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MSC 132/134 Fishing Gear Technology I & II

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 132/134 Fishing Gear Technology I & II

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  1. 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

  2. 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

  3. 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

  4. 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

  5. Geometric DeterminationofHanging Ratios 1 - E² E2 = 1 – E1² E1 = 1 – E2² and

  6. Common Hanging Ratios Gillnets Entanglement Gear Hydrodynamic Gear

  7. Hanging Ratio Tables

  8. Surface Covered at Different Hanging Ratios

  9. (A-2)

  10. (A-3) Sample Plans: Gill NetBottom set, Germany

  11. (A-4) Sample Plans: Gill NetBottom set, Australia

  12. (A-5) Sample Plans: Entangling NetBottom Set, Japan

  13. (A-6) Sample Plans: Entangling Net(Trammel Net) Bottom Set, France

  14. (A-7) Sample Plans: Seine NetNigeria

  15. (A-8)

  16. (A-9) Sample Plans: Four-Seam Flat TrawlShrimp, Gulf & South Atlantic, USA

  17. Standard Net Plan Layout: Cutaway View

  18. Net Plan with Hidden Lines: Uncommon

  19. Full Net Plan Layout: More Detail but not commonly used.

  20. 3P2B

  21. (A-10) Sample Plans: Two-Seam Balloon TrawlShrimp, Gulf & South Atlantic, USA

  22. (A-11) Plans: Four-Seam Semi-Balloon TrawlShrimp, Gulf & South Atlantic, USA

  23. (A-12) Plans: Western-Jib 4-Seam TrawlShrimp, Gulf & South Atlantic, USA

  24. (A-13)

  25. (A-14)

  26. (A-15) Sample Plans: Bottom TrawlCod, Germany

  27. (A-17) Sample Plans: PotSnapper, Venezuela

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