

barge in a turn has been known to overturn the tow-ing vessel. Yawtow-ing a]so greatly reduces the efficiency of the towing operation.

When an external force, such as a wave, throws a

barge off course, a new transverse resistance force is

added. If the moment of this force about the center of gravity opposes and exceeds the restoring

mo-nient of the force exerted by the towline, the barge

will be directionally unstable.

Directional stability may be restored by several

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Figure 1. Bow and stern profiles and body lines of Barge C. This 130'x30'x9' barge was designed for harbor service. Twin skes parallel to the centerline were used for directional stability controL Its rake end design is more complicated than that normally Seen in commercial service.

alternative methods. The use of a towing bridle in-creases the moment arm of the restoring force; the

use of plate skegs or a rudder decreases the moment arm of the transverse resistance by moving the

cen-ter of lacen-teral resistance aft; trimming the barge by the stern moves the center of lateral resistance aft and also, by relocation of the center of gravity,

in-creases the moment arm of the restoring force; fining

the forward profile or filling out the after profile

tends to move the center of lateral resistance aft:

adding a drag at the stern gives an additional restor-ing moment.

Studies at the University of Michigan concluded

that a bridle length of 1.5 barge beams was the most

effective in overcoming yaw. Bridles of this length are now in almost universal use for astern towing

UN IDENTICAL

Figure 5. Bow and stern profiles and body lines of Barge D barge is of interest from a towing standpoint because of the were incorporated in the original design.

and thus additional yaw correction devices need

not be designed to provide greater directional sta-bility than that required for towing with a bridle.

Originally Barges B and C were provided with plate-like skegs to reduce yaw. The model tests

in-(yated that the skegs made no difference in either

or resistance. Both barges were directionally

unstable as designed.

Barge E had an after rudder which proved

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Designed primarily to serve as a floating pier, this 15O',5Ox7' necessity of towing it overseas for forward area service. No skegs

tirely ineffective in the model tests when held in a ftxed position. Rudders, both bow and stern, have

proven notoriously useless on barges since the

helmsman can seldom anticipate yaw. Once yaw has

started the tremendous transverse forces involved are usually beyond the capabilities of a helmsman

to cope with.

Trimming a barge by the stern can be effective in overcoming yaw. The yaw of Barge D could not be A.S.N.E. Jor,a(, Noem.r I9 787

OtMS

.780

788 A,S N E. JouraI. No.r,,ber I9S

controlled by any other method in spite of the fact that three skegs with heavy drags_{were added.} How-ever, when the barge was trimmed one foot by the

stern, the yaw ceased. This is generally an unde-sirable condition from the standpoint of loading

cargo and for shallow draft operation.

Tests on barges B and D were performed to at-tempt to reduce yaw by altering the lateral

resist-ance of the rake ends. The specially designed rake

ends for Barge B which were mentioned earlier

TAGGART

_C)

C-Figure 6. Bow and stern profiles and body lines of Barge E. A so-called "simplified form" is represented by this 112'x24'x6' har bor barge. It was a result of World War II expediency. A manned rudder_{was installed io control yaw under tow.}

were combined in süch a way as to move the center of lateral resistance as far aft as possible. The effect

on yaw wa'-.gligible. A similar experiment was

conducted on Barge D where the forward rake end

was lengthened and carefully designed for minimum

transverse resistance. Again yaw was not affected.

It was concluded, therefore, that little improvement in directional stability could be obtained by this ap-proach.

The most effective method of overcoming yaw Of

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UN IDtNTICAt.

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'igure 7. Bow and stern profiles and body lines of Barge F. The SI'x20'x4' barge depicted here is a special purpose design of ï47 vintage. lt was sectionalized to permit breaking down into small sections which could be nested within each other and carried by rail. No provision was made for control of yaw.

HULL FORMS

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the barge models tested was to provide additional drag at the stern. In general, this added resistance is attained by incorporating an appendage to a plate skeg which causes separation of the flow as far aft as possible. in order to minimize the effect on the

resistance of the barge, the amount of skeg drag

should be no more than that necessary to overcome

yaw when the barge is towed with a bridle. With

790 A.S NE. Jeurr,I. No.mbeç 1954

TAGGART

Figure 8. Bow and stern profiles and body lines of Barge G. This 196'x35'x8.5' oil barge was desigued by Philip H. Rhodes for the Transportation Corps in 1949. As a result of other tests reported herein, twin plate skegs with triangular prisms were pro-vided to overcome yaw.

the exception of Barge D this method was successful in all cases.

