prefit manual

Prefit

Windows Version 12 User Manual

Formation Design Systems Pty Ltd 1984 2006

License & Copyright Prefit Program 1987-2006 Formation Design Systems. Prefit is copyrighted and all rights are reserved. The license for use is granted to the purchaser by Formation Design Systems as a single user license and does not permit the program to be used on more than one machine at one time. Copying of the program to other media is permitted for back-up purposes as long as all copies remain in the possession of the purchaser. Prefit User Manual 2006 Formation Design Systems. All rights reserved. No part of this publication may be reproduced, transmitted, transcribed, stored in a retrieval system, or translated into any language in any form or by any means, without the written permission of Formation Design Systems. Formation Design Systems reserves the right to revise this publication from time to time and to make changes to the contents without obligation to notify any person or organisation of such changes. DISCLAIMER OF WARRANTY Neither Formation Design Systems, nor the author of this program and documentation are liable or responsible to the purchaser or user for loss or damage caused, or alleged to be caused, directly or indirectly by the software and its attendant documentation, including (but not limited to) interruption on service, loss of business, or anticipatory profits. No Formation Design Systems distributor, agent, or employee is authorised to make any modification, extension, or addition to this warranty.

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About this Manual

Contents License & Copyright ........................................................................................................ iii Contents..............................................................................................................................1 About this Manual ..............................................................................................................2 Chapter 1 Introduction........................................................................................................3

Prefit and Maxsurf .........................................................................................3 Bow and Stern Shapes ...................................................................................3 Transverse Splines .........................................................................................4 Fitting a Surface.............................................................................................4

Chapter 2 Using Prefit ........................................................................................................6 Getting Started ...............................................................................................6 Opening a Markers File .................................................................................6 Control Points ................................................................................................8 Sections..........................................................................................................9 Fitting Splines ..............................................................................................10 Generating a Surface....................................................................................11 Creating a Markers Table.............................................................................12

Chapter 3 Prefit Reference ...............................................................................................19 Windows ................................................................................................................20 Toolbars .................................................................................................................21 Menus.....................................................................................................................22

File Menu.....................................................................................................22 Edit Menu ....................................................................................................23 View Menu ..................................................................................................24 Surface Menu...............................................................................................25 Display Menu...............................................................................................26 Grid Submenu ..............................................................................................27 Data Menu....................................................................................................27 Window Menu .............................................................................................28 Help Menu ...................................................................................................29

Index.................................................................................................................................30

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About this Manual This manual describes Prefit, an application that may be used to input existing hull designs into Maxsurf. The manual is organised into three chapters. Chapter 1 Introduction Contains a description of Prefit and its interface to Maxsurf. Chapter 2 Using PrefitExplains how to use Prefit's powerful fitting routines to best advantage. Chapter 3 Prefit ReferenceGives details of each of Prefit 's windows, toolbars and menu commands.

Chapter 1 Introduction

Chapter 1 Introduction Prefit provides a means of keyboard entry of existing offset data for use in the generation of a three dimensional surface. The surface generated by Prefit may be saved as a Maxsurf design file. Offset data may also be loaded from a text file or copied from a spreadsheet. You may find it easier to use the fitting functions provided in the Markers menu in Maxsurf rather than using the standalone version of Prefit. Using Prefit is a three-stage process, entering the bow and stern shapes, fitting the transverse splines, and fitting the surface.

Prefit and Maxsurf The Prefit licence enables you to access many useful fitting tools directly from Maxsurf. The features include a sophisticated automatic fitting tool which uses advanced techniques to produce an accurate fit to marker data as well as a usable control point net. There are also other tools for fitting corner points and edges to markers. These are included in the Markers menu in Maxsurf. Please refer to the Maxsurf manual for full details of these functions.

Bow and Stern Shapes In the first stage, the bow and stern shapes are specified by entering their offsets. This is followed by the offset data for all remaining stations. All offsets appear in the same way as Markers in Maxsurf.

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Transverse Splines Once the markers to be fitted have been entered, a set of transverse splines is generated through the markers on a station-by-station basis. Control points to these splines may also be displayed allowing for manual fairing of the splines.

