HAPTER—IV

CHINESE NET

4.1. Introduction

The Chinese net belongs to that class of nets known asthe lift nets or dip nets. They have their origin in the smallscoop nets which are pushed beneath a fish that is seen orsuspected to be present in a particular area. The dip (netsdiffer from these in that they are lowered into the water in thehope that, over a period of time fish or prawn will swim overthem. Strictly speaking, the term ‘dip net’ is a misnomer. Thecatch is not affected by dipping the net, but by lifting it againfrom the water, when the fish sought to be caught have gatheredover them. The term ‘lift net’ is therefore much more correct(Brandt, 1972).

The earlier lift nets were small baskets made of twigsand bast and were hand operated. Later on netting was used toreplace the twigs and bast. This netting was set horizontallyand fastened to round or square frames. As the size of the netsincreased, transverse rods were used to keep the net spread.These earlier versions were all portable and mostly used to catchcrabs which do not escape quickly, unlike the fish. This was dueto the fact that being hand operated, these nets could be hauledup only slowly. To overcome this lack of hauling speed, theEnglish fishery developed a hand lift net known as the purse hoopnet of Wales, which can be closed by shutting the opening hoop

95

with a line (Davis, 1958). Parry (1954) has described a similarcollapsible hand lift net employed by the Malayan fishery. Whenthe nets increased in size again, they were operated by means ofa long pole, handled like a lever. A further increase in sizenecessitated the use of gallows with a working block. Thesecan be considered as mechanised lift nets and can be installedeither on shore or on a boat. The Chinese net comes under thismechanised type of lift nets, but works instead on the leverprinciple.

Santos (1959) has described two types of lift nets, the‘Basnig' and ‘Bintol' used widely in the Philippines. Akira(1959) gives an account of dip nets used byfishery. These nets are supported on sticksside and lights are used to attract the fishnets were later adopted by the USSR Far Eastsuccess (Ben—Yami, 1976). Floyd (1971)construction and operation of a lift net forattracted to light.

In India the Chinese nets are

the Japanese sauryfixed to the ship'sinto the net. Thesefishermen with greathas described the

catching bait fish

found only in thebackwaters of Kerala. But it is a common gear in almost all ofthe estuaries of China. Iyer (1909) stated that the net is notknown in China nor for that matter in any other places exceptCochin. But Hornell (1938) observed this to be altogethererroneous, stating to have observed scores of these nets inoperation on the way up the Wusung river to Shanhai. Though

96

there is no question about its Chinese origin, these nets weremost probably introduced in this area by the Portuguese (Brandt,1972). The fact that the technical terms in use for the variousparts of the net and its supporting structure in Malayalamlanguage are of Portuguese origin, is an exceedingly strongpresumptive evidence that this net was introduced by thePortuguese and not directly by the Chinese.

The Chinese nets in Kerala are spread over the fivecoastal districts of Trichur, Ernakulam, Kottayam, AllePPY andQuilon. There are a total of about 4823 Chinese nets in thestate (Sanjeevagosh, 1987).

The Chinese nets operated in the Vembanad lake havereached its present stage of development through gradualevolution from a simpler contrivance for sustenance fishing tothe one which is operated on a commercial scale. This gradualdevelopment has been attained through the ingenuity of thefishermen who strive to achieve better efficiency, based on theirpractical knowledge of the gear and the fishery.

Hornell (1938), Gopinath (1953) and Kurian andSebastian (1986) have all given general descriptions of the gear.George (1962) based on his observations on the size groups ofPenaeus indicus in the commercial catches of different nets fromthe backwaters reported that the Chinese net catches showed themaximum sizes in the population mean and modal lengths. George

97

et al.(1974) have suggested codend mesh sizes for variousbackwater gears including the Chinese nets. Inspite of theseworks, a detailed study on the design, construction and operationof this gear is lacking. Considering the commercial significanceof this gear and the large number of fishermen who engage thesenets for their livelihood, it is imperative that a detailed rworkbe undertaken to study the various facets of the gear.

4.2. Objectives

Hence, the present work endeavours to classify theChinese nets operated in the Vembanad lake and to study in detailthe design, construction and operation of the gear. Since anyinformation regarding the basic process of designing is lacking,it was also the objective of this study to establish a fewimportant relationships among the different factors like thedepth of the area of operation, net size and the various parts ofthe net proper and its supporting structure.

4.3. Materials and nethod

Preliminary surveys were conducted in the study areaand eight centres viz. Vaikkom, Chembu, Panangad, Arookutti, FortCochin, Vypeen, Chathanadu and Krishnankotta were selected tostudy the Chinese nets in detail. These stations, between them,had representations of all the size categories of Chinese nets.Twenty five units from among those operated at these centres were

98

,é)4»9‘73 ——-=­

randomly selected for detailed study on their design,

construction and operation. The centres selected for observationare given in Fig.(l.1). _

. ‘ ; w, ;. r; i ax; -. S295:]'*’.»\_ I 3

Miyamoto(1959) was possibly the first author to workout regression equations relating horse power of engine andof trawl gear. Koyama (1962b)also attempted to correlatehorse power of trawlers with the size of the otter board.

