Program UliSail

The third module in the workflow is the simulation of the rig. Classical wing theory can be used to calculate the forces acting on the sails. The theory relies on the input of the aerodynamic characteristics of the 2D sail sections. As a prerequisite, the program XFOIL was used to create a database of discrete values of the required coefficients. The theoretical background can be found in this report. A program Sail2D was written that interpolates in the database. It can be downloaded here. With these coefficients Prandtl's lifting-line method can be used to calculate the 3D-flow around head- and mainsail. Each sail is divided into 31 panels. The designer will get a detailed distribution of angles of attack and force coefficients across all panels. It is possible to optimize the trim parameters for maximum driving force. The theory and the validation of the program are described in this report. Please use the latest version 3.3, as it contains several improvements and error-corrections.

Details of the program are explained in the user's manual that can be downloaded here:
UliSail User's manual:           pdf

A zipped file with the executable program UliSail_3.3 can be downloaded here        Download Sail2D  (click on picture)

If you need a CAD-model of your sails, created with UliSail, you can send an e-mail to: ulrich(at)

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