Welcome to the Bollard Pull Calculator for Barges!

Transcription

1 Welcome to the Bollard Pull Calculator for Barges! What does this Excel Sheet do? This Excel sheet helps you calculate the Required Bollard pull of a Tug used for towing a Ba How is the Excel Sheet Organised? The Excel Sheet provides three different methods for calculations. The First method is using a simple Empirical formula. This is contained in the sheet named " The Second Method is using industry standard OPL Guidelines for Barge Transportation Vol The Third Method is based on Bureau Veritas rules and formulas for Bollard Pull Calculation How to use this Excel Sheet In all the three methods, the user is asked for some inputs to be provided. For example, the The user has to provide all the inputs highlighted in blue. For some inputs, Tables and charts are required to be referred. These Tables and charts are Once all inputs are provided, the components of required bollard pull are calculated and ad

2 arge "Empirical Formula". It provides Bollard Pull for different weather conditions: Calm, Rough and Extreme l 5. This is contained in the sheet named "Bollard Pull - OPL Guideline" ns. This is contained in the sheet named "Bollard Pull - BV" e Wetted Surface area of Barge, Wind Speed etc. The Input cells are highlighted in blue. e provided alongwith for the user to enter these inputs. dded up to give the final Bollard Pull required.

3 CALCULATION OF REQUIRED STATIC BOLLARD PULL FOR BARGE: Empirical Formula INPUTS: Please input the following BARGE NAME Length, L Breadth, B Displacement, Depth, D Draft, d Cargo Height, H Tug Efficiency in percentage(default 75%) Is it Tow by Stern? Unit Value FORMULA USED Using Empirical Formula for towing guide by Port Authorities BARGE 1 BP = { [ ( ⅔ (v 3 / (120 60)) ] + (0.06B D1) } K (tonnes) m m Where: tonnes = full displacement of towed vessel, in tonnes m 5.50 v = tow speed, in knots m 4.24 B = breadth of the vessel, in meters m 4.09 D1 = depth of exposed transverse section of the vessel including deck cargo above the water line, in meters Yes/No No tonnes Actual TUG Bollard Pull BP = Required bollard pull, in tonnes Note: For tow by the stern, then the Bollard Pull requirement is to be increased by 20% K = the factor depending on the likely condition to be met. This factor is intended to reflect desired weather margins. OUTPUTS: CALCULATED BOLLARD PULL WITH VARIOUS WEATHER CONDITIONS & TOWING SPEEDS In General: for exposed tows, K = for sheltered tows, K = Good Rough Extreme for protected tows, K = Length, L Towing Speed, V <---- Please input the different speeds considered for the three weather conditions Breadth, B Displacement, Depth, D Draft, d Cargo Height, H Exposed Height, D Weather Factor, K Required Bollard Pull as per formula, Rt Tug Efficiency in percentage(default 75%), η Bollard Pull considering Tug Efficiency = (RT/η)* Tow by Stern? No No No Final Bollard Pull, BP (in tonnes) Actual TUG Bollard Pull SATISFIED SATISFIED SATISFIED

