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happy-new-year-max

Happy New Year 2020

To all our customers, colleagues, partners, friends and families, everyone of us at MAX wishes all a year of happiness, prosperity and good health ahead.

Happy New Year 2020!! 

happy-new-year-max

And for those celebrating, Chinese New Year is around the corner too! Let’s have an even better Year of the Rat! Gong Xi Fa Cai in advance!

Our factories and offices will be closed during 23/1/2020 until 12/2/2020, with some of our colleagues taking more leave, so we hope you bear with us if we are a little slow in replying.

Thank you very much for your kind understanding!

We pray for a blessed year for all!


3d-printing

How MAX uses 3D Printing to Add Value

A big part of MAX’s business also manages and advises shipyards in launching or ship repair processes. These days, for trickier projects with challenging ship dimensions or special situational slipways, our team uses 3D printing to help with our demo.

3D printing is very commonly referred to as additive manufacturing. It is when successive layers of material (for our use, it’s PLA) are slowly laid down under precise intelligent control to form a 3D shaped object. 3D printers is a rising trend of rapid prototyping in today’s world. For MAX, we use it to make demo kits according to precise specifications of our clients’ vessels.

MAX 3D printer

Unlike our old presentation, now for certain cases, our presentation and discussion features a more lively demo with 3D printed objects scaled down (usually 1:500) according to exact dimensions of our clients’ modules. Besides, this also enabled our team to understand the dimensions of the module more clearly with a physical object in hand. It certainly helps our customers understand better and have a look of a scaled down ratio of things

3D Designing, Rendering & Slicing for Print

Our team studies the dimensions or require clients to send their designs so that we can proceed with slicing for printing preparation. At this stage, the amount of time, materials and configurations are carefully considered. (Due to the confidentiality of the designs, we are unable to showcase photos for real projects).

rendering & design3D slicing

Printing a Demo Kit

The printing process ranges from a couple of minutes up to 20 hours! It mainly depends on printing quality, speed & configurations.

printer maxprinting in action

3D printing is adopted in our sales & marketing team as we hope to establish effective communication with our stakeholders.  MAX is proud to be embracing new technologies like we always have to improve our delivery to clients. This is especially true at the time where we are popularising an extremely versatile ship launching method worldwide especially in America, Europe and South East Asia. Learn more at Shiplaunching.org.

 

RELATED NEWS

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rubber-airbag-launching-hauling-mobilisation-guide

Ship Repair, Launching & Marine Salvage using MAX Airbags

The Ultimate Guide to Ship Launch, Ship Repair & Marine Salvage using MAX Air Bags

MAX Marine Airbag technology is an extremely flexible technology where it can handle heavy structure launchings (ships, boats, floating jetties, caissons), ship repair haul-ins and marine salvaging cases.

While we cannot disclose the details of calculation due to professional competitive advantage, this guide aims to give an overall view of how MAX advises our clients.

Ship launching using such marine rubber inflatables is superior to many other conventional methods.

Airbag ship repair and launching offer shipyards a cheaper, safer and eco-friendlier option than traditional methods. Tweet this!

Guide-marine-airbag-ship-launch-hauling-marine-salvage

Jump directly to:-

Ship Launch Section

Ship Repair Section

Marine Salvage Section

guide-vessel-launch-section

Ship Launch Section

MAX Rubber Airbags are really cost-effective in launching a vessel.

They are very suitable even for smaller-sized barges to tug boats up to bigger-sized chemical tankers and containerships.

However, it is very important to understand that rubber airbag launching is not a ‘one-size-fits-all’ method.

Marine rubber air bag launching is not a ‘one-size-fits-call’ method. Tweet this!

In fact, MAX team would need to understand all the necessary technical specifications of the vessel (or structure, as this launching method can also be used to launch caissons & floating jetties etc) and many external factors.

The first step is to identify the vessel size & dimensions.

identify-vessel-dimensions-step

Identify Main Dimensions & Types of Vessel

At MAX, we believe in listening before we jump to conclusions and putting our clients priorities first.

Before proceeding in advising, MAX staff would normally request our prospects to fill in a technical specifications form.

Factors like:

  • Length overall (L.O.A.),
  • Beam,
  • Draft,
  • Launching weight (light weight) of the vessel
  • Working height (distance between ground and the hull of the vessel), are just a few crucial things we need to know.

This enables our team to understand the weight dynamics of the structure during launching.

Equally as important, we also ask for a GA plan as the main ship design different designs of the structure plays a role in choosing an efficient air bag solution.

air-bag-choice

Selection of MAX Marine Airbag

After understanding the type of vessel and its principal dimensions, MAX staff is then able to recommend the:

  • Types
  • Sizes
  • Numbers of airbags.

A weight allowance of a certain percentage of the vessel weight is taken into consideration.

This helps MAX to ensure a safe launching process by not overexerting the rubber airbags and also have a safety margin, should there be any additional weight carried by the vessel during launching.

It is important to take into consideration a safety factor of weight allowance during selection of marine air bags. Tweet this!

Based on the dimensions and structural design, the team can recommend the dimensions of the airbag in terms of length, diameter and type.

Then, based on calculations and careful projections, MAX staff is able to determine the guaranteed bearing capacity per airbag.

At this point, extra airbags for launchway mobilisation will be included in our recommendations.

The selection process of MAX airbags is also checked by our MAX Smart Ship launching software.

launching calculator

Due to professional competitive advantage, this is a screenshot of just a part of the software.

This software is developed by MAX software engineering team and acs as a double-checking process to enable a safe recommendation of the optimum number and types of airbags for use.

ground-structure

General Ground Structure Preparation

MAX airbag launching process requires a hard ground so that the whole structure will not sink during launching.

