power prediction manual

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Version 15.01.2009 PACKAGE CONTENTS In addition to the manual there is either normally a CD-Rom supplied with this package. New users will be provided with a hardware key or Dongle for software protection. Version updates are available for download from the Wolfson Unit web site at www.wumtia.com on the Software page Customer Download Area. PROTECTION SYSTEM Single user option This program utilises a hardware key or DONGLE which fits into either the Printer or USB port of the computer, if using a printer port type, the printer lead then plugs into the back of the key. The individual programs check for the presence of this key. If it is not found, a warning is given, place the DONGLE in the port before continuing. Network option The network option is a version that provides network license protection using just one key. The network option works with TCP/IP networks. One computer on the network is designated the security server and will have the dongle connected to it. The server software VSSERVER is also installed on this computer. The VSSERVER is a windows application that should be installed on the machine designated as the security server. This machine does not have to be an actual network server but it must be running Windows 95, 98, ME, NT, 2000 or XP, have at least one parallel or USB port and be available for access by client machines. Run the VSSERVER Installation from the server directory. The required device drivers are automatically installed. Connect the hardware dongle key to the parallel or USB port and start the server by selecting it from the Start menu. The first time the server is run the server will attempt to start for a few seconds and then fail because it has not yet been setup. Click the Setup button and enter the server name or IP address, leave the port as 6666 and click Apply and Close. Now click the Retry to start server button which should successfully start the server. Dont worry about the message IP Security not loaded as this can be set up later if required. You can now click OK to place the Security server in the system tray. You can at any time double click the Security Server icon either to change the settings or to view the current status. The hardware drivers are also required by your client computers to enable communication with the security server. On each server computer run the driver install program Sl2inst.exe on the disk provided. Click the Install button to copy the appropriate device driver file for the operating system and add the registry entries. Click the Uninstall button to remove the drivers. A command line version drvinst.exe can also be found in the install folder. Type drvinst install to install and drvinst uninstall to remove the drivers. If you move either of these programs to a different directory ensure to copy both of the driver files windrvr.vxd and windrvr.sys and also wdrvr.dll to the same directory. On each client computer the port and IP address of the license server needs to be set. Nsl2set.exe is a windows program that can be used to set the server address and port. setnet.exe is a windows command line version of nsl2set.exe. Type setnet.exe address port where address is the server name or IP address and port (optional) is the port required (defaults to 6666 if not entered).

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CONTENTS Page No CONFIGURING THE SYSTEM .............................................................................. 1 INTRODUCTION .................................................................................................... 1 PROCESS DESCRIPTION ...................................................................................... 2 GETTING STARTED ............................................................................................. 5 PROGRAM REFERENCE ..................................................................................... 10 General controls ........................................................................................ 10 Display pages ........................................................................................... 12 Dialog boxes ............................................................................................. 15 Menus....................................................................................................... 17 Toolbar ..................................................................................................... 24 POWER PREDICTION GUIDE ............................................................................. 25 GLOSSARY ........................................................................................................... 49 ERROR MESSAGES ............................................................................................. 52 APPENDIX I References ........................................................................... 53 APPENDIX II File Formats.......................................................................... 54 INDEX ................................................................................................................... 58

Power Prediction WOLFSON UNIT FOR MARINE TECHNOLOGY AND INDUSTRIAL AERODYNAMICS

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1.0 CONFIGURING THE SYSTEM Configuration of the system is performed by a file on the program disc entitled SETUP.EXE. Before undertaking the configuration however, take a backup copy of the disc supplied, and then follow this procedure with the backup copy :- A. Place the program disc in CD drive, or download the installation file. B. From the File Manager run SETUP. C. Follow the installation prompts. The sub-directory onto which the program will be installed

defaults to C:\Program Files\Wolfson\Props, and the Windows group file defaults to Wolfson. These may be changed if required.

D. The installation will automatically add a device driver required for correct operation of the protection system. Windows will need to be restarted in order for it to take effect.

The program may then be run from the program manager as normal. 2.0 INTRODUCTION This manual describes a program enabling ship and small craft power predictions to be performed, using standard series data. It is assumed that the user has a basic knowledge of the machine and the operation of programs under Windows. The method used to calculate the resistance of the ship depends upon the type of vessel. Ship forms Merchant ships, single or twin screw Tugs & Trawlers BSRA methodical series High speed forms NPL round bilge Series 64 round bilge SSPA round bilge Davidson Regression, round bilge/chine Savitsky planing hulls Wolfson Unit hard chine

Wolfson Unit round bilge Wolfson Unit catamaran Wolfson Unit high speed

Sailing yacht forms Delft Series The program can calculate the effect of a wide range of appendages and the effect of systematic changes in up to ten hull form parameters. In addition to calculating the resistance and EHP, the program also calculates the propulsive coefficients for each speed. Each method has valid ranges, for speed, length/beam ratio etc. The parameters (e.g. Length) used to define the ship, vary between methods.


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3.0 PROCESS DESCRIPTION The program has a Base definition of a vessel, comprising various of its parameters. Appendages can be defined, and included within the base data, or left for later use when comparing other results against the base. The Cases option creates secondary definitions of the vessel with alternative parameter data. The general flow of program use is to create the basis ship and define any appendages and set up any cases required. The speeds over which the calculations are performed are then selected. Once all the data have been entered they can be checked for validity and the calculations performed. All the data relating to a ship can be loaded from or saved to disc. Once the calculation is complete the results may be stored for future use, shown on the screen as tables or graphs or sent to a printer. If the Wolfson Units GOPlot plotting program is available, data may also be sent to that in order to produce report style plots. Available methods of calculation: Single Screw Ships This analysis is based upon work published by J. Holtrop and G. Mennen [Refs. 1,2,3]. The method was developed through a regression analysis of random model and full-scale data obtained by the Netherlands Ship Model Basin. It uses a wide range of hull parameters from which to calculate calm water resistance and Effective Horsepower of single screw merchant ships in the Froude number range 0.16 - 0.45. In addition to calculating the resistance and EHP, this method also calculates the propulsive coefficients for each of the speeds. Twin Screw Ships This analysis is based upon work published by J. Holtrop and G. Mennen [Refs. 1,2,3]. The method was developed through a regression analysis of random model and full-scale data obtained by the Netherlands Ship Model Basin. It uses a wide range of hull parameters from which to calculate calm water resistance and Effective Horsepower of twin screw merchant ships in the Froude number range 0.16 - 0.45. In addition to calculating the resistance and EHP, this method also calculates the propulsive coefficients for each of the speeds. Tugs and Trawlers Method This analysis is based upon work published by G. van Oortmerssen [Ref. 4]. The method was developed through a regression analysis of data from 93 models of tugs and trawlers obtained by the Netherlands Ship Model Basin. It uses a wide range of parameters from which to calculate calm water resistance and Effective Horsepower of tugs and trawler forms in the Froude number range 0.1 - 0.5. In addition to calculating the resistance and EHP, this method also calculates the propulsive coefficients for each of the speeds.


