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Software Frequently Asked QuestionsPlease note that questions and answers below are relative to the latest version of Wolfson Unit MTIA software. To get the latest version of the programs please do the following: Click on the program name to download the appropriate installation(s). Contents
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General1.1 Can I use my parallel port dongle on a 64-bit machine? No, our parallel port dongles are not compatible with 64-bit machines. As a result, your licence(s) will not be detected and your Wolfson software will not run. Please contact the Wolfson Unit and request an upgrade to a USB dongle. 1.2 The installation of my Wolfson program causes an ‘Invalid Database. The installation will be stopped’ error. Our installation files require write access to a system directory in order to work correctly and anti-viruses such as F-Secure or AVG may prevent that. Disconnect your machine from the web, then switch off your anti-virus and/or firewall temporarily, including Windows Firewall, and run the installations again. Your Wolfson program should install correctly. DXFtoLFH2.1 When importing a set of splines, the program brings in the control points for the curves rather than the actual curves. The DXF to LFH translator is only concerned with line, polyline and arc entities to describe the sections of a ship or yacht. Spline entities are not dealt with as such, and only their control points are imported. A workaround consists in saving a file containing spline entities as an Autocad version 12 DXF. This can be done, for example, via Autocad and Rhinoceros. 2.2 When importing a set of sections, some are brought in as longitudinals. When importing a DXF file, the DXF to LFH translator will identify a line, polyline or arc entity as a section if any of the following conditions hold: the largest variance on X (max-min) is less than a user-defined threshold OR one or more points have a negative Y value. If any negative Y points exist, these can be removed via Tools, Delete Negative Y Points. See also FAQ 1.3 2.3 How does the ‘Largest Variance on X’ parameter work? The ‘Largest Variance on X’ parameter can be found in the Map Curves dialog and is used for setting the maximum variance in the longitudinal or X direction (post mapping) of a curve. If the foremost point of the curve and the aftermost point of the curve are ‘Largest Variance on X’ apart or less, the curve will be set as a section to output in the LFH file. This is useful if there is a slight variance in the X-values set in the DXF file. (N.B. The X-position of the section output in the LFH file is the X-position of the first point defined on the line). 2.4 When should I use the ‘Guess Mapping’ functionality? The ‘Guess Mapping’ option can be found in the Map Curves dialog. It looks at the variance of the X,Y and Z coordinates of the curves and guesses the best mapping function for the current set of curves. This functionality can be used after importing a set of DXF lines, if the coordinate system does not appear to be correct. Also, it should be used after geometry clean-ups, such as Tools, Remove Short Intervals to refresh the lines and the list of curves in the main window. HST3.1 Is the program verified by a third party? The program is not officially approved by any authority. However, our programs is currently used by the UK MCA (Ensign Division) for checking all third party stability submissions, we also have several other National Authorities as users of the programs, and one copy used by Lloyds Register. As far the Wolfson Unit is aware of, no submission from any of our almost 200 customers for Hydrostatic programs has been refused on the basis of the software itself. 3.2 How can I edit the X,Y,Z coordinates for a 3D sounding pipe ? While editing, if you view the sounding pipe in profile or plan (View->Profile/Plan menu item) then you will be able to edit the appropriate X,Z or X,Y information of the pipe respectively. 3.3 Can I customize the output of tank capacity calculations ? Yes, via the ‘Tank or Compartment Conditions’ dialog, Output tab. The Output Columns grid data specifies how the layout of the data is presented in the Main HST window. The first two output columns of sounding and capacity are constant and cannot be altered. The others columns can be edited appropriately. 3.4 Does HST take into account trim and heel when doing tank capacity calculations ? Yes, capacity calculations can be performed across a range of trim and heel angles. Trim and heel ranges can be set via the ‘Tank or Compartment Conditions’ dialog, Tank Capacities tab. The latter dialog allows to enter the coordinates of the base position for the sounding pipe. The tank capacity tables include Sounding Corrections (in cm) across the required range of trim and heel angles. 3.5 Is there a quick way to draw tanks having a circular section with a transverse (i.e. port/starboard) orientation? Yes, a transverse cylindrical tank can be generated as a bow thruster within a box. The latter is needed to define the port/starboard boundary of the cylindrical tank and should be deleted afterwards. 