If the ground consists of sand or is soft, there are many options that our staff will recommend.

Sandbags are a very commonly used solution.

MAX also helped many of our clients prepare concrete ground as launching slipway for airbag use.

This would require a very delicate study of the nature of the ground and in-depth analysis on a case-to-case basis. Thus, it is crucial that this aspect should not be overlooked.

For MAX, we have helped our clients solve these issues in many years of our experience in ship launching.

Contact us if you have such tricky issues with the launching slipway and need professional assistance.

Power and miscellaneous issues:

Other pre-launch conditions like power generation issues including the design & supply of diesel generator systems will also be discussed with our client.

selection-launch-way-marine-winch

Selection of Slipway Winch

We do not recommend other general-usage winches. Our slipway winch is designed specifically for this use – launch or haul-out ships.

  • Winch speed within the industry standard of ship launching with airbags
  • Emergency reverse-braking mechanism
  • Various built-in safety mechanisms for common issues when handling ships.
  • Control panel tailored to conditions in shipyards / marine-use
  • And more.

Safety should be the No.1 consideration here. Our winch is built for the job.

Determining winch capacity:

The force needed to support the vessel will be determined by taking into account the slope angle.

The engineering team will have to calculate and find out the type & strength of slipway winch required to hold the structure in place.

Determining electric or hydraulic powered?

The decision of whether to use an electric or hydraulic winch is also very important.

A hydraulic winch may be more expensive but might be more durable and more suitable in certain cases. Though it depends on the user and conditions.

Pulley blocks, shackles, suitable wire rope types and necessary equipments will also be recommended if needed.

Pulling force plays an especially huge role for certain launching projects that require a slow and steady launch approach, needing the winch to be able to operate long periods of time.

determine-placement

Placing of Rubber Airbags

MAX team uses 3D projections to determine the placement of rubber airbags at ready-launch position.

3D GIF

This helped give a 3D view on how to evenly distribute the weight of the vessel/structure for maximum safety.

MAX takes into careful consideration the distance between components and how to coordinate the metal strut/stand locations.

3D-printing is used for some of MAX’s vessel launch projects, too.

launch

The Actual Process of Launching the Vessel

First time users usually require MAX consultation crew to be on ground to help clients launch their vessel.

We are able to facilitate the whole preparation together with supervision of the launching process at a small consultation fee for our clients.

Equipped with decades of experience in launching and careful projections, our team ensures the project success and the safety of the crew.

With its advantages, launching of structures up to 10,000 Tonnes using this method is pretty common these days.

It is widely acknowledged that our quality launching bags are able to be used up to more than 5 years and is very cost efficient compared to most traditional launching methods.

MAX Airbag launching process

This is a simple breakdown of the common air bag launching process.

  1. It started with a winch holding the vessel in place.
  2. Airbags are placed underneath the ship’s hull.
  3. Air bags are then inflated.
  4. The transfer of weight from support blocks to having the airbags actually lifting the vessel itself.
  5. Remove the support blocks.
  6. Then the winch’s pulling force is slowly decreased to enable mobilisation of vessel towards the sea line.
  7. At a certain point, the connection between winch and vessel will be released using MAX quick release shackle.
  8. The vessel, assisted by gravity and launching bags, will be launched safely into the sea with minimal risk.

max-professional-assistance

Please note that however, there are many different scenarios to cater to different situations and different vessels, so this is just an overall idea of it.

For your projects, drop us an email so MAX team can assist.

You can visit MAX Marine Airbags page for more info on the product.

View a Youtube video of the launching of Sealink Asia 101 by MAX below:


ship-repair-section

Ship Repair Section

Like the ship launching method, the main concept and preparation process are both very similar, just reverse the process. Please go through ship launching section first before reading this section to better grasp the idea.

Most calculations are inverted and the core concept of having strong enough pulling force (in this case, hauling winch) is key to maintaining a steady hauling process for ship repair.

Understanding Principal Dimensions & Weight of Vessel

Similarly to the vessel launching process, the hauling in of vessel for repair projects require MAX to analyse its dimensions in detail.

Weight, overall ship length and width are some of the aspects MAX engineering team would take under consideration.

The design of hull and ship has to be considered as well for hauling process as structural differences can affect the types of airbags used.

Choosing Suitable MAX Airbags

Main dimensions and structural design of the vessel helps MAX team to recommend the dimensions, thickness, specsnumber of air bags needed.

When choosing the most suitable bags for hauling use, safety is our number one priority.

Marine bags should not be overexerted.

That is why MAX’s experienced technicians will add a percentage of weight contingency in calculations.

This will add a ‘safety cushion‘ also to accommodate any excess weight that the vessel may have added.

Next, detailed projections and careful calculations enable MAX to identify the bearing capacity per airbag.

This figure is subsequently used to deduce the total number of bags needed, including extra bags for launchway mobilisation.

MAX team will then use our in-house developed MAX Smart Ship Launching software to double-check the calculations.

Pulling Winch / Hauling Winch with Enough Pulling Force

Depending on the angle of the slope, the dimensions & size of vessel, a winch and the entire pulley system will be recommended to provide sufficient pulling force.

Ship Repair using Launching Airbags

Most of the process is similar to the airbag ship launching process.

You can read more about it here, but reverse the process.

Instead of launching the vessel into the water, rubber airbags help lift the vessel out of the water, supporting its movement towards land using the winch’s pulling force.

This innovative product helps boost a yard’s ship repair capacity without needing to invest in building another dry dock.

