MSC 132/134 Fishing Gear Technology I & II

1. MSC 132/134Fishing Gear Technology I & II Calculating and Cutting Netting Tapers Excerpts from: Calculations for Fishing Gear Designs, A.L. Fridman, Fishing News Books Ltd., Surrey, England. 1986 FAO Catalogue 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, England. 1990 How to Make & Set Nets, John Garner, Fishing News Books Ltd., Surrey, England. 1986.

2. Machine Made Netting

3. Cutting and Shaping Netting • The 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 Points or “Siders” E2 = Depth (90º) Normal Direction All Meshes or Transverse E1 = Length (0º) Base of right angle All Bars 45 degree angle

4. Resultant Angles for Net Tapers Assuming Meshes Are Hung At 71% E1 Value of 50%

5. Common Cutting Rates & Taper Ratios

6. Cuts: Netting Example

7. Body TapersGuidelines and Formula • You 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. 2 x Cut Depth - Cut Bars Points Body Taper = = Bottom - Top Cut = 2

8. Body Taper: Calculations 180 meshes E1 2 Cut = 2 x 20 = 40 = 4 bars Depth – Cut 30 – 20 10 1 points 30 mesh 140 meshes 2 x Cut Depth - Cut Bars Points Body Taper = = Bottom - Top Cut = 2

9. Body TapersCalculating the Cut • For 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. Bottom - Top Cut = 2 180 meshes CUT CUT 30 meshes 180 – 140 = 40 = 20 2 2 E1 140 meshes

10. Body Taper: Cuts • When using the cut formula - if only one side of the netting piece will be cut, do not divide by 2. 140 meshes 60 mesh E1 Cut = 180 – 140 = 40 = 40 180 meshes 2 Cut = 2 x 40 = 80 = 8 bars Depth – Cut 60 – 40 20 2 points 2 x Cut Depth - Cut Bars Points Body Taper = = Bottom - Top Cut = 2

11. Body Taper: Cuts 140 meshes • The body taper is only used if the material to be cut is less than the depth of the netting. 30 mesh E1 Cut = 180 – 140 = 40 = 40 180 meshes 2 Cut = 2 x 40 = 80 = 4 bars Depth – Cut 30 – 40 -10 -1 points 2 x Cut Depth - Cut Bars Points Body Taper = = Bottom - Top Cut = 2

12. 3P2B

13. Body Tapers: Calculations 3P2B

14. Body Tapers: Calculations 200 M

15. Body Tapers: Calculations Body Taper = 2 Cut Depth – Cut Bars Points = 200 M Cut = Top – Bottom ÷ 2 = 340 – 100 ÷ 2 = 120 Body Taper = 2 x 120 ÷ 200 – 120 = 240 Bars 80 Points = 3 Bars 1 Point Body 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.

16. Body Taper Examples 3 Bars 1 Point 2 Bars 1 Point 4 Bars 1 Point

17. Jib TapersGuidelines and Formula • You 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. (2 x Depth) - 2 Length -Depth + 1 Bars Meshes Jib Taper = =

18. Jib Tapers: Calculations The base length of the right triangle represents the cut length. 20 P E1 38 Meshes (2 x 20) – 2 38 2 bars 38 – 20 + 1 19 1 mesh = = (2 x Depth) - 2 Length -Depth + 1 Bars Meshes Jib Taper = =

19. Jib Tapers: Calculations Jib Taper (2 x Depth) - 2 Length -Depth + 1 Bars Mesh = = (2 x 36.5) – 2 73 – 2 71 73 – 36.5 + 1 36.5 + 1 37.5 = = 1.89 Bars 2 1 Mesh 1 = Tapers do not always work out “perfectly”. Your critical thinking skills are essential to properly apply various tapers and/or cutting rates.

20. All Bar TapersGuidelines and Formula • You 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.

21. Tapers: Calculations Prove the “Taper” which is indicated on the circled “panel” shown in the trawl plans (A15) to the right.

22. 31M 35M AB 31M 7P2B 62M 4M 2 Cut Depth – Cut Body Taper = Cut = Top – Bottom = 66 – 62 = 4 2 x 4 31 – 4 8 Bars 27 Pts. 2 Bars 6.75 Pts. 2 Bars 7 Points = = = Body Taper = • Keys 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.

23. Taper Examples Cutting Rate: 1N 2B (1 Point 2 Bars) Cutting Rate: 1T 2B (1 Mesh 2 Bars) Cutting Rate: 1N 2T (1 Point 2 Meshes)

24. Drop Tapers 5 Meshes to 7 Meshes or 1 1 1 1 1 2 1 2 Drop Loops Added

25. Identify the Tapers Shown Below

26. CUT LOSS