Seastead Ocean Wave Simulation Software Recommendations

Design Summary (for Modeling): 40x16 ft living platform (above water), 4x 4ft dia. x 24ft long duplex SS legs at 45° (12ft submerged), bottoms form 50x74 ft rectangle. Cables: 2 per leg bottom to adjacent corners + perimeter rectangle. Weight: ~36,000 lbs. Thrusters: 4x 2.5m prop submersible mixers. Pressurized 10 psi. Semi-submersible "tiny oil platform" profile (low drag).

Note: These tools can model your geometry, waves (e.g., JONSWAP, irregular seas), motions (6DOF), moorings/cables, buoyancy, and thrusters. Full fidelity requires geometry import (e.g., STEP/IGES from FreeCAD). I can't run simulations here but provide ready-to-use model guidance, sample inputs, and links. Commercial tools often need licenses (~$10k+/yr); free options are capable for prototypes.

Top Recommendations

1. OrcaFlex (Best Overall for Seasteads/Offshore Platforms)

Orcina OrcaFlex - Industry standard for floating structures, moorings, waves. Handles your braced legs, cables, buoyancy, thrusters perfectly. Simulates RAOs, extreme waves, drift.

Pros: User-friendly GUI, full 6DOF hydrodynamics, cable dynamics, thruster models, validation against oil platforms.
Cons: Commercial (~£10k license). Free demo available.

Quick Model Setup:

Geometry: Model platform as vessels (40x16ft), legs as line buoys/tubes (4ft dia., 24ft @45°), bottoms as point buoys connected by catenary cables (specify EA=high for SS).
Buoyancy: Set leg volumes (π*(2)^2*24 ≈ 300 cu ft/leg submerged = ~15k lbs buoyancy/leg @62.4 lb/ft³).
Waves: Irregular spectra, Hs=2-10m.
Download demo: Here. Tutorials: Mooring systems match your cable setup.

2. ANSYS AQWA (Professional Hydrodynamics)

ANSYS AQWA - Full offshore suite: diffraction, mooring, dynamics. Ideal for semi-submersibles like yours.

Pros: Accurate panel methods, nonlinear hydro, fatigue. Integrates with Workbench for geometry.
Cons: Expensive (enterprise license).

Quick Model: Import FreeCAD STEP file (legs as cylinders, platform as plate). Add hydrodynamic DB, cable constraints. Free student version limited.

3. OpenFOAM + waves2Foam (Free, High-Fidelity CFD)

OpenFOAM with waves2Foam - Free CFD for waves + floating bodies. Simulate viscous drag, waves, 6DOF motion.

Pros: Free, customizable (add thrusters as actuators), parallel compute. Tutorials for barges/platforms.
Cons: Steep learning curve, mesh-heavy.

Sample Case Setup (Copy-Paste Ready):

Download: OpenFOAM v10+, install waves2Foam.
Geometry: Use blockMesh for platform/legs or snappyHexMesh from STL (generate in FreeCAD).

0/ directory snippet for 6DOF body (platform):

platform
{
    type            rigidBody6DoFRigidBodyMotion;
    mass            36300; // lbs to kg ~16465 kg
    centreOfMass    (0 0 2); // adjust
    momentOfInertia (1e6 1e6 1e6); // estimate
    acceleration    (0 0 -9.81);
    // Add wave boundaries
}

Tutorial: floatingSphere6DoF - adapt for your quad-legs. Cables via dynamicMesh.
Video Guide: YouTube.

4. WEC-Sim (Free for Wave Energy/Floating Structures)

WEC-Sim (MATLAB/Simulink) - NREL tool for floaters/moorings. Handles multi-body like your legs+cables.

Pros: Free (MATLAB needed), PTO/thruster models, BEM integration (Nemoh).
Cons: MATLAB license (~$150/yr student).

Model: Bodies: platform + 4 legs (cylinders). Moorings: 8 radial cables + perimeter. Nemoh for hydro coeffs.

5. Nemoh (Free BEM Hydrodynamics)

Nemoh - Quick RAO/motions calculator. Pre-step for above tools.

Pros: Free, fast panel method. Export to OrcaFlex/OpenFOAM.
Cons: Linear waves only, no viscous/cables.

Model panels for legs/platform mesh. Sample .sto file available in repo.

Simple 3D Visualization of Your Design (SVG Side View)

FreeCAD Model File Snippet (Export to STEP/STL)

Download FreeCAD. Create:

Part → Cylinder: dia=4ft=1.22m, h=24ft=7.32m → Position at 45° (rotate X=45°).
Duplicate x4 at corners (spacing: width=50ft/2=25ft from center, length=74ft/2=37ft).
Box for platform: 40x16x4ft.
Export STEP for AQWA/OpenFOAM.

Full macro script available in FreeCAD Python console for automation.

Next Steps

Start with OpenFOAM (free) or OrcaFlex demo.
Geometry: FreeCAD → Export.
Test: 2m Hs waves, check heave/pitch <10% platform height.
Validate buoyancy: Total ~1200 cu ft submerged → 75k lbs lift >36k lbs weight (stable).
Community: Seasteading Forum or CFD-Online.

Last Updated: 2023. Contact for custom tweaks.