MSC 132/134 Fishing Gear Technology I

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MSC 132/134Fishing Gear Technology I II

• Appendix Netting Theory and Tapers

Excerpts from FAO Cataloque of Small Scale
Fishing Gear, Edited by C. Nedelec, Fishing News
Books Ltd. Whitefriars Press Ltd., London,
England. 1975 Fishermans Workbook,compiled by J.
Prado, Fishing News Books, Oxford1990 Shrimp
Trawl Design Performance, D. Harrington, J.
Watson, L. Parker, J. Rivers, C. Taylor, Georgia
Sea Grant Program, Marine Extension Service,
University of Georgia, Athens, Georgia. 1988
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Meshes Types and Measurement Methods
Knotted Netting
Knotless Netting
Hexagonal Mesh
Bar or Square
Bar or Square
Bar
Mesh Opening
OM Mesh Opening a Stretched Mesh
OM Mesh Opening a Stretched Mesh
a Stretched Mesh
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Primary Hanging RatioHorizontal Orientation of
Netting
E1 L Lo
E1 is the Primary or Horizontal Hanging Ratio.L
is the hung length of the netting or the length
of rope on which a net panel is mounted.Lo is
the length of netting when fully extended.
(stretched netting before hanging)
Therefore L E1 x Lo
and
Lo L E1
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Secondary Hanging RatioVertical Orientation of
Netting
E2 H Ho
E2 is the Secondary or Vertical Hanging Ratio.H
is the hung height or depth of the netting or
the fully mounted net. Ho is the height of the
netting when fully extended. (stretched netting
before hanging)
Therefore H E2 x Ho
and
Ho H E2
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Geometric DeterminationofHanging Ratios
1 - E²
E2 1 E1²
E1 1 E2²
and
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Common Hanging Ratios
Gillnets
Hydrodynamic Gear
Entanglement Gear
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Hanging Ratio Tables
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Surface Covered at Different Hanging Ratios
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(A-2)
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Sample Plans Gill NetBottom set, Germany
(A-3)
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Sample Plans Gill NetBottom set, Australia
(A-4)
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Sample Plans Entangling NetBottom Set, Japan
(A-5)
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Sample Plans Entangling Net(Trammel Net) Bottom
Set, France
(A-6)
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Sample Plans Seine NetNigeria
(A-7)
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(A-8)
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Sample Plans Four-Seam Flat TrawlShrimp, Gulf
South Atlantic, USA
(A-9)
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Standard Net Plan Layout Cutaway View
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Net Plan with Hidden Lines Uncommon
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Full Net Plan Layout More Detail but not
commonly used.
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3P2B
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Sample Plans Two-Seam Balloon TrawlShrimp, Gulf
South Atlantic, USA
(A-10)
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Plans Four-Seam Semi-Balloon TrawlShrimp, Gulf
South Atlantic, USA
(A-11)
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Plans Western-Jib 4-Seam TrawlShrimp, Gulf
South Atlantic, USA
(A-12)
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(A-13)
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(A-14)
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Sample Plans Bottom TrawlCod, Germany
(A-15)
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Sample Plans PotSnapper, Venezuela
(A-17)
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