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APPEN
DIX1:MEASUREMENTSOFBRACKETFORTHEHANDRAIL
ANDC
ATWALKACCORDINGTOANTHROPO
METRYOFTHE
FISHE
RMANINMEXICO.
92
60
Measuresincm
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APPENDIX2:MESHDIMENSIONSANDNETPANEL
1.Thesizeo
fthemeshwasdefinedonthebasisofr
ecommendationsby
Beveridge(
1996).Thelargestmeshsizeandthinnesttwinediameterpossible
waschosen.
Thesmallerthemesh,thegreatertheprojecte
darea,whichcauses
increasedcurrentloads,decreasedwaterflowthroughthe
cagesandincreased
fouling.
Withtheminimum
sizeoffishinthestocking,theformulaof
Fridmanforgillnetwasappliedtoknowapproximately
thesizeofmeshfor
trapthisspe
ciesandwiththisdata,toreducethemeshsize.
OM=LfK
-1
(Fridman,
1986)
Where:
OM:meshopening(mm);
Lf:averagelengthoffishonewantstocatch(mm);
K:coefficientaccordin
gthespecies;
K=5forlongthinfish;
K=3.5
foraveragedsh
apedfish(neitherverythicknorthin),thisisthecasefo
rBlackSnook;
K=2.5
forverythick,wideorhighshapedfish;
2.Theareaof
thenetpanelwascalculatedastheperimeterofthecylindricalbag
(L)timesd
epth(H).Primaryandsecondaryhangingratios(E1andE2)of
0.707.
The
numberofstretchedmeshes(N
sm)andthenumberofrigged
meshes(N
rm
)forthelengthandheightofthepanelofnetwascalculatedwith:
Nsm=LOM-1
(forthelength)
(Prado,1990)
Nsm=HOM-1
(fortheheight)
Nrm=N
smE1-
1(
forthelength)
(Prado,1990)
Nrm=N
smE2-
1(
fortheheight)
3.Thesurface
coveredbythenetting(S:m
2)wascalculated
using:
S=E1(1-E12
)LHOM2
(Prado,1990)
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APPEN
DIX6:EFFECTIVEFLOTATIONFORC
EOFTHECAGE
22.
Theeffectiveflotationforcesforacleanandfouledcage(F
c:kg)and(Ff:
kg)
weredeterminedas:
Fc=F
n-Wtw
Ff=F
n-Wtfw
23.
Theemergencyeffectiveflotationforcesforcleanandfouledcages(F
ec:kg)
and(F
ef:kg)weredeterminedas:
Fec=F
e-Wtw
Fef=F
e-Wtfw
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APPENDIX7:CU
RRENTFORCESAPPLIEDTOTHECO
MPONENTSOF
THECAGE
24.Tocalculatetheloadsofcurrentstothenetpanel(L
n:kg),
thecagebagareain
frontofthe
currentwastakentobeplanepanel,perpendiculartothecurrent
force.This
representstheworstpossiblesituationandmaximumload.
Inthis
designofth
eonefixedpointformoorings,onefaceofth
ebagwillbealways
infrontofc
urrents.
Theactualworkingarea(A
a:m
2)wascalculatedas:
Aa=lh
(Fridman,
1986)
Where:
l:Lengthofthenetting
orthemountedlengthofthemainmountingrope,
infa
cingthecurrent(m).
h:heightofthenetting
orthemountedlengthofthesidehangingline,infacingthecurrent(m)
Thenthefic
titiousareaofnetpanel(Af:m
2)wascalculate
das:
Af=A
a/E1E2
(Fridman,
1986)
Where:
E1andE
2:Primaryand
secondaryhangingratios,previouslydetermined.
Theprojectedarea(A
p:m
2)infacingthecurrentwascalculatedas:
Ap=2Af(d/2a)(1+kkd/2a)
(Fridman,
1986)
Where:
d:diameterofthemeshtwine;
a:lengthofthemeshbar;
kk:coefficientofthe
knot-area,
typicallyis10.1forsquare-knot,9.7forsingle-knotand14.8
for
double-weavers-kno
tnetting.