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BSRA Method This analysis is based upon work published by M. Parker [Ref. 5] and a regression analysis reported by A. Sabit [Ref. 6]. The method was developed through an analysis of the BSRA Methodical Series data. It uses a wide range of hull parameters from which to calculate calm water resistance and Effective Horsepower in the Froude number range of 0.15 - 0.24. In addition to calculating the resistance and EHP, this method also calculates the propulsive coefficients for each of the speeds. NPL Round Bilge Craft This analysis is based upon work presented by D. Bailey [Ref. 7]. This method was developed from a large database and consists of an interpolation of the residuary resistance of a vessel over a wide range of Froude numbers, for different length/displacement and length/beam ratios. An ITTC 1957 frictional coefficient is calculated and the total resistance and Effective Horsepower computed, for high speed round bilge hull forms in the Froude number range 0.24 - 1.22. In addition to calculating the resistance and EHP, this method also calculates the propulsive coefficients for each of the speeds. Series 64 This analysis is based upon work published by H. Yeh [Ref. 8]. It uses a wide range of hull parameters from which to calculate calm water resistance and Effective Horsepower, this method also calculates the propulsive coefficients for each of the speeds. SSPA Series This analysis is based upon work published by H. Lindgren and A. Williams [Ref. 9]. It considers a wide range of hull parameters from which to calculate calm water resistance and Effective Horsepower, this method also calculates the propulsive coefficients for each of the speeds. Davidson Regression for Round Bilge and Planing Craft This analysis is based upon work published by J. Mercier and D. Savitsky [Ref. 10]. The report presents a 14 term regression equation for specific resistance based on five hull parameters: length/displacement ratio, beam loading, half angle of entry, LCB at rest and the ratio of immersed transom area to maximum section area. The equation was derived from 7 model series tests, one of which was a hard chine form, from which is calculated the calm water resistance and Effective Horsepower, this method also calculates the propulsive coefficients for each of the speeds. Savitsky Planing Prediction This routine is based upon a computational procedure presented by D. Savitsky [Ref. 11]. The calculations are based upon hydrodynamic planing equations describing lift, drag, wetted area, centre of pressure and trim, as a function of speed, deadrise and loading. An equilibrium trim condition is determined allowing the calculation of horsepower, wetted length and porpoising stability. The program incorporates an extra iteration loop to allow for reducing beam at high speeds.


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Delft Systematic Yacht Hull Series This series is a regression of 40 hull form variations of sailing yacht hulls, presented papers by J. Gerritsma et al [Ref. 12], and J. A. Keuning et al [Ref. 13]. The revised regression of [Ref. 13] is used in order to calculate the upright residuary resistance of a yacht canoe body, to which frictional resistance for an entered or calculated wetted area is added. The effects of keels, bulbs and rudders can be added via the standard appendage options. Wolfson Unit Chine Craft This series is a regression of 66 hard chine models tested at the Wolfson Unit since 1968, by Robinson [Ref. 16]. The regression calculates a comparative performance coefficient over a range of volume Froude numbers, up to 3.0, which is then faired and used to obtain the vessels total resistance. The data are all taken from test models which have been optimised for trim, either by positioning the LCG, or by trim tabs or wedges. The effects of varying wetted surface area with speed are automatically taken into account. In order to allow for surface roughness, a separate regression of wetted are against speed is made. Wolfson Unit Round Bilge This series is a regression of 30 round bilge models tested at the Wolfson Unit since 1968, by Robinson [Ref. 16]. The regression calculates a comparative performance coefficient over a range of volume Froude numbers, up to 2.75, which is then faired and used to obtain the vessels total resistance. The data are all taken from test models which have been optimised for trim, either by positioning the LCG, or by trim tabs or wedges. The effects of varying wetted surface area with speed are automatically taken into account. In order to allow for surface roughness, a separate regression of wetted are against speed is made. Wolfson Unit Catamaran This series is a regression of 13 parametric variants of round bilge semi-displacement demi-hulled catamarans, tested in the University of Southampton, and described in Molland et al [Ref. 14]. The regression calculates the residuary resistance, and interference factors, over a range of Froude numbers, up to 1.0, for varying length-displacement, length-beam, and hull spacing ratios. The model tests were performed on demi-hulls of the NPL round-bilge series, extended to high length-displacement and length-beam ratios. Wolfson Unit High Speed Hulls This series is a regression of 41 hard chine models tested at the Wolfson Unit since 1999, unpublished. The regression is similar to the original hard chine methods, but the hulls have been chosen to allow calculations up to volume Froude numbers of 5.0, which is then faired and used to obtain the vessels total resistance. The data are all taken from test models which have been optimised for trim, either by positioning the LCG, or by trim tabs or wedges. The effects of varying wetted surface area with speed are automatically taken into account. In order to allow for surface roughness, a separate regression of wetted are against speed is made.


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4.0 GETTING STARTED 4.1 The main screen The screen is divided into four main areas, a menu, a toolbar, a tabbed notebook and a status line: -

Menu - commands etc. Toolbar - quick commands Tabbed notebook - data area Status line - hints

The Menu allows access to a variety of commands for loading and saving data to files, editing information, printing, setting graphics options, and obtaining on-line help. The Toolbar contains icons, which carry out the more common commands such as loading in data. Each icon displays a hint, showing its use, when the mouse cursor is placed over it. All of the data entry and editing, as well as the display of results, occurs in the Tabbed Notebook area, which is split into five pages. Clicking the mouse on the titled tabs, or selecting the page in the Window menu item, changes the page: - 1. Hull page. This page contains the main data concerning the vessel form, the selection of calculation

method, and the speed range. 2. Results page. This page contains the results of the most recently performed calculations. 3. Appendages page. This page allows appendages to be selected from a list of available types, and

defined for inclusion in the calculation. 4. Cases page. This page allows multiple sets of calculations to be defined based upon variations of

the hull and appendage characteristics. 5. Report page. The results of calculations may be copied to the report page, which can then be edited

and printed. The Status Line indicates the function of the various data fields in the notebook area when the mouse cursor is placed over them. If the programs display is maximised, to fill the entire screen, all of the items in the tabbed notebook area are rescaled. The main window may not be resized below its initial value, but dragging with the mouse may increase its boundaries.


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4.2 Preparing file locations Before running calculations, the program can be configured in order to operate with the Wolfson Unit GOPlot graphics program, and also to specify where the temporary results file should be saved. This is especially important in terms of programs operating on network drives, where file permissions may not allow file saving. From the File menu, select the Set up File links option, which displays the File Setup dialog. To specify any of the three fields, click on the appropriate Browse button. The three fields are:- Location of GOPlot Navigate to the GOPLOT.EXE file, if present Graphics Template Navigate to a GoPlot file to be used as a template for the results Results file Navigate to a folder for storing the temporary file created at each run Report logo Navigate to a JPEG file used as am optional logo in the HTML Report

4.3 A simple calculation In this first example the most basic calculations are made for a vessel with no appendages. Start the program, and then: - a) Set the Calculation method to type 5 (NPL Round Bilge Craft), and enter the following values.

Highlight the Length field and enter 20 then use the tab key to move through the required fields:- Base Data Coefficients Speed Length 20 Prop angle 10 First 10 Beam 5 Last 20 Displacement 20 Increment 1 LCB -7 Wetted area 0


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b) Click on the Calculate button. The program will display an error message, showing that the data

are not within the legal range for the calculation method. c) Click the OK button and alter the displacement value to 50 and click the Calculate icon in the

toolbar. The program will perform a calculation and switch to the Results page:- The calculated results will appear in the grid. The resistance, effective power, wake fraction, thrust deduction and rotative and hull efficiencies are calculated at each speed. To view a graph of the effective power, highlight a cell in the EHP column by clicking on it, then either select the Edit option from the main menu, or use the right mouse button to display the pop-up menu, and then select Show graph. This is the most basic form of calculation. Before continuing use the pop-up or Edit Menu and select Copy to Report, then click the report page tab and confirm that the results are displayed there. The text shown may be edited, copied to the clipboard for inclusion in another document, or printed directly by choosing the File|Print option or clicking the Print icon in the toolbar 4.4 Adding an appendage The program allows the user to investigate the effect of appendages on the resistance. In this case, two rudders will be added to the definition. a) Click the Appendages tab on the main tabbed notebook. The available appendage types are shown

in a list box on the right hand side of the screen. Either click them once to highlight and click the