Fitting a Surface When you are satisfied that the splines fit the marker data, you may then fit a complete surface through the transverse splines. The surface may then be saved as a Maxsurf design file. If necessary, the surface net may be refined manually to obtain a better fit to the markers.

Prefit is not suitable for modelling discontinuities in designs such as the hard chined hull shown below.

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Designs featuring chines or discontinuities should be modelled as independent surfaces. The above design should be modelled as below, using two Prefit surfaces, with the chine as a common surface edge. Once the two surfaces have been fitted, they can be merged together in Maxsurf.

Prefit allows you to choose how many control points you wish to use to model the hull surface. The choice of the number of control points to use in the generation of a surface and its net is a matter of trial and error, as different designs will require different numbers of control points. As a rough guide, use slightly more control points than you would use to model a similar hull in Maxsurf.

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Chapter 2 Using Prefit

Chapter 2 Using Prefit You have been introduced to the way in which Prefit works and can now go on to learn in detail how to use Prefit by following the example outlined in this chapter. The example uses a simple yacht hull form whose markers are supplied in a Prefit markers file, with extension .pfd, called Prefit Sample_YachtOffsets. This file may be found in the Sample Designs folder. The example goes through the steps needed to generate a surface from these markers.

Getting Started Install Prefit from the CD. Prefit may then be started, and will display the Perspective, Plan, Profile, Body Plan, Markers and Control Points windows.

Opening a Markers File Choose Open Marker Data from the File menu. Select the file titled Yacht Offsets and open it. This file contains a table of markers for a simple yacht hull form. When it is read in, it will fill the Markers window with marker data, and the markers will be displayed in the Plan, Profile, Body Plan and Perspective views. Each marker point is displayed as a cross in the view windows.

To edit the markers, bring the Markers/Offsets table to the front by choosing Markers from the Window menu. The markers are displayed in a table and you can scroll through the data to examine the markers at any station.

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The Markers window is similar to the Markers window in Maxsurf. The column headings are: Position (longitudinal position); Offset (transverse position) and Height (vertical position). The markers are grouped in stations. The first and last groups, or fields, are labelled Bow and Stern in the Station column. These two groups allow the specification of the bow and stern shape that do not necessarily lie on an individual, planar station, as is the case with the other station fields.

The bow and stern definitions are important as they describe the fore and aft edges of the surface that you will create using Prefit. Note that the longitudinal position of each bow and stern marker may be changed, allowing either to be raked; in general all other sections are vertical (i.e. specified with a constant station position). Markers for each station should be entered in order starting at the centreline and moving out towards the sheerline. Similarly, markers for the bow and stern should start at the keel and move towards the sheerline.

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Control Points When choosing the number of control points to be used in the surface net you should observe the following: 1. The number of stations entered should exceed the number of control point columns. 2. The number of markers, for the station with the smallest number of markers, should exceed the number of control point rows. A surface net with 6 control point columns and 4 control point rows is shown below; the square boxes indicate the net control points.

To set the number of control points and other surface properties, choose Control Points from the Surface menu.

A dialog will appear which allows you to enter the number of control points transversely across the surface (rows) and longitudinally along the surface (columns). For the example yacht data, set both the number of control point rows and columns to 7, as the markers feature a large variation in sectional shape over the length.

Convergence Limits The Control Points dialog also contains several other items, headed Limits and Constraints. These limits control how much time Prefit will spend trying to fit splines or a surface to your markers. You can instruct Prefit to iterate to improve the quality of fit until the maximum error at any marker point is less than a certain level. At the same time it is necessary to tell Prefit the maximum number of iterations to make before it gives up. For the moment, set maximum error to 10 mm. and iterations to 5.

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Iterations After the initial surface fitting, further iterations of the surface fitting procedure may be carried out to obtain a better fit. To do this, select Regenerate Surface from the Surface menu. The surface net may also be manipulated manually between iterations to achieve a smoother and more useable net. The net may be displayed by selecting Net from the Display menu. The control points may be changed by directly dragging the points in the Plan, Profile or Body Plan views or by typing their positions in the Control Points table. Dragging may be constrained to either the vertical or horizontal direction by holding the shift button down.

