```html Seastead 1/6 Scale Model Engineering Report

Seastead 1/6 Scale Model: Engineering Froude Analysis

Using Froude scaling laws for a scale factor of λ = 6, we can map the physical characteristics and dynamics of your full-scale seastead down to the model you will be testing in Sandy Hill Bay.

1. Dimensions and Target Weight

According to Froude scaling, lengths scale by 1/λ (1/6), and mass/weight scales by 1/λ³ (1/216) assuming the water density is identical.

Model Dimensions (in inches)

Living Area: 80 inches long × 32 inches wide (Full scale: 40 ft × 16 ft)
Column Width: 8 inches (Full scale: 4 ft)
Column Length: 48 inches (Full scale: 24 ft)

Model Weight

Target Model Weight: 166.7 lbs (Full scale: 36,000 lbs ÷ 216)
Note: This 166.7 lbs must include all columns, the living area platform, electronics, internal ballast, and test cameras.

2. Simulated Wave Heights

Wave heights follow the standard linear scale of 1/6.

3 foot wave → Look for 6 inch waves on the model
5 foot wave → Look for 10 inch waves on the model
8 foot wave → Look for 16 inch waves on the model

3. Cable Tension & Surgical Tubing

Forces (like tension) scale by the same factor as weight: 1/λ³ (1/216).

Tubing Tension Range: Heavy-duty surgical/latex tubing (like the kind used in slingshots or spearguns) typically stretches fully at a range of 10 lbs to 25 lbs of force depending on wall thickness.

Full-Scale Equivalent: If your model measures 10 to 25 lbs of tension, it corresponds to 2,160 lbs to 5,400 lbs of tension on the full-scale seastead.

Is this reasonable? Yes. A 36,000 lb structure subjected to 5-8 ft waves will easily generate mooring loads in the 2,000 - 6,000 lb range during shock impacts or wave surging. This is a very realistic and useful measurement range.

Alternative: Digital Scales / Data Loggers

A search for "rope tension data logger" won't yield cheap results because they are mostly sold as high-end industrial "mooring load cells" (like the Rock Exotica Enforcer, which is $1,000+). However, here are two practical Amazon alternatives:

Bluetooth Crane Scales / Luggage Scales: You can buy a 50kg/110lb Bluetooth digital hanging/crane scale for around $30-$50. Some come with apps that log peak tension, though standard sampling rates are slow.
The "Old-School" Hardware Hack: Buy a basic $15 digital hanging luggage scale. Put it in-line with your rope. Mount a cheap, lightweight sports camera facing the LCD screen of the scale. When you review the video later, you will have a perfect, visual, high-speed record of exact tension at exact moments!

4. Accelerations, Apps, and Video Overlays

Froude Acceleration: The "Sliding Plates" Rule

Here is a magic quirk of Froude scaling: Acceleration scales at 1:1! This means an acceleration of 0.2g on the model represents exactly 0.2g on the full-scale seastead.

The coefficient of static friction for a ceramic plate on a table is roughly 0.3.
Plates will slide when: The model tilts past roughly 16 degrees (Pitch/Roll), OR when the model experiences lateral accelerations (surge/sway) of about 0.3g (2.9 m/s²).
Human Comfort (Other Metrics): Humans notice motion sickness (MSDV - Motion Sickness Dose Value) at prolonged, rhythmic heave accelerations as low as 0.05g to 0.1g. If your model heaves at 0.1g, a human will feel sick if it occurs at typical sea frequencies.

Data Tracking Apps & Phyphox

Phyphox is incredible for logging raw data (Heave/Pitch/Roll/Acceleration), but it cannot natively record your camera's video with the data overlaid on top.

The Recommended FPV / Telemetry Solution

Instead of relying on a smartphone app to mix video and data, the industry standard for this exact type of scaled model testing is a GoPro (Hero 6 or newer).

Modern GoPros have built-in high-precision IMUs (Gyroscopes and Accelerometers).
Mount the GoPro to the seastead. It will record the FPV video AND log all acceleration/angular velocity data perfectly matched to the video frames.
You can then use free software like GoPro Quik or dedicated software like Telemetry Overlay to "burn" digital gauges (showing G-force, pitch, roll, and heave) directly onto the video.
If you must use a phone, use the Sensor Logger app to record a CSV file, record video separately, and sync them later using video editing software.

5. Additional Measurement Ideas

Your current plan (high frame rate camera on shore, Froude-scaled slow motion, measuring pole driven into sand, cup of water) is excellent. Time in Froude scaling scales by 1/√6 (approx. 0.408). Therefore, playing your video back at roughly 40% speed will perfectly replicate real-time full-scale physics.

Other clever visual methods to consider:

Food Coloring in the Cup: Dye the water in your glass blue or red. On camera, clear water is notoriously difficult to see sloshing. Colored water will provide a highly visible horizon line against the cup's sides.
Hanging Pendulum Inclinometer: Hang a brightly colored weight (like a plumb bob) on a string against a board painted with angle marks (like a protractor). The shore camera will capture exactly what degree the seastead is rolling/pitching at any given second.
Checkerboard / Grid Background: Paint or tape a high-contrast black-and-white grid (with squares exactly 2 inches apart) on the side of your seastead columns or hull. You can use free motion-tracking open-source software like Kinovea on your computer later to automatically track how the grid moves relative to the shoreline.
Ping Pong Ball on a Saucer: In addition to the water cup, an object rolling on a slightly concave plate visually demonstrates horizontal acceleration and tilt very well.
Waterline Marks (Draft Marks): Paint numbers vertically on the columns (like those on the bow of a ship). This will allow your shore camera to instantly read how deep the hull is sinking during wave impacts (heave).

```