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Return to the Results page. As a change to the vessel has occurred and new data not yet calculated the table of results is removed from the display. Click on the Calculate icon to display the revised calculation. The resistance at 20 knots should have increased from 46.13 kN to 47.04 kN. 4.5 Comparing cases The two sets of data calculated so far show that small differences in the definition of the hull make a difference in the resistance. However, rather than calculating the two results individually and comparing the results from one print out with another it is more convenient to calculate both conditions together and make a direct comparison on-screen. This is what the Cases option allows. Any one, or a combination of, defined parameters may be varied and all of the resistance calculations performed together and compared with the Base value set up on the main Hull page. a) First move back to the Appendages page, highlight the Control Surface in the defined appendages

list, and then turn off the Rudders definition by unchecking the On box. This ensures that the base calculation will not include an allowance for the rudders.

b) Move to the Cases page and either highlight the appendages parameter and use the Edit|Add

Parameter menu option, or double click on the word Appendages in the Parameters list. c) Either select the Edit|Add Case option, or use the pop-up menu to select its Add Case, to create a

new case for calculation and then double click the data field in the Case 1 row under the Appendages column. A dialog box will be displayed which lists the defined appendages and allows each to be set On or Off in the calculation. Click the On/Off box to select the rudders, then click OK. The Case 1 Appendages field should display a 1.


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d) The case is now set up. Return to the Results page and click the Calculate icon. This time two of the tabs in the output area will be available to view, the Base data and the Case 1 data. Switch between the two by clicking on the notebook tabs. To see the effect of the rudders view the graph by taking the Edit|Show graph option:-

Up to ten cases can be set up, allowing variation of any of the parameters used in the calculations. These can be used to see the effect of roughness, appendages, or parametric variation in the base parameters. 4.6 Send to GOPlot Once data are calculated, if the Wolfson Units GOPlot program is available, data can be sent to it for creating a more versatile graph for presentation. From the Results Page Edit menu or pop-up menu, select the Send to GOPlot option, and select the cases required for sending via the clipboard:- The program can launch GOPlot automatically by selecting the Launch GOPlot option prior to clicking on OK. 4.7 Review the Report Finally, an HTML formatted report listing the results of the last set of calculations can be viewed in the Report Page. Click on the tab to view this.


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5.0 PROGRAM REFERENCE The program operates by means of the normal Windows screen controls and menus as well as some special features. 5.1 General controls Menus operate in the standard Windows way. Click on a menu item, or press the appropriate hot-key option (the Alt key and underlined letter), or press the Enter key when the menu item is highlighted, and either a further drop down menu opens, or the menu command is performed. Pressing the Alt key on its own toggles the program focus to/from the main menu line. When a drop down menu is displayed the up and down keys move through the list, otherwise use the left and right arrow keys to move between items. The toolbar consists of various small icons, located below the main menu line. To operate a toolbar command click the mouse button when the pointer is located over the icon. Each toolbar icon displays a hint message if the pointer is left over it for a short while. The main area of the screen window is taken up by a Tabbed notebook, see below. The notebook is split into four pages, each containing its own set of controls. As a page is displayed the menu and toolbars change as necessary. Within each of the notebook pages the program uses a variety of controls: - 1. Tabbed notebook. A screen control which displays multiple pages, each of which can contain

other controls. Each page is identified by a tab, which contains the page name as an identifier, e.g. Hull, Results, Appendages, Cases and Report. To change pages click the mouse button when the pointer is over one of the tabs. If a tab is already highlighted, i.e. the notebook itself has the programs focus, the left and right arrows can also be used to change pages.

2. Edit box. A box on the screen which can contain a line of text. The text can be modified

by giving the box the focus, i.e. highlighting it with the mouse, or by using the tab key until the content is highlighted.

3. Selection box. A box on the screen which contains one of a number of choices. To the right

of the box is a downward pointing arrow, clicking on the arrow opens up a drop down list of the text associated with each choice. Scroll down the list and highlight the required value, then click the mouse button. The list is removed and the box content changed to show the chosen item. If the box has focus the option can also be changed using the arrow keys.

4. Check box. A small box, with associated text, used to toggle an option on or off. The box,

containing a check mark, shows the state of the option. An X or tick, indicates that the option is selected. To change the option click the mouse button when the pointer is over the box.


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5. String grid. A matrix of strings drawn in a grid. Each string occupies a cell in the grid.

Cells shown in grey are not available for editing and show headings, e.g. Speed, or calculated values. To alter a value highlight the cell by pressing the mouse button with the pointer located over the cell position. If a cell is already highlighted use the up, down, left or right keys to move the highlight to the required cell. Once the correct cell is highlighted the new value can be typed, or the old one edited.

6. List Box. List boxes, hold a set of text strings e.g. appendage types, which are fixed. If

the number of strings is too large for the space provided, then a vertical scroll bar is shown within the box and can be moved with the mouse to scroll the box contents. If the box has focus, the up and down keys can move the selection to a different line, otherwise a line may be selected by placing the mouse pointer over it and pressing the button.

7. Button. Buttons are used to initiate specific commands. To press a button, locate the

pointer over the button and press the mouse button. Alternatively the Enter key will operate a button if the button has focus, usually the button will form part of a tab sequence and will receive focus by repetitively pressing the tab key. Buttons can also be operated with a hot-key sequence of the Alt key and their underlined letter.

8. Browser. A browser is an area of the screen which can contain HTML formatted text,

e.g. the Report Page. Browsers can contain many lines of text, with variable lengths, tables, and images, and the scroll bars allow different parts of the memo to be displayed in the available space.

The Hull page contains the edit boxes used to enter and edit the various data values required for the calculation, e.g. the Length. The program checks to see that the characters form a valid number before calculating, if non numeric characters are found an error message is displayed and the program requests that the values is corrected. There are also selection boxes for the calculation method, units, and data checks. The Results page is taken up by a further tabbed notebook containing eleven pages, each with a string grid to contain a set of calculated resistance data. When there are no calculated values available the notebook is hidden. Following a successful calculation, the notebook tabs that contain data are displayed with the case number. The Appendages page displays the list of available and defined appendages, and allows them to be selected, de-selected and edited. The Appendage page and associated pop-up menu serve two purposes. Firstly, they allow appendages to be added or removed from Standard types or from User Defined types. Secondly, they allow User Defined types to be created from combinations of the Standard types. The Case page displays a table of the defined cases, and the values of the parameters to be used in their calculation. Parameters may be added to or removed from the list, and new cases created. The output from the program is stored on the Report page, which consists of a browser. The content can be printed or copied to the clipboard or other program.


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5.2 Display pages

5.2.1 Hull Page The hull page is used to describe the vessel geometry and the calculation type to be used. The required speed range is also set on this page. It contains the following elements: - Heading A general heading for the data used in the current file is entered in the

heading edit box. Calculation method

A selection box for choosing the calculation method. The methods and their description are detailed in the Power Prediction Guide.

Checking A selection box for choosing the level of data checking. Input data are checked for validity before running a calculation. Boundary errors occur when the program finds that the input values set fall outside the boundaries of the calculation method. There are two types; range, where the program checks that an individual parameter such as CB or L/B, lies within the allowable range of values, and envelope, where certain of the calculation methods are only applicable to combinations of parameter ranges which form an envelope of acceptable values. Altering the selection in the Checking box can set the level of checking. Strict will only allow a calculation to proceed if both the range and envelope are valid. Free only checks for the range. None does no checking. If checking is not strict then the program includes a warning message in the Report, and on the Results page.

Units

A selection box used to choose the units, either metric or imperial.