L.‘ v { .~' ‘

size

engine

An

empirical approach has been made by Nair and George (1964) andNayar and Nair (1972) to establish a few important relationshipsamong the different factors like horse power of the enginthe size of trawl gear and the various parts of the trawl iGeorge (1985) has applied the same principle to find ou

e andtself.t the

interrelationship between different parts of the ‘Edavalai', alift net operated along the Coromandel coast off Tamil nadusimilar approach was adopted in this study to work

. Aout a

relationship between the depth of the area of operation and thenet size, the net size with the various parts of the net properand also with parts of the supporting structures.

4.4. Results and discussion

The gear has two distinct parts viz. the net proper andthe supporting structure. It works on the lever principlebalanced by counter—weights enabling it to be turned in anto facilitate the dipping and lifting of the net. Figureshows a typical Chinese net with its codend pulled up from

99

and is

angle

(4.1)inside

by means of a line rove through a block hanging from the apex ofthe outer crane.

The net

Design details of Chinese net are given in Fig.(4 2).The net when attached to its immediate supporting structure issquare, gradually assuming a conical shape towards the middle andending in a bag. The whole net is made up of four identicalsections seamed at their sides. Each of these sections consistof three major parts, ‘Perna' at the top, ‘Nilavala' in themiddle and ‘Sanchi' at the bottom (Fig.4.3).

Each ‘Perna’ forms one corner of the net and istriangular in shape. The two outer sides of the ‘Perna' has allbars and the inside edge all points. The two adjacent sides withbar cuts are mounted to a line, which in turn is attached toanother line by tying at regular intervals. These lines areknown as the inner and outer ‘Borda'. The outer line which isoften thicker in diameter, runs along the edge and forms a loopat each of the four corners to facilitate attachment of the netto the supporting frame.

To the inner edges of ‘Perna' is attached the body ofthe net, known as the ‘Nilavala' which is conical in shape andtapers downwards. The circumference is made up of four trapezoidpieces joined together at their non-parallel sides. Each of

100

these four pieces are made up of five panels horizontally.Changes in mesh size or material is affected among these panels,as required. The broader side of the uppermost panel of the‘Nilavala' is attached to the inner edge of the ‘Perna', whichhas all point cuts.

To the narrow, inner edge of the lowest panel of the‘Nilavala' is attached the codend, locally known as ‘Sanchi’.This portion is also made up of four trapezoid pieces of nettingjoined together at their non-parallel sides which also has a IN1B taper ratio.

Supporting structure

The net is attached to a wooden frame work. The whole

structural frame of the Chinese net is supported by two woodenpiles driven into the fishing area. These are known as ‘Kutti'and are made of coconut tree trunk. When land based they areplaced parallel to the shore line. ‘A platform is made from theshore up to the ‘Kutti', with small wooden planks and bamboosplits supported by small wooden poles driven into the ground(Fig.4.4). In nets that are situated away from the shore, theplatform has to be longer than the inner crane, to support it andalso to furnish working space for the fishermen. It should alsobe strong enough to support the weight of the inner crane andthat of the oounter—weights. The platform of the water basednets are usually provided with a small thached cabin to provide

[O1

shelter for the fishermen and also to store the catch.

On the top end of each ‘Kutti', a groove is made. Inthese grooves, which function as a socket, is placed between thema wooden beam invariably of teak wood, and known as ‘Kalsanthi'.The cross section of the body of ‘Kalsanthi' is square while theends are narrow and cylindrical in shape. The ends fit into thesocket of the respective supporting post. The ‘Kalsanthi' actsas a pivot and moves to and fro in an arc facilitating thelowering and lifting of the net (Fig.4.5).

On the ‘Kalsanthi', two cranes, the ‘Puramkazhukol’(outer crane) and the ‘Karakazhukol' (inner crane), projectingtowards water and land respectively are fixed, forming an anglebetween them (Fig.4.8). Each of this is in the shape of atriangle, the long sides of which are made up of two woodenpoles. The poles of respective cranes meet at their apices wherethey are joined together by inserting either a strong wooden pegon an iron rod locally called ‘Chavi'. To impart stability,rigidity and sufficient strength to this large and extendedstructure, the apices of the two cranes are inter—connectedthrough 3 or 4 wire ropes or mild steel wires. These are knownas ‘Savai' (Fig.4.7). Also, a cross bar is tied to the cranestowards their respective apices, to impart additional strength.

