Seastead Leg / Waterplane / Stabilizer Tradeoff Spreadsheet

Inputs

Electric Pow to RIMs, watts RIM Efficiency, % Wave Peak-to-Trough, ft Model uses only the top half of the wave. Wave Period, seconds Rise time assumed to be one quarter period. Stabilizer wingspan, ft Stabilizer chord, ft Stabilizer Lift Coefficient, CL

Results Table

Leg Profile	Dimensions, ft Total L, Draft, Chord, Width	Waterplane Area Total sq ft	Restoring Force lbs per ft water height	Est. Speed using entered power knots	Heave WITHOUT Stabilizer ft for entered wave	Stab Force Total lbs	Stab Influence ft equivalent	Heave WITH Stabilizer Final motion, ft	Estimated Weight of Each Leg Marine Aluminum, lbs	Estimated Cost of 1 Leg + 1 Stabilizer Marine Aluminum

Model Assumptions

Three foil legs are used in all cases.
Baseline is NACA 0030: total leg length 39 ft, draft 19.5 ft, chord 10 ft, width/thickness 3 ft.
NACA 0040 and NACA 0025 keep the same 10 ft chord and same submerged displacement volume as the baseline.
Waterplane area is approximated as the horizontal foil-section area at the water surface: 3 × NACA section area.
Restoring force per foot is 64 lb/ft³ × total waterplane area.
Wave heave model: for the top half of the wave, water rises by wave height / 2 over wave period / 4. The no-stabilizer heave is estimated from the hydrostatic force acceleration during that time and capped at the half-wave height.
Speed model is a simple drag-power estimate using skin/friction drag, streamlined pressure drag, and a small fixed RIM/appendage drag allowance.
Stabilizer force is 0.5 × seawater mass density × speed² × CL × total stabilizer area. Total stabilizer area assumes three stabilizers.
Stabilizer influence in feet is stabilizer force / restoring force per ft. This is subtracted from the no-stabilizer heave.
Leg weight estimate assumes 1/4 inch marine aluminum shell, NACA perimeter, and a structural/framing multiplier. Cost assumes finished marine aluminum fabrication at $25/lb. These are rough concept-level values.