Podcast
Questions and Answers
What is the formula used to calculate Netting Resistance (Rr)?
What is the formula used to calculate Netting Resistance (Rr)?
- $Rr = \frac{dr}{Sr} * (1 + \frac{Lr + Hr}{6.6})$
- $Rr = \frac{Sr}{dr} * (1 + \frac{Lr * Hr}{6.6})$
- $Rr = Sr * \frac{dr}{125} * (1 + \frac{6.6 * Lr * Hr}{Sr})$ (correct)
- $Rr = \frac{6.6 * Sr * dr}{Lr * Hr}$
What is the calculated value of Netting Resistance (Rr) in tonnes?
What is the calculated value of Netting Resistance (Rr) in tonnes?
- 4.50 tonnes
- 3.00 tonnes
- 2.50 tonnes
- 3.83 tonnes (correct)
How is the Netting Resistance (Rr) converted from tonnes to newtons?
How is the Netting Resistance (Rr) converted from tonnes to newtons?
- Rr is multiplied by 1,000 and divided by 9.8 m/s²
- Rr is multiplied by 1,000 and then multiplied by 9.81 m/s² (correct)
- Rr is multiplied by 9.81 m/s²
- Rr is divided by 1,000 and then multiplied by 9.8 m/s²
What does 'dr' represent in the calculations?
What does 'dr' represent in the calculations?
What is the significance of the term 'Sr' in the formula?
What is the significance of the term 'Sr' in the formula?
What is the formula for the taper ratio 𝑅?
What is the formula for the taper ratio 𝑅?
In the taper ratio calculations for a 1N2B configuration, what value is assigned to 𝑇𝑛?
In the taper ratio calculations for a 1N2B configuration, what value is assigned to 𝑇𝑛?
What is the value of the hanging ratio (E) calculated from a rope length of 8 m and stretched mesh size of 50 mm with 200 meshes?
What is the value of the hanging ratio (E) calculated from a rope length of 8 m and stretched mesh size of 50 mm with 200 meshes?
For the taper ratio of 2T1B, what is the computed value for 𝑁𝑛?
For the taper ratio of 2T1B, what is the computed value for 𝑁𝑛?
What is the correct simplification for the taper ratio 𝑅 in the context of 1N1B?
What is the correct simplification for the taper ratio 𝑅 in the context of 1N1B?
For surface panel C, what is its calculated total surface area?
For surface panel C, what is its calculated total surface area?
Which surface panels share the same dimension for the Ø(mm) parameter?
Which surface panels share the same dimension for the Ø(mm) parameter?
When converting 1N1B, what is the correct treatment for 𝑇𝑛?
When converting 1N1B, what is the correct treatment for 𝑇𝑛?
What value represents 𝑇𝑛 in a configuration of 2T4B?
What value represents 𝑇𝑛 in a configuration of 2T4B?
What is the role of the coefficient CD in the formula for calculating Rp?
What is the role of the coefficient CD in the formula for calculating Rp?
What is the calculated 'Total area' for surface panel E?
What is the calculated 'Total area' for surface panel E?
Which statement is true regarding the maximum surface area covered and the value of the hanging ratio?
Which statement is true regarding the maximum surface area covered and the value of the hanging ratio?
Which configuration yields a taper ratio 𝑅 that cannot be determined?
Which configuration yields a taper ratio 𝑅 that cannot be determined?
Which formula correctly calculates the area Sp of a trawler’s Süberkrub if Rp is known?
Which formula correctly calculates the area Sp of a trawler’s Süberkrub if Rp is known?
If the towing speed is increased while other factors remain constant, what happens to the resistance Rp?
If the towing speed is increased while other factors remain constant, what happens to the resistance Rp?
For the configuration 2N1B, how is 𝑇𝑛 calculated?
For the configuration 2N1B, how is 𝑇𝑛 calculated?
What is the formula used to calculate the hanging ratio E?
What is the formula used to calculate the hanging ratio E?
If the stretched mesh size is 50 mm and the number of meshes is 200, what is the value of Lo in meters?
If the stretched mesh size is 50 mm and the number of meshes is 200, what is the value of Lo in meters?
Which type and angle of attack for an otter board has the lowest approximate Rp according to the data?
Which type and angle of attack for an otter board has the lowest approximate Rp according to the data?
