Design Specifications Recap
- Platform: 40' x 16' Living Area
- Legs: 4x 4' Diameter, 24' Long, Angled 45°
- Material: Duplex Stainless Steel (Pressure Vessel)
- Stability: Tension cables at leg bottoms (inverted catenary style)
- Propulsion: 4x Submersible Mixers (0.5 - 1 MPH)
- Weight: ~36,000 lbs
Recommended Software
Your design is unique because it combines hydrodynamics (how it moves in water) with structural tension (the cables holding the legs out). Standard boat design software often fails to model the cable dynamics accurately. Here are the best tools for the job:
Industry Standard
OrcaFlex (Orcina)
This is the global standard for offshore mooring analysis. It is specifically designed to simulate lines, cables, and risers under tension.
- Best For: Simulating the tension cables at the bottom of your legs and how they react to wave forces.
- Pros: Extremely accurate for cable dynamics; handles 6-degree-of-freedom motion.
- Cons: Expensive license; steep learning curve.
Hydrodynamics
ANSYS AQWA
A powerful suite for analyzing the stability and motions of floating offshore structures in waves.
- Best For: Calculating the drag and wave loads on your 45-degree angled legs.
- Pros: Handles complex geometries (like your dished ends) very well.
- Cons: Very expensive; requires high-end computing power.
Open Source / Advanced
OpenFOAM
A free, open-source Computational Fluid Dynamics (CFD) toolbox. It solves the physics of fluid flow from scratch.
- Best For: Visualizing exactly how water flows around your angled legs and thrusters.
- Pros: Free; unlimited customization.
- Cons: Requires Linux knowledge and coding (C++); no graphical interface for setup.
Accessible
Maxsurf / MOSES
Bentley Systems offers a suite that bridges naval architecture and offshore engineering.
- Best For: General stability (will it capsize?) and resistance (how much power to move?).
- Pros: Easier to learn than ANSYS; good for initial hull sizing.
- Cons: Less capable with the complex cable dynamics than OrcaFlex.
Engineering Considerations for Your Design
The "Angled Leg" Challenge:
Because your legs are at 45 degrees, they act as struts. When a wave hits the platform, it pushes the platform sideways. Your cables must resist this. However, because the legs are angled, a vertical wave motion (heave) will try to compress or extend the legs, putting massive stress on the cables. You need software that can simulate Coupled Dynamics.
Suggested Workflow
- Model the Geometry (CAD): Use Fusion 360 or SolidWorks to build the exact 3D model of the platform and angled legs.
- Hydrostatics (Stability): Import that model into Maxsurf to ensure the center of gravity is low enough and the buoyancy of the 4 legs supports the 36,000 lbs properly.
- Motion Analysis (The Critical Step): Use OrcaFlex. You can import the hydrodynamic data from step 2. In OrcaFlex, you will model the cables as "lines" with specific elasticity. You can then run a simulation with "Irregular Waves" (simulating real ocean chop) to see if the cables snap or if the platform pitches dangerously.
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