Douglas Young: An Assessment Of The Strength Of Seizings And Whippings Used To Create Eye Terminations On Sailing Rope.
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AN ASSESMENT OF THE STRENGTHOF SEIZINGS AND WHIPPINGS USEDTO CREATE EYE TERMINATIONS ON SAILING ROPE DOUGLAS YOUNG 200423401 BEng AeroMechanical Engineering Project Supervisor Dr AJ Mclaren Technical Paper Word Count 296810 AbstractThe purpose of this project was to investigate different methods of creating an eyetermination in sailing rope The most common methods of creating eye terminationsin ropes are by knots splices seizings and whippings There is a lot of informationon knots and splices however there is little on the seizing and whipping methods Itwas decided to focus this project on the seizing and whipping methodsInitial tests were then carried out on various whippings and seizings to determinetheir strength The initial results indicated that the seizing method was far superior tothe whipping method On this basis due to the limited strength of the whippings it wasdecided not to investigate whippings any furtherThe rest of the project focused on the seizing method and the variables that alteredthe strength It was concluded that the number of stitches and the length of the strength of the efficiency most notably This project showed thatseizings can have similar strengths to knots 120 Nomenclature Sum percentagecm centimetreslbs pounds forcem metresM15 Laboratory roommm millimetresn number of sampless standard deviationx sample meanxi sample value 230 topics of different types of knots and splices used in the sailing long been the subject of interest Specifically the area of particular interest forthis project is that of the sailing rope used to control the sail itself Due to thisdifferent methods of attaching rope to another rope fixed point or sail are requiredOne way of attaching rope is to create an eye termination the most commonmethods for creating an eye termination are by forming a knot splicing or seizingA seizing is where the end of the rope is stitched to the standing part of the ropeusing binding twine The main objective of this project is to discover the strength ofdifferent types of seizings and what factors contribute to the strengthThere is already sufficient data on knots in sailing ropes and splices from previouswork and projects 1 2 Unlike splices or knots there is very little on the formations of seizings or their specific strength 3 4 As there islittle information available in how to create the seizing to achieve optimum strengthor efficiency assumptions were based off initial tests This project has attempted tofind the most efficient method for creating the seizing as well as analysing theeffects on the seizing by changing several different variablesThe seizings created during this experimented were applied to 12mm braid on braidpolyester sailing rope This was the only type of rope used in the this projectAnother way of constructing an eye termination called whipping 3 4 which issimilar to a seizing creates an eye termination by binding the end of the rope to thestanding end of the rope using binding twine This method did not involve the rope at all This method was tested but it became apparent that thismethod had several limitations and proved very weak compare to the seizings 3To ensure nonbiased and accurate results certain variables were kept the testing of the seizings The variables that were kept constant are 12mm polyester braid on braid rope Same size needle of 60cm length The same type of binding twineThe variables which were altered to analyse the performance of the seizings were The type of stitching The number of stitches per unit length The length of stitching along the rope The size of the eye termination The manufacturerIt should be noted that when one variable was altered the rest were kept constant inorder to analyse the individual effect of the variable being altered on the The efficiency of each seizing was then calculated in excel usingequation 11 Failure Load of seizing Whipping Efficiency Failure Load of rope Equation 11A testing technique was developed to measure the failure load of the for this project The same testing procedure was then carried out andapplied to every seizing constructed for testing The failure load of each test wasthen recorded into the lab book The data recorded was then inputted into excel tocalculate the efficiency for each seizing 440 different procedures were carried out before the main body of testing wascarried out for this project The first step of the proceedings was to carry outresearch before any experimental procedures and tests were conceived Once theresearch was completed to gain any previous information on eye terminations 1 2the main focus of this project and its objectives were decidedA testing method and procedure then had to be derived in order to test the and seizings The test specimens could then be conceived andconstructed for testing once the testing procedure was decidedFirstly initial tests were conceived to determine the strength of the various and whippings From the results of these tests a seizing construction wasthen chosen to analyse in more detail for the remainder of this projectA datum seizing was also established from these results so that when one variablewas altered all other variables remained constant 5 6 This ensured a fairexperiment and an accurate depiction of the effect of the variable altered on theseizings efficiency41 Testing proceduresThe first test to be carried out before any whippings or seizings were tested was theactual strength of the rope This test was very important as the result was then usedin all calculations to work out the efficiency for each individual seizing Themachine used for the testing procedures was a Tinius Olsen tensile testing machineTesting of rope strengthTo test the rope strength the following procedures were carried out Firstly twometers of 12mm braid on braid polyester was cut using a hot knife The test wasthen carried out on the tension and compression machine as illustrated in figure 1 5 Figure 1The rope was then secured by tying a knot at either end after it was wrapped roundthe drums twice at either end The rope was then clamped between two metal platesby bolting the plates together with the rope in between to secure the rope Once therope was secured between the two drums on the testing machine the test was carriedout The test essentially involves subjecting the rope to a tensile load until failureoccurs