A hard ground is sufficient to enable vessel hauling using airbags, and repair works can be performed at the same location.

The entire hauling process is a delicate case-to-case situation.

MAX’s experience and detailed projections will ensure you a safe ship haul-out process.

These launching bags are also used by our team to solve launch way limitation problems, maximising the return on investment of our clients.

max-professional-assistance

marine-salvage-section


Marine Salvage Section

Marine Salvage is the process/project of recovering a vessel (ship), its cargo, or items after a ship wreck.

This includes towing of a vessel, patching of a ship or re-floating a sunken/grounded ship.

MAX Airbags is a popular product for re-floating a sunken/grounded ship.

Marine salvage using rubber bags are mainly case-to-case studies where MAX technical team will advise only based on known data.

Here is just a general idea of how MAX would assist in vessel salvaging projects:

Buoyancy Needed to Re-float Vessel

The in-depth study & calculations of buoyancy needed will be carried out by MAX.

With this, MAX is able to advise on the size and type of MAX salvaging bags (There are custom made and very different when compared to launching bags with more emphasis on floating ability etc).

Depth or Water Pressure

MAX needs to understand the scale of the project and the magnitude of it to determine the strength & type of mobilisation/re-floating airbags.

max-professional-assistance

We have worked closely with marine salvaging teams in many parts of the world since Hurricane Katrina in 2005.

Our experience in these projects would ensure the success of your marine salvage projects.

So if you’re a marine salvaging team, contact us for high quality and reasonably-priced MAX rubber airbags.

View MAX Rubber Airbag product if you’ll like to learn more.

 

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Airbags, the Best Ship Launch Method?

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Airbag Ship Launching. Cheaper than dry dock launching, eco-friendlier than oiled slipway launching?…[Read More]

Case Study: Sideways Mobilisation using MAX Rubber Inflatables

barge 3 in place

This newly established ship repair yard has limited launch way/slipway. Supposedly, only 1 barge can be hauled in for repairs at a time…[Read More]


airbag-best-ship-launching-hauling-option

Ship Launching Airbags, the best ship launching method?

Launching a ship is the most important process in ship construction. It not done right, it erases all the hard work building the ship itself. Sometimes, people take ship launching for granted and it came as no surprise that many ship launching projects fail due to negligence.

MAX Turkey 2007 ShiplaunchPenang shiplaunch max airbags

A table for some of the most popular ship launching method comparisons:

METHOD

COST

SAFETY

ENVIRONMENT

Oiled Slideway Launching

(Longitudinal & Side)

Low costs.

Dangerous as front part of the ship undergoes huge pressure. The immediate drop into water also might cause collision with the bottom of the river/sea. Many accidents happen for especially side ship launching.

Oil used will pollute the water.

Roller Slideway Launching

Initial installation costs are high.

Moderate.

Eco-Friendly

MAX Ship Launching Airbags

Very cost-effective. Ship launching airbags can be re-used many times & usually has a lifespan of 5-8 years.

Safe. MAX Ship launching airbags provide support to the hull of the ship and aids its launching motion into the water.

Eco-Friendly

Dry Dock Floating-Out Launching

Initial investment is extremely high.

Safe.

Eco-friendly

Mechanical Type Launching

(With mechanical features)

The construction and maintenance for mechanical features are extremely high.

Risky, and only for smaller vessels. You can see many accidents happen for this type of ship launching.

Eco-friendly

 

If you are still using oiled slideway ship launching, it may be time to consider a more eco-friendly and safe ship launching method.

If you are launching your ship with dry dock float-out method, consider whether it is necessary for such a huge initial investment for your vessel. The float-out method is great for massive ships (more than 15,000DWT ships) but for ships with a DWT of less than 10,000 tonnes, ship launching airbags can help launch the vessel with relative ease. For those more than 10,000 tonne DWT ship launches, careful projection and a professional team’s assistance may be required. Still, it is usually much more cost-effective than dry dock ship launching. Rubber air bag vessel launching is a much preferred option especially popular in South East Asia, though it is already picking up momentum in many other regions like Europe and North America.

Airbag Ship Launching. Cheaper than dry dock launching, more eco-friendly than oiled slipway launching. Tweet this!

pneumatic rubber roller launch

You can read our extensive guide to learn more about the methodology of advising usage of pneumatic rollers (a.k.a. rubber marine airbags) for ship launching, repair and salvage operations.

Do you experience a short lifespan for your marine products like ship launching airbags? Deal with a supplier who is slow in responding and service? Or did you pay extremely high prices for an average quality product that often fails you? 83% of our global clients claim that these are the problems that made them search for a better alternative and subsequently worked with us since.

max-professional-assistance

MAX is known for our products’ great quality-to-price ratio and responsive customer serviceMoreover, from our global sales office to manufacturing plants, we are committed to ‘Go Green‘ for the environment. Drop us an email and we will assist!

Here’s what makes our airbags special:

MAX Groups Marine has launched various types of vessels in 6 continents using marine airbag technology. For more info of our projects, visit <http://max-groups.com/projects/>


View all our products at our Product Page HERE.

