**Yes — here is a ready-to-use HTML page** that explains the best current options (open-source + low-cost commercial) and includes an **interactive weight-estimator** tailored to your exact seastead description. Copy the entire code below into a file called `seastead-design-tool.html` and open it in any browser. ```html Seastead Design & Weight Estimator (Open Source Focus)

Seastead Structural Design & Weight Estimator

Your exact geometry (80 ft triangle, 19 ft NACA legs, 14×45 ft living module, stabilizers, RIB davits, etc.)

Recommended Software (2025)

Software	Type	Open Source?	Best For Your Use Case	Learning Curve
FreeCAD + Ship / Hull workbench + Arch	Full parametric CAD + FEM	Yes (LGPL)	Best overall choice. Can model truss, NACA foils, living module, calculate weights and CoG automatically.	Medium
Python + OpenSees / CalculiX + CadQuery / Build123d	Scripting + FEA	Yes	Perfect for rapid design iteration and automatic weight reports. You describe the triangle once and change spacing/foil depth in one line.	Medium-High
Blender + BlenderBIM + custom Python add-on	3D modeling	Yes	Good for visualization and quick mass estimates. Not ideal for marine structural engineering.	Low
MAESTRO (academic license) or Orca3D + Rhino	Naval architecture	No	Industry standard for hull + structure weight. Expensive but very accurate stability & weight tracking.	High
ANSYS AQWA / Siemens Simcenter	Professional	No	Only if you get university or startup licensing.	Very High

Recommended starting path: Install FreeCAD 0.21+ with the Ship, Lattice2, and Arch workbenches + a small Python macro that outputs a Bill of Materials (BOM) in CSV with marine aluminum 5083-H321 and 6061-T6 properties already built in.

Interactive Seastead Weight Estimator (Marine Aluminum 5083/6061)

Change any value below and click Calculate.

Triangle length (front to back, ft):

Triangle width (ft):

Truss height (floor-ceiling, ft):

Leg length (ft):

Leg chord (ft):

Leg thickness / max width (ft):

Living module length (ft):

Living module width (ft):

Aluminum density (lb/ft³) — 5083:

Stabilizer count:

Sample Python / FreeCAD Automation Snippet

# Example using build123d (pure Python, open source)
from build123d import *
from ocp_vscode import show

# Define your triangle truss once — change numbers and everything updates
tri = RegularPolygon(40/2, 3)  # 40 ft wide
legs = [Box(10, 3, 19) for _ in range(3)]   # NACA approximation
# ... add truss members with Lattice2 style or parametric beams
# Export BOM with mass properties automatically

Would you like me to generate a complete FreeCAD Python macro or a full build123d script that models your exact 80×40 ft triangle, the three NACA legs, living module, porch, stabilizers, solar roof, and davits, and prints a detailed marine-aluminum BOM with weights and CoG?

``` ### How to use it 1. Save as `seastead-design-tool.html` 2. Open in Chrome / Firefox 3. Change any dimension — the weight table updates instantly 4. When you are happy with the rough numbers, move to **FreeCAD + Python** or **build123d** for a production-grade parametric model and exact BOM. Would you like me to generate the full parametric **build123d** (or FreeCAD macro) script next that creates every tube, plate, and hydrofoil stabilizer exactly as you described?