```html Seastead Design & 1/6 Scale Model Specifications

Seastead Design Analysis & 1/6 Scale Model Specifications

1. Full-Scale Displaced Water Mass

Based on the cylindrical leg dimensions (3.9 ft diameter, 24 ft length) with two-thirds immersion:

Volume per leg = π × r² × h_immersed
= π × (1.95 ft)² × 16 ft
= π × 3.8025 × 16
≈ 191.1 cubic feet per leg

Total Volume (3 legs) = 3 × 191.1 = 573.4 ft³

Using seawater density (64 lbs/ft³):
Weight = 573.4 × 64 ≈ 36,700 lbs
Mass ≈ 1,140 slugs (or 16,650 kg)

Note: This is the target displacement. The full-scale seastead must weigh approximately 36,700 lbs (16.7 tons) to float at the designed waterline with 16 feet of each leg submerged.

2. 1/6 Scale Model Dimensions (Froude Scaling)

Using Froude scaling law (λ = 1/6): Lengths scale by 1/6, areas by 1/36, and volumes/weights by 1/216.

Component	Full Scale	Model Scale (inches)	Model Scale (feet/inches)
Leg Diameter	3.9 ft (46.8")	7.8"	7 13/16"
Leg Length	24 ft (288")	48.0"	4 feet 0"
Immersed Length (2/3)	16 ft (192")	32.0"	2 feet 8"
Frame Triangle Side	60 ft (720")	120.0"	10 feet 0"
Leg Angle	45°	45°	45° (angles unchanged)

Target Weight (Model Ballast)

Total Target Weight: 170 lbs (specifically: 169.9 lbs)

Calculation: 36,700 lbs ÷ 216 = 169.9 lbs

This includes the frame, legs, cables, and any additional ballast needed to achieve the correct draft with 32 inches of each leg submerged.

3. Cable Length Specifications

Geometry: Equilateral triangle frame (60 ft sides), legs angled 45° down and outward from corners.

Full-Scale Cable Lengths

Cable Type	Length (feet)	Quantity
Stabilizing cables (bottom of leg to adjacent corner)	~77.1 ft	6 (2 per leg)
Loop cable (perimeter connecting leg bottoms)	~89.4 ft (each side)	3 sides (268 ft total loop)

Model-Scale Cable Lengths (1/6 scale)

Cable Type	Length (inches)	Length (feet)	Notes
Stabilizing cables	154.2"	12.85 ft	6 cables needed
Loop cable (each side)	178.8"	14.9 ft	3 sections
Total loop length	536.4"	44.7 ft	Continuous or spliced

Tip: Add 5-10% extra length for turnbuckles, eye splices, or adjustment hardware. Consider using stainless steel cable or Dyneema rope with appropriate breaking strength (safety factor of 5+ recommended).

4. Wave Simulation Parameters

Scaled Wave Heights

Wave heights scale linearly (λ = 1/6):

Full Scale Wave	Model Wave Height	Target in Sandy Hill Bay
3 feet	6 inches	0.5 ft
5 feet	10 inches	0.83 ft
8 feet	16 inches	1.33 ft

Water Depth Requirements

To simulate open ocean (deep water) conditions rather than shallow breaking waves:

Critical: Water depth must be greater than half the wavelength of the model waves to avoid bottom effects (deep water regime: h > λ/2).

For the 8-foot full-scale wave equivalent (16" model wave):

Full scale wavelength (est. 8s period): ~328 feet
Model wavelength: 328 ÷ 6 = 55 feet
Required depth: > 27 feet (ideally > 30 ft)

For the 3-foot wave simulation:

Model wavelength (est. 5s period): ~21 feet
Required depth: > 10-11 feet

Sandy Hill Bay Reality Check: If the bay is shallower than these depths, you will be testing shallow-water wave dynamics (where waves feel the bottom and may break differently than open ocean). This is still valuable data but represents different physics than deep ocean conditions. Look for the deepest sections of the bay, or consider testing in deeper water offshore if possible.

5. Recommended Android Apps for Acceleration Recording

Free apps that export data (CSV/txt) for desktop analysis:

App Name	Features	Export Format
Physics Toolbox Suite (Vieyra Software)	Multi-sensor logging, precise timestamps, customizable sampling rates	CSV, txt
Sensor Logger (by Tyler Beauchamp)	Simple interface, high-frequency sampling, cloud upload options	CSV
AndroSensor	Classic choice, records all phone sensors simultaneously	CSV
Mobile Science - Accelerometer	Designed for physics experiments, real-time graphs	CSV, email

Testing Tip: Secure the phone at the center of the triangle frame (or at a known position) with the axes aligned to the seastead's longitudinal/lateral axes. Set sampling rate to at least 50 Hz (preferably 100 Hz) to capture wave frequencies properly. Transfer files via email, Google Drive, or USB cable.

6. Testing Protocol Notes

Mooring/Restraint

Use bungie cord/shock cord or surgical tubing for the restraint line to provide gentle restoring force without affecting the natural heave/roll/pitch periods
Attach at the centroid of the triangle (where the frame axes intersect)
Keep the anchor point upwind/upwave so the line is slack during the approach

Positioning in Sandy Hill Bay

3-foot wave simulation: Shallower areas or wind-protected zones
8-foot wave simulation: Requires fetch; position where wind/waves have longest uninterrupted path across the bay
Avoid areas with reflected waves from seawalls or rocks

Safety Checklist

170 lbs is substantial weight—use adequate lifting assistance during launch/recovery
Secure all cables before launch; check for chafing at connection points
Have a kill switch or quick-release for the mooring line
Mark the model with bright flags for visibility to boat traffic

Technical notes: Calculations assume seawater density 64 lbs/ft³, standard gravity 32.2 ft/s², and deep-water wave dispersion relationships. Frame assumed equilateral with legs attached at waterplane level.

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