- Table of Contents
- 1. Introduction
- 1.1. About Sailcut CAD
- 1.2. Technical info
- 2. Installation
- 3. Using Sailcut CAD
- 4. Questions and Answers
- 5. Copyright
1. Introduction
1.1. About Sailcut CAD
Sailcut is a software for designing boat sails and developing then into flat panels. Sails can be either 4 sided main sails for old timer gaff rig or 3 sided sails like jibs or main sails for Marconi rig.
The first version of Sailcut was developed in 1978 and used by Robert Lainé for making the sails of his IOR 1/4 ton named "Flying Sheep III". Sailcut has been available on the web since 1994 and is used by many professional and amateur sail makers for offshore racing, cruising and recently for model yacht.
Sailcut uses a unique mathematical definition of the surface of the sail which ensure that the sail is smooth and aerodynamic.
1.2. Technical info
Sailcut CAD is written with portability in mind. As such it is written in C++ and uses the Qt library from Trolltech for the graphical user interface. Sailcut CAD uses OpenGL to display the 3D view of the sail. Sailcut CAD is known to compile and run on GNU/Linux, Windows and MacOS/X.
2. Installation
2.1. How to obtain Sailcut CAD
You can download the latest version of Sailcut CAD from the project's home page, http://sailcut.sourceforge.net/. Sailcut CAD is made available both in binary (compiled for you) and in source code form.
2.2. Compilation requirements
Sailcut builds on both POSIX (e.g. GNU/Linux, MacOS/X) and Windows platforms.
on POSIX systems, you need a C++ compiler and the Qt toolkit.
on MacOS/X systems, you will also need to get hold of the Fink package system which is available from http://fink.sourceforge.net/
on Windows systems, you need Microsoft Visual C++ 6 and the Qt Non-Commercial toolkit which can be found at http://www.trolltech.com/ in the download section.
You will need OpenGL support on your system to run Sailcut CAD.
2.3. Compilation and installation
2.3.1. Compiling on POSIX systems
Since Sailcut CAD uses autoconf you should have no trouble compiling it. In order to compile and install Sailcut CAD on your system, type the following in the base directory of the Sailcut distribution:
% ./configure
% make
% make install
2.3.2. Compiling on MacOS/X
Sailcut CAD is known to compile and run when using the Fink package manager. In order to compile and install Sailcut CAD on your system, type the following in the base directory of the Sailcut distribution:
% ./configure --with-qt-includes=/sw/include/qt
% make
% make install
2.3.3. Windows systems
A Microsoft Visual C++ 6 project file is included with the distribution. You can just open this file and compile the project, using either the “Debug” or the “Release” profile. Please note that the “Debug” profile is considerably slower than the “Release” one which is used for the official Sailcut CAD releases!
3. Using Sailcut CAD
3.1. Upgrade notes
As of release 0.6.5, Sailcut CAD uses different extensions for each file type instead of ending all files with “.xml”. If you wish to open sails created with a previous version of Sailcut CAD you should rename your sail definition file so that it ends with “.saildef”. When opening the resulting file, all data except for the mould will be preserved. Redefine your sail mould, then save the file.
3.2. User preferences
3.2.1. Preferences file
Your preferences are stored in a file called “.sailcutrc”. On UNIX-like platforms, this file is located in your home directory. On Windows this file is located in “C:\”.
3.2.2. Internationalisation
As of release 0.5.5, Sailcut CAD has support for internationalisation. Full translations of the user interface in French, Dutch, German, Italian and Norwegian are currently provided. On startup, Sailcut selects the language corresponding to your locale. You can use the View->Language menu entry to switch to another language.
3.3. Creating a sail
When you start Sailcut CAD, you are presented with a default sail. At the top of the window you will find a number of roll down menus. The File menu is used for loading an existing sail, saving the parameters of the sail and Export the developed panels.
You can modify the dimensions of the sail by using the View->Dimensions menu entry.
