# Seastead Leg Design Tradeoff Analysis This interactive tool calculates the hydrodynamic and structural tradeoffs for the three proposed leg profiles. The model assumes **constant displacement (buoyancy)** across profiles, with the 50% submergence constraint fixing the draft for each geometry. **Key Assumptions:** - **Displacement Fixed:** 107,136 lbs (from baseline NACA 0030 at 19.5 ft draft) - **Mass:** 3,329 slugs (Displacement / g) - **Waterplane Coefficient (Cp):** 0.95 (foil ends) - **Structural Damping Ratio (ζ):** 0.15 (heave plates) - **Shell Thickness:** 0.25 in (6.35 mm) Marine Aluminum 5086 - **Fabrication Factor:** 2.0× (shell + ribs/bulkheads/plates) - **Aluminum Density:** 168 lbs/ft³ | **Cost:** $22/lb (material + welding) - **Stabilizer Cost:** $1,200/ft² (composite/aluminum foil + actuation) ```html Seastead Leg Profile Tradeoff Analysis

Seastead Leg Profile Tradeoff Analysis

Interactive hydrodynamic & structural calculator for NACA foil legs. Constant displacement (107,136 lbs) with 50% submergence constraint.

Input Parameters

Results Comparison

Leg Profile Dimensions
L × Draft × Chord × Thick (ft)		 Waterplane Area
Total (ft²)		 Restoring Force
lbs/ft		 Est. Speed
knots @ Power		 Heave w/o Stab
ft (Amp, 5ft wave)		 Stab Force
Total (lbs)		 Stab Influence
ft Equivalent		 Heave w/ Stab
ft (Final Amp)		 Est. Weight/Leg
Marine Al (lbs)		 Est. Cost
Leg + Stab ($)

Model Notes: Displacement fixed at 107,136 lbs (Baseline NACA 0030 @ 19.5ft draft). Mass = 3,329 slugs. Waterplane Area = 3 × Chord × Thickness × 0.95. Restoring Force = WPA × 64 lbs/ft³. Heave RAO = 1/√((1−r²)²+(2ζr)²), r=ω_wave/ω_n, ζ=0.15. Speed from 40% RIM efficiency, Drag = Skin Friction (ITTC-57) + Pressure Drag (Cd_frontal × Thickness × Draft × 3). Stabilizer Force = ½ρV²S_CL. Stab Influence = Stab Force / Restoring Force. Weight: 0.25" shell + 2× fabrication factor. Cost: $22/lb structure + $1,200/ft² stabilizer.