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### Transcript of MSC 132/134 Fishing Gear Technology I & II Calculating and Cutting Netting Tapers Excerpts from:...

• MSC 132/134Fishing Gear Technology I & IICalculating and Cutting Netting TapersExcerpts from:Calculations for Fishing Gear Designs, A.L. Fridman, Fishing News Books Ltd., Surrey, England. 1986FAO Catalogue of Small Scale Fishing Gear, Edited by C. Nedelec, Fishing News Books Ltd. & Whitefriars Press Ltd., London, England. 1975Fishermans Workbook, Compiled by J. Prado, Fishing News Books, Oxford, England. 1990How to Make & Set Nets, John Garner, Fishing News Books Ltd., Surrey, England. 1986.

• Machine Made Netting

• Cutting and Shaping NettingThe number of meshes at the start of the cut.The number of meshes required at the end of the cut.The length or depth in meshes of the section to be cut.All Meshes or Transverse E1 = Length (0) Base of right angleAll Points or SidersE2 = Depth (90)Normal Direction All Bars45 degree angle

• Resultant Angles for Net TapersAssuming Meshes Are Hung At 71%E1 Value of 50%

• Common Cutting Rates & Taper Ratios

• Cuts: Netting Example

• Body TapersGuidelines and FormulaYou can only cut or calculate a cut by evaluating one side of the intended shape or piece of netting .Always establish which way your E values are oriented.The body taper is only used if the material to be cut is less than the depth of the netting.

Body Taper = 2 x CutDepth - Cut=BarsPointsCut =Bottom - Top2

• Body Taper: CalculationsBody Taper = 2 x CutDepth - Cut=BarsPointsCut =Bottom - Top2180 meshes140 meshes30 mesh 2 Cut = 2 x 20 = 40 = 4 barsDepth Cut 30 20 10 1 pointsE1

• Body TapersCalculating the CutFor calculation purposes when applying the cut formula, always assume the bottom of the netting piece is represented by the larger mesh count.When using the cut formula - if only one side of the netting piece will be cut, do not divide by 2.Cut =Bottom - Top2180 meshes140 meshes30meshesE1CUTCUT180 140 = 40 = 20 2 2

• Body Taper: CutsBody Taper = 2 x CutDepth - Cut=BarsPointsCut =Bottom - Top2 2 Cut = 2 x 40 = 80 = 8 barsDepth Cut 60 40 20 2 pointsE1180 meshes140 meshes60 meshCut = 180 140 = 40 = 40When using the cut formula - if only one side of the netting piece will be cut, do not divide by 2.

• Body Taper: CutsBody Taper = 2 x CutDepth - Cut=BarsPointsCut =Bottom - Top2 2 Cut = 2 x 40 = 80 = 4 barsDepth Cut 30 40 -10 -1 pointsE1180 meshes140 meshes30 meshThe body taper is only used if the material to be cut is less than the depth of the netting.Cut = 180 140 = 40 = 40

• 3P2B

• Body Tapers: Calculations3P2B

• Body Tapers: Calculations200 M

• Body Tapers: Calculations200 MBody Taper = 2 Cut Depth CutCut = Top Bottom 2 = 340 100 2 = 120

Body Taper = 2 x 120 200 120 = 240 Bars 80 Points = 3 Bars 1 PointBody Taper = 3 Bars 1 Point however, even tapers are easier and neater to sew. A 6 Bar to 2 Point Body Taper (4B1P, 2B1P) is the same as a 3Bar to 1Point taper. =BarsPoints

• Body Taper Examples3 Bars1 Point2 Bars1 Point4 Bars1 Point

• Jib TapersGuidelines and FormulaYou can only cut or calculate a cut by evaluating one side of the intended shape or piece of netting .Always establish which way your E values are oriented.The jib taper is only used if the material to be cut is greater than the depth of the netting.Length replaces the cut on jib tapers.Jib Taper = (2 x Depth) - 2Length -Depth + 1BarsMeshes=

• Jib Tapers: Calculations Jib Taper = (2 x Depth) - 2Length -Depth + 1BarsMeshes=20 P38 MeshesE1The base length of the right triangle represents the cut length.(2 x 20) 2 38 2 bars 38 20 + 1 19 1 mesh= =

• Jib Tapers: CalculationsTapers do not always work out perfectly. Your critical thinking skills are essential to properly apply various tapers and/or cutting rates.(2 x Depth) - 2Length -Depth + 1JibTaperBarsMesh= =(2 x 36.5) 2 73 2 7173 36.5 + 1 36.5 + 1 37.51.89 Bars 2 1 Mesh 1= ==

• All Bar TapersGuidelines and FormulaYou can only cut or calculate a cut by evaluating one side of the intended shape or piece of netting .Always establish which way your E values are oriented.If the cut or length is equal to the depth of the netting you would have an all bar (AB) taper.If statement #3 is true there are no calculations necessary.

• Tapers: CalculationsProve the Taper which is indicated on the circled panel shown in the trawl plans (A15) to the right.

• 31M35M62MAB7P2B4M31M 2 Cut Depth Cut2 x 4 31 4Keys to Finding and/or Proving the Taper: You can only cut and/or calculate a cut by evaluating one side of the intended shape or piece of netting at a time. An All Bar (AB) taper will yield a 45 degree angle, which means the Cut is equal to the Depth of the netting. Cut = Top Bottom = 66 62 = 4Body Taper =Body Taper =8 Bars 27 Pts.2 Bars 6.75 Pts.2 Bars 7 Points= = =

• Taper ExamplesCutting Rate: 1N 2B(1 Point 2 Bars)Cutting Rate: 1T 2B(1 Mesh 2 Bars)Cutting Rate: 1N 2T(1 Point 2 Meshes)

• Drop Tapers5 Meshes to 7 Meshesor1 1 1 11 2 1 2Drop Loops Added

• Identify the Tapers Shown Below

• CUTLOSS