Foam weight needed: 1.73 lbs (at 2 lb density) Liquid mix required:≈ 1.6 cups of Part A and 1.6 cups of Part B (Assumes typical 1:1 mix by volume and ≈8.5 lb/gallon liquid density. Final foam density = 2 pcf.)
Always test small batch first. Expansion can vary with temperature and mixing technique.
2. Scale Model Buoyancy (3 Legs)
Each leg is 50% submerged in seawater (density ≈ 64 lb/ft³).
Displaced volume per leg: 0.432 ft³ Buoyancy per leg: 27.6 lbs Total model weight for equilibrium:82.9 lbs
This is the target weight of the completed scale model (including structure, tensegrity cables, deck, etc.) to float at the desired half-submerged leg level.
Full Scale (1:6 Froude Scaling)
Scale Factor: 6× linear • 216× volume
Full-scale leg length: 21 feet Full-scale chord: ≈ 8.94 feet Full-scale max thickness: 1.875 feet (22.5 inches)
Displaced Seawater (Half Submerged)
Item
Volume (ft³)
Weight (lbs)
One leg (50% submerged)
93.25
5,968
Three legs
279.75
17,904
This is the total displacement tonnage the full-scale platform should be designed around (≈ 8.95 tons).
3. Drag Force at 1, 2, and 3 MPH
Assumptions:
• Legs oriented with wing chord parallel to travel (lowest drag orientation)
• Submerged length per leg: 10.5 ft
• Frontal area (3 legs): 59.06 ft²
• Cd = 0.10 (reasonable for thick streamlined strut/foil shape)
• Seawater density = 1.99 slugs/ft³
Speed (MPH)
Speed (ft/s)
Drag Force (lbs)
1
1.47
12.6 lbs
2
2.93
50.6 lbs
3
4.40
113.8 lbs
4. Electrical Power Requirements
Assumptions for Propulsion:
• Ideal thrust power = Force × Velocity
• Overall system efficiency ≈ 50% (motor 85% × propeller in water 60% — conservative for small electric pods)
• No appendage drag or wave drag included (this is strut drag only)
Speed (MPH)
Ideal Thrust Power
Estimated Electrical Power
1
25 W
≈ 50 watts
2
201 W
≈ 400 watts
3
679 W
≈ 1,360 watts (1.36 kW)
At 3 MPH you could run comfortably on a single 2–3 kW electric outboard or pod drive. At 1–2 MPH the power requirement is very low — excellent for solar-powered station-keeping.
Summary of Key Results
Model foam per leg: ≈ 1.6 cups Part A + 1.6 cups Part B (2 lb/ft³ foam)
Target model weight: 83 lbs
Full scale leg length: 21 ft
Full scale displacement (3 legs @ 50% submersion): 17,904 lbs (≈ 9 tons)
Drag at 2 MPH: ≈ 51 lbs → ≈ 400 watts electrical
Drag at 3 MPH: ≈ 114 lbs → ≈ 1.4 kW electrical
All calculations use Froude scaling laws appropriate for wave-making and dynamic similarity. Real-world testing of the scale model in a pool or sheltered water is highly recommended to validate these estimates.