Seastead Wave Simulation: Software Comparison & Recommendation

You are looking for the "Sweet Spot" between engineering accuracy (to detect cable snap loads) and ease of use/visualization (to understand the design). Based on your specific requirements (Linux, GPU, Python/AI assistance, cable dynamics), here is the breakdown of the best open-source options.

1. Executive Summary: The Winner

🏆 Top Recommendation: Project Chrono (specifically Chrono::FSI)

Why: It is the only free, open-source engine that natively combines Rigid Body Dynamics (your platform), Cable Dynamics (your mooring lines with tension/slack), and Hydrodynamics (waves/buoyancy) in a single physics engine.

AI Compatibility: High. Since it has Python bindings (pychrono), Cursor.ai and Claude Code can write the setup scripts for you effectively.

Visualization: Built-in 3D viewer (Irrlicht) allows you to watch the simulation in real-time.

2. Detailed Comparison Table

Software	Physics Accuracy	Cable/Snap Load Accuracy	Learning Curve	Est. Time to First Sim	Visualization
Project Chrono (Python Bindings)	High (Multibody + Hydro)	Excellent (FEA Cables)	Steep	2-4 Weeks (with AI help)	Good (Real-time 3D)
Capytaine + MoorDyn	Medium (Linear Potential Flow)	Good (Quasi-static)	Medium	1-2 Weeks	Poor (Requires export to ParaView)
DualSPHysics	Very High (SPH Fluid)	Medium (Coupling is complex)	Very Steep	1-2 Months	Post-Processing Required
Blender (Mantaflow/Rigid Body)	Low (Game Physics)	Poor (Unstable tension)	Low	2-3 Days	Excellent
WEC-Sim (MATLAB)	High	Excellent	High	N/A (Cost Prohibitive)	Good (Simulink 3D)

3. Deep Dive: Project Chrono (The Best Fit)

Project Chrono is a C++ library with Python bindings. It is used by NASA and automotive engineers. It handles the exact physics problem you described: a floating body connected by tension-only elements (cables) in a fluid environment.

How it works for you: You define your 4 legs as rigid bodies. You define the cables using the ChElementCableANCF or similar beam/cable elements which calculate tension based on stretch. You apply hydrodynamic forces (buoyancy + drag + wave excitation) to the submerged parts.
The "Snap Load" Factor: Unlike game engines, Chrono calculates the actual derivative of tension. If a cable goes slack and then snaps tight, Chrono captures the shock load accurately.
AI Implementation: You can ask Cursor.ai: "Write a PyChrono script that creates a rigid box, attaches 4 cables to the corners, and applies a sinusoidal vertical force to simulate waves."

Example Search: Search "Project Chrono FSI" on YouTube

4. Deep Dive: Capytaine + MoorDyn (The "Naval Architect" Approach)

This is the standard open-source workflow for floating structures, but it has a limitation for your specific brainstorming phase.

Capytaine: Calculates how waves push the hull (Hydrodynamics). It uses Linear Potential Theory. This assumes small motions. If your seastead tilts 20 degrees, Capytaine's math breaks down.
MoorDyn: Calculates the cable forces. It is excellent for this.
Verdict: Great for checking if the design floats in calm water or small chop. Bad for checking what happens in a storm when the legs might emerge from the water or cables go violently slack.

Example Search: Search "Capytaine MoorDyn" on YouTube

5. Deep Dive: DualSPHysics (The GPU Powerhouse)

Since you have a Linux machine with a good GPU, this is technically the most accurate for fluid behavior (splashing, water hitting the underside of the deck).

Pros: It simulates every particle of water. It handles the "slamming" of the platform onto waves perfectly.
Cons: It is very hard to set up cables. You usually have to couple it with another code (like Chrono or Project Chrono) to handle the cable physics. It is overkill for the "brainstorming" stage.

Example Search: Search "DualSPHysics Floating" on YouTube

6. Why NOT Blender? (Important Warning)

Do not use Blender for engineering decisions regarding cable snap loads.

Blender's physics engine (Bullet/Mantaflow) is designed for movies, not engineering.
1. Cable Physics: Blender cables often "explode" or stretch unrealistically under high tension. They do not accurately model the "stiffness" required to calculate a snap load.
2. Buoyancy: Blender does not have native, accurate hydrostatics. You have to fake it with force fields, which will not react correctly if the leg tilts 45 degrees.
3. Result: You might get a pretty video, but if the video says "this cable holds," the real cable might snap immediately.

7. Implementation Plan with AI (Cursor.ai / Claude)

Since you want to use AI to speed this up, here is the recommended workflow using Project Chrono:

Install PyChrono: pip install pychrono
Prompt Strategy: Don't ask for the whole seastead at once. Break it down.
- Step 1: "Create a PyChrono simulation with a rigid box floating in water. Apply buoyancy forces based on submerged volume."
- Step 2: "Add 4 cable elements connecting the box corners to fixed points below. Ensure cables only exert tension."
- Step 3: "Apply a sinusoidal wave force to the box to simulate heave and pitch."
- Step 4: "Log the maximum tension in the cables and visualize the system using ChIrrApp."
Visualization: Use the built-in Chrono visualization window. It is not "Pixar quality," but it shows wireframes and movement in real-time, which is perfect for debugging physics.

8. Cost Estimate for MATLAB (Anguilla)

You asked about WEC-Sim costs. For a non-student in Anguilla (assuming standard international commercial pricing):

MATLAB Base: ~$2,300 USD / year
Simulink: ~$1,100 USD / year
Simscape Multibody: ~$1,100 USD / year
Total: ~$4,500+ USD per year.

Verdict: Definitely stick to Open Source (Chrono) for this stage.

Conclusion

For a seastead design where cable integrity and stability are the main concerns, Project Chrono is the correct engineering tool. It is free, runs on Linux, handles cables and fluids, and is scriptable via Python for use with AI assistants.