COMPARISON OF aPLRGE RESISTANCE

Expansion of model test results to a length.of 100

feet for all barges is the first step in placing them

on a comparable basis. The primary purpose of

barges is to carry cargo and the cargo carrying

ca-pacity is a function of the displacement. It is, there-L 5eI3

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fore, desirable to compare the resistance of barges in relation to their displacement.

The factor chosen for this comparison is the volu-YThtric resistance coefficient, or R

_{Ct y where}

L..)

tVV2

R is the total resistance in pounds, p is the mass

l202

.400

Figure 9. Bow and stern profiles and body lines of Barge H. This_{130'x33'xS' oil barge was also designed for the Transportation} Corps in 1949, by John H. Wells, Inc. Skegs similar to those o Barge G were provided on this vessel

density of water, V is the displacement in cubic feet, and y is the velocity in feet per second. Values_{of this}

coefficient versus the Froude Number _are plot-ted in Figure 14 for the barges tesplot-ted.

A.S.N.E. Jourtal, Nov,mbr 9S ₇₉₁ 20

_ HULL FORMS

792 zJ G Df C(

__________

I

Figure IO. Bow and stern profiles and body lines of Barge 1. As a result of the highly unsatisfactory performance of existing barges tested under this program at the University of Michigan, L. _{A. Baier recommended the replacement design of two barges} using simplified, straight-element construction. This 11'x3O'xD was designed by him as a replacement for Barge E and another barge of similar dimensions.

For purposes of single number comparison the

average value of the volumetric resistance coefficient

between Froude Numbers of 0.10 and 0.20 can be used. These values are given in Table II.

TABLE II

A.S.N.E. Journal, Nor.mb.r I9S

TAGGART

O

Earlier it was stated that the sectional area curve

gives a positive clue of potential barge performance. The sectional area curves of the eleven barges tested

are given in Figure 15.

_{It should be noted that}

Barges G and H were fitted with _{yaw-correcting}

skegs during these tests.

As a general rule the length of entrance and run is an important factor in determining barge

resist-ance. The barges with greater rake end lengths are

usually less resistive than those with the shorter

rake end lengths. The differences in Barge A, the

best of the group, and Barge E, the worst of the

group, are obvious in this respect.

There are some contradictions to this general rule

which are evident. Barge D with the shortest

en-trance and run is superior to Barge E. Examination

()

Barge 103Ce A 23.9 B-1 _45.1 B-2 ₃₈₂ C _40.3 D 6.4.0 E 77.4 F 68.8 G 30.3 H 57.9 I 33.3

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of the sectional area curves indicates a part of the

reason for this superiority. The design of Barge E

vas such that the sectional area curve attains an

infinite curvature at the points where the rake _ends

join the parallel middlebody, thus causingexcessive

acceleration of the flow in these regions leading _to

high resistance. In addition, the fenders which were

placed oblique to the flow lines on this design con--bute to its high resistance.

L..-îairness of load waterline is also an important

fac-tor. The rectangular waterlines of Barges D and F and the infinite curvature in the waterline of_Barge

oze

Figure 11. Bow and stern profiles and body lines of Barge .1. This

barge was designed by L. A. Baier as a replacement for the obsolescent types of 130' barges tested. It is a straight-element form 130x33x9'.

E place them in the high resistance category.

The differences between Barges _{I and J are more}

difficult to explain since their _{waterline and} sec-tional area curves are almost identical, as is their

general design configuration. It _{appears that either}

the greater cross sectional _{area or the greater}

dis-placement length ratio of Barge J explains its higher resistance.

The complicated rake end design of Barge C was apparently not justified since it was inferior in per-formance to the "straight-element" _{designs, Barges}

I and J. The long, ship-shape bow of Barge A is

evi-A.SN.E. JournI. Nov.mb.r 195& _"J', 20

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LLFORMS

794 A.S N.e. Jorr,aI Noeb,r 19S6

8000 7000 6000 200G 1000 4000

DRAFT -- LOAD DRAFT

Figure 11. Effect of Draft on Resistance.

TAGGART

D

Each of the skegs designed _{was completely}

suc-cessful in overcoming _{yaw (with the exception}

of

those on Barge D). Unfortunately, _{due to time} lim-itation, each design could not be varied to permit determination of the optimum _{dimensions for}

cor-rection of yaw with minimum _resistance.

Conse-quently, the discussion which follows is necessarily based upon those tests which were conducted.

