Seastead 1/6 Scale Model Specifications

1. Full Scale Analysis

Before applying the scale factor, we calculate the displacement of the full-sized structure.

Leg Dimensions: 3.9 ft diameter, 24 ft length.
Immersion: 16 ft (2/3 of length).
Water: Saltwater (Density approx 64 lbs/ft³).

Displacement Calculation

The displaced volume for a single leg is calculated as:

Volume = π × r² × h

Radius = 3.9 ft / 2 = 1.95 ft
Submerged Height = 16 ft

Single Leg Volume: π × (1.95)² × 16 ≈ 191.06 ft³

Total Volume (3 Legs): 191.06 × 3 ≈ 573.18 ft³

Total Mass of Water Displaced (Full Scale):
573.18 ft³ × 64 lbs/ft³ ≈ 36,683 lbs

2. 1/6 Scale Model Dimensions

Using Froude scaling laws, the scale factor ($\lambda$) is 6. Linear dimensions scale directly by $1/\lambda$.

Component	Full Scale	Model Scale (1/6th)	Model Size (Inches)
Leg Diameter	3.9 ft	0.65 ft	7.8 in
Leg Length	24 ft	4.0 ft	48 in
Submerged Length	16 ft	2.67 ft	32 in
Frame Triangle Side	60 ft	10.0 ft	120 in

3. Target Weight of Model

According to Froude's law, mass and weight scale by the cube of the scale factor ($\lambda^3$).

Scale Factor Cube = 6³ = 216

Full Scale Displacement Weight = 36,683 lbs

Model Target Weight = 36,683 / 216 ≈ 169.8 lbs

Total Target Weight of Model:
~170 lbs

Note: Ensure the model ballast is adjustable to hit exactly 32 inches of draft (submersion).

4. Cable Lengths

Calculated based on geometry. Legs angle out 45° from corners. Full scale lengths calculated first, then scaled to inches.

Leg Bottom Coordinates (Full Scale Geometry)

Assuming the legs splay "out" (away from the triangle center) at 45 degrees:

The bottom of the leg is horizontally ~17 ft from the corner attachment.
Vertical drop is ~17 ft (Depth of leg bottom).

Cable 1 & 2: Leg Bottom to Adjacent Corners

Distance from Leg Bottom to neighboring corner:

Full Scale Length: ~77.1 ft
Scale Factor: 1/6

Corner Cable Length (Model): 154 inches (12.85 ft)

Cable 3: Loop Between Legs

Distance between bottoms of adjacent legs:

Full Scale Length: ~89.4 ft
Scale Factor: 1/6

Loop Cable Length (Model): 179 inches (14.9 ft)

5. Wave Height & Water Depth Simulation

To accurately simulate the dynamics of the full-size seastead, the wave environment must also be scaled.

Target Wave Heights (Model Scale)

Linear scaling (1:6) applies to wave height.

Real World Wave	Model Wave Height
3 foot waves	6 inches
5 foot waves	10 inches
8 foot waves	16 inches

Required Water Depth

To simulate "open ocean" conditions (deep water waves) rather than shore breaking waves, the water depth must be sufficient so the waves do not feel the bottom.

The general rule is that depth ($d$) should be greater than half the wavelength ($L$), i.e., $d > L/2$.

Estimated Wavelength: Ocean waves with 8ft heights often have periods of 6-8 seconds. Using Froude scaling, the model wave period should be approx 2.5 - 3.3 seconds.
Calculated Deep Water Limit: For a 2.5s period wave, wavelength is approx 10.5 ft. Therefore, you need water deeper than 5.2 ft (approx 5 ft 3 in) to avoid wave shoaling/breaking errors.

Recommended Water Depth:
Minimum 6 feet
(Ideally deeper to ensure the waves pass over without distortion).

Important Note for Sandy Hill Bay: If the water in the bay is shallower than 6 feet (e.g., typical sandy bottom depths of 3-4 feet), the waves will behave as "shallow water waves" or break. This creates forces not present in the open ocean design. If you cannot find a spot deeper than 6ft, the test will still be valuable, but you must note that the wave forces will be higher than scaled due to bottom interaction.

6. Recommended Android Apps

You need an app that logs data from the accelerometer (IMU) to a CSV or text file for export.

Physics Toolbox Sensor Suite (by Vieyra Software)
Why: This is the gold standard for citizen science. It has a specific "G-Force" or "Accelerometer" logger. You can record, stop, and instantly email yourself a .CSV file. It records timestamps, X, Y, and Z acceleration.
Sensor Kinetics
Why: Good for advanced users, provides raw data and allows file exports.
AccDataRecorder
Why: A simpler, lightweight option specifically designed to record acceleration data to a file.

Tip: Ensure the phone is firmly secured to the model frame so it does not rattle. Orient the phone so the screen faces up (Z-axis vertical) to easily measure heave acceleration.

Seastead Design Analysis: 1/6 Scale Model