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Related Articles

The Ultimate Guide to Ship Repair, Launching & Marine Salvage using MAX Airbags

3D GIF

MAX Marine Airbag technology is a flexible technology where it can handle heavy structure launchings (ships, boats, floating jetties, caissons), ship repair haul-ins and marine salvaging cases…[Read More]

Case Study: Sideways Mobilisation using MAX Rubber Inflatables

barge launching

This newly established ship repair yard has limited launch way/slipway. Supposedly, only 1 barge can be hauled in for repairs at a time…[Read More]


defensa-yokohama

Ventajas & Tipos de Defensas Neumáticas (Yokohama)

Defensas Neumáticas Flotantes de goma, tipo Yokohama

Las defensas neumáticas flotantes de caucho son consideradas como uno de los principales equipos anticolisiones para las aplicaciones marinas. De acuerdo con la norma ISO 17357: 2002, las defensas neumáticas flotantes de goma en ocasiones son denominadas de forma coloquial como “defensas Yokohama” o “defensas tipo Yokohama”.

Juegan un rol activo como medio de protección contra las colisiones en las operaciones de contacto de barco a barco y de barco a embarcadero. Su mayor ventaja es que absorben una gran cantidad de energía, con baja presión en superficie de la unidad sobre barco. También se utilizan como defensas de emergencia, en buques petroleros, gaseros y barcos de carga a granel.

marinas defensas de goma

Composición

La composición básica de las defensas neumáticas de caucho consiste en una capa externa de goma, capas de cuerdas y una capa interior de caucho vulcanizadas juntas. Las bridas de los extremos están disponibles en ambos extremos para propósitos de carga. La capa de goma externa está hecha de material de caucho fuerte para resistir fuerzas externas y proteger a las otras capas de la abrasión, así como para uso rudo en malas condiciones meteorológicas. Las capas de cuerdas están diseñadas de forma innovadora en ángulos ideales para distribuir uniformemente la tensión que actúa sobre la defensa. Se aplican tanto la tecnología de entramado de cuerdas como la fibra de poliamida de alta resistencia a la tensión para proporcionar resistencia y mantener la presión interna durante el uso. Esto ayuda a distribuir uniformemente la tensión, manteniendo la absorción de energía y aumentando su eficiencia. La capa interior tiene la tarea de sellar el aire que se encuentra dentro, reduciendo al mínimo las fugas de aire ya que utiliza un material con cualidades herméticas.

Composición

 

Principales tipos de redes protectoras

Las defensas neumáticas pueden venir sin red de protección y generalmente son de color negro. Los colores se pueden variar según las necesidades del cliente y suelen tener 3 tipos de redes de protección para mejorar la vida útil de los productos.

(i) Red de cadenas de neumáticos

tire-chain net fender

(ii) Red de alambre de caucho

rubber mat wire net

(iii) Red de fibra

fiber net

Ventajas de las defensas neumáticas

Ventajas

(Clic para agrandar)

Hay varias razones por las que las defensas neumáticas marinas son la opción preferida para muchos.

Ventajas durante los atraques inclinados

Durante el atraque, el contacto inicial con el muelle suele tener un ángulo oblicuo y pone mucha presión en ambas superficies (la del muelle y la del barco).

En las típicas defensas de goma sólidas, al tener una compresión inclinada, la absorción de la energía disminuye considerablemente. Por lo tanto, no son poco comunes las situaciones en las que las personas optan por defensas sólidas de mayor tamaño. Por otro lado, la tasa de absorción de energía de las defensas neumáticas se mantiene en un nivel superior incluso cuando las comprimen en determinados ángulos. Debido a una distribución más uniforme de la presión de carga, el rendimiento del par de torsión contra el muelle suele ser menor en comparación con los diseños convencionales de los sistemas de las defensas sólidas.

Mayor resistencia contra las fuerzas de torsión

Al hacer contacto con el muelle, los barcos son por lo general movidos lentamente a una posición óptima de amarre. Esta acción ejerce una gran fuerza de cizallamiento y compresión en la superficie de las defensas. La mayoría de las defensas sólidas están severamente dañadas a causa de estas fuerzas ya que no están diseñadas para resistir intensas fuerzas de cizallamiento y fricción. Ese es el motivo por el que la mayoría de las defensas marinas tienen paneles frontales para hacer frente a este problema y proteger las defensas de goma de las fuerzas directas de cizallamiento. De esta forma, las defensas no entran directamente en contacto con el barco. A diferencia de las defensas de normales, las defensas Yokohama pueden resistir altas fuerzas de cizallamiento desde todos los ángulos gracias a sus propiedades neumáticas (llenas de aire). Esto las convierte en una alternativa ideal en comparación con las voluminosas dimensiones de los marcos de las defensas frontales.

Son relativamente seguras incluso durante una carga excesiva

En general, todas las defensas deben utilizarse dentro del impacto del límite de carga. Sin embargo, en situaciones de la vida real, es común ver que las defensas suelen recibir exceso de cargas accidentalmente. Cuando eso sucede, lo fantástico de las defensas Yokohama es que la fuerza de reacción no aumenta considerablemente bajo una carga excesiva. En contraste, las fuerzas de reacción de las defensas sólidas tienden a subir marcadamente bajo condiciones de carga excesiva y dañan la nave durante el proceso de amarre. Las características de las defensas neumáticas flotantes también contribuyen al proceso ya que permiten una distribución más uniforme de la tensión.

Ventajas durante condiciones climáticas cruciales

Durante condiciones climáticas cruciales, cuando la acción de las olas es intensa, los procesos de amarre se complican aún más debido a la acción desequilibrada de movimientos hacia arriba y hacia abajo en el muelle. Esto ejerce una fuerza de torsión más alta en las defensas y el cambio de frecuencia en las fuerzas durante el amarre en tales condiciones meteorológicas ocasionará fatiga en las típicas defensas de tipo sólido. Sin embargo, por otro lado, el área de contacto flexible de las defensas Yokohama, así como sus amplias características de deflexión permisible minimizan la fatiga durante dichas situaciones. Debido a que las defensas son defensas flotantes, su rendimiento de absorción de energía se ve menos afectado por las diferencias severas en las olas de la marea. Para mares con situaciones difíciles o con frecuentes condiciones meteorológicas adversas, así como fuertes diferencias en la marea, las defensas neumáticas flotantes marinas de caucho pueden ser una mejor opción ya que suelen mostrar una vida más larga.