Roughness

The hull roughness allowance. If the number entered is less than 1.0 then it is used as an addition to the calculated skin friction coefficient (Cf), e.g. 0.0004. Alternatively if a number greater that 1.0 is entered then this is used as a multiplication factor for Cf, and so can be used as a form factor term e.g. 1.1.

Vessel Data

This is split into three groups, the contents of which alter depending upon which calculation method is employed. For a full description of each item, including units, see the Design Guide.

Base Data (Depending upon method) Length The length (waterline or overall) of the vessel. Beam The beam (extreme or waterline) of the vessel. Draught The maximum draught of the vessel excluding appendages. Displacement The weight of the vessel. LCB The longitudinal centre of buoyancy as a percentage of the length. Wetted Area The wetted surface area at rest excluding appendages.


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Coefficients

Cp The prismatic coefficient. Cw The waterline coefficient Prop Diam The diameter of the vessels propellers. Pitch/diam The ratio of the propeller pitch to its diameter. BAR The propellers blade area ratio. Trim The vessels trim, expressed as a draught difference. Prop angle The angle which the propeller line makes with the buttock line. VCG The vertical centre of gravity. Thrust arm The perpendicular distance from VCG to the propeller shaft line. Deadrise (Sav) The average deadrise angle of the vessel's planing surface. Deadrise (Wolf) The deadrise angle at the transom. LCF The longitudinal centre of flotation.

Special Bulb Ht The height of the centre of cross sectional area of the bulbous bow. Bulb area The transverse cross sectional area of the vessel's bulbous bow. Transom area The area of the transom immersed when stationary. Shape factor A coefficient relating the shape of the vessel's afterbody. Half angle The half angle of entrance at the forward end of the waterline. T/Amax The ratio of the area of the transom to the maximum section.

Speed These data set the speed range required for calculation.

First The first speed for calculation. Last The last speed for calculation. Increment The increment between speeds

5.2.2 Results page The Results page holds the latest results of a calculation. If input values have been altered, the tables cannot be viewed until another calculation is performed. Once valid data are available for viewing, a tabbed notebook is displayed, with the results of the base calculation and any valid cases. To view a case, click on the appropriate notebook tab. The results displayed may be viewed as a graph, or sent to the Report page, using the Edit menu, or pop-up, and new speeds can be added to the list. The available range of speeds is shown at the top of the page, together with any calculated quantity such as wetted area.


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5.2.3 Appendages Page The Appendages page displays the list of available and defined appendages, and allows them to be selected, de-selected and edited. User Defined appendages are combinations of standard types which, when grouped together, define a new appendage, e.g. a P Bracket can be defined as a combination of a control surface, the strut, and a cylinder, the boss. The Appendages page and associated pop-up menu serve two purposes. Firstly, they allow appendages to be added or removed from the definition. Secondly, they allow User Defined types to be created from combinations of the Standard types. The page is divided into three regions: - On the right is a list of the Available Types, i.e. the standard and any user-defined appendage types. In the middle of the page is a list of the Appendages Defined, i.e. those currently associated with the hull. Initially this list is empty. The left-hand portion of the screen is reserved for details of individual appendages. When one of the defined appendages is selected in the Appendages Defined list box, a set of edit boxes showing its parameters is displayed, and values may be entered or edited as required. At the bottom of these a check box is shown allowing the appendage to be automatically included in the calculations, or left unused in the base calculation but available for use in the Cases. When a User Defined appendage is selected, a further list box is displayed below the Appendages Defined box, allowing selection of the individual parts of the appendage. 5.2.4 Cases Page The Case page displays a table of the defined cases, and the values of the parameters to be used in their calculation. Parameters may be added to or removed from the list, and new cases created. The edit cases screen is divided into two regions: On the right is a list of the parameters required for defining the base vessel, which is defined by the calculation method. The rest of the page is a taken up by a table of case conditions, initially empty. To add a parameter to the table either double click the parameter in the list, or highlight it and take the Add Parameter option in the Edit or Pop-Up menus. To remove a parameter from the table, select the appropriate column and take the Delete parameter option in the Edit or pop-up menus. To add a new case take the Add Case option in the Edit or pop-up menus. The parameter values for the new case will be taken initially from the base vessel definition, i.e. that set on the Hull page. To remove a case select the appropriate row in the table and take the Delete Case option from the Edit or Pop-Up menus. To edit the values of parameters in the case table, select the appropriate column and row and type a new value. If the parameter selected is the number of appendages, a special dialog box is displayed, allowing the defined appendages to be selected for inclusion in the calculation or ignored.


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5.2.5 Report Page The report page is a means of viewing and printing the Power Prediction Program results. The report page always holds the results of the last performed calculation. The page can optionally include the input definition, appendage definition, and graphs of EHP and resistance. The document can be printed, or copied from the report page to the clipboard for inclusion in other programs.

5.2.6 Output Window The output window is a means of viewing and printing the results graphically. It is activated from the Results Page menu or pop-up. The output graph can be altered using the File|Plot Options command on the windows menu bar and then printed or stored.

5.3 Dialog boxes

5.3.1 Set File Links Dialog The dialog is used to locate the GOPlot program and a graphics template file, if available, and also to set the location for the temporary results file, created at each calculation.

5.3.2 Send to GOPlot dialog This dialog allows the user to specify which calculated cases to send to GOPlot via the clipboard. Check the required cases, and click OK. Optionally, check the box to launch GOPlot.

5.3.3 About Dialog The About Dialog indicates the Power Prediction Program version. Click on the dialog to close it.

5.3.4 Plot Options Dialog The Plot Options Dialog is used to set-up the way in which graph plots are presented on the Output Window. It contains the following controls: - Font button Used to specify the font on the particular graph plot. The font button

activates the standard Font Dialog. Margin edit box

Sets the margin on the page around the graph plot as a percentage of the width.

Tick length edit box

Sets the tick length on the axes as a percentage of the total graph size.

XY Squares

These edit boxes set the maximum number of ticks along the x-axis and y-axis respectively.


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Show all A check box determining whether to show the results of all defined cases, or just the data relating to the case selected on the Results page.

Show colour

The curves are normally displayed in black, with the curve for the selected case shown in red. Unchecking this box results in all of the curves being shown in black, but with the non-selected results drawn with a dotted line, which may help the clarity of printed output.

OK button

Closes the dialog and effects the changes.

5.3.5 Add User Type Dialog This dialog is used when creating new user type appendages. The dialog contains the following elements: Available types A list of appendage types, which can be used to create a user type. Add

parts to the definition either by double clicking on the required types in the list box or by highlighting and clicking on the


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5.4 Menus The Menu changes with the notebook page that is selected: - All Pages File Menu Window Menu Help menu New Propeller Design... Contents Open Hull Topic search Save Results How to use help Save as Appendages About Exit Cases Report Toolbar All Pages|File Menu

New . The New command creates a new blank power prediction file in the

program. If a set of data already exists, or a file has been read into the program and changes have occurred, a prompt will appear asking if you want to save any changes to the current working file. This command can also be accessed via the New Button on the File Toolbar

Open

The Open command activates the Open Dialog to load a new power prediction file into the program. If data exist in the program a prompt will appear asking if you want to save any changes to the current working file. This command can also be accessed via the Open Button on the File Toolbar.

Save

The Save command stores the current values in the program to a file. If the file has not been saved before the command activates the Save Dialog and prompts the user for a file name. This command can also be accessed via the Save Button on the File Toolbar.

Save As

The Save As command stores the current working power prediction to a file. The command activates the Save As Dialog and prompts the user for a file name.

Exit

The Exit command is used for exiting the Power Prediction Program. If data exist in the program, or changes have occurred, a prompt will appear asking to save any changes to the current working file. As the program closes the current data are stored in a file called Lastone.ppf.


