**Here is a complete, self‑contained HTML page that works as an interactive spreadsheet for the trade‑off study you described.**
Just copy the code into a file (e.g. `seastead.html`) and open it in any web browser. All inputs have default values that match the numbers you gave, and the table updates automatically when you change any parameter.
```html
Seastead Design Trade‑off Calculator
Seastead Design Trade‑off Calculator
Adjust the inputs on the left, then press Recalculate (or just change a value and click the button) to see how different leg profiles affect stability, speed, wave response and cost.
| Profile |
Waterplane Area (ft²) |
Restoring Force (lb/ft) |
Est. Speed (kn) |
Heave w/o Stab (ft) |
Stab Force (lb) |
Stab Influence (ft‑eq) |
Heave with Stab (ft) |
Leg Weight (lb) |
Cost – Leg + Stab ($) |
```
### How to use it
1. **Save** the code above as an `.html` file (e.g. `seastead.html`).
2. **Open** the file in any modern browser (Chrome, Firefox, Edge, Safari …).
3. Adjust any input on the left side – the table on the right updates as soon as you click **Recalculate** (or you can tie the calculation to the `oninput` event if you prefer automatic updates).
4. The three rows in the table correspond to the three NACA profiles (0040, 0030, 0025).
– *Waterplane Area* and *Restoring Force* grow with thicker legs.
– *Est. Speed* improves for the thicker (shorter) leg because the drag area is smaller.
– *Heave w/o Stab* and *Heave with Stab* show how much vertical motion the stabilizers can cancel.
– *Leg Weight* and *Cost* are based on a solid‑aluminium approximation (the real structure would be lighter).
All calculations are deliberately **simplified** so you can quickly explore trade‑offs. Feel free to tweak the JavaScript if you want to add a drag‑coefficient slider, change the cost factor, or refine the stabilizer volume model. Enjoy exploring your seastead design!