Mooring Winch Brake Render Test – Shipboard Practice & Requirements
- Admin
- Apr 30
- 3 min read
Updated: May 25
The Brake Holding Test (also known as a Brake Render Test) is an essential onboard safety task that ensures the winch brake holds the mooring line under load without slipping too early.
What Is the Brake Render Test? 🧰
A brake render test checks whether the mooring winch brake can hold the line at the required tension before it slips (renders).This verifies that brakes are set correctly and ready for mooring operations — especially in ports with strict rules like Hay Point.
What Is Render Point and How to Mark It? 🎯
The render point is when the mooring line starts to slip due to applied force.✅ Mark the line (chalk/tape) and observe movement.
The brake must not render before reaching the required force.
Understanding LDBF and SDMBL 🧩
🔹 LDBF – Line Design Break Force
The certified breaking strength of the mooring line. Found on the rope certificate.
🔹 SDMBL – Ship Design Minimum Breaking Load
The highest load that the ship’s fittings (winch, bollards, fairleads) can safely withstand.
⚠️ The mooring line must match SDMBL, not be too weak or too strong, as this can damage ship fittings or fail vetting inspections.
Required Brake Holding Force ⚙️
Rope Type | Brake Holding Requirement |
Synthetic (e.g., HMPE) | At least 60% of LDBF |
Wire Rope | At least 80% of LDBF |
🧮 Example:
LDBF = 65 t →
Synthetic rope: must hold at 39 t (60%)
Wire rope: must hold at 52 t (80%)
How to Calculate Jack Pressure (mooring winch brake render test) 🔧
Use this formula to estimate the pressure needed in your hydraulic jack during the test:
✅ One-line Formula:
Pressure (bar) = (Required Force in kN × 100) ÷ Jack Piston Area (cm²)
🧮 Example Calculation:
Target brake force = 39 t = 382.6 kN
Jack piston area = 95 cm²
Pressure = (382.6 × 100) ÷ 95 = ~403 bar
Always confirm piston area from jack’s certificate.
Step-by-Step Test Procedure 🛠️
Step 1: Prepare
Isolate winch motor
Select mooring line and mark it
Check rope LDBF and SDMBL
Get certified jack/load cell ready
Step 2: Apply Brake
Engage brake manually
Confirm correct setting
Step 3: Apply Load
Gradually apply jack pressure
Watch for line movement at render point
Step 4: Record & Compare
Note pressure, convert to kN
Confirm brake holds required force
Adjust if slipping happens too early
Test Report – What to Include 📋
Date & port
Mooring line type + certificate
Jack type, piston area
Required force & measured pressure
Result (Pass/Fail)
Photos of setup and render point
Signatures of responsible officers
Important Reminders ❗
📌 Always follow your:
Company SMS or policy
Ship’s Mooring Line Management Plan (MLMP)
Terminal requirements (some ports require full reports and photos)
This guide is general and for understanding only — always apply vessel-specific instructions.
Why the Test Is Important 🚢
Proves brake is holding safely
Prevents premature line failure
Required by terminals and RightShip inspections
Shows crew professionalism and preparedness
💬 Share Your Questions or Experience
Have you done the mooring winch brake render test recently?
Do you have a method, tip, or challenge to share?
🗨️ Leave a comment below to help other seafarers!
We encourage open sharing of real onboard experience in the Shipboard Practice & Experience section ⚓