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Hydrodynamic coefficients viewer and converter for Boundary Element Method solver formats.

License: GPL v3 Platforms Build status Last commit

Boundary Element Methods are extensively used to model hydrodynamic forces in offshore devices like ships, offshore wind platforms and wave energy converters. These solvers use device geometry mesh to get some hydrodynamics coefficients as radiation damping, added mass, wave diffraction force, and wave excitation force. All these data is saved in file formats incompatible between them. These may avoid to use the coefficients between programs.

BEMRosetta allows to load the hydrodynamic coefficients from a format saving it in another. In addition it allows to compare the results obtained between programs, the results between similar geometries and the same geometry with different discretization levels.

Moreover, BEMRosetta allows to view and visually compare the meshes from different programs.

BEMRosetta runs on Windows and Linux, no install is necessary in Windows (see Install), and it includes a GUI, a command line version and a library (DLL).


- Supported file formats

  • BEM coefficients

    • Load-View
      • Wamit: .out, .3sc, 3fk, .1, .3, .4, .hst, .12s, .12d
      • HAMS:
      • Nemoh and Capytaine:, Mesh/Hydrostatics*.dat, Mesh/KH*.dat, RadiationCoefficients.tec, ExcitationForce.tec, DiffractionForce.tec, FKForce.tec, IRF.tec
      • FAST-Wamit: HydroDyn.dat, .1, .3, .hst, .ss, .12s, .12d
      • SeaFEM-Nemoh: .flavia.inf, RadiationCoefficients.tec, ExcitationForce.tec, DiffractionForce.tec, FKForce.tec
      • Ansys AQWA: .lis, .ah1, .qtf
      • FOAMM: .mat
    • Save
      • Wamit: .out, .1, .3, .hst, .4, .12s, .12d
      • HAMS: and all the folder structure.
      • FAST-Wamit: HydroDyn.dat, .1, .3, .hst, .ss, .12s, .12d
      • Other solvers that may use these files: Bladed, Orcaflex
  • Case files

  • Mesh files

- Load the hydrodynamic coefficients from one format and save them in another

The goal is to have a good robustness in the handling of files

- Compare the hydrodynamic coefficients for the same geometry from different software

  • Damping for the same geometry got from different solvers

  • Excitation force for the same geometry got from different solvers_

- Forces handling

It simmetrizes the available forces in all directions, averaging them when they are available on both possitive and negative headings. Some examples cases:

  • Only the forces on positive headings from 0 to 180º have been processed: Symmetrize duplicates them to the negative heading values from 0 to -180º
  • Both positive and negative headings forces have been processed: Symmetrize averages them

- Compare the hydrodynamic coefficients for the same geometry for different discretization levels

- Compare the hydrodynamic coefficients for different geometries

  • Damping for different offshore wind floating platforms_

  • Excitation force for different offshore wind floating platforms_

- FOAMM connection

Finite Order Approximation by Moment-Matching (FOAMM) is an application developed by N. Faedo, Y. Peña-Sanchez and J. V. Ringwood in the Maynooth University's Centre for Ocean Energy Research (COER), that implements the moment-matching based frequency-domain identification algorithm.

BEMRosetta allows an interactive and seamless FOAMM connection to get state space coefficients.

- Mesh loading, combining them for visual comparison

Several meshes can be loaded in this basic viewer, allowing a visual comparison of geometries.

- Mesh handling

  • Interactive mesh rotation and translation around user defined center
  • Automatic free surface, underwater surface, center of buoyancy, hydrostatic stiffness matrix, and other parameters calculation
  • Improved viewer including dropdown menu in viewer screen
  • Hydrostatic stiffness matrix viewer
  • Mesh healing option

- Case launcher, Nemoh & HAMS

Added Nemoh and HAMS launcher. It can loadexisting files from HAMS, Nemoh or ANSYS AQWA, it lets you editing it, and creates the set of files to launch Nemoh and HAMS from a .bat file (it replaces the classic Nemoh MATLAB launcher)

- Bonus

BEMRosetta now includes an OpenFAST .out/.outb file reader, designed to be very easy to use. It includes an online mode for updating the plot while the simulation is in progress. Files may be opened by drag and drop, and parameters are filtered by name or units.

- Other

All files, mesh, case or BEM files, can be loaded by Drag and Drop or Copy and Paste from file explorer in Windows and Linux.


J. C. C. Portillo, J. C. C. Henriques, M. J. Sanchez-Lara, J. Galvan, A. Otter, M. Alonso, A. Aristondo.
Some file parsing strategies taken from the BEMIO project.
Done with the U++ multiplatform library.


Copyright © 2019-2021 Iñaki Zabala, Markel Peñalba, Yerai Peña-Sanchez, Thomas Kelly.

BEMRosetta 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 3 of the License, or (at your option) any later version.
BEMRosetta 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 details. You should have received a copy of the GNU General Public License along with BEMRosetta. If not, see
Rosetta stone image from The pictures are free for personal and even for commercial use. You can modify, copy and distribute the vectors on The Rosetta Stone in All without asking for permission or setting a link to the source. So, attribution is not required.