Seastead 1/6 Scale Model Design and Testing Guide

1. Scale Model Dimensions (in inches)

Component	Full Scale	1/6 Scale Model (inches)
Living Area Length	40 ft (480 in)	80 in
Living Area Width	16 ft (192 in)	32 in
Column Width	4 ft (48 in)	8 in
Column Length	24 ft (288 in)	48 in
Column Angle	45°	45° (half submerged: 24 in underwater)
Bottom Cable Rectangle	Scaled to match corners	Scale living area corners at base

            Total Target Model Weight: 36,000 lbs / 216 ≈ 167 lbs

            (Achieve via dense foam/ballast/wood; ensure correct buoyancy for half-submerged columns.)

2. Surgical Tubing for Tension Measurement

Typical Tension Range for Surgical Tubing: Common latex surgical tubing (e.g., #12 to #16 sizes, available at medical/pharmacy suppliers):

Light stretch (1-2 lbs): Minor tension
Moderate (3-7 lbs): Typical working range
Heavy (8-15 lbs max): Before fatigue/failure

Full-Scale Equivalent (λ³ scaling): Model 1-15 lbs → Full-scale 216-3,240 lbs per cable.

Is this reasonable? Marginally. Full-scale mooring cables for a 36k lb seastead in 3-8 ft waves might see 1,000-10,000 lbs tension (depending on storm/wave period). 1/6 model tensions of 5-50 lbs would be ideal (full equiv. 1k-10k lbs), so use stiffer/thicker tubing or multiple strands. Calibrate stretch vs. load first. Not precise for logging, but good visual/qualitative.

3. Low-Cost Waterproof Digital Tension Data Loggers (Amazon Suggestions)

No exact "rope tension data logger," but these in-line digital scales/load cells work well for rope (hang in series, waterproof IP67+):

Product	Range	Features	Price (approx.)	Amazon Search
Dr.meter Digital Hanging Scale (ESL3000)	0-3000g (6.6 lbs)	Waterproof, USB data export (logger via app/PC), hook for rope	$20	"Dr.meter hanging scale waterproof"
RUNLEADER Digital Tension Meter	0-110 lbs	IP67 waterproof, Bluetooth logging to app, rope-clamp	$50-80	"RUNLEADER rope tension meter"
Bettersun Load Cell Scale	0-100 lbs	Digital crane scale, data hold/export, waterproof	$25	"waterproof digital crane scale 100lb"
KERN Digital Dynamometer	0-22 lbs	High accuracy, logging software, hook/shackle	$100	"digital dynamometer load cell amazon"

Tip: Use shackles/eyes to inline with rope. Pair with Bluetooth for phone logging. Scale readings by 216x for full-scale equiv.

4. Target Wave Heights in Sandy Hill Bay (inches)

Full Scale Waves	1/6 Model Waves (inches)
3 ft	6 in
5 ft	10 in
8 ft	16 in

Position model in bay for varying fetch/wind to hit these. Use gentle mooring/stretchy line/human hold (<1 lb force).

5. Android Apps for Sensors and Video

App	Features	Recommendation
Phyphox (Physics Toolbox Sensor Suite)	Accel/gyro/mag (velocity, jerk, pitch/roll/heave), logging CSV, video analysis (post-process), AR overlays. Records sensors + video separately; combine in free tools like DaVinci Resolve/Kdenlive (add accel graph overlay).	Top rec. Free, precise, experiments for waves/motion.
Sensors Logger / Sensor Kinetics	Full IMU logging (accel/jerk/pitch/roll), graphs, export.	Good for pure data; no native video overlay.
Camera FV-5 / Open Camera + Overlay Apps	High-FPS video; pair with "Sensor Overlay" or "HUDway" for live accel on video (Android 10+).	For FPV: Use "FPV Camera" apps with sensor overlay.
CamRecord / Physics Toolbox (Pro)	Video + sensor sync/stamp.	Alternative if Phyphox lacks overlay.

FPV Video + Accel Overlay: Phyphox doesn't do live overlay on video recording, but logs sync'd timestamps—combine in video editor (e.g., CapCut free app overlays CSV graphs). Test: Mount phone on model, record 60+FPS.

6. Accelerations and Motion Metrics

Key Insight: Accelerations are identical in model/full scale (Froude).

Plates Sliding Threshold: ~0.3-0.5g lateral accel (3-5 m/s²) or 0.2g vertical heave/jerk. Model readings = full-scale!
Other Metrics:
- Pitch/Roll angles: Same (linear scale, but angular same).
- Jerk (da/dt): Scale by 1/τ³ = 1/λ^{1.5} ≈ 14.7x higher in model—divide model jerk by 14.7 for full-scale.
- Glass/Water Test: Excellent! Water surface tilt = pitch/roll angle (same scale). Rocks slide at same accel thresholds. Video slosh height scales by 1/6.

7. Testing Setup Validation

Your plan is solid: Shore tripod high-FPS zoom (slow video 2.45x), model GoPro FPV (slow same), pole for waves, glass/rocks for intuition.

Additional Measurements to Consider:

Strain Gauges: Cheap Arduino flex sensors on model legs/cables (~$5, log via Bluetooth).
GPS Logger: Phone app (GPS Logger) for drift/position in waves.
IMU on Pole: Compare model vs. fixed reference for relative motion.
Wave Buoy Mini: Small float with accel logger for incident waves.
Photogrammetry: Multiple cams for 3D motion tracking (free COLMAP software).
Data Sync: Clapboard or LED flash at start for video/sensor alignment.