3.6 Can I calculate the effect of liquids in tanks over the full range of heel angles in HST ? Yes, use the Damage Stability option, with the displacement condition including tank content, and set the tank to have a Fixed Volume. The stability calculation then allows for the correct movement of the liquid at each heel angle and trim. 3.7 Is there a recommended digitiser to use with HST ? WE use a GTCO Calcomp Drawingboard VI, and run it using the GTCO Calcomp TabletWorks™ drivers, which should be provided with it and must be installed for a digitizing tablet to work. The direct link to download the drivers is http://www.gtcocalcomp.com/supportdigitizing.htm and click on the appropriate manufacturer and continue to the Driver and Software Downloads. 3.8 How do I draw a circular moonpool in HST ? For a simple cylindrical moonpool, follow the same approach you would use when drawing bow thrusters. The process is thoroughly described in the ‘Bow Thruster Hole’ topic in the HST online help. In order to generate the moonpool Volume Element, three sections should suffice, i.e. A-1, A and A+1. For a more complex shape, we would advise increasing the number of sections to give a more precise definition of the complex shape. More sections will usually give more accuracy. 3.9 Is there a shortcut to calculate the volume of an element which is part of the ship's hull ? Yes, there is. First, copy the element via Ctrl+C or Edit, Copy. This will bring up the ‘New Element’ dialog, where the element being copied should be set as a new compartment, say ‘newComp’. Secondly, calculate the volume of ‘newComp’ via Calc, Tank Capacities: the required volume will be shown as ‘Capacity as 100%’ in the Tank Capacity Data sheet. 3.10 Can I export a Results page to a Microsoft Excel spreadsheet ? Yes, right-click anywhere on the Results page and select the ‘Export to Excel’ option in the pop-up menu. The main output should be correctly imported as numeric, unless there is a default setting in your Excel set up. The ‘Export to Excel’ procedure has been tested on Excel versions up to 2007. 3.11 Can I fix geometry errors for an entire set of sections ? Yes, provided that the sections of the set are contiguous. First, go to the Edit Element dialog, left-hand side table, Description column, and left-click the first, i.e. aftermost section of the set. Then left-click the last, i.e. foremost section of the set while pressing the ‘Shift’ key: this will select the entire set. Finally, go Tools, Fix Errors and select the required option. All sections of the set will be fixed at once. 3.12 How can I prevent negative Bonjean curves ? A decreasing Z-order (i.e. deck to keel) for the points of a section results in the Bonjean curve for the section being negative. The solution is to fix this error via the Reverse Point Order option in the Edit Element dialog, Fix Errors menu. If Bonjean curves are negative across a range of sections, the process may be done just once: see HST FAQ 3.11. 3.13 In my HST Damage file some floodable compartments are shown in blue, others in black. Why is that ? HST Damage shows Floodable Compartments' sections in blue or black according to their parent element being the main Hull or a Compartment, as per Hull/Compartment definition in the Floodable Compartment dialog. If a Flooded Compartment derives from the main Hull, their sections are shown in blue. If the parent element of a Floodable Compartment is a compartment, its sections are shown in black. 3.14 In my Hydrostatics Report the Draught at Mid Marks and the Moulded Draught are very different for large trims. In general, one should not expect the Draught at Mid Marks and the Molded Draught necessarily to be the same. The Draught at Mid Marks is the input draught relative to the draught datum at mid marks, that is the value entered in the Hydrostatics & Stability dialog if the ‘Draught at Mid Marks, Trim Over Marks’ option is chosen. The Moulded Draught is the height of waterplane above Vertical Datum (Z=0) measured at X=0. Hence, the two draughts will be close if midships is used as longitudinal datum. However if X=0 is, for example, the longitudinal position of the Aft Marks, the Moulded Draught will be the vessel’s draught taken at Aft Marks. The difference between the two draughts will therefore be large for large trims. 3.15 How can I plot Bonjean curves ? Plotting Bonjean curves requires Wolfson Unit’s GoPlot program and a .dat file obtained from HST. A .dat file can be obtained as follows. In HST open the Edit Element window for the Element you require Bonjean curves of. In the Edit Element window select the ‘Hydrostatics to Draughts’ option in the File menu, then click View > Offsets and Hydrostatics. This launches the Hydrostatics Information results page which by default presents a table of sectional properties at zero trim and zero draught. The required draughts and trims can be set by clicking Edit > Draughts and Trims in the Results page. A Bonjean File (.dat) can now be saved by clicking Results > Save in the Results window. 