Figure 17 shows the difference in _volumetric

re-sistance coefficient of several barges with and with-out yaw-correcting skegs. These curves indicate that

the angled-pate.-type skeg causes the greatest

in-crease in resistance. The plate skeg with, prisms _on

Barge A was superior to the pyramid-type _skeg. These few tests are admittedly insufficient

evi-dence that any of these skegs will be superior for

every design. It is quite possible in all cases that the skegs were over designed. Yet the results presented

can be analyzed in light of the previous statements

regarding enhancement of d irc t.onal stab lit:-.

It is quite evident that addition of lateral

resist-ance aft has little effect on yaw since transverse

mo-tion in yaw is of relatively low velocity. Therefore, the plate portion of the skeg serves little purpose other than to support the member which _provides

resistance to the longitudinal flow.

The maximum effect of the dragging member is achieved by placing it as far astern and as far

out-board as possible. This gives the maximum restoring moment to the yawing barge _{or conversely the yaw} can be corrected with a minimum amount of drag if

these precepts are followed.

The angled-plate-type of skeg tested on Barges I

and J redirects the flow at the angle of the plate and

thee. se:artion takes plate

a: he after tn

of skeg. The pyramid-type skeg tested on Barge A

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Figure 12. Total Resistance of Barges Tested.

dently justified from a resistance standpoint since it

is by far the least resistive of the barges tested. Yet for any application other than seagoing tows, it is dubious whether such a design is feasible from a

construction and operating cost standpoint.

Practically it appears that Barges B, G, H, I, and

J

incorporate the best design principles for river and

harbor barges. Barge A appears as a desirable design for deep sea towing.

SKEG DESIGN AND PERFORMANCE

The three general categories of skegs tested are shown in Figure 16. These _{may be referred to as} pyramid-type skegs, plate skegs with prisms, and angled-plate-type skegs. The pyramid-type skegs were designed and patented by the Ingalls

Ship-building Corporation. The plate skegs with prisms are a design evolved by the Experimental Towing Tank. The angled-plate-type skegs _{were developed}

ing of rake ends. In dealing with rounded bilge

forms, the use of a constant radius simplifies fitting by reducing the rolling or furnacing operation to a single pair of strakes.

Two types of barges are shown in Figure 18. The rake end profiles are identical. In one barge a good

sectional area curve has been obtained by tapering in

the sides to the headlog. Where a large deckarea is required, the sectional area curve can be retained by

varying the deadrise as shown in the second body plan. The fore and after rakes are symmetrical with 15% being cut from the rake aft. This feature has the added advantage that if flotilla operation is

de-sired, the barges may be secured stern to stern.

As another alternative type, the "straight-element"

forni for bage rake ends is shown in Figure 19.

The proportions shown represent optimum values established by a series of tests at the University of Michigan. This form is adaptable to the use of

de-veloped plates between the upper and lower chines. A conical development can be used with the apex of

the cone at point "A." A cylindrical development is also possibe or straight elements, _{as shown, may be}

used.

As previously stated, yaw may be successfully overcome by the addition of drag inducing skegs at

the stern. The twin plate skegs with prisms shown in Figure 16 are recommended for this purpose. These skegs should be so placed that the prisms are located as far aft and as far outboard as possible within prac-tical esign limitation..;.

The bare hull resistance of barges designed in this manner cannot be predicted with any great accuracy

from the limited amount of model test information available. However, it does _{appear that a general}

formula for the resistance of such forms can be

approximated from the data. The formula given

be-low assumes that the resistance varies with thecross

sectional area of the barge and that the shape of the resistance curve relative to displacement is similar

for all barges of this type.

The following symbols are used:

Rresistance of barge in pounds

v=speed of barge in feet per second

g=acceleration of gravity in feet per second

squared

L=waterline length of barge in feet

Across section area of underwater body of

barge in square feet

Vunderwater volume of barge in cubic feet

S=wetted surface of barge in square feet C1 = Schoen.herr frictional resistance coefficient The total resistance of the barge for _{any speed is}

then given by the formula:

RSv (Cf ±0.0004) +10 (O.1SA±K) Vv

where K is derived from Table III

A.S.NE. Jo,rnar No.mb.r 956 ₇₉₅

A

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JO .15 .20 .25

FROUDE NUMBER V

Figure 14. Non-dimensional Comparison of Barge

Resist-ances.

vides increasing resistance to the flow by success-ively larger pyramids as the flow movep aft. Both the

double prism on the single pla.e skeg on Barge B and the single prism on double skegs on Barge A cause separation, and therefore maximum drag at the aftermost part of the skeg. It would, therefore, appear logical that the prism-type skegs employed on Barge A should give maximum yaw correction

with minimum increase in resistance.