Considering the surface panels, which panel has the largest total area?
Considering the surface panels, which panel has the largest total area?
In the given context, what primarily affects the resistance of warps and ground ropes?
In the given context, what primarily affects the resistance of warps and ground ropes?
What is the correct formula to calculate the surface area using the hanging ratio?
What is the correct formula to calculate the surface area using the hanging ratio?
If the hanging ratio (E) is equal to 0.9, what effect does it have on the total surface area (S)?
If the hanging ratio (E) is equal to 0.9, what effect does it have on the total surface area (S)?
Given E = 0.9, L = 10000, H = 500, and a = 0.030 m, which of the following values is correct for the calculated surface area S?
Given E = 0.9, L = 10000, H = 500, and a = 0.030 m, which of the following values is correct for the calculated surface area S?
In the W. Dickson Method for calculating netting resistance, which variable represents the average diameter of twine?
In the W. Dickson Method for calculating netting resistance, which variable represents the average diameter of twine?
What is the result of multiplying the twine surface area (Sr), average diameter (dr), and the ratio of openings in the net according to the W. Dickson Method?
What is the result of multiplying the twine surface area (Sr), average diameter (dr), and the ratio of openings in the net according to the W. Dickson Method?
If the horizontal and vertical openings of the net are both 10 m and 7 m respectively, which values should be used in the equation for calculating netting resistance Rr?
If the horizontal and vertical openings of the net are both 10 m and 7 m respectively, which values should be used in the equation for calculating netting resistance Rr?
When deriving netting resistance (Rr), what does the term $Sr$ represent?
When deriving netting resistance (Rr), what does the term $Sr$ represent?
Based on the formula $Rr = Sr ∗ (6.6 ∗ Lr ∗ Hr / 125 ∗ Sr) ∗ (1 + dr / Sr)$, which term would increase resistance most significantly if increased?
Based on the formula $Rr = Sr ∗ (6.6 ∗ Lr ∗ Hr / 125 ∗ Sr) ∗ (1 + dr / Sr)$, which term would increase resistance most significantly if increased?
What is the calculated value of Rfl for the given parameters?
What is the calculated value of Rfl for the given parameters?
Which formula correctly calculates the friction resistance (Rf) in water?
Which formula correctly calculates the friction resistance (Rf) in water?
What value does G represent in the calculation of friction resistance?
What value does G represent in the calculation of friction resistance?
How is the coefficient of frictional resistance (f) calculated?
How is the coefficient of frictional resistance (f) calculated?
What was the calculated friction resistance (Rf) for the 50 sinkers dragged on fine sand?
What was the calculated friction resistance (Rf) for the 50 sinkers dragged on fine sand?
What does a calculated f value of 0.61 indicate about the type of material used in the sinkers?
What does a calculated f value of 0.61 indicate about the type of material used in the sinkers?
If the weight of each sinker is increased, what would be the expected effect on the friction resistance (Rf)?
If the weight of each sinker is increased, what would be the expected effect on the friction resistance (Rf)?
In the Rfl calculation, which parameter is squared along with velocity?
In the Rfl calculation, which parameter is squared along with velocity?
Flashcards
Taper Ratio (R)
Taper Ratio (R)
The ratio of T-cuts (T) to N-cuts (N) in a textile design.
T-cuts (Tn)
T-cuts (Tn)
Number of T-type cuts in a textile design.
N-cuts (Nn)
N-cuts (Nn)
Number of N-type cuts in a textile design.