Constraints Constraints restrict control points to lie within certain areas to improve the regularity of the control point net that is generated. The constraints available are: Flat Bottom.

This prevents any control points in a particular column being below the level of centreline at that position. This is a reasonable constraint for the vast majority of hull designs, the only exceptions being those tunnel hulls or concave bottoms.

Flat Side.

This prevents control points from going further from the centreline than the widest point at the sheerline. Only hulls with tumblehome in their topsides would need to have this option turned off.

Surface Columns.

This option constrains columns in the fitted surface net to a particular arrangement. For example, if a design has a lot of longitudinal curvature in the bow it is reasonable to constrain the control point columns so that they are concentrated more in the bow. If a hull shape has fairly even curvature from bow to stern, Even Spacing or no column constraint at all is acceptable. If the Surface Columns constraints box is ticked, the desired control point distribution may be selected from the Control Point Distribution radio buttons.

For the sample hull, all the Constraints may be left on.

Flexibility Before generating splines through the markers, it is necessary to set the flexibility of the splines to be used. Order 4 splines are most suited to the generation of surfaces in Prefit. As you gain experience with the program you may wish to experiment with other spline stiffnesses. Click the OK button in the Control Points dialog to accept the changes and close the dialog.

Sections Next choose the Body Plan window from the Window menu.

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When fitting the transverse splines you will need to show individual sections. As in Maxsurf, either all the sections or just the current section may be displayed depending on whether the Sections option is on or off. Select the Sections tick box in the Contours dialog to turn on all sections; remove the tick to view only the current section. The contours dialog is activated by selecting Contours from the Display menu.

Remove the tick from the stations check box so that only the current section is displayed. As in Maxsurf, the current section is chosen from the inset box in the Body Plan view to display the section and markers for the current section.

Fitting Splines Now that you have set the flexibility of the splines to be used, you can fit the splines through the markers by choosing Section Splines from the Display menu. This will calculate all the splines and display the spline, which has been fitted through the current section. Selecting Edge Splines from the Display menu will calculate and display the splines, which are fitted through the sheerline and keel. Once Prefit has calculated the spline, it will be drawn as a solid line through, or very close to, the marker points.

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If you wish you can modify any spline control point. To do this, select Spline Controls from the Display menu. Spline Controls shows the control points for the spline as generated by Prefit. You can drag the control points with the mouse to modify the fit of the spline to the marker points. The movement may be constrained to the vertical or horizontal direction by pressing the shift key while dragging the control point. Remember that if you are only showing one section at a time, you can change the current section by clicking on the desired station marker in the inset box at the top right of the Body Plan window. When modifying the bow and stern definitions be sure to refer to the Plan and Profile windows to check for fairness as well as in the Body Plan window.

Profile and Plan views showing control points with constant longitudinal position for intermediate stations and a completed definition of the bow and stern.

The splines generated through the top and bottom edges of the surface (normally keel and sheerline) may be manipulated in a similar manner.

Generating a Surface Now that you have automatically and manually fitted the splines to the points, you can go ahead and generate the surface. Note that Prefit does not fit the surface to the marker points but to the splines, which have been fitted to the points. Choose Generate Surface from the Surface menu to fit the surface. The calculation of a surface may take some time, as it is a complex mathematical problem. The time taken depends on the size of the required control point net. The larger the net, the greater the time taken to fit the surface. To speed up the process, fewer initial iterations can be specified. At a later stage, subsequent iterations may be calculated to refine the surface if greater accuracy is required. Chose Regenerate Surface from the Surface menu to do this. The resulting surface will be displayed superimposed over the original splines to check for the accuracy of the fit.

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You may save the surface by selecting Save Surface As from the File menu. The surface will be saved as a Maxsurf design file and may then be opened in Maxsurf. The markers will also be saved and can be viewed in Maxsurf. After the surface has been generated you may display the net to see if the result is a net that is clean and easily usable in Maxsurf. Choose Net from the Display menu to display the net.

Creating a Markers Table Now that you have learned how to generate a surface from a table of markers, you can start to create your own table of markers as you would for a new design. Choose Close Marker Data from the File menu to close the table of yacht markers you have been working with. Next, select New Marker Data from the File menu and you will be presented with a dialog box in which you may input the four corners of a new surface.