_f

Hanging from the apex of the outer crane is thestructure known as ‘Bras’, which is formed by tying together four

102

wooden poles at one end in such a way that their free ends arekept extended, resembling the four edges of a pyramid (Fig. 4.8).The two inner limbs (those lying towards the shore or theplatfform) are longer than the two outer limbs (those situatedaway from the shore or platform) The ‘Bras’ is suspended fromthe outer crane with the help of ‘Harbola', which is a ropeloosely passed around their joints many times. It isoccasionally strengthened with an old tyre or wire ropes. Eachpole of the ‘Bras’ is tied to the ‘Harbola' with a rope called‘Akshakkayar', so as to prevent them from slipping. A rope knownas ‘Padachikkayar' is used to tie together the diagonallyopposite two poles of the ‘Bras’, to get the required extend ofspread (Fig. 4.9). There is another set of ropes, known as‘Udhara', that are used to tie the inner and in some cases theouter limbs to posts on shore or in shallow water, which helps tomaintain the position of the ‘Bras’ and to aviod any movementthat may be caused by strong winds or currents. It is to thefree ends of the four poles of the ‘Bras’ that the net proper isattached by means of the four loops at the corners of the net.

At the apex region of the outer crane, one or morehauling ropes, depending on the size of the net and supportingstructure, are tied. The ends of these ropes are left free andreach the ground when the outer crane is in the raised positionie. when the net is in the dipped position. By pulling theseropes the inner crane is brought down, which in turn facilitatesthe raising of the outer crane along with the net. These ropes

103

are called ‘Valikamba' locally. Another set of ropes,‘Kallukamba', are also attached to the two limbs of the innercrane towards its apex. To these ropes are attached the granitestones which function as counter-weights to balance the net. Thenumber and weight of the stones depend on the size of the net.

Construction

The net

The length of one side of the mouth of the net is takenas the net size and is fixed in relation to the depth of theregion, which in turn is determined in relation with theoperating parameters and the nature of the fishery. Though avariety of species are regularly caught, the target species ofthe Chinese net are prawns. Mostly those prawns which move abouteither in search of food or are carried by currents and tides orare attracted towards light would be caught by this net (George,1962). Hence it is imperative that the operating area has aminimum depth and optimum current, since stronger currentsdistort the net reducing its efficiency. No nets are operated inregions with less than two meters of water depth.

The relationship between the water depth (D) and thenet size (NS) is shown in Fig.(4 10) and expressed in theequation,

NS = 2.8 D + 0.11 . . . . . . . . . . . . ...(4.1)(n = 25; r I 0.9786; p < 0.001)

1.011

where n is the number of observations,r is the correlation coefficient andp is the level of significance (Probability).

The relation between net size (NS) and net depth (ND)is represented in Fig.(4.11) and the equation derived from thefigure is

ND = 0.907 NS - 0.132 . . . . . . . . . . . . ...(4.2)(n = 25; r = 0.9937; p < 0.001)

The net is constructed first as four separate unitswhich are joined together to form the complete net. Thefabrication of these units start with the triangular corner piece‘Perna'. The outer edges of each ‘Perna' have all bar cut andirrespective of the mesh size or number of meshes, the stretchedlength of the outer edge (PO) was equal to half the net size andcan be expressed as

PO = 0.5 NS . . . . . . . . . . . . ...(4.3)

Thus the outer edges of two corresponding ‘Pernas'complete one side of the mouth of the net. The inner edge ofeach ‘Perna' has all point cut and the stretched length is equalto the net size or twice that of the outer edge.

After ‘Perna', the ‘Nilavala' which constitutes thebody of the net is made. Each unit of ‘Ni1avala' is atrapezoidal netting comprising of five panels horizontally. Thetaper at the sides of each panel is affected by employing acutting ratio of 1N 1B. The broader upper edge of the first

105

panel of ‘Nilavala' is attached to the inner edge of the ‘Perna'by working a half mesh between them. As in the case of ‘Perna',here also, it is the stretched length of the netting that istaken as the criterion and not the mesh size or number of meshes.

The net size in relation to the proportionate dimensions of thestretched length of the upper edge of each panel is depicted inFig.(4.12). The following equations outline the relationships.

N1 = 0.895 NS + 0.042 ...stl(n = 25; r = 0

= 0.65 NS + 0.045 ...(n = 25; r = 0

Nzstl

N3Stl = 0.46 NS - 0.086 ...(n = 25; r = 0

= 0.297 NS + 0.033 ...(n = 25; r = 0

N4st1

N5 = 0.199 NS + 0.009 ...stl(n = 25; r = 0

where Nlstl, N2Stl , N3Stl, N4Stland

9984;

9985;

9973;

9944;

O I Q I Q

9879;

N5St

...(4.4)< 0.001)

...(4.5)< 0.001)

...(4.6)< 0.001)

...(4.7)< 0.001)

...(4.8)< 0.001)

are thestretched lengths of the upper edge of panels 1, 2, 3, 4 and 5respectively.