3.16 My Stability Report shows a downflooding/margine line angle as ‘EXPOSED’. What does it mean ? A downflooding angle is ‘EXPOSED’ to starboard or port when the corresponding downflooding point never gets submerged as the ship heels from 0 to +180 degrees or 0 to -180 degrees respectively. This also applies to margin line points, in both intact and damage stability. For example, if a downflooding point on the starboard side of a vessel has a relatively low freeboard and the vessel itself has enough buoyancy above the downflooding point height, then it is likely to be ‘EXPOSED’ to port. 3.17 My vessel’s equilibrium list angle is zero. However, in the Intact Stability Report the waterline at zero degrees heel and the equilibrium draught do not agree. The two values do not necessarily match, as they may be calculated from different vertical datums depending on the vessel’s setup. Waterlines are measured from Z=0 whereas the equilibrium draught is measured from the draught marks datum line, ie line through the set draught marks. Please see an unmodified testhull file, where the two vertical datums coincide at mid marks. 3.18 As I change my vessel’s loading, waterline at zero degrees heel and equilibrium draught do not change by the same amount. The two values do not necessarily change by the same amount for a given loading variation, as they may be calculated at different longitudinal locations depending on the vessel’s setup. Waterlines are measured at X=0 whereas the equilibrium draught is measured at mid marks, so they would change the same amount only if the initial and final trim coincide or the Mid Marks X is 0. 3.19 My maximum KG calculation is very slow, can I make it faster? Select Conditions > Maximum KG and in the Options tab select ‘Calculate and Show only Summary for Conditions Results’. This option provides pass/fail results only and does not involve KG iterations. Should you require maximum KG results, then reduce the extent of the test matrix eg draught, trim and heel angle range. The latter option is particularly effective for catamarans. At large angles, at some stage during the iterations, a catamaran might be in the situation where only the bridge deck is at the waterline, with one hull submerged and the other out of the water. The low waterplane area will not be conducive to accurate iterations and might even prevent a solution being found. 3.20 I want to calculate Maximum KG on Loading Conditions. How do I enter wind heeling moments and heeling lever curves for criteria nos. 11-12-13-17-19-20? Go to the Conditions tab of the Maximum KG dialog and click the ‘Copy Loading Conditions’ button to copy the conditions set in the Weights and Loading window. You can then enter the relevant heeling moments and/or heeling lever curves for each condition. The program will use such data for calculating Maximum KG and Loading Stability Book for the Loading Condition(s) required. Hullscant4.1 What version of the ISO 12215 standard is used in the software ? The program is in accordance with the April 2008 publication (2008-04-15) of 12215 part 5. We have released updates after every version change of the standard, free of charge to existing customers. The version of the standard used within a given version of HullScant is listed in the Report section, as well as the About screen. If you need to update your existing copy, please go to our customer download area 4.2 Is the program verified by a third party ? The program has not gone through an official third party verification process and certification but it is endorsed by both the RYA (a notified body) and ISAF. 4.3 The Results report shows a bending moment. Is that the maximum value that the stiffener can support? Yes the ‘offered BM’ is the greatest BM the stiffener can support using the safety factors on materials as per the ISO standard. 4.4 Transverse and longitudinal stiffeners: do I have to specify a stiffener length as the gap between the crossing bonds ? It depends on the stiffener and what it is expected to support. Usually transverse stiffeners are fully supporting the panels either side. Refer to Section 9.2. of ISO12215:5 4.5 Scantling bulkheads: do I have to input a bulkhead as a beam, divide it into longitudinal frames, and define it with the local height ? Yes this is the method required. Refer to Section 9.2 of ISO12215:5 4.6 Is there a way to manually change the design pressure for a stiffener or panel ? No, there is no way to manually set the design pressure. This is calculated by Hullscant via Section 8 of ISO the Standard and is therefore an output of the program, not an input. All in all, the software should not be considered to be a design tool; it checks conformity to the ISO standard, which in turn is a ‘sizing rule’. i.e. no part of the standard should be used in isolation. 4.7 Does HullScant cover multihulls? No, HullScant currently only covers monohulls, as per Part 5 of the ISO 12215 standard. Part 7 of the ISO 12215 standard is currently (June 2009) deleted, and hence there is no standard upon which to base the software. LPP5.1 I need to create an offset file for the IMS VPP, however the export option in the LPP is greyed out. If you go to the ‘Sections’ menu, and then click on ‘calc IMS sections’, the IMS export options should become active. WinDesign6.1 Where is the rig positioned in the Vpp ? WinDesign does not attempt to calculate a longitudinal balance of forces, as it is primarily intended to predict optimum speed only, and attempting to find a longitudinal equilibrium makes that a lot harder. So there is no physical position set for the rig, and the program assumes that the boat is always in balance. 