MoorPy
MoorPy is an open-source quasi-static mooring toolset that can be used for a variety of mooring system applications. It is under ongoing development at NREL and publicly available under an open-source license at github.com/NREL/MoorPy.
See the pages on this site for information about the operation, usage, and theory of MoorPy.
Overview
MoorPy is a quasi-static mooring model and a suite of associated functions for mooring system analysis. The core model supports quasi-static analysis of moored floating systems including any arrangement of mooring lines and floating platforms. It solves the distributed position and tension of each mooring line segment using standard catenary equations. Floating platforms can be represented with linear hydrostatic characteristics. MoorPy automatically computes a floating system’s equilibrium state and can be queried to identify a mooring system’s nonlinear force-displacement relationships. Linearized stiffness matrices are efficiently computed using semi-analytic Jacobians. MoorPy also includes plotting functions and a library of mooring component property and cost coefficients. MoorPy can be used directly from Python scripts to perform mooring design and analysis tasks, or it can be coupled with other tools to compute quasi-static mooring reactions as part of a larger simulation.
Citation and References
The MoorPy software record can be cited as
M. Hall, S. Housner, S. Sirnivas, and S. Wilson. MoorPy: Quasi-Static Mooring Analysis in Python. National Renewable Energy Laboratory, 2021. doi.org/10.11578/dc.20210726.1.
The core MoorPy theory is described in
M. Hall. “Generalized Quasi-Static Mooring System Modeling with Analytic Jacobians.” Energies 17 (13), 3155. doi.org/10.3390/en17133155.
Some of the theory behind additional MoorPy capabilities related to rope elasticity, current loads, seabed slope, and frequency-domain reponse can be found in the following papers:
M. Hall, B. Duong, E. Lozon. “Streamlined Loads Analysis of Floating Wind Turbines With Fiber Rope Mooring Lines” in Proceedings of the ASME 2023 5th International Offshore Wind Technical Conference. https://docs.nrel.gov/docs/fy24osti/87481.pdf
M. Hall, W. West, S. Housner, E. Lozon. “Efficient Modeling of Floating Wind Arrays Including Current Loads and Seabed Bathymetry” in Proceedings of the ASME 2023 5th International Offshore Wind Technical Conference. https://docs.nrel.gov/docs/fy24osti/87475.pdf
S. Abdelmoteleb, E. Bachynski-Polić, “A frequency-domain optimization procedure for catenary and semi-taut mooring systems of floating wind turbines.” Marine Structures, Volume 101, 2025, 103768, https://doi.org/10.1016/j.marstruc.2024.103768.
Information about cost coefficients recently added to MoorPy can be found in