The instant the rope failed was then recorded on an analogue gaugeattached to the Tinius Olsen machine that recorded the failure load to the nearest10lbs The scale on the Tinius Olsen machine used for all the tests was a maximumof 10000lbs with 10lb increments on the scale Once failure occurred the testingwas stopped and the failure load of the rope recorded in a lab book 6Testing procedure of Seizings and WhippingsThe same experimental methods and procedures are used to test the seizings andwhippings bar one difference The only difference between the rope test and thewhipping and seizing tests is in the set up of the machinery Instead of a drum beingattached to the bottom part of the machine a different attachment was used in theform of a shackle This set up is illustrated in figure 2 Figure 2The test specimen consisted of a 13m length of 12mm braided rope which had aseizing or whipping formed at one end The standing end of the rope was attached tothe top part of the machine as before The seizing was then attached using theshackle to the bottom platformThis procedure was then carried out for every other seizing and to ensure a fair experiment and that there were no discrepancies in theresults due to a difference in testing procedure 742 Processing the ResultsOnce all the data collected in the lab had been recorded into the lab book andinserted into excel various equations and graphs were used to analyse the datacollected Several different spreadsheets were formed in order to analyse thedifferent types of seizings For the main body of results three separate tests werecarried out on each different type of seizing This was in order to achieve anaccurate representation of the efficiency of each different type of As three results were obtained for each type of seizing it was thenpossible to calculate the error involved The efficiency for each seizing wascalculated by inputting equation 11 into excel After each of the efficiencies werecalculated for all the seizings the mean average efficiency median efficiency andthe standard deviation was calculated from each of the three tests for the differenttypes of seizings The equations used to calculate the standard deviation and meanare shown in appendix A 850 Results from TestingFor the rest of this project it was decided to analyse the seizing method in moredetail In order to do this different variables were altered and there effects on theefficiency recorded Although the manufacturer published a breaking load for therope the rope was tested to find its actual strength and give a more of the seizing efficiencies The failure load of this rope is givenbelow along with the manufacturers rated valueTested Rope failure load rated value 6380lbs 7Results of different stitching methodsThe next set of tests focuses on the different stitching methods used in creating theseizings This was carried out to obtain the most effective method of stitching thatyielded the most efficient seizings Three different types of stitching were appliedand different variables were altered for each For each type and variable alteredthree different tests were carried out on each to give an average and obtain an errorfor each stitching type An illustration of the final seizing choice that from the initial results is shown below in figure 3 Figure 3From the seizing in figure 3 the following datum values were used and applied to allother seizings 9 Eye termination length 14cm length 6cm Table 11 gives the information from the most efficient stitching type obtained from the results This stitching type was then applied as a datum for the remaining tests involving the seizings Seizing data set Average mean Standard efficiency Deviation S025 to S030 480 183 Table 11 The other variables applied in the final seizing choice were as follows 24 stitches along the 6cm datum length ie 4stitchescm Two lengths of binding twine used to complete the stitching Throughout the process of testing the different types of stitching gradually the least favourable variables were discovered and discarded from further testing A graph of all the different seizings and their respective altered variables is illustrated in figure 4 Sitiching type against efficiency 60 50 mean efficiecny 40 30 20 10 0 0 2 4 6 8 10 data set for stitching type Figure 4 Graph of different stitching methods and their respective efficiencies 10 Different colours represent the three different stitching types the alterations in position are with the changing variables applied to each stitching method An illustration of the final most efficient stitching method used for the rest of the testing is shown below in Figure 5 Figure 5Results of seizings created by different manufacturers The final seizing choice decided from the previous section was then used to test seizings created by different manufacturers This was carried out in order to determine whether the seizings created by different manufacturers yielded different efficiencies In order to carry out this test firstly a set of instructions were written and distributed to different users to manufacture the seizings Three different manufacturers created three seizings each these were then tested and compared to the users results The results from the testing of the seizings created by different manufacturers are shown in table 12 11 Manufacturer Seizing data set Average Standard Efficiency deviation User Author S025 to S030 480 183 from table 58 Subject 1 M001 to M003 478 350 Subject 2 M004 to M006 500 430 Subject 3 M007 to M009 481 362 Table 12From table 12 a graph shown in figure 6 was created to highlight and anydifferences between manufacturers 70 60 Mean Efficiency 50 40 30 20 10 0 0 1 2 3 4 5 Subje ct data se t Figure 6 Seizing efficiencies from different illustrated by the graph there is little difference between the results obtainedfrom the different manufacturers It should be mentioned that some of had no previous knowledge of constructing seizings while others didthe results indicate that this is not a significant factor 12 Results of Seizing Efficiency from altering stitching length The next variable to be altered was the length over which the rope was stitched With all previous experiments this length was kept constant at 6cm The stitching density remained constant at 4 stitches per centimetre whilst the length over which the rope was stitched was varied The various lengths tested and their corresponding efficiencies are shown in table 13 Stitching length Seizing data set Average Standard cm Efficiency