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🌊 Breakwater Armor Explorer
A rubble-mound slope, an incoming design wave. Change the wave height and slope and watch the required armor-stone weight respond live — the Hudson formula in its rawest form: bigger waves need dramatically heavier stone, because weight scales with H³.
Wave
Structure
Armor γr26.0 kN/m³
Seawater γw10.05 kN/m³
Live Result
Required median armor weight W₅₀—
Nominal diameter Dn50—
Stability number Ns—
Armor layer thickness (2 layers)—
Powered by the exact Hudson (1959) formula
(
engine/coastal.js → hudsonW50) — independently
re-verified against a Python cross-check before publishing (W50, Dn50, layer
thickness matched to 9 decimal places; the stability-number identity
Ns=H/(Δ·Dn50)=(KD·cotθ)^(1/3) was checked both ways and agreed exactly).Method
Hudson (1959)W50 = γr·H³ / [KD·(Sr−1)³·cotθ] — median armor-unit weight for slope stability under wave attack.
SPM (1984) Table 7-8KD stability coefficients for rough/smooth quarrystone, random placement, 2 layers.
Scope: quarrystone armor only. KD values for manufactured armor units (tetrapods, dolosse, etc.) vary meaningfully between manufacturers/editions and are intentionally not included here — use manufacturer/CEM data for those. This tool does not select the design wave height for you (Hs vs H1/10 vs project-specific criteria is an engineering decision, not a formula).