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All pages|Window menu Run Propeller Design

Initiates a copy of the Propeller Design Program. This feature only works if you have a copy of the Windows version of Propeller design. You can transfer the calculated Resistance data into the Propeller program via the clipboard. Once a resistance calculation has been performed use the Copy to Clipboard option from the Results Page, then run the Propeller Design program and use its EHP Data Page Paste from Clipboard method

Hull

The Hull command activates the main Hull Page.

Results

The Results command activates the Results Page.

Appendages

The Appendages command activates the Appendages Page.

Cases

The Propeller command activates the Cases Page.

Report

The Report command activates the Report Page.

Toolbar

Toggles the Toolbar on and off.

All pages|Help menu Contents The Contents command activates help at the index page. Topic Search

The Topic Search command activates the help topic search.

How to use

Activates Windows How to Use Help function.

About

The About command activates the About Dialog.

Hull Page Set up file links Calc

Hull page|File menu Set up file links Opens a dialog that allow the program to locate the GoPlot source file, and

any template, as well as setting the location for temporary results files.

Hull page|Calc menu Calc Run the calculation as set on the page.


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Results Page (There is also a popup menu that is activated by the right mouse button when the cursor is located over the Results notebook.) File Menu Edit Menu & Popup

Save EHP data Insert row Set up file links Delete row Copy EHP to clipboard Show graph Send to GOPlot

Results page|File menu Save EHP Data The Load EHP command loads an EHP curve into the Propeller Design

Program. The command activates the Open Dialog.

Set up File links Opens a dialog that allow the program to locate the GoPlot source file, and any template, as well as setting the location for temporary results files.

Results page|Edit menu Insert row The Insert Row command inserts a new speed above the cursor on the

Results Page. This option brings up the Add Speed Dialog. Delete row

The Delete Row command deletes the line that currently has the cursor focus on the Results Page.

Copy EHP to clipboard

The Paste to clipboard command allows the transfer Speed/Resistance data to other applications via the clipboard. This option is the quickest way to transfer calculated resistance and propulsion data to the Windows version of the Propeller Design Program, which can then be run directly from the menu.

Show graph

The Show graph command creates a line graph of data and opens the Output Window to display it. The graph displays the currently selected column in the results table against the speed. Data from all of the defined cases are shown, with the line for the selected case highlighted, to show only the selected case data use the Plot Options command.

Send to GOPlot

Allows data to be sent to the Wolfson Units GOPlot general purpose plotting program, if available. Cases to be sent can be specified by checking the appropriate boxes in the dialog box. Data are then prepared and sent to the clipboard in an appropriate format. GOPlot can be started automatically by checking the Launch GOPlot option. If GOPlot is available the HullPage|File option Set up file links can be used to store the location of GOPlot itself, and any required template file.


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Appendages Page (There is also a popup menu which is activated by the right mouse button.) File Menu Edit Menu & Popup Menu Load Appendages Add Usertype Save Appendages Delete Usertype

Appendages Page|File menu Load Appendages The Load Appendages command loads a previously saved set of

appendage definitions into the program. See Appendage Files in Appendix II for further information.

Save Appendages The Save Appendages command saves the defined set of appendages to a

file, allowing for their use in subsequent calculations. The data saved includes information about any currently defined user types. See Appendage Files for further information.

Appendages Page|Edit menu Add Usertype This option allows for the definition of a new User Defined appendage

type. The User Appendage Dialog box is displayed which allows standard appendage types to be added to or removed from the user type definition.

Delete Usertype This option removes the highlighted definition of a User Defined

appendage from the list of available appendages.


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Cases Page (There is also a popup menu that is activated by the right mouse button when the cursor is over the Cases table.) Edit Menu & Pop Up Menu

Add parameter Delete parameter Add Case Delete Case Clear All Edit Appendages

Cases Page|Edit Menu Add parameter Adds the currently highlighted calculation parameter to the table of Cases.

The base value of the parameter is initially selected for all defined cases. Delete parameter Removes the currently highlighted parameter column from the table of

Cases. Add Case Adds a new Case into the table. The base values of the selected parameters

are initially selected for the new case. Delete Case Deletes the currently highlighted Case from the table. Clear All Removes all parameters and Cases from the table. The program prompts

before deletion. Edit Appendages Allows the user to set the number of the defined appendages, which will be

included in the Cases. A special dialog box is displayed, allowing the defined appendages to be selected for inclusion in the calculation or ignored.


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Report Page File menu Edit menu

Set up File links Font Show logo Show borders Include input Include appendages Include graphs

Report Page|File Menu Set up File links Opens a dialog that allow the program to locate the GoPlot source file, and

any template, as well as setting the location for temporary results files.

Report Page|Edit Menu Font The font command activates the Font Dialog. The font chosen in the dialog

then becomes the font that is presented in the Report Page only Fixed Pitch fonts may be selected

Show logo This option turns ON or OFF the display of a graphics JPEG logo in the HTML report. Clicking on it checks or un-checks the option.

Show borders This option turns ON or OFF the table borders in the HTML report. Clicking on it checks or un-checks the option.

Include input Determines whether or not the detailed input parameter table is included in

the HTML report. Clicking on it checks or un-checks the option. Include appendages Determines whether or not detailed appendage parameters are included in

the HTML report. Clicking on it checks or un-checks the option. Include graphs Determines whether or not the resistance and power graphs are included in

the HTML report. Clicking on it checks or un-checks the option. The report page pop-up includes a standard set of browser options, including printing, print preview


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Output Window File Menu

Plot Options Print Setup Print Save Bitmap

Close Output Window|File Menu Plot Options The plot options command activates the Plot Option Dialog. Print Setup The Printer Setup command activates the Printer Setup dialog. Print The Print command activates the Print dialog. Save Bitmap This command saves the current graph to a Windows Bitmap file, with the

same dimension in pixels as the screen plot. The Save Dialog is activated and prompts the user for a file name.

Close The Close command closes the Output Window.


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5.5 The Toolbar All Pages

New Open Save Run Propeller Design About

The toolbar icons change depending upon the current notebook page that is selected. Icons that are available to all pages are listed below: -

New Operates the New menu option to clear all data. Open Operates the Open menu option to load a new power prediction file. Save Operates the Save menu option to save the current data to a power

prediction file. Run Propeller Design

Initiates a copy of the Propeller Design Program. This feature only works if you have a copy of the Windows version of Propeller design. You can transfer the calculated Resistance data into the Propeller program via the clipboard. Once a resistance calculation has been performed use the Copy to Clipboard option from the Results Page, then run the Propeller Design program and use its EHP Data Page Paste from Clipboard method

Calculate Runs a calculation using the data as set.

About Operates the About Dialog.


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6.0 POWER PREDICTION GUIDE

6.1 Nomenclature

Within the program the following items are set, or calculated: -

Hull Inputs

As some of the parameter requirements differ between calculation methods, the program displays the required values and units on the status line when the mouse pointer is held over the relevant data field. The valid ranges of input data are shown in section 6.2.

BAR The blade area of the propeller divided by the area of a circle whose diameter is the diameter of the propeller.

Beam Depending upon the method used this is either the moulded beam or the extreme beam of the vessel at the static waterline, in metres or feet.

Bulb Area The transverse cross sectional area of the vessel's bulbous bow, at the intersection of the still water surface and the stem, in square metres or square feet.

Bulb Ht. The height of the centre of cross sectional area of the bulbous bow above the keel line, in metres or feet.

Cp (Prismatic coefficient) The ratio of the displacement of the vessel, to the weight of a volume of water with a cross section of the vessel's maximum section and a length of the vessel's waterline length.