These corners are input as Bow at deck edge, Bow at foot, Transom at deck edge, and Transom at keel. You may also enter the number of points you intend using in the definition of the bow and in the definition of the stern, including the edge points.

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The remaining stations may then be entered in the Markers window and the splining and surface fitting performed as in the preceding example. Choose Markers from the Window menu to bring the Markers window to the front.

Editing Markers All cells in the Markers table are editable except:

The column titles The row numbers The station column

Under most circumstances, it is desirable to have vertical stations (except for the Bow and Stern). However, it is possible to have non-vertical stations. To change the number in a cell, simple click on the cell to select it and then type in the new number. You can use the tab key to move to the next cell to the right and the Return key to move to the cell below. You can also use the arrow keys to move around in the table. In order to add and delete information from the table of markers, it is necessary to select cells and rows in the table.

Selecting a Cell Clicking in a cell selects that individual cell and highlights it. When an editable cell is selected new data may be entered from the keyboard. The data may be input in any units and Prefit converts to the current units as set in the Units option of the Display menu. Append the appropriate units symbol to enter data, which is not in the current units. See Data Menu | Units in the Reference section for further details.

Selecting a Row Clicking on a row number selects that row. When a row is selected a marker may be inserted or removed from the marker definition of the surface.

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Selecting a Column Clicking in a column title selects that column. A selected column may be copied to the clipboard or may have the contents of the clipboard pasted into it.

Selecting all Markers Clicking in the Sheet Select box (top left cell of table) selects the entire Markers window. This is useful only to copy the entire Markers window.

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Apart from the basic numerical editing of individual cells, operations may be performed on whole rows or individual stations in the Markers window. Holding down the shift key while copying data from the table, will also copy the column titles. On Windows, various other features relating to the table may be selected from the context menu, which is activated by right clicking in the table window.

Inserting a Marker To insert an marker at a given station:

Select a row in the table. The marker will be inserted immediately below this row. Select Add Marker from the Edit Menu.

Deleting a Marker To delete an marker from the table:

Select the row of the marker to be deleted. Select Delete Marker from the Edit Menu.

Adding a Station To add a new station to the table:

Choose Add Station from the Edit menu. A dialog box will appear allowing you to enter the position of the station and the

number of markers you require at this station.

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Enter the longitudinal position of the station and the number of markers you require at this station.

Click OK. The new station will be inserted in the table at the correct location.

Deleting a Station To delete a station from the table:

Choose Delete Station from the Edit menu. A dialog box will appear:

Enter the numbers of the first and last stations to be deleted. To delete a single station enter the same number in the From and To boxes.

Click OK. All of the markers for these stations (inclusive) will be removed from the table.

Saving a Markers Table From time to time during the creation of your markers table, it is a good idea to save your table to disk. Choose Save Marker Data from the File menu to save your table. If you have not yet saved the data, Prefit will ask you to name your file.

Importing Markers From Text File Markers may be imported from a standard, tab delimited text file. The text file should have the following format:

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There are 4 columns: the first contains the station number; the second the station longitudinal position; the third the transverse offset and the fourth column contains the vertical height of the markers. A text file may be imported by selecting Open Text from the File menu.

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Chapter 3 Prefit Reference

Chapter 3 Prefit Reference This chapter describes the toolbars, windows and menu commands available in Prefit.

Windows Toolbars Menus

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Windows Prefit uses a range of windows. There are the four view windows that are similar to Maxsurf as well as the following windows:

Marker / Offset Data Window Displays an editable table containing the markers/offsets data (stations, position, offset and height).

Control Points Displays an editable table containing the control point net data (surface, row, column, position, offset, height and weighting).

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Toolbars Users of the Windows version of Prefit can use the icons on the toolbars to speed up access to some commonly used functions. You can hold your mouse over an icon to reveal a pop-up tip of what the icon does.

