# Seastead Model Scaling & Testing Plan
## 1. Original Full-Scale Design Specifications
### Leg/Float Cylinders:
- Diameter: 3.9 ft = 1.95 ft radius
- Length: 24 ft
- Immersed portion: 16 ft (2/3 of length)
- Angled at 45° outward and downward from triangle corners
### Triangular Frame:
- Side length: 60 ft
- 3 legs at corners
## 2. Froude Scaling to 1/6 Scale Model
**Froude scaling principle:** Since wave forces and buoyancy are dominated by gravity, we scale by Froude number similarity:
\[
Fr = \frac{v}{\sqrt{gL}} \quad \Rightarrow \quad L_{\text{model}} = \frac{L_{\text{full}}}{6}
\]
### Scale Model Dimensions (in inches):
| Component | Full-scale (ft) | Model-scale (ft) | Model-scale (inches) |
|-----------|----------------|------------------|---------------------|
| Leg diameter | 3.9 ft | 0.65 ft | **7.8 inches** |
| Leg length | 24 ft | 4 ft | **48 inches** |
| Immersed length | 16 ft | 2.6667 ft | **32 inches** |
| Triangle side | 60 ft | 10 ft | **120 inches** |
| Leg radius | 1.95 ft | 0.325 ft | **3.9 inches** |
**Note:** Legs angled at 45° outward/downward — maintain same angle.
### Cable Lengths:
Cables run from bottom of leg to adjacent corners.
At 45° angle, submerged portion of leg extends diagonally.
For triangular side = 120 inches between corners, cable length ≈ √(horizontal projection² + vertical drop²).
Horizontal projection of leg bottom point (from triangle geometry with 45° outward angle):
Assuming legs mounted at corners pointing outward, cable connects bottom of one leg to adjacent corner — precise length requires 3D geometry.
**Approximate cable length ≈ 85-100 inches** (scale by 1/6 from full-scale cable length).
### Total Target Weight of Scale Model:
Displaced water volume for one leg (immersed portion):
\[
V_{\text{leg}} = \pi r^2 h = \pi (0.325^2) \times 2.6667 \ \text{ft}^3
\]
For 3 legs:
\[
V_{\text{total}} = 3 \times \pi \times (0.325^2) \times 2.6667 \approx 0.832 \ \text{ft}^3
\]
Water density: 62.4 lb/ft³ → displaced weight = \( 0.832 \times 62.4 \approx 51.9 \ \text{lb} \).
**Model total mass ≈ 52 lb** (to float with immersed portion as specified).
## 3. Wave Height Scaling
Wave heights scale linearly with length scale (1/6):
| Full-scale wave height | Model-scale wave height |
|------------------------|-------------------------|
| 3 ft | **0.5 ft = 6 inches** |
| 5 ft | **0.833 ft = 10 inches** |
| 8 ft | **1.333 ft = 16 inches** |
Test in Sandy Hill Bay, Anguilla: seek wave conditions matching these heights.
## x. Water Depth for Wave Simulation
To avoid shallow-water wave distortion (where depth affects wave speed and shape), water depth \( d \) should be > ~\( L/2 \) where \( L \) is wavelength.
For typical ocean waves, wavelength ~ 10–100 times wave height.
For model testing, ensure depth > **24 inches** (2 ft) for 6–16 inch waves to approximate deep-water conditions.
## 5. Android Apps for Acceleration Recording
Recommended free Android apps that log accelerometer data to file:
1. **Physics Toolbox Sensor Suite** – logs acceleration, GPS, etc., exports CSV.
2. **Sensor Logger** – customizable logging intervals, multiple sensor data.
3. **Accelerometer Meter Pro** (free version) – records with timestamps.
4. **Science Journal** (by Google) – logs sensors, exports data.
Transfer data via USB or cloud to desktop for analysis.
---
```html
Seastead Scale Model Testing Specifications
Seastead 1/6 Scale Model Testing Plan
Scale Model Dimensions
| Component | Full-scale (ft) | Model-scale (ft) | Model-scale (inches) |
|---|
| Leg diameter | 3.9 | 0.65 | 7.8 |
| Leg length | 24 | 4 | 48 |
| Immersed length | 16 | 2.667 | 32 |
| Triangle side | 60 | 10 | 120 |
| Leg radius | 1.95 | 0.325 | 3.9 |
Target model weight: ≈ 52 lb (to match displaced water volume)
Cable lengths: ≈ 85–100 inches (from leg bottom to adjacent corners)
Leg angle: Maintain 45° outward/downward
Wave Height Scaling
| Full-scale wave (ft) | Model-scale wave (ft) | Model-scale wave (inches) |
|---|
| 3 | 0.5 | 6 |
| 5 | 0.833 | 10 |
| 8 | 1.333 | 16 |
Testing Environment Requirements
- Location: Sandy Hill Bay, Anguilla
- Water depth: 24 inches (2 ft) to avoid shallow-water wave distortion
- Mooring: Use stretchy line or mooring to provide gentle restraint
Android Apps for Acceleration Recording
- Physics Toolbox Sensor Suite – CSV export
- Sensor Logger – customizable intervals
- Accelerometer Meter Pro (free) – timestamped records
- Science Journal (Google) – multi-sensor logging
Export data via USB/cloud to desktop for analysis.
All scaling based on Froude number similarity for gravity-dominated hydrodynamic behavior.
```