Cw (Waterplane coefficient)

The ratio of the waterplane area of the vessel, to a rectangle defined by the vessel's beam and length.

Deadrise For the Savitsky method this is the average angle of deadrise over the vessel's planing surface, in degrees, for the Wolfson High Speed method it is the deadrise angle at the transom section.

Displacement The weight of the vessel in tonnes or tons.

Draught The maximum draught, excluding appendages, in metres or feet.

Half angle The half angle of entrance at the forward end of the vessel's waterline, in degrees.

LCB The longitudinal centre of buoyancy defined as a percentage of the waterline length forward of midships.

LCF The longitudinal centre of flotation defined as a percentage of the waterline length forward of midships.


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Length The length of the vessel, on the static waterline, appropriate to its trim and displacement, in metres or feet. Note that in the Tugs & Trawlers method this value is taken as the Displacement Length which is the mean of the waterline length and the length between perpendiculars.

Pitch/Diam The ratio of the pitch of the propeller to its diameter.

Prop. Angle The angle that the propeller line makes with the buttock line, in degrees.

Prop. Diam. The diameter of the vessel's propellers, in metres or feet.

Roughness The hull roughness allowance. If the number entered is less than 1.0 then it is used as an addition to the calculated skin friction coefficient (Cf), e.g. 0.0004. Alternatively if a number greater that 1.0 is entered then this is used as a multiplication factor for Cf, and so can be used as a form factor term e.g. 1.1.

Shape Factor A coefficient relating the shape of the vessel's afterbody. The shape coefficient's main effect is on the Wake Fraction, with negative values reducing its size and positive values increasing it. Typical values:- Shape Coeff Stern type

-10 V shaped sections 0 Normal section shapes 10 U shaped sections with Hogner stern

Speeds All speeds entered and shown within the program are in knots. The valid range of speed is a function of the calculation method and hull parameters, usually it is Length or Volume Froude number limited. The First Last and Increment Edit boxes are shown in the top right of the Hull Page, and the required set of speed is set by altering these values.

T/Amax The ratio of the cross sectional area of the transom immersed when stationary, and the cross sectional area of the vessels maximum section.

Thrust arm The perpendicular separation of the VCG from the extended propeller shaft line, in metres or feet.

Transom Area The area of the transom immersed when stationary, in square metres or square feet.

Trim The longitudinal attitude of the vessel relative to its datum. Bow up trim is positive, bow down trim is negative. The trim is defined as the difference in draught measured at the FP and AP.

VCG Vertical Centre of Gravity, the height of the centre of gravity above the keel line, in metres or feet.


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Wetted Area The wetted surface area at rest in square metres or square feet, excluding appendages. All the methods that require a wetted surface area have routines that can estimate the area. If the entered area is less than half the estimate or greater than twice the estimate, then the estimated value will be used and the estimated value displayed on the results file. Enter a value of zero to force calculation.

Hull Outputs

The results of calculations fall into the following categories:

Beam The wetted beam at speed, calculated by the Savitsky prediction.

EHP The Effective Horsepower in kW or HP.

Hull Efficiency An overall hull efficiency factor, (1-thrust deduction factor)/(1-wake fraction).

Length The wetted length at speed, calculated by the Savitsky prediction. This may sometimes exceed the LWL, which indicates erroneous results.

Porpoising The empirical porpoising stability calculated by the Savitsky prediction. If the deadrise is greater than 20 degrees, then results are given assuming a 20 degree deadrise. Where no result is given then the condition is out of range of the empirical results and is indeterminate.

Resistance The predicted calm water resistance of the vessel, in kN or tons f.

Rotative Efficiency The ratio of the efficiency of the propeller behind the ship, to the open water efficiency

Thrust Deduction A factor relating the vessel's required thrust to the resistance, which is (thrust - resistance)/thrust.

Trim The calculated trim from the Savitsky planing calculation, in degrees.

Wake Fraction A factor relating the vessel speed to the speed of the flow through the propeller (speed of advance), (Vessel speed - Speed of advance)/Vessel Speed.


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6.2 Calculation method input reference & ranges

Single Screw Ships

Input Reference

Base Data: Length - Beam - Draught - Displacement - LCB - Wetted Area Coefficients: Cp - Cw - Prop. Diam - BAR - Trim Special: Bulb Ht. - Bulb Area - Transom Area - Shape Factor Range Checks 0.55


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Twin Screw Ships

Input Reference

Base Data: Length - Beam - Draught - Displacement - LCB - Wetted Area Coefficients: Cp - Cw - Prop. Diam - Pitch/Diam - Trim Special: Bulb Ht. - Bulb Area - Transom Area - Shape Factor Range Checks 0.55


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Tugs and Trawlers Method

Input Reference

Base Data: Length - Beam - Draught - Displacement - LCB - Wetted Area Coefficients: Cp - Prop. Diam Special: Half angle

Range checks 0.365


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BSRA Method

Input Reference

Base Data: Length - Beam - Draught - Displacement - LCB Coefficients: Prop. Diam

Range checks 4.23


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NPL Round Bilge Craft

Input Reference

Base Data: Length - Beam - Displacement - LCB - Wetted Area Coefficients: Prop. Angle

Range checks 4.5


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Series 64

Input Reference

Base Data: Length - Beam - Draught - Displacement - Wetted Area Coefficients: Prop. Angle

Range checks 8.60


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SSPA Series

Input Reference

Base Data: Length - Beam - Draught - Displacement - LCB - Wetted Area Coefficients: Prop. Angle

Range checks 3.00


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Davidson Regression for Round Bilge and Planing Craft

Input Reference

Base Data: Length - Beam - Draught - Displacement - LCB - Wetted Area Coefficients: Prop. Angle Special: Half angle - T/Amax

Range checks 0.00


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Savitsky Planing Prediction

Input Reference

Base Data: Length - Beam - Displacement - LCB Coefficients: Prop. Angle - VCG - Thrust Arm - Deadrise

Range checks Planing


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Delft Systematic Yacht Hull Series

Input Reference

Base Data: Length - Beam - Draught - Displacement - LCB - Wetted Area Coefficients: Cp - LCF

Range checks 0.51


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Wolfson Unit Chine Hulls

Input Reference

Base Data: Length - Beam - Displacement

Coefficients: Prop. Angle

Range checks 4.0


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Wolfson Unit Round Bilge

Input Reference

Base Data: Length - Beam Displacement Wetted Area

Coefficients: Prop. Angle

Range checks 4.5


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Wolfson Unit Catamarans

Input Reference Base Data: Length - Beam - Displacement - Wetted Area Coefficients: Prop. Angle Range checks 6.3


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Wolfson Unit High Speed

Input Reference

Base Data: Length - Beam - Displacement - LCB

Coefficients: Prop. Angle - Deadrise

Range checks 3.0


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6.4 Appendages

There are two types of appendage used by the program: (a) Standard This is an individual component such as a cylinder (shaft) or bilge keel. (b) User Defined This is an appendage created from up to ten standard types such as a P-bracket comprising a strut (control surface) and a bossing (cylinder). The Appendage page and associated pop-up menu serve two purposes. Firstly they allow appendages to be defined from Standard types or from User Defined types. Secondly they allow User Defined types to be created from combinations of the Standard types. The page is divided into three regions: - On the right is a list of the Available Types, i.e. the standard and user defined appendage types. In the middle of the page is a list of the Appendages Defined, i.e. those currently associated with the hull. Initially this list is empty. Appendages can be added or removed from this list by using the Add and Remove buttons located between the Appendages Defined and Available Types list boxes. The left-hand portion of the screen is reserved for details of the individual appendages. When one of the defined appendages is selected in the Appendages Defined list box, a set of edit boxes showing its parameters is displayed, and values may be entered or edited as required. When a User Defined appendage is selected, a further list box is displayed below the Appendages Defined box, allowing selection of the individual parts of the appendage.