The total depth of ‘Nilava1a' as well as that of eachseparate panel that goes into its construction was also taken instretched lengths.

106

The relation between the net size, total depth of‘Nilavala' (Nd) and the proportionate dimensions of the depth ofpanels of ‘Nilavala' are illustrated in Figures (4.13) and (4.14)respectively. The equations derived from the figures are

Nd = 0.557 NS - 0.074 . . . . . . . . . . . . . ...(4.9)

Nld =

N2d =

N3d =

N4d =

N5d =

173 NS

144 NS

112 NS

081 NS

050 NS

(n

— 0.045(n

- 0.039(n

- 0.031(n = 25,

- 0.025(n

— 0.002(n = 25,

111

O

11

9982

9936

9934

9952

9758

9810

0.001)

(4.10)0.001)

(4.11)0.001)

(4.12)0.001)

(4.13)0.001)

(4.14)0.001)

respectivewhere Nld, N2d, N3d, N4d and N5d are thedepths of panels 1 to 5 of ‘Nilavala'.

A closer observation of the data show that thedifference in the stretched lengths of the upper edge ofsuccessive panels of ‘Nilavala' follow an arithmetic progressionstarting with 0.25 m and diminishes successively by 0.05 m (Fig.4.15). The relationship worked out is

107

Pstl = 1.023 - 0.174 Pn . . . . . . . . . . ...(4.l5)(n I 5; r = —0.9879; p < 0.01)

where Pstl is the stretched length of each panel andPn is the panel number.

The relationship between panel numbers and depth isgiven in Fig. (4.16). The linear relationship worked out is

Pd = 0.025 - 0.031 Pn . . . . . . . . . . . . . ...(4.16)(n = 5; r = —0.9999; p < 0.01)

where Pd is the panel depth

This analysis shows that as the panel number increases,there is a decrease of 0.031 m in depth.

The oodend, which in local dialect is known as ‘Sanchi'was also fabricated as four separate units having trapezoidalshape. The relationship between the net size, stretched length

of the upper edge (Cstl) and the stretched depth (Cd) of theoodend are depicted in Figs. (4.17) and (4.18). The equationsderived are

= 0.144 NS + 0.054 . . . . . . . . . . . ...(4 17)(n = 25; r = 0.9907; p < 0.001)

Cstl

Cd I 0.209 NS - 0.15 . . . . . . . . . . . . . ...(4.18)(n I 25; r = 0.9341; p < 0.001)

The different panels of ‘Nilavala' and the oodend arejoined with one another by working out a half mesh between the

108

respective panels and affecting either a baiting or creasing(Fig. 4.19). A uniform take-up ratio is maintained, depending onthe number of meshes present at the corresponding upper and loweredges of the panels. A cutting ratio of 1N 1B is maintainedthroughout, at the sides of the ‘Nilavala' as well as the codendto achieve the required taper.

The four separate units, each with a ‘Perna',‘Nilavala' and ‘Sanchi', are then seamed together at their sidesto complete the net. The outer edges of the ‘Perna' are mountedto the inner ‘Borda' by clove hitches (Fig. 4.20).

Supporting structures

The dimension of important parts of the supportingstructures are also correlated to the net size. The relationbetween the net size and the length of the limbs of outer crane(OC) is shown in Fig.(4.21). The equation derived from thefigure is

OC = 1.006 NS — 1.06 . . . . . . . . . . . . . . . ...(4.19)(n = 25; r I 0.9993; p < 0.001)

The length of the limbs of inner crane (IC) wasrelated to the length of the outer crane limbs. The relationshipbetween the two is given in Fig. (4.22) and the equation derivedis

IC = 1.21 OC + 0.964 . . . . . . . . . . . . . . ...(4.20)(n = 25; r = 0.9936; p < 0.001)

[09

The two cranes are fixed on the ‘Kalsanthi', thehorizontal beam that functions as the pivot, by a tenon andmortise joint. The length of the tenon (T) at the base of thelimbs of the two cranes was related to the length of the limbs ofthe inner crane and the relation is as illustrated in Fig. (4.23)and expressed in the appropriate equation.