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5 CALCULATION OF REQUIRED STATIC BOLLARD PULL FOR BARGE: OPL Guidelines BARGE NAME BARGE 1 Directions: 1. Fill the input cells which are in blue. TOWING SPEED -----> knots The outputs will show in the bottom as the final Bollard Pull required. Actual Bollard Pull of Tug -----> tonnes 40.0 Towing Efficiency in % (Default value 75%) 75.0 Calculation of Frictional Resistance: R F = f 1 (S)(v/6) 2, lbs. 3. Use Table 1 for calculating the Height coefficient for Wind 4. Use Table 2 for finding the Shape Coefficient for wind Unit Value 5. Use Table 3 to calculate the Wave Effect Resistance which depends on the wave height. Fouling coefficient(0.4 clean hull, 0.85 fouled hull, usually In case the value of Wave Height falls in between two values given in the table, interpolation is to be used f 0.625) Wetted Surface of the Hull S ft Still water tow speed in knots v knots 4.0 Frictional Resistance R F tonnes 4.11 Factor Ch (Height coefficient for wind calculations) Calculation of Wave Forming Resistance: R WF = 3.42 (f 2)(A T)(v) 2, lbs. Hull Shape Coefficient (0.20 for rake ended barges and bluff bowed vessels and 0.50 for square bowed vessels) f2-0.2 Height Unit Factor 0-50 feet 1 Unit Value feet feet 1.2 Transverse Area(Underwater) A T ft feet 1.3 Still water tow speed in knots v knots feet 1.4 Wave Forming Resistance R WF tonnes feet feet 1.6 Calculation for Wind Resistance: R W = (A T)(v W+v) 2, lbs. Table 1: Cargo Height Coefficient for Wind Calculations Unit Value Height Coefficient for Cargo Exposed to Wind (See Table 1) Ch - 1 Shape Coefficient for Cargo Exposed to Wind (See Table 2) Cs - 1 Factor Cs (Shape coefficient for wind calculations) Cargo Transverse Area (Exposed to wind) A C ft Shape Cs Topside Transverse Area (Exposed to wind) A H ft Cylinder 0.5 Total Transverse Area A T ft Flat Perpendicular Surface 1 Wind Velocity v W knots 40.0 Isolated Structure Beam-channel angle braces 1.5 Still water tow speed in knots v knots 4.0 Exposed Beams 1.3 Force at 20 knots wind velocity R W tonnes 4.23 Derrick (latticed structures) Sphere Calculation of Current Effect: R C = (S)(v C) 2, lbs. Table 2: Carge Shape Coefficient for Wind Calculations Unit Value Wetted Surface of the Hull S ft Current Speed v C knots 1.0 Current Effect Resistance R C tonnes feet 2000 lbs Calculation of Wave Effect: 10 feet lbs At 7 feet = 6000 lbs resistance 15 feet lbs Unit Value 20 feet lbs Wave Height ft feet lbs Force at 16 feet wave F WR lbs 23, feet lbs Wave Effect Resistance R WH tonnes Calculation of Hawser Resistance: R H = 0.10 (R F + R WF) Unit Value Frictional Resistance R F tonnes 4.1 Wave Forming Resistance R WF tonnes 5.8 Hawser Resistance R H tonnes 0.99 Wave Height Effect For wave Force on Hull: Significant Wave Height Table 3: Wave Effect Resistance Table Added Resistance OUTPUTS Calculation of Total Resistance: R T = R F + R WF + R W + R C + R WH + R H Frictional Resistance R F tonnes 4.11 Wave Forming Resistance R WF tonnes 5.81 Wind Resistance R WH tonnes 4.23 Current Effect Resistance R C tonnes 0.24 Wave Effect Resistance R WH tonnes Hawser Resistance R H tonnes 0.99 Total Resistance R T tonnes 26.0 Tug Efficiency in percentage(default value 75%) η 75.0 Required Bollard Pull = (R T/η)*100 BP TONNES 34.67

6 CALCULATION OF REQUIRED STATIC BOLLARD PULL FOR BARGE: BV Rules and Formulas BARGE NAME: BARGE 1 INPUTS Symbol Value Unit L = m Waterline Length B = m Breadth T = 4.50 m Draft V = 4 Kn Vessel Speed (Towing Speed) Vc = 1 Kn Assumed Current Speed D = t Displacement S = m^2 Windage Area d = 65 mm Tow Line Diameter l = 700 m Tow Line Immersed Length Z = 1 m Sag of Tow Line P = 900 m Tug to Towed Vessel Distance N = 150 days Number of Days Elapsed Since last Dry Docking Vfr = 11 Kn Maximum Towing Vessel Speed in Free Run rsw = t/m^3 Sea Water Specific Gravity (default value 1.025) rair = 1.22 kg/m^3 Air Specific Gravity (default value 1.22) n = 1.2E-06 m^2/s Viscosity (default value ^-6) Vw = 40 Kn Wind Speed (default value 40) BPt = 40 Tonnes Actual Bollard Pull of Tug RESULTS Symbol Value Unit Frictional Resistance Rf Rf = ½ Cf (rsw)(sw)(v) 2 R = Reynolds Number, R = vl / ν Cf = Friction Coefficient, Cf = / [log 10 R)-2] 2 DCf = Addition to Friction Coefficient due to Hull Fouling, DCf = (N)(Cf) Cft = Total Friction Coefficient, Cft = Cf + DCf Sw = m^2 Wetted Surface Area Rf = N Frictional Resistance Wave Resistance Rv L/B = 3.13 B/T = 6.11 V/(L)^0.5 = 0.28 Rv / D = (To be taken from the Graph 1 on the right) Rv = N Wave Resistance Total Hydrodynamic Resistance Rh Rh = Aerodynamic Resistance Ra N Total Hydrodynamic Resistance Ra = ½ Cx * Ch * (rair)(s)(vw)2 Cx = 1 Drag Coefficient(To be taken from the Appendix1 on the right) Ch = 1 Height Coefficient(To be taken from the Appendix1 on the right) Ra = N Aerodynamic Resistance Tow Line Resistance Rr Rr = 4.6 x10-3 (d)(v) 2 ( l + (71.6 Z/P)), in Newton Rr = 1385 N Tow Line Resistance Total Resistance of Towed Vessel Rtot = N Bollard Pull Coefficients (V+Vc)/Vfr = 0.45 Cef = 0.55 Percentage of Static Bollard Pull = (1 - (V+Vc)/Vfr) Total Required Static Bollard Pull for Tug, Rt Rt = 35.6 T

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