RECOMMENDATIONS FOR BARGE HULL FORM DESIGN The tests conducted under this study alone are not

sufficiently definitive to draw specific conclusions regarding barge hull form design. However, when

the results of these tests are added to the

knowl-edge gained in other barge model studies, it is

possi-ble to derive some general recommendations for

barge design.

A rounded bilge barge will generally have a

slightly lower resistance than a "straight-element"

form. Its construction cost will be higher but its

maintenance will be slightly less.

Figure 18 delineates the lines development

rec-ommended for barges with rounded bilges and formed rake ends. It is assumed that the length,

I

beam, and draft will be determined by economic and

operational factors. Thus, attempts to lower

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SECTION DOUSLE SINGLE SINGLE PLAfE SKEG WITH PRISMS SECTION

The resistance which should be added for yaw

correcting skegs is much more difficult to determine because of the wide variations in the results obtained.

The best estimate which can be made is that these

skegs will increase the bare hull resistance by 5O7o

to 1OOÇ.

SUMMARY

In the foregoing review of barge hull form design

an attempt has been made to demonstratethose

de-a combinde-ation of fde-amilide-arity with operde-ationde-al prob_

lerns, design experience, and extensive model

test-ing. It is believed, however, that with the information presented, it is possible for a designer with relatively

little experience to avoid the major pitfalls and to

evolve a barge form design which will be generally acceptable for operating service.

REFZRENCES

Baier, L. A., 1947, Trans. Soc. Naval Architects and Ma-rine Engrs. 'The Resistance of Barges and Flotillas." Corps of Engineers, U. S. Army, 17 June 1929. "Investi-galions of the Board on Experimental Towboats for Mis-sissippi Rivers and Tributaries."

Sadler, H. C., 191G, Trans. Soc. Naval Architects and Marine Engrs. "The Resistance of Various Typas of

Barges in Shallow and Deep Water."

Edwards, V. B. and Cole, F. C., Historical Trans. Soc. Nava' Achitects and Mari-ie Fr.rs. "Water Trrrispo'ta-lion on Inland Rivers."

Baker, G. S., 1930, Trans. Inst. Naval Architects. "Experi-ments on the Resistance and Form of Towed Barges." Bernhard, J. H., 1915, Trans. Soc. Naval Architects and Marine Engrs. "Inland Navigation and Barge Construc-tion Versus Floating Bridges."

Hay, A. D., 1 Nov. 1946, Princeton University Publication. "Effects of Varying One End of Barge Forms with Simple Geometrically Shaped Ends."

Hay, A. D., Aug. 1948, Marine Eng, and Shipping Review. "Resistance of Barge Forms With Simple Geometrically Shaped Ends."

63d Congress, 2d Session, House Document No. 857. 67th Congress, ist Session, House Document No. 108.

German, J. G., and McPherson, R. P., 1947, University of Michigan Thesis. "Bridle Effect on the Yaw of Towed Barres."

Dawson, A. J., 1950, Trans. Soc. Naval Architects and Marine Engrs. "The Design of Inland Waterways Barges." Strandhagen, A. G., Schoenherr, K. E., and Kobayashi, F. M., 1950, Trans. Soc. Naval Architects and Marine Engra. "The Dynamic Stability on Course of Towed Ships." Taggart, R., 1950, Transportation Corps Board Report on Project 9-57-01-04, "Hull Forms, Barge Hull Form Studies."

TAGGART

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03

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sign characteristics which differentiate good forms Figure 17. Increase in Resistance Due to Yaw Correcting

from bad forms. Successful barge design requires Skegs.

j

o

BARG J ANGLED LA1E

BARGE I -ANGLED

9ARiE B-I - DOUBLE PISMS

BARGE A-PV AMI S

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BAR E A- PRISMS vgL K 0.6 -7.6 0.8 -8.9 1.0 -9.5 12 -10.1 1.4 -9.8 1.6 -7.9 1.8 2.0 -0.8 2.2 +2.6 2.4 +6.2 2.6 +12.4 .08 .12 .15 .20 .24 FROUDE NUMBER

PLAN ANGLED PLATE

TYPE SKEG Figure 16. Types of Skegs Tested.

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SECTION

31 X B o CONSTANT RADIUS (12 RECO .D) 6

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LENGTH OF FORWARD RAKE f

PRO FiLE o t 4 D. ZSX LOA ST

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SZ X FORWARD RAI<E LENGTH

Figure 18. Recommended lines development for barges with formed r2ke ends

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Figure 19. Recommended lines ievelopnìent for barges with "straight-element" rake ends.

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HULL FORMS TAGGRT