Hudson & Van der Meer Armour Stone Calculator – Breakwater Rock Stability

Hudson & Van der Meer Armour Stone Calculator

Breakwater rock stability • Hudson (K_D) • Van der Meer (S, P) • Stone weight • Layer thickness • Damage level

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📐 1. Armour Stone Design – Hudson vs Van der Meer

Rubble mound breakwaters require stable armour layers. Two widely used methods:

• Hudson (1953): W = γ_r · H³ / (K_D · (S_r-1)³ · cotθ)
• Van der Meer (1988): H_s / Δ·D_n50 = (6.2 · P^0.18 · (S/√N)^0.2) for plunging waves; similar for surging.

This calculator compares both methods, computes stone weight (W), nominal diameter D_n50, layer thickness t, and damage level S.

🚀 2. Armour Stone Design (Hudson + Van der Meer)

Significant wave height H_s (m)

Rock specific gravity γ_r (kN/m³) – typical 26

Water specific gravity γ_w (kN/m³)

Slope angle (cotθ) – e.g., 1.5 for 1:1.5

Hudson stability coefficient K_D (typical 2–4 for quarrystone)

Van der Meer: Permeability P (0.1 = impermeable, 0.6 = very permeable)

Number of waves N (typically 3000)

Damage level S (0.5–10; 2 = moderate, 5–10 = heavy)

Batch CSV (Hs, KD, P)

Get PDF Report via Email

CSV Template

📊 3. Breakwater Cross‑Section & Stone Layer

📈 4. Stone Weight vs H_s & Design History

📘 5. How to Use the Calculator

1. Enter wave height (H_s), rock density, slope cotθ, and Hudson K_D.
2. For Van der Meer, provide permeability P, number of waves N, target damage level S.
3. Click "Compute" – both methods calculate stone weight (W), nominal diameter D_n50, and layer thickness.
4. 2D schematic shows armour layer thickness and slope.
5. Batch CSV: upload multiple designs to compare stone weights.
6. PDF report includes both results and sketch.

❓ Frequently Asked Questions

❓ Which method is more reliable?

Van der Meer is preferred for rubble mounds because it accounts for damage level and permeability. Hudson is simpler but less accurate for steep slopes or low-crested structures.

❓ What is typical K_D value?

Quarrystone (rough, angular): 2–3 for breaking waves; 3–4 for non-breaking. Smooth armour units: 4–6.

❓ How to choose damage level S?

S=2 (minor damage, no repair), S=5 (moderate), S=10 (heavy). Use S=2–3 for design conditions.

🌐 References

Coastal Engineering Manual (CEM) | Van der Meer (1988) – Rock slopes & rubble mound | Hudson formula (USACE)

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© ERH Armour Stone Design – Hudson & Van der Meer. Data processed locally.