T = 0.020 IC — 0.001 . . . . . . . . . . . . . . . ...(4.21)(n = 25; r = 0.9657; p < 0 001)

The thickness of ‘Kalsanthi' was fixed so as to be notless than the length of the tenon of the limbs of the two cranes.The mortises on the ‘Ka1santhi' run vertically, while the tenonof each limb of both the inner and outer cranes are shaped insuch a way that the respective limbs of both the cranes are madeto meet at the apices. The distance between the two limbs of the

outer crane (OCdSt) and that between those of the inner crane(IC ) on ‘Kalsanthi' are related to the lengths of the limbs ofdstthe respective cranes. The relations are illustrated in Figs.(4.24) and (4.25). The equations derived from the figures are

= 0.251 OC — 0.008 . . . . . . . . . . . ...(4.22)(n = 25; r = 0.9996; p < 0.001)

Ocdst

= 0.148 IC + 0.013 . . . . . . . . . . ...(4.23)(n = 25; r = 0.9983; p < 0.001)

Icdst

The angle at the base of the limbs with the ‘Kalsanthi'was calculated using the formula,

110

A = Cos_l kg; )where a is the length of limbs of the respective crane

c is the distance between the limbs of therespective crane on ‘Kalsanthi',

and was found to be about 82.50 and 85.50 for the outer and inner

cranes respectively. The angle between the two cranes was alsoaffected by shaping the tenon of each limb and was about 115.50.It was calculated using the formula

A I Cos ._." _ .1”.2bc-1 [ b2 + c2 — a2 ]

where a is the length of ‘Savai'b is the distance from the apex of the outer

crane to the ‘Kalsanthi', andc is the distance from the apex of the inner

crane to the ‘Ka1santhi'

The relation between the net size and length of‘Kalsanthi' is shown in Fig.(4.26) and can be expressed by theequation

K = 0.339 NS - 0.052 . . . . . . . . . . . . . . ...(4.24)(n = 25; r = 0.9981; p < 0.001)

The length of ‘Kalsanthi' is divided in such a way thatthe two cranes are aligned at the centre. A distance equal tothat which separate the limbs of inner and outer cranes on‘ oneside, is left on the outside of the outer crane limbs. Theremaining portion on either ends from the tenon, which is placedin the socket provided on the ‘kutti'.

lll

To the apex of the outer crane is attached the ‘Bras'with the help of ‘Harbola', which encircles the joint of the‘Bras’ and the apex of the crane in such a way that the ‘Bras’freely hangs from the outer crane. The looseness of ‘Harbola' isfixed so that the joint is not congested. The length of the twoouter limbs of ‘Bras’ (OB) are first determined in relation tothe net size (NS), and then that of the inner limbs (IB) inrelation to the outer limbs. The relationships are shown inFigs. (4.27) and (4.28) and the equations are

OB = 0.948 NS - 0.459 . . . . . . . . . . . . . ...(4.25)(n = 25; r = 0.9898; p < 0.001)

IB = 1.038 OB + 0.159 . . . . . . . . . . . . . ...(4.26)(n = 25; r = 0.9986; p < 0.001)

The net is attached to the four arms of ‘Bras’ by theloop formed by the outer ‘Borda' at the four corners of the mouthof the net.

The counter-weights are tied to the limbs of the cranetowards its apex. The number and weight of stones used are sofixed to ensure a gradual lowering of the net and minimum effortto haul. The first stone is tied close to the ‘Key’. Thesucceeding stones are hung about 15 cm. apart from the two limbsalternately.

112

Operation

The Chinese net operation is based on _the fishingprinciple of keeping the net submerged over an interval of timeand then lifting it rapidly out of water so as to catch any fishwhich happens to be over it (Joseph and Narayanan, 1965). Thenets are mostly operated during nights and to facilitate thecongregation of prawns, powerful lights are used. Kurian at al.(1952) based on comparative study on the effect of light ofdifferent intensities and colours in luring prawns and fishes inChinese nets in Kerala backwaters, have reported that, withincrease in intensity of light 200 to 600 percent increase incatch was obtained upto a maximum of 200 watts, after which thecatch reduced. The operation of the net commences when the nulltide begins and terminates when the speed of flow increases, lestthe net get distorted. The net is lowered by lifting the innercrane mannually until the first ballast is lifted from the groundor platform. The net then get slowly lowered, counterpoised bythe ballasts.

Depending on the catch, the net is kept immersed forfive to fifteen minutes. The net is hauled by pulling thehauling lines, the effort being reduced by the ballasts. Thecatch from the codend is taken out in an ingenious way. Twolines, locally known as ‘Kayyayi' are made use of for this. Oneend of these lines are attached to the ‘Sanchi' or codend atabout 25 and 30 cm. respectively from above the bottom of thecodend. The free end of these two lines are loosely attached to

113

that side of the mouth of the net, which faces the platfcrm andcan be easily reached from the ‘Kalsanthi' after each hauling.When these two lines are pulled together a bag is formed at thecodend, in which the catch in collected and brought to the edgeof the net and is finally taken out using a scoop net.

Classification

The analysis of data collected on the Chinese netsoperated in the Vembanad lake enables a broad classification ofthis gear into three size categories viz., Small, Medium andLarge. The net size is expressed in terms of the length on oneside of the mouth of the net.

Nets with a size upto 9 m. are classified as smallnets. They are mainly operated on a sustenance level in theinterior areas where the depth in relatively low.