File Toolbar

The File toolbar contains icons, which execute the following commands: New Data Open Markers Save Markers | Cut - Copy - Paste | Print Preview

View Toolbar

The View toolbar contains icons, which execute the following commands: Zoom Shrink Pan Home View

Display Toolbar

The Display toolbar contains icons, which change the state of the following parts of the display: Shape Net Half Compress | Section Splines Edge Splines Spline Control Points Markers

Contour Toolbar

The Contours toolbar contains icons, which facilitate the display of surface contours: Sections Waterlines Buttocks Intersections Edges

Window Toolbar

The Window toolbar contains icons, which make the corresponding window come to the front: Perspective Plan profile Body Plan Control Points Markers

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Menus Prefit uses the standard set of Windows menu commands for File, Edit and Window operations. It also has a range of menus for control point and surface manipulation and control of data and view displays.

File Menu Edit Menu View Menu Surface Menu Display Menu Grid Submenu Data Menu Window Menu Help Menu

File Menu The File menu contains commands for opening and saving files, importing and exporting data, and printing.

New Marker Data Selecting New Marker Data will present a dialog box where you may input the four corners of the desired surface. These points are input as Bow at deck edge, Bow at foot, Transom at deck edge, and Transom at keel. You may also enter the number of points you intend using, including the edge points, in the definition of the bow and in the definition of the stern.

Open Marker Data Prefit has the ability to save markers to disk and recall them at a later date. By selecting Open Marker Data, a dialog box appears with a list of marker files available. Select the Markers file you wish to recall, click the Open button and the requested marker file will be opened. In windows, the Prefit marker files are given the extension .pfd.

Open Text If you wish to format a table of markers using a spreadsheet or word processor, or if you have a file of points generated by another computer program, Prefit is capable of reading in a text file of marker points directly. The requirements for a text file are: The data is in columns of station number, station position, offset from centre and height. Each line should terminate with a Carriage Return (CR) and each column should be separated with a TAB character. The first marker for each station should be the centreline, and the final marker for each station should be the sheerline.

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Close Marker Data Select Close Marker Data when you wish to finish with the current set of markers. Before closing, a dialog box will appear asking whether you wish to save the current set of markers. If you select Yes the current set of marker will be saved to the disk.

Save Marker Data Selecting Save Marker Data will save the current set of markers to disk.

Save Marker Data As Selecting Save Marker Data As enables you to save the current set of markers under a new name. This is useful if you modify a set of markers, but wish to keep a copy of the old version as well as the new.

Save Surface As This allows you to save the surface you have generated to disk as a Maxsurf design file. The file can then be opened by Maxsurf. All the markers entered in Prefit will also appear in Maxsurf.

Page Setup The Page Setup dialog allows you to change page size and orientation for printing.

Print Choosing the Print function prints out the contents of the uppermost Prefit window.

Exit Prefit Exit will close down Prefit and return you to the Desktop. If Prefit has a set of markers or a surface open that has not been saved to disk, you will be asked whether you wish them to be saved.

Edit Menu The Edit menu contains commands for working in the Data window.

Undo Undo may be used remove the last change made to either the Marker or Control Point tables.

Cut Cut may not be used in Prefit.

Copy Copy may be used to copy data from the Markers or Control Points tables. It may also be used to copy the contents of one of the view windows into a picture or metafile, which may then be pasted into other programs.

Paste Paste may be used input data into the Markers table.

Add Marker When a row of the Markers window is selected, you may insert a marker below the selected row. The new marker is given the same position as the selected marker, and you can then edit the marker and height (initialised to zero) to the required position. No sorting is done, Prefit assumes you have inserted these points in the correct order.

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Delete Marker When a row of the Markers window is selected, choosing Delete Marker will delete that marker point from the marker table.

Add Station When you select Add Station, a dialog appears asking for the station position, and the number of points you will use in the definition of that station. The station position is sorted into place with respect to the other stations in the marker table, and all marker offsets and heights are initialised to zero.

Delete Stations When you select Delete Stations a dialog appears asking for the numbers of the first and last contiguous stations to be deleted. Type in the new numbers, click the OK button, and markers on the chosen stations will be deleted.

View Menu The View menu contains commands for changing the way in which the drawing and data windows are displayed.

Zoom The Zoom function allows you to examine the contents of the Perspective, Plan, Body Plan or Profile window in detail by enlarging any particular area to fill the screen.

