Mooring Line Load & Cable Tension Calculator – API RP 2SK, DNVGL-RP-E301

Mooring Line Load & Cable Tension Calculator

API RP 2SK / DNVGL-RP-E301 · Wind + current forces · 2D force diagram · PDF report

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📐 1. Mooring Line Load & Cable Tension

Mooring lines keep vessels and floating structures in position against environmental forces. The load on each line depends on wind, current, wave drift, and line geometry. This calculator implements methods from API RP 2SK (Design and Analysis of Stationkeeping Systems) and DNVGL-RP-E301 (Position Mooring).

Wind force: F_w = ½·ρ·C_d·A·V²
Current force: F_c = ½·ρ·C_d·L·T·V²
Line tension (simplified): T = (F_total) / (n·cosθ)

🚀 2. Live Mooring Line Load Calculator

Wind speed (V_w) m/s

Vessel projected area (A) m²

Current speed (V_c) m/s

Vessel length (L) m

Vessel draft (T) m

Number of mooring lines (n)

Line angle to horizontal (θ) deg

MethodAPI RP 2SKDNVGL-RP-E301

Batch CSV Upload

✅ CSV: wind, area, current, length, draft, lines, angle

Get PDF Report via Email

CSV Template

📊 2D Mooring Force Diagram

📊 Force Components & Line Tension

📈 Line Tension Trend & History

📂 3. How to Use the Calculator

1. Enter environmental data: wind speed, vessel projected area, current speed, vessel length and draft.
2. Enter mooring configuration: number of lines, line angle to horizontal.
3. Select method: API or DNV (affects force coefficients).
4. Compute: Click "Compute Load" – total environmental force and line tension appear.
5. 2D force diagram shows wind, current, and line tension vectors.
6. Batch CSV: Upload multiple designs for bulk analysis.
7. PDF Report: Download a report with the force diagram.
8. History: All calculations saved locally; export or clear anytime.

📈 4. Real‑World Example

Tanker at Chittagong port anchorage
Wind=20 m/s, area=500 m², current=1.5 m/s, L=120 m, draft=8 m, 6 lines, angle=45°.
Wind force ≈ 115 kN, current force ≈ 140 kN, total ≈ 255 kN → line tension ≈ 60 kN/line.

❓ Frequently Asked Questions

❓ What is a safe line tension?

Depends on line MBL (minimum breaking load). Typical safety factor 3–5. See our pipeline stability tool for similar concepts.

❓ How does angle affect tension?

Smaller angle (more horizontal) reduces tension, but increases footprint. Our slope stability tool uses similar force resolution.

❓ Which method is more conservative?

API tends to give slightly higher loads. Both are accepted by classification societies.

🌐 Industry Standards & References

API RP 2SK – Stationkeeping | DNVGL-RP-E301 – Position Mooring | OCIMF – Mooring Equipment Guidelines

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© ERH Mooring Load Calculator – Based on API RP 2SK and DNVGL-RP-E301. For preliminary engineering.