For your specific needs—simulating a seastead with articulated legs, cables, and pivot points in waves to detect snap loads—Project Chrono is the strongest open-source candidate.
While Capytaine + MoorDyn is excellent for traditional moored structures, your design functions more like a mechanism (a "reverse tension leg platform") where the legs move relative to the platform. Project Chrono is built specifically to handle these mechanical joints and cable dynamics simultaneously.
| Software | Best For | Joints/Pivots | Cable Physics | Learning Curve | Accuracy |
|---|---|---|---|---|---|
| Project Chrono | Mechanisms, Vehicles, Complex Couplings | Excellent | FEA Cables (High Accuracy) | Moderate | High |
| Capytaine + MoorDyn | Standard Floating Bodies & Moorings | Difficult | Dynamic Mooring Lines | Moderate | High |
| WEC-Sim | Wave Energy Converters (MATLAB) | Good | MoorDyn Integration | High (Cost) | Industry Standard |
| DualSPHysics | Violent Waves, Flooding, Impact | Possible | Basic | High | Very High (CFD) |
| Blender | Visualization & Animation | Animation Rigging | Game Physics Only | Low | Low |
Status: Recommended
Project Chrono is a physics engine primarily designed for multi-body dynamics. Unlike standard marine software that assumes the vessel is a rigid block, Chrono excels at simulating mechanisms—exactly what your articulated leg design requires.
HdroChrono module couples the rigid body physics with wave forces (using a simplified potential flow solver or imported coefficients).Example Video: Project Chrono Ocean Simulation (Shows a floating structure in waves).
Status: Possible, but requires custom integration
Capytaine is a fantastic Python library for calculating hydrodynamic coefficients (how water moves around the hull). MoorDyn is the standard for simulating mooring lines. They are often used together for floating wind turbines.
Capytaine assumes the floating body is rigid. To simulate your legs moving independently (pivoting), you would have to write your own physics engine in Python to handle the joint rotations and then feed those forces back into Capytaine. This is complex engineering work.
Example Video: Capytaine Simulation Example.
Status: Not Open Source (Requires MATLAB)
WEC-Sim (Wave Energy Converter SIMulator) is developed by NREL and Sandia National Labs. It is perfect for your needs technically—it handles rigid bodies, joints, and cables (via MoorDyn) very well.
Since you are not a student, you need a commercial license.
This is likely too expensive for the brainstorming phase, though it is the "correct" industry tool.
Example Video: WEC-Sim Wave Tank Test.
Status: High visual fidelity, steep learning curve
This is a Smoothed Particle Hydrodynamics (SPH) solver. It simulates actual water particles.
Recommendation: Use this later when your design is finalized and you want to test it against a "100-year storm" wave. Use Project Chrono for the initial cable/pivot brainstorming.
Example Video: DualSPHysics Floating Body.
Status: Not Recommended for Engineering
Blender is a fantastic tool, but its "Cloth" and "Soft Body" simulations are designed for visual effects (movies/games), not engineering.
However, once you run a simulation in Project Chrono, you can import that data into Blender to make a beautiful movie of your seastead.
ChLinkLockSpherical or ChLinkRevolute to connect the top of the legs to the platform corners. This replicates the pivot point you described.ChElementCableANCF to define the cables running from leg bottom to leg bottom.This approach allows you to use your AI coding assistants effectively to write the Python script, while relying on a physics engine that honors real-world mechanical constraints.