Pan Choosing Pan allows you to move the image around within the front window.

Shrink Choosing Shrink will reduce the size of the displayed image in the front window by a factor of two.

Home View Choosing Home View will set the image back to its Home View size. Prefit starts up with default Home View settings for the view window. However, the Home View may be set at any time by choosing the Set Home View function.

Set Home View Choosing Set Home View allows you to set the Home View in the View window. To set the Home View, use Zoom, Shrink, and Pan to arrange the view as you require, then select Set Home View from the View menu.

Colour The Colour function allows you to set the colour of lines and controls. Prefit will display a list of items that allows you to set any of the items to any colour and intensity by using a colour pallet. To set the colour of a given line or set of lines:

Select Colour from the View menu. Select the line type from the scrollable list. Select a colour from the colour picker.

Note that the items in the list refer to the following line types used by Prefit:

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List Name: Prefit Item: Stringers Splines Grouped Control Points

Spline Control Points

Plates Spline Net

Font / Text Style Font allows you to set the size and style of text used in the windows.

Toolbars See Toolbar Section

Status Bar The Status Bar command makes the Status Bar at the bottom of the screen visible. This Status Bar displays information about the current state of what is being viewed in the window, short descriptions of the functions of some commands as your mouse passes over them and indicates the state of some control keys.

Surface Menu The Surface menu contains commands for fitting a surface to your markers.

Generate Surface Selecting Generate Surface sets Prefit to work generating a surface through the marker spline points.

Regenerate Surface Selecting Regenerate Surface performs a further iteration of the surface fitting algorithm, this will refine the surface net and improve the fit. Modifications to the surface control points may be made prior to selecting Regenerate Surface.

Delete Surface When you select Delete Surface, the surface you have generated is removed from memory permanently.

Measure max. Error This function measures the maximum error between the input marker points and the fitted surface.

Enhance Data This function adds further marker points to the stations. These new points are interpolated along the splines, which have been fitted through the original marker data. This may improve the surface fit.

Control Points Selecting Control Points presents a dialog in which you may specify the details of the surface which Prefit will fit to the markers. You may specify the number of rows and columns of controls to be used in the fitted surface. Rows run transversely and columns run longitudinally through the surface, as in Maxsurf.

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In general it is best to use about the same number of control points as you would use to design the hull in Maxsurf. If more controls are used, the more exact the fit through the markers will be, but with a corresponding reduction in surface fairness. The smoothness of the net generated may also deteriorate to the point that it is unworkable. If too few controls are used, Prefit will not be able to achieve a close fit of the surface to the markers. Constraints may be imposed on the positions of the surfaces control points; see Section: Control Points for further details. The maximum number of iterations used in the surface fitting algorithm and the desired error may also be specified.

Display Menu The Display menu contains commands for turning on and off items displayed in the graphics windows.

Marker Points When the Markers option is activated, the marker points as specified in the Markers window are shown as crosses in all the drawing windows.

Section Splines When the Section Splines option is activated, splines are fitted through the marker points of each section and displayed.

Edge Splines When the Edge Splines option is activated, splines are fitted through the marker points of the top and bottom of the surface and displayed. These splines will normally correspond to the sheerline and centreline of the hull.

Spline Controls When the Spline Controls option is activated, the splines and their control points are generated and displayed through all visible marker points. The splines may then be adjusted by dragging the control points.

Sections Allows you to view all of the sections of the design at the same time.

Shape When the Shape option is selected, the surface will be displayed. It is possible to display the surface being worked on, or the surface control point net. Alternatively, it is possible to show both the shape and the net simultaneously. This allows for the modification of an entire control point net while viewing the changes in the surface itself.

Net The Net display shows the complete control point net for the surface.

Half As the net of control points only needs to exist for one half of a symmetrical shape, the Half function controls whether the shape is mirrored across the longitudinal centreline.

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Units The Units command allows you to nominate the dimension units and the weight units.

Compress By choosing Compress it is possible to foreshorten the display of the surface in the Plan and Profile windows. This foreshortened display is valuable for fairing long slender hulls on screen. The vertical axis is increased relative to the longitudinal axis by a factor of four.