Deterioro en el rendimiento minimizado

El envejecimiento y la fatiga causan frecuentemente que las defensas se deterioren en términos de rendimiento. Sin embargo, debido a su composición llena de aire y que son altamente elásticas, estos problemas se reducen al mínimo. Las defensas de caucho sólidas o las defensas de espuma dependen más de la dureza del material, y dicha dependencia puede resultar en la disminución del rendimiento de absorción de energía y en cambio de temperatura después de años de uso. Por otro lado, siempre y cuando se les de mantenimiento básico y control de la presión del aire, las defensas neumáticas se desempeñarán con un rendimiento óptimo a temperaturas extremadamente bajas de hasta -50 grados Celsius, o incluso durante fluctuaciones de temperaturas altas.

Adaptación a la marea

Las defensas Yokohama son principalmente del tipo flotante, lo que significa que las defensas flotan en el agua en un plano vertical sin restricciones a la amplitud de la marea y al movimiento vertical del barco. Por lo tanto, la absorción de la energía de las defensas siempre sucede en la posición más óptima.

Instalación sencilla y mantenimiento de bajo costo

Las defensas neumáticas pueden instalarse simplemente por medio de cuerdas o cadenas a un costo adicional mínimo. En este tipo de defensas flotantes, la transferencia o remoción también es muy flexible y fácil. El mantenimiento de las defensas neumáticas (defensas tipoYokohama) incluye revisiones anuales sobre la presión interna del aire, inspección de las condiciones físicas de la red de la cadena y de la superficie de la defensa. Por lo general, las redes de las cadenas tienen una vida útil de aproximadamente 3 a 4 años, dependiendo de su uso.

Pneumatic fenderDefensas tipo Yokohama
Para aprender más sobre las defensas neumáticas flotantes de caucho, visite nuestra página del producto ‘Pneumatic Fender‘.

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calculate-choose-marine-fender

Choose a suitable marine fender design system

If you are looking for a post that lists out all available rubber fender design types like “pneumatic fender”, “modular fender”, “D-shaped bumper” etc, you should visit “Rubber Fenders: Types & Things to Note” article.

chain selection

This article post aim to discuss the generally used equations, formulas, factors to determine a suitable port fender design. All formulas and equations are only intended as reference only. If you have a project, drop us an email so our technical staff can advise you.

Contributed by Wang.

Defensas para muelles super cell

A solution to absorb collision & prevent damage

Since the early days of floating crafts & small wooden boats, fenders were woven from ropes to absorb collision during berthings. Similar to the products we have today, they came in various sizes and patterns to serve different needs. The primary function of such a “soft-contact” system is to prevent the vessel from sustaining damage as the ship or boat is being moored against the quay wall. However, the vast amount of variations may confuse some looking to purchase certain fenders for their new-built port or jetty. In short, impact forces during the vessel berth, abrasive action, among other factors must be taken into consideration as well as the block safety coefficient to provide some allowance. The multi dimensional forces may cause extensive damage to the jetty structure AND the ship at the same time if a less suitable fender is used (or worse, a low performance fender system is deployed). So, it is about absorbing contact and distributing the force onto a larger surface area to prevent damage. Aside from mostly uniformly distributing collision force, it also increases impact time to lower the reaction force in whole.

Yes, it is important to have a structure of this kind to prevent damage to the quay wall or jetty or harbour.

Quite simply, determining a suitable marine fender system comes down to considering:

Amount of Energy Absorbed and Maximum Impact Force Imparted

Common Selection Process: All Conditions must be Carefully Studied

It is important to keep in mind that the local marine condition is as big a factor as the ships the quay is accomodating. Both aspects affect the choice of “marine bumpers” used. So it is not surprising to see two different types of fender systems being deployed in the same city, but to accommodate different types of ships. Harbor conditions are also rarely the same. Successful previous local experience must be considered. The best way to figure out what type of port fender is suitable for your berthing structure would be to carefully study your own local marine condition that includes:

  • Site condition and depth
  • Local temperature range & weather
  • Wind velocity
  • Direction of ship when berthing
  • Tidal range & wave height
  • Berthing structure
  • Type of ships, along with class, configuration, size
  • Velocity of ship approaching the quay wall during berthing
  • Exposure of harbor basins
  • Available docking assistance
Before diving into this guide, one has to understand that the design criteria differ from one person to another. So this article is aimed to act as jsut a reference for many. For detailed project designing & fender choosing, kindly contact a professional team to design suitable marine fender system.
Prior to designing and doing any calculations, one has to prioritise one’s design standard and criteria.
  • Are there any specific codes and standards that you need to conform to?
  • Intended useful life of product? Some fenders are longer lasting than others.
  • Safety factor?
  • Designated vessels for berthing calculations?
  • Velocity range?
  • Costs: From installation fees, to maintenance costs. All has to be thoroughly considered.

Guide:

The law of energy conversation is the basis for all fender design selection. When choosing fenders, it is vital to base calculations and considerations on the largest (heaviest) vessel sizes to be berthed at the wharf. Besides, vessels are getting larger as ship design evolves from time to time. It is important to take into consideration those expected to arrive in the near foreseeable future.

