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MSC 132/134 Fishing 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
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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 Fisherman’s Workbook,compiled by J. Prado, Fishing News Books, Oxford:1990 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
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
Primary Hanging Ratio“Horizontal Orientation of Netting” E1= L ÷ Lo E1 is the Primary or Horizontal Hanging Ratio.Lis 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
Secondary Hanging Ratio“Vertical Orientation of Netting” E2= H ÷ Ho E2 is the Secondary or Vertical Hanging Ratio.His 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
Geometric DeterminationofHanging Ratios 1 - E² E2 = 1 – E1² E1 = 1 – E2² and
Common Hanging Ratios Gillnets Entanglement Gear Hydrodynamic Gear
(A-3) Sample Plans: Gill NetBottom set, Germany
(A-4) Sample Plans: Gill NetBottom set, Australia
(A-5) Sample Plans: Entangling NetBottom Set, Japan
(A-6) Sample Plans: Entangling Net(Trammel Net) Bottom Set, France
(A-7) Sample Plans: Seine NetNigeria
(A-9) Sample Plans: Four-Seam Flat TrawlShrimp, Gulf & South Atlantic, USA
(A-10) Sample Plans: Two-Seam Balloon TrawlShrimp, Gulf & South Atlantic, USA
(A-11) Plans: Four-Seam Semi-Balloon TrawlShrimp, Gulf & South Atlantic, USA
(A-12) Plans: Western-Jib 4-Seam TrawlShrimp, Gulf & South Atlantic, USA
(A-15) Sample Plans: Bottom TrawlCod, Germany
(A-17) Sample Plans: PotSnapper, Venezuela