Nets having a size of 9 to 12 m. are categorised asmedium nets. About 97 percent of the nets operated in the studyarea belong to this group.

Nets belonging to the large size group are these withthe net size above 12 m. These nets are operated only in theFort Cochin and Vypeen areas.

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FIO.1uT' THE CHINESE NET WITH THE CODENO PULLED UPAFTER OPERATION

1) PERNA A2) NILAVALA

3) SANCHI (CODEND)a) BORDA

5 & 6) KAYYAYI7) UDHARA

8) SAVAI9) BRAS

10) HARBOLA

11) KALSANTHI

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T7)

KUTTI

PURAMKAZHUKOL

(OUTER CRANE)

KARAKAZHUKOL

(INNER CRANE)

COUNTER-WEIGHTS

KALLUKAMBA

VALIKAMBA

(HAULING ROPES)

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////7'///// ///5’// /4// /,’Z// /// “'/ 'Q” /§'3’ /75/’ //7’ /////////

§\\\\\\\\

// //

//9////’//'//5/ /4//?/ /

44 /5’//// ///§ //0

‘PENIS ‘\\"fN*1’a'A'\\~1a\E" 5'" A m16“‘­\\ \\\ \*\\E /// //L ' " / // /

\ 1 1 _1 4A 2 \\ 11» E @ \§\ \\<\ / /‘ \ $4’ /// 0 _ Perm:‘ O\\\ 5 /,//' DA 8‘ .0: Nllclvolu\ :4,/ panels1 c .. Cocend

1>

to

/

5/¢

//// _\*' A“\\\\\

__ ni­-_.i_- .\_-1-..._-i1_ ____

A // // //A 1 A /4' // // \\ \\\ \\ \\ :/ / / // // \\ Q \\ \\/ / // // C - \\\ \\K // 77"" // ,| // /// 2A /;/ 4/ A/ 1 I7' /7 // // Z ‘// /// // // , ?// / / /E 1 1 / I1

i

‘J-qi---__--— -_ -_._­

\

I

I

I

1

1

/ /I/I //5/I 1// /// /

>

|

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I

\

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A

P

FIG. 11.2 DESIGN OF THE CHINESE NET.

Q

Perna p O7' 1" ./ A %" *"“""*"* *i* A *” // hJ1sfl

“<1Nilavala NZ“

K hlsstlSanchi

.L

FIG. 4.3 AN IDENTIC/-1L SECTION OF THE NET

Nzsfl

“"\

» =, N2dii

-,-A

\

1L-7..k %J4N “N%= \\ stl // hlbd*0-an

i

1

\

\

1

j

.bJ1d

N3ND l d|N d

Cd

v

FIG. 4.4 PLATFORM OF THE CHINESE NET

Kclsunthl

sgwfa IP51:

\_,

.L_ __ _&____D

I

II --0I

I

I

I

I

I

I

?:____jQ

5 61I

/.;="~'~zr_ r

iii iia

‘Inner CronemortiseOuter Crone

-11\,| J H iKolsonthi

Ienon

mortise Kutti

l\J4'\.;f'§-/ -L‘:-*7; ; ~ 7'-1;’ 4,-‘_— 4.>4¢'\,;_l74_@—t4a->%4

-—-=a

--1

’ 5_;4'l4Q4

FIG. 4.5 THE TWO 'KUTTI'(PILES) SUPPORTING 'KAI_SI\NTHI'.

+

w~\ 0\\ 5 ////\k<>‘*°

I

FIG.ln6 AT'ACHMENT OF THE INNER AND OUTER CRANES

."“-' V

._ J

I

e, _ /,\’’ 4* . / inner cranefv ' 'I ll // :I,/<~ __

~_~

Outer crane

" _ /|

>/II

L‘

\..l..

“LQ

UN THE 'Kl5\LSANTHI'.

i

FIG.ln7 'SAVAI'-THE LINES BETWEEN THE OUTERAND INNER CRANES.

FIG.lu8 'BRAS' AND THE NET.

4

FIG. 4.9 'PADACHIKKAYI3\R'-LINES USED TU SPREAD 'BRAS'

15_Ne1 size, NS (m)

13*11f =T '9i us:-2.a0+o.11T (r = 0.9705)7" (p < 0.001)5 __lW_._ --.0.-.0.-I - -- -I I; _._!1 Z 3 4 5 6

Woier depth, D (m)

FIG. 4.10 WATER DEPTH vs NET SIZE

14_Nef depfh, ND (m)T

12.1TOT" ‘3. ND = 0.907 us - 0.132" (r = 0.9937)6_ (p < 0.001)

A .._.._ 4__.. A A — ‘ __,_i'_,; f-A;-'* ‘4 ______._._ L ___..____.¥ —5 7 9 11 13 15Net size, NS (rn)

FIG. 4.11 NET SIZE ‘:5 NET DEPTH

Sfreiched lengih of Nilczvolcl panels (m)150'1 O11- .­4 Panel 19 .