Fender Energy Absorption = Energy Delivered upon impact – Energy absorbed by pier

To understand how much energy absorption is needed, one needs to first determine the energy that will be delivered to the quay wall upon initial impact.

Secondly, one has to then carry out calculation to find out the energy that requires to be absorbed. For linearly elastic structures, the energy is ½ the maximum static load level times amount of deflection. Some allowance should be added. If the structure is very rigid, one can assume no energy absorption from the pier.

Minus the energy amount absorbed by pier and one can determine the fender energy absorption value that is required for a safe berth.

Then, one can choose a suitable fender type and design from a wide range of available marine fenders in the market today: from super cone type, arch type, cylindrical shaped, to floating types like Yokohama fenders and foam fenders. Be sure to select a manufacturer that adheres to PIANC2002 and/or other standards to ensure great quality fender products.

GT Gross Tonnage Total volume of cargo + vessel
NT Net Tonnage Total volume of cargo on vessel
DPT Displacement Tonnage Total weight of the cargo-filled vessel when vessel is loaded to the draft line
DWT DeadWeight Tonnage Weight of cargo + people (including crew) + fuel + food on the vessel
LOW Light Weight Vessel weight
BW Ballast Weight Weight of the vessel when water is added in the ballast

Types of Berthing Approach:

Side Berthing:

Side Berthing

‘Dolphin’ Berthing:

dolphin berthing

End Berthing:

end berthing

Lock Entrances:

lock entrances

Ship-to-ship (STS) Approach:

Ship-to-ship Berthing Operation

This article only discusses berthing calculations for side berthing. If you have a Ship-to-ship (STS) operation or End Berthing, certain equations may be different. Contact our team for assistance.

Effective Berthing Energy formula for Side Berthing:

Vessel side berth fender selectionside-berthing

This is the most common berthing method for docks. The berthing energy is calculated with the equation:

EB = Berthing energy (kJ, N*m, or lbF*ft)

 EB = 0.5 × WD × VB × VB  × CM × CE × CC × C

*click to open/close

WD = Water displacement of the vessel (kg, tons, lbs)

WD = Water displacement of the vessel (kg, tons, lbs)This is the Total Displacement Tonnage(DPT) of the vessel.

VB = Berthing velocity of the vessel at the moment of impact (m/sec, ft/sec)

VB = Berthing velocity of the vessel at the moment of impact (m/sec, ft/sec). Berthing velocity is an important parameter in fender system design. It depends on the size of the vessel, loading condition, port structure, and the difficulty of the approach. The most appropriate method to determine berthing velocity is based on actual previous statistical data. If that is not possible, the most widely used reference would be the Brolsma table, adopted by BSI, PIANC and other standards. However, it is important to keep in mind that the best option is still to base on previous statistical information.

berthing-velocity-fender-design

CM = Virtual mass factor

 

CM =  Mass Coefficient/Virtual mass factor: During the sudden stop of movement as a vessel comes into contact with the berth, the mass of water moving with the vessel adds to the energy acting upon the vessel and fender. This situation is referred to as “Added Mass Coefficient” or “Mass Factor”. Weight of water moving that adds to that is called “ Additional Weight” in these berthing studies.

As the vessel is stopped by the fenders, the momentum of the water continues to push against the vessel and this actually increases its overall mass, so CM has to be calculated. There are 2 ways to calculate its mass coefficient.

The most commonly used “Vasco Costa (1964) method”:

virtual mass factor calculation

Formula B:

virtual mass factor 2 fender

C E = Eccentricity factor

  C E = Eccentricity factor. The reaction force will give a rotational movement at the moment of contact. This will dissipate an amount of the energy. There are 2 formulas to determine the eccentricity factor:

vessel berthing essentricity

You require these info:

  • Distance between center of mass (vessel’s) to the point of impact (R)
  • Velocity vector angle (v)
  • Radius of gyration (K)
  • Berthing angle(α)

NOTE: 

K: Radius of vessel rotation (usually 1/4 of the vessel’s length)

R: Distance of the line paralleled to wharf from the vessel’s Center of Gravity (CG) to the contact point. Common cases are 1/4 to 1/5 of vessel’s length.

CB: Block Coefficient, which is related to the hull shape.

WD: Water displacement of the berthing ship(kg, Tons, lbs)

sea water density symbol: Sea Water density(1.025 Tons/m3)

LBP: Length between perpendiculars. Please see sketch below for better explanation:

x: Distance from bow to point of impact

B: Beam(m, ft)

 

Formula (i): The more detailed calculation to find out C E :

Eccentricity formula

If the beam, length and draft information are not available, this table can be used to estimate:

Typical Block Coefficients(CB)
Type of Vessel  CB
BS 6349
 CB
PIANC 2002
Tankers 0.72~0.85 0.85
Bullk Carriers 0.72~0.85 0.72~0.85
Container Ships 0.65~0.75 0.60~0.80
General Cargo 0.60~0.75 0.72~0.85
RoRo Vessels 0.65~0.70 0.70~0.80
Ferries 0.50~0.65 0.55~0.65

Formula (ii): The more simple formula to find out C E :

eccentricity 2

This method can lead to a serious underestimation of Berthing Energy when the berthing angle (α) is greater than 10° and/or the point of impact is aft of quarter-point(x > LBP/4).

To verify your calculations, one can check the calculated C E values to ensure they generally fall within the following limits:

Quarter-Point Berthing x = L/4 Ce = 0.5
Third-Point Berthing x = L/3 Ce = 0.6 ~ 0.8
Mid-Vessel Berthing x = L/2 Ce = 1
CC = Berth configuration factor

 CC = Berth configuration factor. This is the part of berthing energy absorbed by the cushion effect of water between the approaching vessel and the quay wall. The smaller the draft (D) of the vessel is, or the larger the under keel clearance(KC), the more trapped water can escape under the vessel, and would give a higher CC value.  Also, if the berthing angle of the vessel is greater than 5°, we can consider CC = 1. Different dock types would have different variations.