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6.4.1 Standard appendages Bilge keels These are taken as paired sets of low aspect ratio appendages, with Cf calculated with the vessels Reynolds number.

Input Parameters Length (metres/feet) - length of bilge keel Depth (metres/feet) - mean depth of keel Thickness (metres/feet) - mean thickness of keel


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Control Surfaces Used for rudders, yacht fins, stabilisers etc., with Cf calculated with the vessels Reynolds number.

Input Parameters Span (metres/feet) - mean span of control surface Chord (metres/feet) - mean chord of control surface t/c - thickness/chord ratio of control surface Skegs Centreline appendages, with Cf calculated with the vessels Reynolds number.

Input Parameters Length (metres/feet) - length of skeg Depth (metres/feet) - depth of skeg Thickness (metres/feet) - mean thickness of skeg


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Cylinders Shafts and bossings.

Input Parameters Length (metres/feet) - length of cylinder Diameter (metres/feet) - diameter of cylinder Angle (degrees) - angle of cylinder to flow Air Drag Frontal area pressure drag, using the standard properties of air to calculate their resistance.

Input Parameters Area (sq.metres/sq.feet) - cross sectional area Drag Coefficient - drag coefficient, typically 1.0


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Additional Drag Frontal area pressure drag, using the standard properties of seawater to calculate their resistance.

Input Parameters Area (sq.metres/sq.feet) - cross sectional area Drag Coefficient - drag coefficient, typically 1.0 Additional Friction Used for appendages with only a skin friction component, Cf calculated with their own local Reynolds number.

Input Parameters Area (sq.metres/sq.feet) - cross sectional area Length (metres/feet) - length of appendage, used to calculate Reynolds number


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6.4.2 Adding a new appendage To create new appendages follow this procedure:- 1. Either double click on the appropriate type in the Available Types list box, or highlight tit and click

on the > button. 6.4.4 User defined appendages User defined appendages are combinations of standard appendage types which can be grouped together in order to model features such as propeller brackets, of keel/bulb combinations. To create new user types take the Add Usertype option from the Edit or pop-up menu. A dialog box is displayed which allows standard appendage types to be added to or removed from the user type definition. In order for the program to accept the new type it must be given a name before closing the dialog.

6.5 Cases The program can calculate results for a series of hulls that are variations of the parameters that define the base vessel. Cases are defined by changing one or more of the parameters entered as base data on the Hull Page, or changing the combination of appendages that are added to the naked hull. Up to 10 additional cases can be defined, with any of the parameters changing. The edit cases screen is divided into two regions: On the right is a list of the parameters required for defining the base vessel, which is defined by the calculation method. The rest of the page is a table of case conditions


48

To Add a parameter to the table, either double click the parameter in the list, or highlight it and take the Add Parameter option in the Edit or Pop-Up menus. To Remove a parameter from the table, select the appropriate column and take the Delete parameter option in the Edit or pop-up menus. To Add a new case take the Add Case option in the Edit or pop-up menus. The parameter values for the new case will be taken initially from the base vessel definition, i.e. that set on the Hull page. To Remove a case select the appropriate row in the table and take the Delete Case option from the Edit or pop-up menus. To Edit the values of parameters in the case table, select the appropriate column and row and type a new value. If the parameter selected is the number of appendages, a special dialog box is displayed, allowing the defined appendages to be selected for inclusion in the calculation or ignored.


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7.0 GLOSSARY Angle of Entry The half angle of entrance, measured between the load waterline and

the vessel's centreline, in degrees. Appendages Items additional to the main hull e.g. rudders, propeller shafts, bilge

keels etc. Base results The calculated results for the vessel data set on the Hull page. Beam The beam of the vessel, either extreme or at the waterline, in metres

or feet. Bulb Cross Sect Area The transverse sectional area of the bulb at the position where the still

water surface intersects the stem, in square metres or square feet. Bulb Centreline Height The position of the centre of the bulb area above the keel line, in

metres or feet. Calculation method A list box on the Hull page containing the list of the published

methods built into the program for calculating resistance. Cases A notebook page allowing calculation cases to be set up. Cases form

a way in which hull parameter variations may be checked. Substituting the hull parameters, on the Hull page, with alternative values set on this page, forms a case.

Case n results The results calculated for the case number, in the Results page. Click

on the tab to view the data. CB Block coefficient, which is the moulded volume of the ship/(waterline

length * waterline beam * mean draught. Checking A list box containing the different parameter checking options. Strict

checking ensures that no calculation is made if any parameter values fall outside the allowable ranges and envelopes of tested data. Free checking only looks for overall ranges of data. None allows the program to attempt any calculation, but results may not be calculated in certain circumstances.

CM Midship section coefficient, which is CB/Cp. Cp Prismatic coefficient, which is the moulded volume/(waterline length *

(area of the midship section)). Cw Water plane area coefficient, which is the (water plane

area)/(waterline length * waterline beam). Displacement The full displacement of the vessel in tonnes or tons.


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Deadrise Angle (mean) For Savitsky, the average angle of deadrise over the vessel's planing surface, for Wolfson High Speed, the transom deadrise.

Draught The vessel draught (to the keel line) excluding appendages in metres

or feet. EHP The Effective Horsepower in kW or HP. Froude Number Froude No. = V gL/ , (speed over sq.root g.length) Hull Efficiency An overall hull efficiency factor, which is (1-thrust deduction

factor)/(1-wake fraction). Immersed Transom Area The area of the immersed portion of the transom at zero speed,

measured in square metres or square feet. Length/Beam Ratio, L/B The waterline length to beam ratio. LCB The longitudinal centre of buoyancy forward of 0.5 LBP expressed as

a percentage of LBP. It is positive forward of midships. Porpoising The empirical porpoising stability calculated by the Savitsky

prediction. If the deadrise is greater than 20 degrees, then results are given assuming a 20 degree deadrise. Where no result is given then the condition is out of range of the empirical results and is indeterminate.

Propeller Shaft Angle The angle that the propeller shaft makes with the keel, in degrees. Roughness Coefficient An addition to the ITTC 1957 frictional coefficient, used to add the

effect of hull roughness to the calculated resistance. Its standard value is taken as 0.0004.

Relative rotative efficiency The ratio of the efficiency of the propeller behind the ship, to the open

water efficiency. Resistance The predicted calm water resistance of the vessel, in kN or tons f. Shape Factor Coefficient relating to the afterbody form. The shape coefficient's

main effect is on the Wake Fraction, with negative values reducing its size and positive values increasing it. Typical values might be:- Shape Coeff Stern type -10 V shaped sections 0 Normal section shapes 10 U shaped sections with Hogner stern

Thrust Deduction Factor A factor relating the vessel's required thrust to the resistance, which is

((thrust - resistance)/thrust).


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Thrust Moment Arm The perpendicular distance between the centre of gravity and the

thrust line. Positive if the thrust line is below CG, negative if above, in metres or feet.

Transom/Max Area Ratio The ratio of the cross sectional area of transom immersed when

stationary, and the cross sectional area of the vessel's maximum section.

Trim The longitudinal attitude of the ship relative to its datum. Bow up

trim is positive, bow down is negative. It is defined as the difference in draught between two points on the base line, separated by the waterline length.

Units The units used by the program are either metric or imperial. VCG The height of the centre of gravity above the keel line excluding any

appendages, in metres or feet. Wake Fraction A factor relating the vessel speed to the speed of the flow through the

propeller (speed of advance), which is ((Vessel speed - Speed of advance)/Vessel Speed).