Grid See Grid Submenu

Contours The Contours option allows you to select which contours are drawn on the screen at any given time. Any combination of contours may be chosen from the Contours dialog. When the Sections item is activated, all sections will be shown on the Body Plan and Perspective windows, otherwise only one section will be displayed. This option is useful when modifying the shape in the Body Plan window, as this operation does not require that all sections be shown, which may clutter up the display. See Maxsurf manual for further details.

Render Selecting Render performs hidden line removal on the design with a choice of the type of surface shading used. See Maxsurf manual for further details.

Grid Submenu The Grid submenu allows you to turn on and off some of the grid options.

Hide Grid When Hide Grid is selected, the grid will not be drawn.

Show Grid Only When Show Grid Only is selected, the positions of the Sections, Waterlines, Buttocks and Diagonals as specified by the Grid Spacing function from the Data menu, will be drawn.

Show Grid & Labels When Show Grid And Labels is selected, the names assigned to each grid line in the Grid Spacing option, as well as the grid, will be shown on the screen and printed on any prints or plots.

Data Menu The Data menu contains commands for setting the size of your design.

Units A variety of metric and imperial units may be used in Prefit. This command gives you a dialog box where you may choose your preferred units.

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Irrespective of the default units specified the Markers window will accept dimensional data in any units. For Example, if the default units were metres, all of the following input would be accepted and converted accordingly - 3 (interprets as 3.00 metres)

2.5c 3.25" 33cm 4 inches 328mm 5'4" 650.44mil 11.25feet 6ft 3.1in 5f5I

Grid Spacing This menu function allows you to precisely specify positions for all Waterlines, Buttocks, and Diagonals. Stations are disabled since they are specified by the positions of the defined markers.

Window Menu Selecting item in the Window menu brings the appropriate window to the front on the screen.

Cascade This function stacks up all the currently visible windows into the bounds of the screen in a staggered arrangement.

Tile Horizontal Tiles the open windows horizontally within the application window.

Tile Vertical Tiles the open windows vertically within the application window.

Arrange Icons Arranges the closed windows within the application window.

Perspective A perspective view of the hull.

Plan A plan view of the hull.

Profile A profile view of the hull.

Body Plan A body plan view of the hull.

Markers / Offsets Data Displays the Marker / Offsets data window.

Control Points Displays a window containing the control points of the fitted surface mesh.

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Help Menu Provides access to Prefit Help.

Prefit Help Provides access to Prefit Help.

Online Support Provides access to a wide range of support resources available on the internet.

Check for Updates Provides access to our website with the most recent version listed.

About Prefit Displays information about the current version of Prefit you are using.

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Index

Index Generating a Surface.................................... 11 A Getting Started ............................................... 6

About Prefit.................................................. 29 Grid .............................................................. 27 Add Marker.................................................. 24 Grid Spacing ................................................ 28 Add Station .................................................. 24 H Arrange Icons............................................... 28

Half .............................................................. 27 B Help Menu ................................................... 29 Body Plan..................................................... 29 Hide Grid ..................................................... 27 Bow Shape ..................................................... 3 Home View .................................................. 24

C I Cascade ........................................................ 28 Iterations ........................................................ 9 Check for Updates........................................ 29 L Close Marker Data ....................................... 23 Colour .......................................................... 24 Limits ............................................................. 8 Compress...................................................... 27 M Constraints ..................................................... 9

Marker / Offset Data Window ..................... 20 Contour Toolbar........................................... 21 Marker Points............................................... 26 Contours................................................. 10, 27 Marker, Deleting .......................................... 15 Control Points .............................. 8, 20, 26, 29 Marker, Inserting ......................................... 15 Convergence Limits ....................................... 8 Markers / Offsets Data ................................. 29 Copy............................................................. 23 Markers Table .............................................. 12 Cut................................................................ 23 Markers, Editing .......................................... 13 D Markers, Importing from Text File .............. 16

Data Menu.................................................... 28 Markers, Saving ........................................... 16 Delete Marker .............................................. 24 Measure max. Error ..................................... 25 Delete Stations ............................................. 24 Menus........................................................... 22 Delete Surface.............................................. 25 N Display Menu............................................... 26

