```html Seastead Design & Scale Model Specifications

Seastead Scale Model Specifications

Project Overview: Tri-float seastead, 60 ft frame, using three angled cylindrical legs (3.9 ft diameter, 24 ft long, 16 ft draft). Model scaling factor: 1/6th scale.

1. Full-Scale Water Displacement & Mass

To find the total mass of the water displaced by the full-scale structure, we calculate the volume of the submerged portion of the 3 cylindrical legs.

Submerged Volume per Leg: π × (1.95 ft)² × 16 ft = 191.13 cubic feet
Total Submerged Volume (3 legs): 3 × 191.13 = 573.4 cubic feet
Density of Seawater: ~64 lbs per cubic foot

Full-Scale Displaced Mass: 573.4 cu ft × 64 lbs/cu ft = 36,698 lbs.

2. Froude Scaling: 1/6 Model Target Dimensions & Weight

Using Froude scaling laws, lengths scale linearly by the scale factor (λ = 1/6), while volumes and masses scale by the cube of the scale factor (λ³ = 1/216).

Parameter	Full Scale	1/6 Scale Model (Inches)
Triangle Frame Side Length	60 ft	120.0 inches
Leg Length (Total)	24 ft	48.0 inches
Leg Submerged Length (Draft)	16 ft	32.0 inches
Leg Diameter	3.9 ft	7.8 inches

Target Weight for Scale Model

To sit at the correct 32-inch draft in seawater (Sandy Hill Bay), your model must displace exactly 1/216th of the full-scale mass.

Model Target Weight: 36,698 lbs / 216 = 169.9 lbs (This includes the frame, legs, ballast, cables, electronics, and rigging).

3. Cable Lengths (Diagonal and Perimeter)

Using 3D trigonometry based on legs angling outward and downward at 45 degrees directly away from the triangle's center:

Diagonal Support Cables (Bottom of leg to adjacent corners):
Full Scale: ~77.1 feet.
1/6 Scale Model: 154.1 inches (You will need 6 of these in total).
Perimeter Loop Cable (Connecting the bottoms of all 3 legs):
Full Scale: ~89.4 feet between each leg.
1/6 Scale Model: 178.8 inches between each leg pair (Complete triangle loop = 536.4 inches).

Note: Cut cables slightly shorter and use turnbuckles to allow you to tension the design and account for attachment hardware.

4. Wave Testing Parameters in Sandy Hill Bay

Because lengths scale by 1/6, the wave heights you seek out in the bay must also be scaled linearly to accurately represent your full-scale target waves.

Full-Scale Wave Target	Required Bay Wave Height (1/6 track)
3 foot waves	6 inches
5 foot waves	10 inches
8 foot waves	16 inches

Required Water Depth

To ensure you are modeling open ocean waves rather than shore-breaking or shallow-water dragging waves, test in "deep water" conditions. The hydrodynamic rule for deep water is that the depth must be greater than half the wavelength (d > L/2).

Assuming standard Caribbean ocean wave periods (e.g., 6 seconds), the full-scale wavelength is around 180 feet. At 1/6 scale, your model wavelength is approximately 30 feet.

Recommendation: Do your testing in areas of the bay where the water depth is at least 15 to 20 feet. Depths shallower than this will cause the waves to "feel the bottom," artificially steepening them and skewing your acceleration data.

5. Android Apps For Recording Accelerations

When sealing a smartphone inside your waterproof model, the best apps are those that export easily to CSV and, ideally, allow remote access.

Phyphox (Highly Recommended): Developed by RWTH Aachen University, this app is completely free and ad-free. Its killer feature for seastead testing is its remote access capability. If the phone is on the same local network (e.g., connected to a mobile hotspot on your tracking boat), you can start, stop, and download the acceleration recordings directly from a laptop browser without opening the watertight seals of your model.
Physics Toolbox Sensor Suite: An excellent, free, widely-used app by Vieyra Software. It allows you to record linear accelerometer data (excluding gravity) directly into a .CSV file. Very robust, but requires you to start the recording physically before sealing the phone.
Sensor Logger: Another free tool that records 3-axis acceleration and gyroscope data. It exports clean, timestamped CSV files and is very battery efficient for longer test runs.

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