Wetted Length The wetted length at speed, calculated by the Savitsky prediction.

This may sometimes exceed the LWL, which indicates erroneous results.

Wetted Surface Area The wetted surface area of the vessel at rest. If entered as zero, the

program will calculate its value according to procedures given in Ref. 1,2.


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8.0 ERROR MESSAGES Errors are displayed in a message box. The box describes the type of error. To continue operation the OK button must be clicked. Within the program there are three types of error messages: Data Checking Data Boundary File Input/Output Data Checking Errors Data checking errors arise whenever a value which is required by the program for calculation is not set correctly, usually because its value is zero.

Data boundary errors Data boundary errors occur when the program finds that the input values set fall outside the boundaries of the calculation methods. Unless the No Checking option is selected all data are checked before a calculation is performed. There are two boundaries that the program checks. 1. Range.

The program checks that an individual parameter, e.g. CB or L/B lies within the allowable range of values.

2. Envelope.

Certain of the calculation methods are only applicable to combinations of parameter ranges, which form an envelope of acceptable values.

In each case the allowable range is shown within the error message. Pressing the OK button continues the checking process in order to highlight other boundary errors, but does not perform a calculation. Pressing the Cancel stops checking immediately.

File Input/Output errors File errors arise either because the file contents do not correspond to the required File Format when loading data from disc, or because the file name or path is invalid.


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APPENDIX I REFERENCES 1. Holtrop and G. Mennen, 'A Statistical Power Prediction Method', International Shipbuilding

Progress, Vol. 25, October 1978 2. Holtrop and G. Mennen, 'An Approximate Power Prediction Method', International Shipbuilding

Progress, Vol. 29, July 1982 3. Holtrop, 'A Statistical Re-Analysis of Resistance and Propulsion Data', International Shipbuilding

Progress, Vol. 31, November 1984 4. van Oortmerssen, 'A Power Prediction Method and its Application to Small Ships', International

Shipbuilding Progress, Vol. 18, November 1971 5. Parker, 'The BSRA Methodical Series - An Overall Presentation', Transactions of the Royal

Institution of Naval Architects, 1966 6. Sabit, 'Regression Analysis of the Resistance Results of the BSRA Series', International

Shipbuilding Progress, Vol. 18, November 1971 7. Bailey, 'The NPL High Speed Round Bilge Displacement Hull Series', published as the 'Maritime

Technology Monograph No.4' by The Royal Institution of Naval Architects 8. Yeh, 'Series 64 Resistance Experiments on High Speed Displacement Forms', Marine Technology,

Vol.2, No.3, July 1965 9. Lindgren and A. Williams, 'Systematic Tests with Small, Fast Displacement Vessels, including a

Study of the Influence of Spray Strips', Swedish State Shipbuilding Experimental Tank Report, No.65, 1969

10. Mercier and D. Savitsky, 'Resistance of Transom-Stern Craft in the Pre-Planing Regime', Davidson

Laboratory Report, SIT-DL-73-1667, 1973 11. Savitsky, 'Hydrodynamic Design of Planing Hulls', Marine Technology, Vol.1, No.1, Oct 1964 12. Gerritsma Prof J., Onnick R. And Versluis A, Geometry, Resistance and Stability of the Delft

Systematic Yacht Hull Series, 7th HISWA Symposium 1981. 13. Keuning J.A., Onnick R., Versluis A. And van Gulik A., The Bare Hull Resistance of the Delft

Systematic Yacht Hull Series, 14th HISWA Symposium 1996. 14. Molland A.F.,Wellicome J.F. and Couser P.R. Resistance experiments on a systematic series of high

speed displacement catamaran forms: variation of length-displacement ratio and breadth-draught ratio. Transactions of the Royal Institution of Naval Architects, Vol. 138, 1996

15. Molland A.F. and Lee A.R. An investigation into the effect of prismatic coefficient on catamaran

resistance. Transactions of the Royal Institution of Naval Architects, Vol. 139, 1997.

16. Robinson John. Performance Prediction of Chine and Round Bilge Hull Forms. Hydrodynamics of High Speed Craft. RINA November 1999.


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17. APPENDIX II FILE FORMATS The program uses three types of file: Power Prediction Files Appendage Files EHP Data Files

Power Prediction Files *.PPF

The main file type used in the program stores all of the data from the main Hull Page., the Appendage Page, and Cases Page and the names of other files used. Each item in the file is prefaced by its meaning, followed by a colon. A typical file looks like: - Wolfson Unit Power prediction Data Title:Maxi Yacht. Calc type:10 Check type:3 Units:1 Show graph:0 Length:20.050 Beam:4.7 Draught:.75 Displacement:35.5 LCB:-3 Wetted Area:0.000 Prismatic Coeff:.55 Waterplane Coeff:-3 Prop Diam:0.000 Prop P/D:0 Trim:0.000 BAR:0 Prop shaft angle:0 VCG:0.000 Thrustarm:0.000 Deadrise:0 Bulb height:0.000 Bulb area:0.000 Transom area:0.000 Shape factor:0 Half entrance angle:0 Transom/Max area ratio:0 Roughness:0 First Speed:3.0 Last Speed:16.0 Speed Increment:1 Speeds:4 13.00 14.00 15.00


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16.00 Report file: User types:0 Appendages:3 1 :Control Surface Rudder 1 0 0 0.68000 3.00000 0.10000 :On 1 1 0 0 0 0 0 0 0 0 2 :Control Surface Keel 1 0 0 0.75000 2.00000 0.10000 :On 1 0 0 0 0 0 0 0 0 0 3 :Additional friction Bulb 1 0 0 2.00000 3.00000 0.00000 :On 0 0 0 0 0 0 0 0 0 0 Cases defined :3 Case parameters :2 Case data: Case\Param Base Case 1 Case 2 Case 3 Appendages 3 2 1 0 Roughness 0 .0004 .0002 .0001


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Appendage Files *.PPA

This file saves only the data from the Appendage Page,. A typical file looks like:- Wolfson Unit Power prediction Appendages User types:1 1 :P-Bracket 2 1 3 0 0 0 0 0 0 0 0 Appendages:2 1 :Control Surface Rudders 55 0 0 0.50000 0.50000 0.14000 :On 0 0 0 0 0 0 0 0 0 0 2 :P-Bracket Brackets 2 1 2 0.00000 0.00000 0.00000 :On 0 0 0 0 0 0 0 0 0 0 User definition:P-Bracket No:2 Strut 1 0.20000 0.20000 0.15000 Boss 1 0.20000 0.25000 0.00000


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EHP Data *.PPG The EHP data file type stores the values of Speed, Resistance, Wt, and t shown in the Results Page. The file format is compatible with the input to the Wolfson Unit Propeller Design Program. The first line contains a descriptor, followed by two lines describing the content and units of the first two columns. Column 1 must be speed in knots. Column 2 is Resistance in kN or tonf. The fourth line contains the number 1, and the fifth contains a descriptor, however this program ignores data on this line. Line 6 contains the number of speeds present in the data, and subsequent lines contain; Speed, Resistance Wake Fraction and Thrust Deduction. A typical file looks like: - A test Speed - kts Resistance - kN 1 Basis Ship 11 20.000 33.820 -0.034 0.063 21.000 35.207 -0.029 0.064 22.000 36.568 -0.024 0.067 23.000 38.104 -0.019 0.073 24.000 39.605 -0.013 0.082 25.000 41.229 -0.007 0.097 26.000 42.999 -0.001 0.116 27.000 44.811 0.003 0.143 28.000 46.952 0.006 0.177 29.000 49.876 0.007 0.220 30.000 53.274 0.006 0.275


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INDEX

A

A simple calculation .....

power prediction manual

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