Net................................................................ 27 Display Toolbar ........................................... 21 New Marker Data......................................... 22 E O Edge Splines ................................................ 26 Online Support ............................................. 29 Edit Menu .................................................... 23 Open Marker Data........................................ 22 Enhance Data ............................................... 25 Open Text... ................................................. 22 Exit............................................................... 23 Opening a Markers File ................................. 6 F P File Menu..................................................... 22 Page Setup.................................................... 23 File Toolbar.................................................. 21 Pan ............................................................... 24 Fitting a Surface............................................. 4 Paste ............................................................. 23 Fitting Splines .............................................. 10 Perspective ................................................... 28 Flat Bottom .................................................... 9 Plan .............................................................. 28 Flat Side ......................................................... 9 Prefit and Maxsurf ......................................... 3 Flexibility....................................................... 9 Prefit Help.................................................... 29 Font .............................................................. 25 Print.............................................................. 23 G Profile........................................................... 28

Generate Surface.......................................... 25

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Index

R

Regenerate Surface ...................................... 25 Render .......................................................... 27

S

Save Marker Data ........................................ 23 Save Marker Data As ............................... 23 Save Surface As ....................................... 23 Section Splines............................................. 26 Sections .................................................... 9, 26 Selecting a Cell. ........................................... 13 Selecting a Column. ..................................... 14 Selecting a Row. .......................................... 13 Selecting all markers.................................... 14 Set Home View ............................................ 24 Shape............................................................ 26 Shrink........................................................... 24 Spline Controls ............................................ 26 Station, Adding ............................................ 15 Station, Deleting .......................................... 16 Status Bar ..................................................... 25 Stern Shape .................................................... 3 Surface Columns............................................ 9

Surface Menu............................................... 25

T

Text Style..................................................... 25 Tile Horizontal ............................................. 28 Tile Vertical ................................................. 28 Toolbars ................................................. 21, 25 Transverse Splines ......................................... 4

U

Undo............................................................. 23 Units....................................................... 27, 28

V

View Menu .................................................. 24 View Toolbar ............................................... 21

W

Window Menu ............................................. 28 Window Toolbar .......................................... 21

Z

Zoom............................................................ 24

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License & CopyrightContentsAbout this ManualChapter 1 IntroductionPrefit and MaxsurfBow and Stern ShapesTransverse SplinesFitting a Surface

Chapter 2 Using PrefitGetting StartedOpening a Markers FileControl PointsConvergence LimitsIterationsConstraintsFlexibility

SectionsFitting SplinesGenerating a SurfaceCreating a Markers TableEditing MarkersSelecting a CellSelecting a RowSelecting a ColumnSelecting all MarkersInserting a MarkerDeleting a MarkerAdding a StationDeleting a StationSaving a Markers TableImporting Markers From Text File

Chapter 3 Prefit ReferenceWindowsMarker / Offset Data WindowControl Points

ToolbarsFile ToolbarView ToolbarDisplay ToolbarContour ToolbarWindow Toolbar

MenusFile MenuNew Marker DataOpen Marker Data Open TextClose Marker Data Save Marker Data Save Marker Data AsSave Surface AsPage SetupPrintExit Prefit

Edit MenuUndoCut CopyPasteAdd MarkerDelete MarkerAdd StationDelete Stations

View MenuZoomPan ShrinkHome ViewSet Home ViewColourFont / Text StyleToolbarsStatus Bar

Surface MenuGenerate SurfaceRegenerate SurfaceDelete SurfaceMeasure max. ErrorEnhance DataControl Points

Display MenuMarker PointsSection SplinesEdge SplinesSpline ControlsSectionsShapeNetHalfUnitsCompressGridContoursRender

Grid SubmenuHide GridShow Grid OnlyShow Grid & Labels

Data MenuUnitsGrid Spacing

Window MenuCascadeTile HorizontalTile VerticalArrange IconsPerspectivePlanProfileBody PlanMarkers / Offsets DataControl Points

Help MenuPrefit HelpOnline SupportCheck for UpdatesAbout Prefit

Index

prefit manual

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