MSC 134 Fishing Gear Technology .2015-12-03 · MSC 132/134 Fishing Gear Technology I & II...

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Transcript of MSC 134 Fishing Gear Technology .2015-12-03 · MSC 132/134 Fishing Gear Technology I & II...

  • MSC 132/134

    Fishing Gear Technology I & II

    Calculating and Cutting Netting TapersExcerpts 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

    Fishermans 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.

  • Machine Made Netting

  • Cutting and Shaping Netting

    1. The number of meshes at the start of the cut.

    2. The number of meshes required at the end of the

    cut.

    3. The length or depth in meshes of the section to be

    cut.

    All Meshes or Transverse

    E1 = Length (0)

    Base of right angle

    All Points or Siders

    E2 = Depth (90)

    Normal Direction

    All Bars

    45 degree angle

  • Resultant Angles for Net Tapers

    Assuming Meshes Are Hung At 71% E1 Value of 50%

  • Common Cutting Rates & Taper Ratios

  • Cuts: Netting Example

  • Body Tapers

    Guidelines and Formula1. You can only cut or calculate a cut by evaluating

    one side of the intended shape or piece of netting .

    2. Always establish which way your E values are

    oriented.

    3. The body taper is only used if the material to be

    cut is less than the depth of the netting.

    Body Taper =2 x Cut

    Depth - Cut=

    Bars

    Points

    Cut = Bottom - Top2

  • Body Taper: Calculations

    Body Taper =2 x Cut

    Depth - Cut=

    Bars

    Points

    Cut = Bottom - Top2

    180 meshes

    140 meshes

    30 mesh

    2 Cut = 2 x 20 = 40 = 4 bars

    Depth Cut 30 20 10 1 points

    E1

  • Body Tapers

    Calculating the Cut

    1. For calculation purposes when applying the cut

    formula, always assume the bottom of the netting

    piece is represented by the larger mesh count.

    2. When using the cut formula - if only one side of

    the netting piece will be cut, do not divide by 2.

    Cut =Bottom - Top

    2 180 meshes

    140 meshes

    30

    meshes

    E1CUT CUT

    180 140 = 40 = 202 2

  • Body Taper: Cuts

    Body Taper =2 x Cut

    Depth - Cut=

    Bars

    Points

    Cut = Bottom - Top2

    2 Cut = 2 x 40 = 80 = 8 bars

    Depth Cut 60 40 20 2 points

    E1

    180 meshes

    140 meshes

    60 mesh

    Cut = 180 140 = 40 = 40

    When using the cut formula - if

    only one side of the netting piece

    will be cut, do not divide by 2.

  • Body Taper: Cuts

    Body Taper =2 x Cut

    Depth - Cut=

    Bars

    Points

    Cut = Bottom - Top2

    2 Cut = 2 x 40 = 80 = 8 bars

    Depth Cut 30 40 -10 -1 points

    E1

    180 meshes

    140 meshes

    30 mesh The body taper is only used if

    the material to be cut is less

    than the depth of the netting.

    Cut = 180 140 = 40 = 40

  • Body Tapers: Calculations

  • Body Tapers: Calculations

    200 M

  • Body Tapers: Calculations

    200 M

    Body Taper = 2 Cut

    Depth Cut

    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.

    =Bars

    Points

  • Body Taper Examples

    3 Bars

    1 Point

    2 Bars

    1 Point 4 Bars

    1 Point

  • Jib Tapers

    Guidelines and Formula1. You can only cut or calculate a cut by evaluating

    one side of the intended shape or piece of netting .

    2. Always establish which way your E values are

    oriented.

    3. The jib taper is only used if the material to be

    cut is greater than the depth of the netting.

    4. Length replaces the cut on jib tapers.

    Jib Taper = (2 x Depth) - 2Length -Depth + 1

    Bars

    Meshes=

  • Jib Tapers: Calculations

    Jib Taper = (2 x Depth) - 2Length -Depth + 1

    Bars

    Meshes=

    20 P

    38 Meshes

    E1

    The 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: Calculations

    Tapers do not always work out perfectly. Your critical thinking skills are

    essential to properly apply various tapers and/or cutting rates.

    (2 x Depth) - 2

    Length -Depth + 1

    Jib

    Taper

    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

    = =

    =

  • All Bar Tapers

    Guidelines and Formula1. You can only cut or calculate a cut by evaluating

    one side of the intended shape or piece of netting .

    2. Always establish which way your E values are

    oriented.

    3. If the cut or length is equal to the depth of

    the netting you would have an all bar (AB)

    taper.

    4. If statement #3 is true there are no calculations

    necessary.

  • Prove the Taper which is

    indicated on the circled

    panel shown in the trawl

    plans (A15) to the right.

    Tapers: Calculations

  • 31M

    35M

    62M

    4M

    31M

    2 Cut

    Depth Cut

    2 x 4

    31 4

    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.

    Cut = Top Bottom = 66 62 = 4Body Taper =

    Body Taper =8 Bars

    27 Pts.

    2 Bars

    6.75 Pts.

    2 Bars

    7 Points= = =

  • 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)

  • Drop Tapers

    5 Meshes to 7 Meshes

    or

    1 1 1 1

    1 2 1 2

    Drop Loops Added

  • Identify the Tapers Shown Below

  • CUT LOSS