Closed Dock case
A closed Dock would be a wharf, where you have a concrete wall going directly to the sea ground. In this case the quay wall will push back all the water that is being moved by the vessel. This creates a resistance factor that can be calculated as follows:

If KC ≤  D / 2, C≈ 0.8

If KC >  D / 2, C≈ 0.9

Open / Semi-Closed Dock case
A semi-closed dock is when water can flow underneath the dock, but the depth changes below the dock. Open dock is usually a dock with piles underneath and the water can flow freely underneath the dock. In such case we can assume the following value of 1.

C≈ 1

CS = Softness factor

  CS = Softness factor. This is the energy absorbed by the deformation of the vessel’s hull and fender. Usually, we can assume CS ≈ 0.9.

When selecting the size of fenders, it should be selected base on the consideration of kinetic energy of contact between two vessels or between vessel and berthing facilities may be absorbed by a single fender. The following tables are given for determining the energy absorption depends on approaching velocities for various ships.

Energy absorption for ship-to-Jetty (for reference only)

*click to open/close

Energy Absorption of Oil Tankers at ¼ point Berthing (kJ)

Table (i) Energy Absorption of Oil Tankers at ¼ point Berthing (kJ)

DWT Assumed

Weight(t)

Approaching velocity (m/s)
0.10 0.12 0.15 0.18 0.20 0.25 0.30 0.40
300 668 1.7 2.5 3.8 5.5 6.8 11.0 15.0 27.0
500 1,091 2.8 4.0 6.3 9.0 11.0 17.0 25.0 45.0
700 1,558 4.0 5.7 8.9 13.0 16.0 25.0 36.0 64.0
1,000 2,228 5.7 8.2 14.0 18.0 23.0 36.0 51.0 91.0
2,000 4,294 11.0 16.0 28.0 35.0 44.0 68.0 99.0 175
3,000 6,470 17.0 24.0 37.0 53.0 66.0 103 149 264
4,000 8,363 21.0 31.0 54.0 69.0 85.0 133 192 341
5,000 10,594 27.0 39.0 61.0 88.0 108 169 243 432
6,000 12,184 31.0 45.0 70.0 101 124 194 280 497
7,000 14,084 36.0 52.0 81.0 116 144 225 323 575
8,000 16,066 41.0 59.0 92.0 133 164 256 369 656
10,000 20,373 52.0 75.0 117 168 208 325 468 832
12,000 23,851 61.0 88.0 137 197 243 380 548 974
15,000 29,493 75.0 108 169 244 301 470 677 1200
17,000 33,056 84.0 121 190 273 337 527 759 1350
20,000 38,623 99.0 142 222 319 394 616 887 1580
25,000 45,946 117.0 169 264 380 469 733 1050 1880
30,000 56,093 143.0 206 322 464 572 894 1290 2290
35,000 63,084 161.0 232 362 521 644 1010 1450 2570
40,000 72,771 186.0 267 418 601 743 1160 1670 2970
45,000 77,986 199.0 286 448 645 796 1240 1790 3180
50,000 89,818 229.0 330 516 742 917 1430 2060 3670
60,000 104,300 266.0 383 599 862 1060 1660 2390 4260
65,000 114,637 292.0 421 658 948 1170 1830 2630 4680
70,000 122,108 312.0 449 701 1010 1250 1950 2800 4980
80,000 136,972 349.0 503 786 1130 1400 2180 3140 5590
85,000 143,359 366.0 527 823 1180 1460 2290 3290 5850
100,000 166,004 423.0 610 953 1370 1690 2650 3810 6780
120,000 200,083 510.0 735 1150 1650 2040 3190 4590 8170
150,000 251,896 643.0 925 1450 2080 2570 4020 5780 10280
200,000 327,735 836.0 1200 1880 2710 3340 5230 7520 13380
250,000 401,268 1020 1470 2300 3320 4090 6400 9210 16380
330,000 548,670 1400 2020 3150 4530 5600 8750 12600 22390
370,000 627,016 1600 2300 3600 5180 6400 10000 14400 25590
480,000 795,540 2030 2920 4570 6580 8120 12680 18260 32470
Energy Absorption of Ore Carriers at ¼ point Berthing (kJ)

Table (ii) Energy Absorption of Ore Carriers at ¼ point Berthing (kJ)

DWT Assumed

Weight(t)