' NI m = 0.000 us + 0.042(r = 0.0004)7? (p < 0.001)

I

5 +4’; 7.1 . _ }_ .4 - V. - _; ll, _;;;,,;-_: ~:L;¢— *5 7 0 11 13 1510

3).

6 _ Panel 2N2 m = 0.00 us + 0.040

(r = 0.9985)" {p < 0.001)F

2; ‘TY; ‘ ‘ 1 1 _ +-.111; 1 '7 9 11 13 155Br

‘T0 Pond 34%\» as all = 0.40 as - 0.0001 [r = 0.0970)4 (p < 0.001)

—~ 1 T 1 1*-if 1 ;* I _—' :_J|

25 7 9 11 13 155..

41­3?. .4 Ponel 4' N4 all = 0.297 NS + 0.03321.. (r = 0.9044)(p < 0.001)1 , I __ 1'7 —-_-,1; ,_-,___ l_ 1 I7 9 1 1 13 15

OIF-4U‘

5*’

_E"__'_.?;‘

2 ,­' ' Panel 51 N5 ON : 0.199 NS + 0.0091.5*

(F = 0.9079)(p < 0.001)

1 _ 4__- 1 . +7; 1 .______n5 7 9 11 13 15Nei size, NS (m)

FIG. £1.12 NET SIZE VS STRETCHED LENGTH OF NILAWXLA PANELS

N

1;

E

-_­\

JJ,

l|OVCl|(J depih Nd m

N =O557 NS-0074=-099 2)

(p < O*OO1)

5 7 9 1 1 '13 15Ne’r s\2e, NS m

FIG A 13 NET SIZE vs DEPTH OF NILN/ALA

DepH1cfi Nflowflo Poneh fin)3:­-2.5 - ­2 .

"5? Ponol11- 111 =1 = 0.17: us - 0.04:

(1 = 0.91135)0_5 . [p < 0.001)o!__;:___ 1 , 1 _ 1 A _ 1 . 15 7 9 11 13 15

2.5.­

2?

1.5.?

Ponol 21 +I N1 d = 0.144 NS — 0.039

0.5 ' (9 < 0.001)O _ _ 1 _ 1 ,1_;_0T___~1 ­7 9 1 1 13 15521­

1.5?- _1'- ' Panel 31‘ N3 d = 0.112 NS — O.C311 (r = 0.9952)0'57 (p < 0.001)

01' _ 1 %_1 _ 1__ __1 _15 7 9 1 1 13 151.5-,"

1.25­11- _0.75 - "Penal 4

0-5* N4 <1 = 0.001 us — 0.025{r = 0.9750)0.25 '" (p < 0.001)

O1. 1__ 1'__;_ 1 1 L-L.-__1 1 .._ 15 7 9 1 1 13 151.

O.8*0.61 "Q_4 . Ponol 5

N5 d = 0.050 NS — 0.0920.2 _ (F = 0.9510)(p < 0.001)01~__ 1 1 1 1 15 7 9 11 13 15

Ne1she,NS fin)' r\

FIG. 1.11 NET 5125 vs DEPTH OF 5111311 PANEL OF NILAVALA

o_9S1re’rched lengih of panels, P sil (m)

; -P ail =1.o2:s - 0.174 P n0-79“ (r = -o.9a19)(p < 0.01)

0.5 .1­

0.3L

0.1 * = » —=1»e L 1 »1 2 3 4 5Panels of Nilavala, P n (m)

4.15 NILAVALA PANELS VS STRETCHED LENGTH UF PANELS

0_2Pep’rh of panels, P d (m)

F P <1 = 0.205 - 0.031 P nA (r = — 0.9999)0.15% (p < 0.01)

K

0.1­

LI 1 _L.a, e-L--~*__­°-O5; 5 3 4 5Panels of Nilavala, P n (m)

FIG. 4.16 NILA\/ALA PANELS VS DEPTH OF PANELS

zsflodend sirefched lengfh, C s’rI (m)

2*I1

OD

1.5- _.- '1 c =1: = 0.144 us + 0.0541 l , (r = 0.9907)

(p < 0.001)

O0 5 - L--1 —--I _ ——-- I 1 , ,__} ~—~.’ __. 15 7 9 11 13 15Nei size, NS (m)

£1.17 NET SIZE VS STRETCHED LENGTH UF CUDEHD

3TCodend dep’rh, C d (m)

2.5;»21- .­; C d = 0.209 NS - 0.150L52’. (r = 0.9341)1 _, (p < 0.001)1 - _0 1*” 0 __1- __ |_‘_ _. 1 _ 15 7 9 11 13 15

Net size, NS (m)

FIG. 4.18 NET SIZE vs DEPTH OF CUDEND

“\_ _/II

I

I1

' -I1 ..\_\\

‘\

G .

