LashCon IMO - User Guide
Contents
1. LASHCON IMO USER GUIDE BY DET NORSKE VERITAS Version 9 0 Date 2003 12 08 1 General 1 1 Introduction LASHCONTM is a MS EXCEL based calculation tool for evaluation of semi and non standardised securing arrangements The program calculates accelerations and balance of forces in semi and non standardised lashing arrangements in accordance with annex 13 to the Code of Safe Practice for Cargo Stowage and Securing the CSS code from IMO 1 2 System requirements LASHCONTM requires Microsoft Windows version 3 1 or later with Microsoft Excel 5 0 installed Resources needed to run Microsoft Excel 5 0 are described in Microsoft Excel User s Guide 1 3 User requirements The user should be familiar with Microsoft products such as Excel and Word This includes the use of mouse pointer NOTE The decimal separator may differ from the examples given in this booklet Normally either or is used 2 User guide 2 1 Input sequence 1 Once LASHCONTM has been started the following screen picture will appear 2 Input cells are marked white in LASHCONTM Not all input cells are necessary for successful computation Ship name and identification is solely for user reference Vessel main particulars are used for acceleration computation and must be filled in before proceeding See 2 2 Input Data for details 3 After successful completion of the input data click on the button Next Page gt gt2. proceed to the Cargo and lashing data sheet The following picture will then appear For help on input data press the button to the right of the respective input The input parameters are the same as explained in Code of Safe Practice for Cargo Stowage and Securing Annex 13 4 Fill in the in the Input of cargo unit data field 5 Select the Cargo unit stowage position vertical and longitudinal by using the drop down selection boxes in the upper right corner of the screen 6 Select the desired method of calculation Advanced calculation see 2 3 Calculation Methods Alternative calculation see 2 3 Calculation Methods 7 Give the applicable lashing particulars MSL of lashing kN Lashing direction for drop down boxes Vertical securing angle deg Horizontal securing angle deg Alternative method only Horizontal securing point distance m 8 Calculation results are shown in the yellow area Actual forces is the forces acting on the cargo unit due to the Accelerations at the given lashing position Securing capacity is the accumulated lashing forces from applied lashings If sufficient number of lashings is applied compliance will be shown by OK in red fonts to the right of each capacity 9 Acceleration data for the whole ship can be extracted from the Tables and graphs sheet This can be accessed by either pressing the Show graph gt gt button or by pr
3. advanced calculations only the vertical angle of lashings is included Calculated strength of lashing CS is MSL 1 5 For detailed theory outline please refer to CSS Annex 13 Alternative calculation method The alternative calculation method is based on force equilibrium of internal inertia forces and external lashing forces Additionally the risk of tipping is evaluated on basis of moment equilibrium Forces due to wind sea and friction are accounted for Elastic characteristics of lashings are not included The alternative method accounts for both the vertical of lashings and horizontal angle of lashing The alternative method approach is regarded as more accurate than the advanced method Hence the utilization of lashing strength is higher Calculated strength of lashing CS is MSL 1 35 Which calculation method to choose The alternative calculation method is the most sophisticated with respect to force equilibrium Hence the allowable usage of the MSL is slightly higher This method is therefore recommended It should be noted that none of the calculation methods includes the elastic properties of the lashings It is therefore important that the cargo unit is lashed with lashings of same type with approximate equal elasticity Lahing ropes and chains should not be combined It is recommended to keep the lashings of approximately same lengths 2 4 Special features of Lashcon IMO Stack function LASHCONTM of
4. essing the Tables and graphs tab Chart and table showing the accelerations along the ship length based on the annex 13 to the IMO CSS code 2 2 Input data Main ship data Lpp Length between perpendiculars in meters m B Ship breadth in meters m V Ship speed in knots knots GM Ship GM value in meters m Main cargo data m Mass of cargo unit in tonnes ton Coefficient of friction Aw Wind exposed area in square meters m2 As Sea exposed area 2 meters above BL in meters m2 a Lever arm of tipping i e height of cargo unit CG above deck in meters m b Lever arm of stableness in meters m PORT STBD Fy Tipping axis a CG b c 2 Advanced calculation lashing parameters MSL Max securing load kN Vertical securing angle degrees d Lever arm of securing force m Alternative calculation lashing parameters MSL Max securing load kN Vertical securing angle degrees Horizontal securing angle degrees d Lever arm of securing force m See Advanced Calculation lashing parameters 2 3 Calculation methods Advanced calculation method The advanced method is based on force equilibrium of internal inertia forces and external lashing forces Additionally the risk of tipping is evaluated on basis of moment equilibrium Forces due to wind sea and friction are accounted for Elastic characteristics of lashings are not included In
5. fers the possibility of saving your results in a stack Lashing results together with basic input is saved in a compact form in a table In this way the effect of different lashing arrangements or stowing positions can be compared in an easy manner Stack buttons Save to stack Current lashing data and results are saved to the stack Clear last Removes the last entry in the stack Clear stack Removes the contents of the entire stack Show stack Shows the stack 2 5 Program assumptions The calculation of accelerations and evaluation of lashing arrangements is based on the method described in annex 13 to the CSS code For details on theory for evaluation of forces please refer to CSS Annex 13 The following assumptions are directly quoted from the code A vertical securing angle greater than 60 will reduce the effectiveness of this particular securing device in respect of sliding of the unit Disregarding of such devices from the balance of forces should be considered unless the necessary load is gained by the imminent tendency to tipping or by a reliable pre tensioning of the securing device and maintaining the pre tension throughout the voyage Any horisontal securing angle i e deviation from the transverse direction should not exceed 30 otherwise an exclusion of this securing device from the transverse sliding balance should be considered LASHCONTM applies to lashing arrangements with vertical securing ang
6. les in the range according to table 5 in annex 13 i e 30 90 Lashing angles outside this range may give corrupt results In case such angle is given the program will give the following warning lt 30 or gt 90 Warning Securing angle outside range stated in annex 13 The acceleration figures shown in table 3 in annex 13 are basis for the calculation of accelerations in LASHCONTM and apply in principle to ships with 50 m L 200 m 9 kn V 24 kn and B GM 7 In LASHCONTM however the accelerations have been extrapolated by means of power series to apply for ships with L gt 30 m and speed up to 25 knots The B GM has been extrapolated to apply down to B GM 4 LASHCONTM does not calculate transverse accelerations if B GM lt 4 If input parameters are outside the applicable range the following warnings will appear L gt 200 m Warning L gt 200 Accelerations are extrapolated outside the range given in annex 13 B GM lt 7 Warning B GM lt 7 Accelerations are extrapolated outside the range given in annex 13 B GM lt 4 Warning B GM lt 4 Transverse accelerations are not calculated V gt 25 kn Warning V gt 25 kn Accelerations are not calculated Explanation of variables is given in the Help function in LASHCONTM A complete explanation of variables involved and a full set of assumptions may be found in annex 13
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