You can modify the profile of the sail through the View->Mould menu entry.
You can display several sails on the same rig through the View->Rig menu entry.
3.3.1. Dimensions dialog (View->Dimensions menu)
The program is tailored to design either triangular or quadrangular boat sails. A classical triangular sail is essentially a quadrangular sail with a very small top edge.
The surface of the sail is generated from a single set of equations defining the profile of the sail at all levels. The profiles rest on the edges of the sails which are defined by their length and the amount of round (also called roach) in each side and the twist of the sail. The “Dimensions” window is divided into a number of boxes which group the parameters defining the sail.
When you have finished entering the dimensions, press OK to display the sail in 3D.
3.3.1.1. “Rig geometry” box
The first step is to select the type of sail you are going to work on, and enter the data defining the rig geometry and sail plan (see figure for sail plan definition).
Select the type of sail by pressing the corresponding Radio Button:
Jib for any sail which will be set on a stay,
Mainsail for any sail set on a mast,
Wing for any type of kite symetrical about the foot.
The rig data are used for displaying the sails in their proper relative position with the rig viewer.
3.3.1.2. “Sail dimensions” box
This is where the dimensions of the sail are entered.
On a main sail the minimum value for the gaff length (headboard) is constrained to 5 mm. Value smaller than that will default back to 5 mm. The gaff angle is constrained to values such that the angle between the gaff and the straight leech is at most 90 degrees.
Positive round (roach) of the luff, foot, leech and gaff extend the sail outside of the straight line.
Negative round is equivalent to hollowing that edge of the sail.
The position of the round or roach is expressed in percentage of the side length starting from the lower or most leftward end of that edge.
Dimensions and angles defining the sail plan are expressed in millimetre and degrees.
Length of the sail sides and diagonal are the 3D straight line distance between the corners of the sail.
The actual length on the finished sail lais on the floor can be slightly longer depending on the shape of the sail. For example, the foot length entered in the screen below is 3600 mm. If the foot camber is null then that will be the actual distance between clew and tack (straight foot) of the finished sail. If a 10% camber is entered for the foot depth, then the actual foot will be the length of the arc which has 10% camber, that is 2.7% longer than the straight line foot length.
3.3.1.4. “Sail shape” box
Enter there the depth of the sail at 3 levels.
The twist angle is the angle expressed in degrees by which the top of the sail is rotated with respect to the foot. The twist is globally determined by the amount by which the apparent wind at the top of the mast is rotated with respect to the apparent wind at deck level. For a jib the twist is sometime driven by the need to have the upper part of the leech sufficiently open to clear the spreaders. For a mainsail the twist is also driven by the ability of the rig to carry the tension in the leech, in particular a gaff rig will have more twist in its main sail than a Bermuda rig. It is important that the twist angle entered in Sailcut reflects the reality of the shape of the leech when sailing in an average wind.
The sheeting angle value is the actual sheeting angle measured from the boat centerline when the sail is set on the boat. For a jib the minimum value is 5 degrees. The value is of importance to ensure that the sail is properly position when displayed in the rig viewer.
3.3.1.5. “Cloth” box
Enter there the width of cloth used, the width of the seams between adjacent panels, the width of material to be added to the leech to make the leech hem and the width of material for the other edges hems. The figure below describes de location of the various hems and seam width.
Sailcut will compute the panels such that they fit in the declared cloth width including the seam and hems width as appropriate.
3.3.2. Mould dialog (View->Mould menu)
The depth of the sail can be entered at three levels located at the bottom (foot) the middle (maximum depth level) and near the top.
The vertical position of the maximum depth profile is controlled by the vertical slide bar to the right of the left vertical frame.
The luff shape and the leech shape can be adjusted for the Top profile and Middle profile only. The foot profile is always an arc of circle.
In order to avoid that the leech makes a hook in the upper part of the sail when the wind increases it is recommended that the Top profile luff shape value be higher than that of the middle profile and that the leech shape value at the top be lower than the middle value.