1

r.I

Z

_ *5 (_

If \./ _O - - _\\::’- \‘r{‘/O \\($ \ ' \ -"" /I \_ / /.’ I ' 4 ._'| I ‘.-"' / _, ' / \"'*% ,§,/

.. /D/ \- |/ \ "‘ ~~\ /_ \£/ ’\n f\/ 1' :3, \1/I \ V \\ _\ 41/ \

j}ii!l;i@§1._ ,."""'%\\/’/ - -‘\"\/

\“i!lIliii%§L\\ ',// \___,/ /’ \_\/ K w-I-O)\,/ \ \__ /,­

_,/;3@\ ‘\\

\

7-///I\

//

\~.-.i\.__-J

(a) (D)FIG.A.19 METHOD OF JOINING OF PANELS BY

8) CREASING or D) BAITINO.

/’*~‘\1' " " P-*.'*—‘-IE7-“ "N """"""""‘r3.-{J \\

W // O:-7 )*m. .' , /‘\ ,,‘ ' , . '­I

' 0I,. ' 5

Hf, - ._ _ M__ In _ A& ‘I.¢_ O __ ___,',;'.O_ - I( \

FIG. a.20 MOUNTING OF ‘PERM!-1' [mm 'BORDA'.

15_§)uf0r crane length, OC (m)

13-'

11*

9+ ' oc =1.00s NS -1.001 (r = 0.0003)71* (p < 0.001)

'—l

:._ *4 1 1 .--___-_1 I5 7 0 1 1 13 15N01 size, NS (m)

FIB. 4.21 NET SIZE VS LENGTH OF OUTER CRANE

zolnner crane lengfh, IC (m)

ii

151»i 1c = 1.21 oc + 0.00410¢ (r = 0.0050)

(p < 0.001)

5 -__* _*-1_ -.__ -_._.__ -_.1_____._.._._.-.-01: _._+_._|_ 15 7 9 11 13 15Ouier crone lengih, OC (m)

FIB. 0.22 LENGTH OF OUTER CRANE vs LENGTH OF INNER CRANE

Ienon leng’rh, T (m)

_+.__ __':

I

+ (r = 0.9057)f (p <fCLOO1)0 hf--A-_l__ _ ___,_.__ I _ -0 l_0-- ______ _ H -1-_- __l____________

<- T = 0.02 IC - 0.001

05 7 9 11 13 15 17Inner crane Iengih, OC

FIG. 4.23 LENGTH OF INNER CRANE vs LENGTH UF TEFNJS

5Disf. beiween crane limbs, OC ds’r (m)TT

4­

3;.

2 OC dsl‘ = 0.251 OC — 0.008(r = 0.9996)f (p < 0.001)1 T A_~_ 10;;-_-_-_ T_—l-E— L__ _ -_ --_<-AT I I ___ '_ I->l _ A5 7 9 11 13 T5

Outer crane lengih, OC (m)

FIC.lu2A LENGTH UF UUTER CRANE VS DISTANCE BETWEENTHE LIMBS OF OUTER CRANE

25pisf. befween crane limbs, IC ds’r (m)

Zr

1.5rIC dsf = 0.148 IC + 0.013' (r = 0.9983)I ' (p < 0.001)1 I

0.5 '4! A _L__I-~~,~—— 1 |____H -- _ ~—1 1 _ _ _ I5 7 9 11 13 15 17Inner crane lengih, IC (m)

FIC.lu25 LENGTH UF INNER CRANE VS DISTANCE BETWEENTHE LIMBS OF INNER CRANE

5__Leng’rh of Kolscmihi, K (m)

TI

L

* K = 0.339 NS - 0.052(r = 0.9981)F. (p < 0.001)

5 7 9 11 13 15Nei size, NS (m)

FIG. me NET SIZE vs LENGTH OF KALSANTHI

15

131'W

HI1,

11f

9".­

7_

Quier bros lengih, OB (m)

I

00 = 0.940 us - 0.450(r = 0.0000)(p < 0.001)

0 <?_,L,__ I —l- - ,-0 77 0_,_- - 1 "J55 7 9 11 13 15

Ne? size, NS (m)

FIG. £4.27 NET SIZE VS LENGTH OF JUTER BRHS

13’­

11","

5

9% (I,7_ (p < 0.001)

winner bras length, IB (m)

|0 =1.0s0 00 + 0.100= 0.0000)

A |_ | ___ __ L0-0 _ 015 7 9 11 13 15

FIB. 4.28 LENGTH OF OUTER BR!-\S VS LESSTH OF INNER BRRS

Outer bros lengfh, OB (m)