Definitive Guide to Mooring Bollard Selection:How to Determine the Correct Bollard Pull Capacity Based on Vessel Tonnage

Definitive Guide to Mooring Bollard Selection:How to Determine the Correct Bollard Pull Capacity Based on Vessel Tonnage

 

Introduction

For any port, terminal, or jetty, the mooring bollard is a seemingly simple but critically important component. It is the point where a vessel's immense power is transferred to the shore. Selecting the wrong bollard—one with insufficient capacity—can lead to catastrophic failures, resulting in vessel damage, structural damage to the berth, environmental hazards, and even loss of life.

Conversely,over-specifying a bollard can lead to unnecessary capital expenditure and potential structural overloading of the quay wall.This guide provides a clear,engineering-based methodology for selecting the correct mooring bollard pull capacity based on a vessel's deadweight tonnage (DWT), ensuring safe,efficient,and cost-effective operations.

Step 1: Understanding the Core Concept – Bollard Pull Capacity

The most critical specification for any mooring bollard is its nominal pull capacity (kN) . This is the maximum horizontal force (in kilonewtons) that the bollard is designed to withstand without permanent deformation or damage.

It is crucial to understand that the bollard's capacity must be greater than the individual line loads from the vessel's mooring lines.The bollard is the anchor point; it must be strong enough to handle the forces exerted by the ship's ropes, which are influenced by wind, current, and the vessel's own maneuvering power.

Step 2: The Primary Input – Vessel Deadweight Tonnage (DWT)

The most widely accepted starting point for bollard selection is the vessel's deadweight tonnage (DWT). DWT is a measure of how much weight a ship can safely carry (cargo, fuel, crew, etc.) and is a reliable proxy for a vessel's size and the forces it can generate.

While specific calculations exist for environmental forces (wind and current), maritime industry standards and guidelines (such as from PIANC, OCIMF, or national port authorities) provide a simplified, reliable table correlating vessel DWT to a recommended bollard pull capacity.

Step 3: The DWT to Bollard Pull Correlation Table

Below is a standard guideline for selecting a mooring bollard's nominal capacity based on the largest vessel expected to berth regularly.

Note: These values are for general guidance. Final selection should be confirmed by a qualified structural engineer for your specific project.

Vessel Size (DWT)	Typical Vessel Type	Recommended Bollard Pull Capacity (kN)
< 1,000	Small tugs, barges, fishing boats	150-300 kN
1,000 – 5,000	Small cargo, coasters	400-600 kN
5,000 – 20,000	General cargo, small bulk carriers	600-800 kN
20,000 – 50,000	Handysize bulk carriers, medium tankers	800-,200 kN
50,000 – 100,000	Panamax bulk carriers, Aframax tankers	1,200-1,600 kN
100,000-200,000	Capesize bulk carriers, Suezmax tankers	1,600-2,000 kN
> 200,000	VLCC, ULCC, Very large ore carriers	2,000-2,500+ kN

Step 4: Key Factors That Modify the Base Selection

The DWT table provides the foundation. However, site-specific conditions can increase the required bollard capacity. You must consider these factors, especially if your port is exposed:

1. Exposure:A berth in a sheltered river or harbor will experience lower forces than a berth in an open-sea, exposed location. For exposed terminals, it is standard practice to select a bollard from the next higher DWT category.

2.Berth Structure:The bollard’s capacity must be compatible with the concrete or steel structure of the quay wall. A bollard can be rated for 1,500 kN, but if the quay wall can only handle 1,000 kN, the bollard's effective capacity is limited. The structural capacity of the berth is often the final deciding factor.

3.Vessel Type:While DWT is the primary metric, certain vessels generate unique forces. For example:

①Container Ships:They have large windage areas (above-water surface area). Even with a lower DWT, they can exert significant wind forces. A detailed calculation using wind area is recommended.

②LNG Carriers:These often require specialized bollard arrangements and capacities as per operator (e.g., Shell, ExxonMobil) standards, which can be more stringent.

4.Line Size and Rope Type:The bollard must be physically compatible with the mooring lines used. The bollard's horn height and overall dimensions should accommodate the diameter of the largest lines without the line jumping off. For synthetic fiber ropes, a larger bollard diameter is often required to prevent over-bending and damage.

Step 5: Beyond Capacity – Other Critical Specifications

Selecting the correct bollard involves more than just force capacity. As a professional supplier, we ensure our clients consider the complete specification:

1,Type:Common types include Pillow/Pier Bollards(for container/ bulk),

Double Bollards(for general cargo)

Quick Release Hooks(for large tankers where rapid release is critical).

2,Material & Corrosion Protection:Bollards are typically cast steel or fabricated steel. For long life in a marine environment, they must be protected. Our standard finish is zinc coating + epoxy paint or thermal spray aluminum (TSA), which provides superior corrosion resistance compared to simple paint.

3,Certification:For many projects, proof of quality is essential. We can provide mill test certificates, material certificates, and load test certifications from third-party bodies like SGS or BV to verify the bollard meets its stated capacity.

 

Conclusion: Making the Safe Choice

Selecting a mooring bollard is an exercise in balancing vessel characteristics, environmental forces, and structural limitations. Using the DWT-to-pull capacity table provides a reliable, industry-accepted foundation. From there, factoring in exposure and vessel type allows you to fine-tune the selection for safety and longevity.

An under specified bollard is a safety hazard. An over specified bollard is an economic inefficiency. The goal is a perfectly matched, certified, and durably protected bollard that will serve your terminal safely for decades.

 

Are You Planning a New Project or a Replacement?

Choosing the right mooring bollard is a critical decision. If you have a specific project in mind—whether it's for a new port development, a terminal upgrade, or simply replacing aging equipment—we are here to help.

We can provide:

1,Free Technical Consultation:Share your vessel DWT, site exposure, and berth structure details, and we will provide a tailored bollard recommendation.

2,Certified Products: All our bollards come with full material and load test certifications.

3,Global Delivery:We have extensive experience shipping heavy marine equipment worldwide.

Contact us today to discuss your requirements. Simply fill out the form below or send us a message with your project details, and one of our marine engineers will respond within 24 hours.