1N1B Taper Ratio Calculation
1N1B Taper Ratio Calculation
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Taper Ratio Calculation (general)
Taper Ratio Calculation (general)
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1N2B Taper Ratio
1N2B Taper Ratio
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2T1B Taper Ratio
2T1B Taper Ratio
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Possible Undefined Taper Ratio
Possible Undefined Taper Ratio
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Hanging Ratio (E)
Hanging Ratio (E)
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Surface Area (S)
Surface Area (S)
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Horizontal Meshes (L)
Horizontal Meshes (L)
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Vertical Meshes (H)
Vertical Meshes (H)
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Stretch Mesh Size (a)
Stretch Mesh Size (a)
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Netting Resistance (Rr)
Netting Resistance (Rr)
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Twine Surface Area (Sr)
Twine Surface Area (Sr)
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Average Twine Diameter (dr)
Average Twine Diameter (dr)
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Hanging Ratio Formula
Hanging Ratio Formula
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Hanging Ratio Calculation
Hanging Ratio Calculation
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Maximum Surface Area Hanging Ratio
Maximum Surface Area Hanging Ratio
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Hanging Ratio Example
Hanging Ratio Example
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Net Panel Area
Net Panel Area
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Net Mesh Size
Net Mesh Size
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Surface Area Calculation Example
Surface Area Calculation Example
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Net Panel Identification
Net Panel Identification
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Netting Resistance Equation
Netting Resistance Equation
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Units in Netting Resistance
Units in Netting Resistance
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Otter Board Function
Otter Board Function
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Otter Board Resistance (Rp)
Otter Board Resistance (Rp)
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Otter Board Area (Sp)
Otter Board Area (Sp)
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Drag Coefficient (CD)
Drag Coefficient (CD)
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Towing Speed (v)
Towing Speed (v)
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How does otter board area affect resistance?
How does otter board area affect resistance?
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What is Rfl?
What is Rfl?
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Rfl formula
Rfl formula
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What is Rf?
What is Rf?
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Rf formula
Rf formula
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What is 'f'?
What is 'f'?
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What is 'G'?
What is 'G'?
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Sample Problem: Calculate 'f'
Sample Problem: Calculate 'f'
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What does 'f' tell us?
What does 'f' tell us?
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Study Notes
Fishing Gear Design and Hydrodynamics
- This module covers fishing gear design and hydrodynamics, specifically within a fisheries engineering context (Fish 119).
- Students will learn to estimate cutting rates and taper ratios of netting.
- Students will calculate twine surface area for trawl nets.
- Estimating hanging ratios is a key aspect of the module.
- Calculating and estimating hydrodynamic resistance for trawl nets, otter boards, warps, and floats is part of the curriculum.
Net Cutting
- Net cutting is crucial for shaping fishing gear and netting.
- Key dimensions of a net are noted, including headline, fishing line length, and mesh sizes (nylon #21, 50 mm mesh size, nylon 2.0 mm, 50 mm mesh size).
- Different types of cuts (N-cuts, B-cuts, T-cuts) are identified. N-cuts are vertical, B-cuts are diagonal, and T-cuts are horizontal.
- Cutting rates are important in understanding netting design efficiency.
- Combining different cuts (e.g., 1T2B, 1N2B) influence netting design and are discussed. A "taper ratio" (R) is used for comparing different cutting combinations. Formula for calculating taper ratio is provided.
Twine Surface Area
- Students need to calculate and measure the surface area in square meters (m²).
- Relevant variables include the number of meshes above (N), below (n), and the vertical meshes (H).
- Twine diameters (Ø) and stretched mesh dimensions (a) are crucial to the calculation.
- A sample problem using these variables is presented.
Hanging Ratio
- This module defines hanging ratio as the relationship between the length of rope (L) supporting a net panel and the total length of the stretched netting panel (L₀).
- The formula E=L/L₀ is presented.
- A sample problem detailing calculating the hanging ratio (E) is provided. The sample problem utilizes the provided formula with specific given values.
- Different hanging ratios (E values) affect surface area covered by the netting. The maximum surface area achieved occurs at E = 0.71.
Fishing Gear Resistance
- Resistance (R) is a force in newtons (N) that opposes the thrust of a trawling vessel.
- The total resistance (R₁) is the sum of several components: netting resistance (Rₙ), otter board resistance (Rₒ), warp resistance (Rₐ), float resistance (Rf₁), and friction resistance (Rₓ).
- A formula, including variables such as twine surface area (S), average twine diameter (d), horizontal opening (L), and vertical opening (H), is presented for calculate netting resistance.
- A sample problem illustrating the calculation of netting resistance is included.
- Similar formulas (with different variables) are provided for calculating otter board resistance, warp resistance, and float/sinkers resistance.
- These resistance calculations are presented with example problems and relevant data, including appropriate units.
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Description
This quiz focuses on fishing gear design and the principles of hydrodynamics in a fisheries engineering context. Students will explore net cutting techniques, estimate cutting rates, and calculate hydrodynamic resistance. Key concepts include taper ratios, twine surface area, and hanging ratios for trawl nets.