deviation 4 16 stitches L011 to L012 394 214 6 24 stitches S025 to S030 480 183 8 32 stitches L001 to L003 511 154 10 40 stitches L004 to L006 633 626 12 48 stitches L007 to L009 599 712 14 56 stitches L013 to L015 688 372 Table 13A graph of stitching length against efficiency was then plotted shown in figure 7 Length efficiencies of seizings 80 70 Mean efficiency 60 50 40 30 20 10 0 0 2 4 6 8 10 12 14 16 Stitching length cm Figure 7 Stitching length compared to the seizing efficiency 13As illustrated by the graph in figure 7 increasing the stitching length of the increases the efficiency of the seizingResults of Seizing Efficiency from altering eye termination sizeThe final variable that was altered in order to establish whether it affects the was the size or length of the eye termination Several different eyetermination lengths were altered and tested The results for the efficiencies of eachdifferent eye length are shown in table 14Eye termination Seizing data set Average Standard length cm Efficiency deviation 10 E001 to E003 465 332 14 S025 to S030 480 183 16 E004 to E006 456 197 22 E007 to E009 457 166 30 E010 to E012 431 191 Table 14The results are plotted in graph to illustrate the eye termination length againstseizing efficiency in figure 8 14 Eye termination length efficiencies 60 50 Mean Efficiency 40 30 20 10 0 0 5 10 15 20 25 30 35 length of eye termination cm Figure 8 Length of eye termination against seizing efficiencyFrom the graph it is clear that altering the eye size of the diameter had very littleeffect on the seizing efficiencies From the results we can obtain that increasing theeye size may very slightly decrease the efficiency of the seizingSummary of ResultsThe alteration of the variables on the seizings so far yielded some definitive resultsand conclusions It was clear that the alteration of all the variables each affected the results in some way The values given in red in thetables were from the results of the datum stitching and variables decided It wasconcluded that the stitching length and number of stitches per centimetre applied tothe seizing altered the efficiency of the seizings most notably The other the efficiency but only very slightly Taking all the results into account afinal seizing was manufactured with the most favourable dimensions of the applied However in keeping with the objectives of this project the finalseizings were also manufactured for practicality and favourable size 15Final Seizing ChoiceTaking into account the results so far the following seizing dimensions were appliedand altered from the original datum seizing to manufacture the final seizing choiceNumber of stitches per centimetre 4Number of lengths of binding twine used in stitching 2Stitching length 10Eye termination length 10This seizing was then tested and the results are shown in table 15Seizing data set Average mean Standard efficiency Deviation F001 to F003 575 612 Table 15From the final set of results we can obtain that the average seizing efficiency was575 which is comparable to that of any eye termination formed by a weak knotIt should be mentioned that the highest efficiencies obtained for some of thevariables altered were not applied to this final choice seizing This was partly due tothe fact that the final seizing choice involved the manufacture of as small as seizingas possible 1660 ConclusionThe assessment of the strength of eye terminations created by seizings andwhippings throughout the course of this project was successfully carried outHowever not all areas of seizings and whippings were investigated thoroughly dueto time and resource limitations The emphasis of this project was on the analysis ofthe seizing types which was extensively carried outThe conclusions made from the results were made from analysis of all results andtrends indicated rather than directly comparing average values The most made was generally how much stronger the seizings proved than thewhipping method tested However it was also obvious that several factors influencethe strength of the seizing The most notable factors that were discovered to alter theseizings efficiency were the number of stitches and stitching length The othervariables altered had very little effect on the seizings efficiency if any thereforeany further testing on these parameters was deemed to be areas for investigation include expanding the current data sets on theeffective variables manufacture of seizings on different rope types and the modes relevant to seizings Another area considered during this process wasthe concept of building a testing rig to measure the forces acting on the there are still considerable areas to be investigated any further work mustbe applied relevantly This project has tried to provide the most important factorsthat affect the strength of seizings author would like to express his gratitude for the continual support andguidance throughout this project provided by his supervisor Dr AJ thanks are also due to Mr A Crockett for his continual help and this project in the set up and use of apparatus Thanks are also given toMr James Kelly who patiently assisted with the photography of the test should also be mentioned to the different subjects that helped contributed inthe manufacturing processes of this ISEA Sports Engineering volume 9 Article 1 KA Milne AJ Mclaren2 University of Strathclyde An assessment of the strength of knots andsplices used as eye terminations in a sailing environment Katherine Milne3 International Marine the Splicing Handbook second edition BarbaraMerry with John Darwin4 Adlard Coles Nautical Knots in Use third edition Colin Jarman5 18 Appendix AThe following equations for the standard deviation and the mean calculated for theresults are shown below with the relevant terms explainedTo calculate the sum for the data sets the following equation was usedN number of samples sum of the number of samplesX value associated with each sampleX numerical average value of samplesThe standard deviation is calculated using the following equationWhere the same symbols as used before have the same meaningS standard deviationx sample mean for each type of seizing or whipping type testedxi sample value for each individual test carried out in that specific data seti 1 the first of the values in the series of samples up to the last sample defined as NThe standard deviation was calculated for each different seizing types multiple tests were carried out to obtain the average and error 19
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