3.3.3. Rig viewer (View->Rig menu)
This viewer is used to display several sails on the same rig.
The File->Add sail menu entry is used to purge the viewer.
The File->Add sail menu entry is used to add sails already created and saved with Sailcut.
Once a sail is added to the rig viewer the sail information frame appears below and it is possible to translate the sail in the 3 directions by adding X-Y-Z displacement values. If you have misplaced a sail use the Reload button to recover the initial sail. You can also use the Remove button to eliminate a sail. 2 slides allows you to ratate the rig in azimuth and elevation and view the ig from any vantage point.
The File->Save menu entry is used to save a rig with a combination of sails.
Rigs which have been saved can be later opened as an entity with File->Open menu entry.
Note that the rig viewer must be close to allow you to return to the main screen of Sailcut.
3.4. View controls
It is possible to zoom, pan and rotate the sail in the view window:
rotation : you can control the rotation that is applied to the sail by using the elevation and azimuth sliders.
pan : clicking on a point with the left mouse centers the view on that point.
zoom : to zoom in press CTRL and + and to zoom out press CTRL and -. You can also use the zoom buttons in the view controls or your mouse wheel to zoom in and out.
3.5. Panel development (File->Export development menu)
It is possible to view the developed sail by clicking on the “Development” tab from Sailcut CAD's main window. This presents you with a view of the developed (flat) panels of the sail. The view controls are the same as those of the main window. The blue line represents the edge of the finished panel (draw line) and the red line represents outer edge taking into account the seam and hem width allowance (cut line).
You can export the points which define the edges of the developed panels with the draw and cut lines to the following file formats:
Carlson Design plotter (.sp4) using File->Export development->to Carlson plotter
AutoCAD DXF using File->Export development->to DXF
XML dump of the points using File->Export development->to XML sail
plain text dump of the points using File->Export development->to TXT sail
3.6. Loading / saving sails
Once you have customised you sail, you can save it to a file (File->Save or File->Save As) and load it (File->Open) next time you want to work on it. Both the sail's dimensions and the parameters of the mould are saved.
Sailcut CAD uses XML files to store the sail data. These files are plain text so they can easily be viewed using your favourite text editor.
3.7. Exporting 3D sails (File->Export 3D sail menu)
On top of Sailcut CAD's native file format it is possible to export the points of the edges of the panels that make up a sail. You export the three dimensional sail to the following file formats:
AutoCAD DXF using File->Export 3D sail->to DXF
XML dump of the points using File->Export 3D sail->to XML sail
plain text dump of the points using File->Export 3D sail->to TXT sail
4. Questions and Answers
4.1. Where can I find more information about Sailcut CAD?
The Sailcut CAD project lives at http://sailcut.sourceforge.net/. This is where you will find links to all matters related to Sailcut CAD!
4.2. I think I found a bug, what should I do?
Sailcut CAD is constantly under development and feedback from users is very welcome! If you think you found bug, visit Sailcut's homepage , you will find instructions in the “Reporting a Bug” section.
4.3. I would like to help develop Sailcut CAD, what should I do?
You can help us improve Sailcut even if you are not a programmer! Simply using Sailcut and reporting any bugs you might find is of considerable help to us. We are also looking for people to help keep translations up to date and to produce new translations. If you are interested in translating Sailcut into your native language, visit the Sailcut CAD homepage and send an email to the development mailing list!
If you have some knowledge of C++ and are interested in making Sailcut CAD a better program, visit the Sailcut CAD homepage where you will find both snapshots of the Sailcut CAD code and how to access to the CVS repository. Once you have had a chance to familiarise yourself with the code, contact us via the forums or our mailing lists!
5. Copyright
Copyright (C) 1993-2005 Robert & Jeremy Lainé.
Sailcut is a Registered Trademark of Robert Lainé.
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. See http://www.fsf.org/ for details.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
The authors would appreciate that publications on sails designed with Sailcut include some acknowledgement of their work.