6.2 What is the effect of leeway in the Vpp ? Leeway is primarily an output from the Vpp, which is concerned with balancing the Aero and Hydrodynamic forces, and has only a second order effect on speed. Predicted leeway can be influenced by the optional trim tab or forward rudder angle settings, in the Flotation dialog’s Modelling tab. 6.3 The Vpp polar plots appear to be discontinuous, what should I do ? Yacht that have very flat righting arm curves, due to large offset weights from canting keels, water ballast, or significant hiking, can cause the program difficulty in converging to a solution. Normally, these type of boats should be sailed fairly upright, so there are two methods of improving the calculation’s convergence; firstly try artificially increasing the righting arm value at 40 degrees, in the flotation dialog, this kicks up the top end stability in a region that is unimportant to the solution, secondly try forcing the program to a maximum heel angle much lower than the normal, say 10 or 15 degrees, which you do in the Opset box. This removes the problem by not allowing the program to try and determine answers at unfeasibly high heel. 6.4 How does the multihull Vpp decide what heel angle to sail at ? There are two special angles to set on the Flotation page. ‘Hull clear’ is the angle at which the windward hull clears the water (canoe part only). ‘Flying’ is the maximum angle that you want to sail the boat at. 6.5 What happens if my opsets keep resetting ? With the affected yacht or yachts open in the VPP, go to File>New Race Committee. Select Blank or Sample, it doesn’t make a difference. Go up to Edit on the Race Committee menubar, and UNCHECK the Overide Individual Boats. The act of unchecking should propagate through the various open yachts and reset the wOverideBoats to FALSE. Then go ahead and Close the Race Committee, no need to save it. Now the max (or min) values the opsets can be changed, and the values of min and max Bt and Vt that are carried with any ocean courses will not override. GoPlot7.1 I´m trying to look at a plot of the active data, but the green markers identifying the active data are obscuring the plot, even if there are no symbols associated with the data. How do I remove these green markers ? The markers are specified to be 1mm bigger than that specified for the symbols (even if the type of symbol is specified to be ‘none’). Therefore, set the symbol size to -1 and the symbol line width to 1 in the ‘Series Properties’ dialog box and the green markers are reduced to a barely visible series of dots. Equally, a different value in the symbol size will change the green markers accordingly. Propeller Design Program8.1 My propellers are for a 13" diameter duct. The Kaplan data lists the series as 19, 24 and 37. Can the data be used on smaller propellers ? The nomenclature of the propeller files in the nozzle series is as follows:
In the KT-KQ-J charts, all of the data is dimensionless, with most test propellers in the region of 4"-6" diameter for example, and run at high revs so increasing Reynolds numbers to reasonable levels. We would be happy to recommend the program to design props at any size between 3” and 10 metres diameter. 8.2 Can you provide further information upon nozzle / duct shaping ? A number of differing nozzle designs have been developed by MARIN (MArine Research Institute, Netherlands) for unique thrust characteristics. MARIN Nozzle No. 37 has a rather thick trailing edge, while MARIN Nozzle No. 19A was crafted with a thinner trailing edge. Nos. 22 and 24 were designed with larger length-diameter ratios (0.8 and 1, respectively). Although all four of these nozzle types present a large improvement over a non-ducted propeller, the differences between them are relatively small and refined. Nozzles No. 19A, 22, and 24 are somewhat more efficient than No. 37. Power Prediction Program9.1 When using the Wolfson Catamaran model, is Base Data for the entire vessel or one demi-hull ? The base data is for one demi-hull, you can check your input by placing the cursor over the relevant input box and its description is displayed in the lower left corner of the program page. 9.2 How do I know exactly what to input into the entry fields ? Hover the mouse pointer over the entry field and details of the required input will appear at the bottom left hand corner of the program window. 9.3 How does the input propeller shaft angle in the Wolfson Unit methods (11, 12, 13, 14) affect the prediction of EHP/Resistance ? It doesn’t. The only influence that the shaft angle will have is in the prediction of propeller coefficients for use in propeller design calculations. If you want to make the program run and aren’t interested in the propeller coefficients then just enter a value between 7 and 14 degrees. |
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Wolfson Unit MTIA, Building 15/A, University of Southampton, Highfield, Southampton SO17 1BJ, UK Telephone: +44 (0)23 8058 5044 Fax: +44 (0)23 8059 7594 Email: wumtia@soton.ac.uk |