When choosing marine fenders for a port, it’s a big decision. The right fender system keeps vessels safe, protects port structures, and ensures smooth operations. Cylindrical and arch fenders are common choices. They each have unique pros and cons, making them suitable for different situations.
Cylindrical Fenders
Cylindrical fenders are among the oldest and most widely used types. They’re basically hollow rubber cylinders. You can install them horizontally or vertically.
Advantages of Cylindrical Fenders
These fenders are versatile, working well for many vessel sizes and berthing conditions. This makes them a great general-purpose option. They’re also easy to install and replace because of their simple design. This can save money on maintenance. They offer consistent performance, absorbing energy and providing low reaction force reliably. For berths with moderate tides, horizontal mounting gives good coverage.
Disadvantages of Cylindrical Fenders
Vessels can be more prone to surging motion with cylindrical fenders if they aren’t properly secured. They can also create higher hull pressure on vessels. This might be a concern for ships with thinner side plating, like some oil tankers. When mounted horizontally, they offer limited vertical coverage for areas with significant tidal changes. You might need multiple rows or different fender types in such cases. They can also roll up the berth face if not properly restrained. Lastly, they have lower energy absorption per unit weight. This means you might need longer lengths to spread the force, or they could be larger than other fender types to absorb the same amount of energy.
Arch Fenders (DA/SA Type)
Arch fenders, also known as DA or Super Arch (SA) fenders, have an arch shape. They’re made of solid rubber. Typically, one side is attached to the dock, creating a strong buffer.
Advantages of Arch Fenders
Arch fenders are designed for high energy absorption with a relatively low reaction force. This is good for both the vessel and the port. Their design also provides excellent shear resistance, keeping them stable even under horizontal forces from surging vessels. They are space-efficient due to their compact design. Made of solid rubber, they need low maintenance. While their initial cost might be higher than some basic cylindrical fenders, their durability and low maintenance often make them cost-effective over time. Some variations with an anti-impact board and PE panel can reduce surface pressure and friction. They also adapt well to uneven ship side plates.
Disadvantages of Arch Fenders
The pressure on a ship’s side plate can be high with arch fenders. This makes them less suitable for vessels with weaker side plates, like certain oil tankers. Without special frames, their tidal range coverage is limited, similar to horizontally mounted cylindrical fenders. They might not be ideal for very large vessels in all situations, as these might need more advanced fender systems.
Choosing the Right Fender for Your Port
Selecting the best fender system requires careful thought. You’ll need to consider several factors.
Vessel Size and Type
Larger vessels need fenders that absorb more energy and create less reaction force to prevent damage. Vessels with unique hull shapes or sensitive plating, like cruise ships, might need fenders that spread pressure more evenly. Tugboats have specific fender needs because of their pushing and towing work.
Berthing Conditions
Consider the berthing speed and angle. High-speed or angled approaches need fenders that can handle significant impact. For ports with large tidal variations, you’ll need fenders that protect across the entire vertical range. This might mean vertical mounting, multiple rows, or self-floating fenders like pneumatic types. If the harbor is exposed to waves and currents, you’ll need tougher fender systems.
Port Infrastructure and Layout
Limited berthing space might favor compact fender designs, like arch fenders. The quay wall’s type and strength will influence how much reaction force the fenders can handle. It’s also important to integrate fenders with existing mooring lines, cranes, and other equipment.
Energy Absorption and Reaction Force Requirements
Fenders must effectively absorb the kinetic energy of the berthing vessel. They also need to keep the reaction force on both the vessel and the structure within safe limits. Industry standards and project needs often determine these limits.
Maintenance and Longevity
Think about the long-term maintenance and expected lifespan of the fender system. Low-maintenance options, like solid rubber arch fenders, can save money over time. It’s also crucial that the fenders are durable in the marine environment, resisting UV, ozone, saltwater, and abrasion.
Budget
While the initial cost matters, also consider the total lifecycle cost. This includes installation, maintenance, and potential repairs. A cheaper fender might end up costing more in the long run due to frequent repairs or vessel damage.
In summary:
- Cylindrical fenders are versatile and economical for general use and moderate conditions.
- Arch fenders offer higher energy absorption and excellent shear resistance in a compact design. They’re good for tight spaces and higher impact forces, though they can put more localized pressure on the hull.
It’s always best to conduct a thorough engineering assessment. Consider all these factors and even consult with fender manufacturers. This will help you choose the best fender system for your port.
What kind of vessels typically use your port, and what are the main berthing challenges you face?