Seastead Scale Model Test Plan

Location: Sandy Hill Bay, Anguilla
Scale: 1:6 (Froude Scaling)
Full Scale Configuration: 3-Leg Triangular Platform

Engineering Note: All calculations below utilize Froude scaling laws, which preserve the ratio of inertial to gravitational forces. This is the standard for free-surface hydrodynamic testing (waves).

1. Full Scale Displacement Calculation

Before scaling, we determine the buoyancy requirements of the full-size vessel.

Leg Dimensions: 3.9 ft Diameter (1.95 ft Radius), 24 ft Length.
Immersion: 16 ft per leg (2/3 submerged).
Leg Volume (Immersed): π × 1.95² × 16 ≈ 191.13 ft³
Total Immersed Volume (3 Legs): 573.4 ft³
Seawater Density: ~64 lbs/ft³

Total Mass of Water Displaced (Full Scale): ~36,700 lbs

2. 1/6 Scale Model Dimensions

To maintain dynamic similarity, linear dimensions are divided by 6. Areas are divided by 36, and Volumes/Weights are divided by 216 (6³).

Component	Full Scale (ft)	Model Scale (inches)
Leg Diameter	3.9 ft	7.8 inches
Leg Total Length	24 ft	48 inches
Leg Immersed Length	16 ft	32 inches
Triangle Frame Side	60 ft	120 inches (10 ft)
Leg Angle	45°	45° (Unchanged)

Target Weight

To float at the correct waterline (16ft immersion scaled), the model must displace the scaled weight of water.

Full Scale Displacement: 36,700 lbs
Scale Factor (Weight): 1/216
Total Target Model Weight: ~170 lbs

Note: This weight includes the structure, ballast, and instrumentation. You will likely need to add lead ballast inside the floats to achieve this exact weight.

3. Cabling Specifications (Model Scale)

Cables maintain the geometry of the legs against wave loads.

Cable Type	Connection	Approx Length (Model)
Bracing Cables (2 per leg)	Bottom of Leg to Adjacent Corner	24 inches
Perimeter Loop Cable	Bottom of Leg to Bottom of Leg	26 inches

Recommendation: Use turnbuckles or adjustable shackles on these cables. Small variations in construction angle can change the required tension and length.

4. Wave Testing Parameters

To simulate open ocean conditions using Froude scaling, wave heights must be scaled linearly (1/6).

Target Ocean Wave (Full)	Model Test Wave Height
3 feet	6 inches
5 feet	10 inches
8 feet	16 inches

Water Depth Requirements

To ensure you are testing Deep Water Waves (where the wave motion does not interact with the seabed) rather than shallow water breaking waves:

Rule: Water depth should be greater than 1/2 the wavelength.
Estimated Model Wavelength: For an 8ft (full scale) sea state, the scaled wavelength is approximately 9 to 10 feet.
Minimum Test Depth: 5 feet

Ensure the model is positioned in Sandy Hill Bay where the depth is consistently at least 5 feet to avoid bottom friction effects.

5. Data Acquisition (Android)

To record accelerations (heave, pitch, roll) for later analysis on a desktop.

Physics Toolbox Sensor Suite: Highly recommended. Allows recording of accelerometer, gyroscope, and GPS. Exports to .csv or .txt.
Sensor Kinetics: Good visualization and logging capabilities.
Accelerometer Log: Simple, lightweight option for raw data logging.

Workflow: Mount the phone securely in the center of the triangle frame (near the center of gravity). Start logging, run the test, stop logging, and transfer the file via USB or Cloud to your desktop for analysis in Excel or MATLAB.

Safety Warning: A 170 lb floating structure in open water presents hazards.

Ensure all ballast is securely sealed inside the floats.
Use high-visibility colors on the model.
If using a human to hold the line, ensure they are on a stable platform or shore, not in the water, to avoid injury from sudden tension loads.
Use a stretchy bungee section on the mooring line to prevent shock loading if the model surges.