Finallythecurrentloadsinthenetpanel(L
n)werecalcula
tedas:
Ln=CdV
2 (A
p/2)
(Milne,1
972)
Knottedmaterials:
Cd=1+3.77(d/a)+9.37(d/a)2
Knotlessmaterials:
Cd=1+2.73(d/a)+3.12(d/a)2
Where:
Cd:coefficientofdrag
ofthematerial(dimensionless);
:massdensityofwater(kgs2m
-4);freshwater=100andseawater=105;
V:currentvelocity(ms-
1).
Thecurrentforcesincleannetting,
Cd
wascalculatedusingtheoriginal
measurementsofthemesh;forcalculatingloadsinfouled
netting(L
nf:
kg)the
twinethicknesswasincreased3times.
Forthecalculation
,thecurrentvelocity
was:0.75m
s-1
(~1.5knots)and,forsecurity,oneextremevelocityof1.0ms-
1
(2.0
knots);thiswasdoneforallthecomponentsofthe
cageaffectedbythe
current.
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APPEN
DIX8:WINDFORCESAPPLIEDINTHESUPERSTRUCTUREOF
THEC
AGE
29.
Theloadsofthewindinthesuperstructureof
thecage(L
w:kg)wascalculated
using:
Lw=0.0965AV
2 (B
oven,1968,citedbyBeveridge,1996)
Whe
re:
A:sumoftheareasofpartsexposedtothewind,-freeboard
netting,handrail,floats-,(m
2);
V:w
indvelocity(ms-
1).
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APPENDIX9:WAVEFORCESAPPLIEDTOTHECAGE
30.Tocalculatethewaveforcesactingonacagecollar,
thehorizontaland
verticalorbitalvelocitiesofthewaterparticles(:ms-
1)a
nd(:ms-
1)mustbe
known,(Beveridge1996).Thesecanbecalculatedas:
=
{{H
wcosd[2(z+d)/L
w]}/twsind(2d/L
w)}cos
=
{{H
wsind[2(z+d)/L
w]}/twsind(2d
/L
w)}sin
(MuirWood&Fleming1981,citedbyBeveridge1996)
Where:
Hw:waveheight(m);
d:depthofwater(
m);
z:variationfromm
eanwaterlevel(m);
Lw
:wavelength(m
);
tw:waveperiod(s);
:angleofwaverelativetothestructure()
AccordingtoMilne(1972),isunlikelytoexceed2ms
-1
inmostfishfarming
conditions,
andthusthisvaluecanbeusedfordesigning
purposesformarine
cages.Beveridge(1996),proposesthattheequationfor
calculatingthedrag
forcesexertedbycurrentsonnettingisapplicable.
The
forceexertedonthe
collarbyth
ewave(L
sw:kg)canbedescribedbyanequationsimilartothat
derivedfor
effectofcurrents:
Lsw=Kd
2
A
Where:
Kd:
dimensionlessconstant,similartoC
dfornetting,whosevaluedependofthematerialandshapeof
thecollar,
inthisc
aseforapproximatelycalculationscanbetakenthevaluesoftable9.
:massdensityofwater(kgs2m
-4);forseawater105.
:horizontalcomponentofwaveparticleorbitalvelocity;formarinecages2m
s-1;
A:areaofthecagecollarperpendiculartothewavetrain(m2).
Theverticalcom
ponentofwaveparticlemaximum
orbitalvelocity()is
approximately83%
ofthe,
(Wiegel1964,c
itedbyBeveridge1996).
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APPEN
DIX10:GENERALARRANGEMENTOFPARTS,DIMENSIONS
ANDM
ATERIALSOFTHEMOORINGANDANCHORSYSTEMSFORTHE
CAGE.
Measuresinm
Swivelalwaysin
tension
2.1tonsX3
PP24
PP26
PP40
PP40
14
14
14
2x34kgf
250kgf
250kgf
150kgf
~35
6
3
10
~6
10
400kgf
6
106kgf
Chain+swivel+rope
40kgf
Tubeofmoorings
PP24
10
6
9
RaisedropePA3
m
Raisedchain26
7m
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