Approaching velocity (m/s)
0.10 0.12 0.15 0.18 0.20 0.25 0.30 0.40
1,000 2,360 6.0 8.7 14.0 20.0 24.0 38.0 54.0 96.0
2,000  4,429 11.0 16.0 25.0 37.0 45.0 71.0 102 181
3,000 6,453 16.0 24.0 37.0 53.0 66.0 103 148 263
4,000 8,341 21.0 31.0 48.0 69.0 85.0 133 192 340
5,000 10,301 26.0 38.0 59.0 85.0 105 164 237 420
6,000 12,574 32.0 46.0 72.0 104 128 200 289 513
8,000 16,332 42.0 60.0 94.0 135 167 260 375 667
10,000 20,516 52.0 75.0 118 170 209 327 471 837
12,000 24,345 62.0 89.0 140 201 248 388 559 994
15,000 29,572 75.0 109 170 244 302 471 679 1210
20,000 38,068 97.0 140 219 315 388 607 874 1550
25,000 45,116 115 166 259 373 460 719 1040 1840
30,000 54,874 140 202 315 454 560 875 1260 2240
40,000 71,143 181 261 408 588 726 1130 1630 2900
50,000 86,432 220 318 496 714 882 1380 1980 3530
60,000 101,383 259 372 582 838 1030 1620 2330 4140
70,000 119,062 304 437 683 984 1210 1900 2730 4860
80,000 132,125 337 485 758 1090 1350 2110 3030 5390
90,000 149,528 381 549 858 1240 1530 2380 3430 6100
100,000 175,960 449 646 1010 1450 1800 2810 4040 7180
150,000 256,357 654 942 1470 2120 2620 4090 5890 10460
200,000 319,149 814 1170 1830 2640 3260 5090 7330 13030
270,000 426,459 1090 1570 2450 3520 4350 6800 9790 17410
Energy Absorption of Freighters at ¼ point Berthing (kJ)

Table (iii) Energy Absorption of Freighters at ¼ point Berthing (kJ)

DWT Assumed

Weight(t)

Approaching velocity (m/s)
0.10 0.12 0.15 0.18 0.20 0.25 0.30 0.40
700 1,585 4.0 5.8 9.1 13.0 16.0 25.0 36.0 65.0
1,000 2,237 5.7 8.2 13.0 18.0 23.0 36.0 51.0 91.0
2,000 4,357 11.0 16.0 25.0 36.0 44.0 69.0 100 178
3,000 6,606 17.0 24.0 38.0 55.0 67.0 105 152 270
4,000 8,712 22.0 32.0 50.0 72.0 89.0 139 200 356
5,000 10,795 28.0 40.0 62.0 89.0 110 172 248 441
6,000 13,515 34.0 50.0 78.0 112 138 215 310 552
7,000 15,557 40.0 55.0 89.0 129 159 248 357 635
8,000 17,703 45.0 65.0 102 146 181 282 406 723
9,000 19,625 50.0 72.0 113 162 200 313 451 801
10,000 21,630 55.0 79.0 124 179 221 345 497 883
12,000 26,052 66.0 96.0 150 215 266 415 598 1060
15,000 31,477 80.0 116 181 260 321 502 723 1280
17,000 36,784 94.0 135 211 304 375 586 845 1500
20,000 41,748 107 153 240 345 426 666 959 1700
30,000 60,483 154 222 347 500 617 964 1390 2470
40,000 79,393 203 292 456 656 810 1270 1820 3240
50,000 98,306 251 361 564 813 1000 1570 2260 4010
Energy Absorption of Passenger Ships at ¼ point Berthing (kJ)

Table (iv) Energy Absorption of Passenger Ships at ¼ point Berthing (kJ)

DWT Assumed

Weight(t)

Approaching velocity (m/s)
0.10 0.12 0.15 0.18 0.20 0.25 0.30 0.40
500 845 2.2 3.1 4.9 7.0 8.6 13.0 19.0 34.0
1,000 1,709 4.3 6.2 9.8 14.0 17.0 27.0 39.0 70.0
2,000 3,500 8.9 13.0 20.0 29.0 36.0 56.0 80.0 143
3,000 5,282 13.0 19.0 30.0 44.0 54.0 84.0 121 216
4,000 7,105 18.0 26.0 41.0 59.0 73.0 113 163 290
5,000 8,912 23.0 33.0 51.0 74.0 91.0 142 205 364
6,000 12,083 31.0 44.0 69.0 100 123 193 277 493
7,000 13,873 35.0 51.0 80.0 115 142 221 319 566
8,000 15,346 39.0 56.0 88.0 127 157 245 352 626
9,000 16,986 43.0 62.0 97.0 140 173 271 390 693
10,000 18,661 48.0 69.0 107 154 190 298 428 762
15,000 26,283 67.0 97.0 151 217 268 419 603 1070
20,000 33,423 85.0 123 192 276 341 533 767 1360
30,000 47,952 122 176 275 396 489 765 1100 1960
50,000 71,744 183 264 412 593 732 1140 1650 2930
80,000 111,956 286 411 643 925 1140 1790 2570 4570
Energy Absorption of Barges or Lighters at ¼ point Berthing (kJ)

Table (v) Energy Absorption of Barges or Lighters at ¼ point Berthing (kJ)

G/T Assuming Weight ( t ) Approaching velocity ( m/s )
0.20 0.25 0.30 0.35 0.40 0.50 0.60
50 85 0.9 1.4 2.0 2.7 3.5 5.4 7.8
100 161 1.6 2.6 3.7 5.0 6.6 11.0 15.0
150 241 2.5 3.8 5.5 7.5 9.8 15.0 22.0
200 319 3.3 5.1 7.3 10.0 13/0 20.0 29.0
300 496 5.1 7.9 11.0 15.0 20.0 32.0 46.0
Energy Absorption of Container Ships at ¼ point Berthing (kJ)

Table (vi) Energy Absorption of Container Ships at ¼ point Berthing (kJ)

G/T DWT Assumed Weight (t) Approaching velocity ( m/s )
0.10 0.15 0.20 0.25 0.30 0.40
8,000 12,000 26,752 68 154 273 427 614 1090
9,000 14,000 33,567 86 193 343 535 771 1370
16,626 16,004 38,172 97 219 390 609 876 1560
21,057 20,400 48,995 125 281 500 781 1120 2000
23,600 23,650 55,560 142 319 567 886 1280 2270
30,992 27,203 64,264 164 369 656 1020 1480 2620
38,826 33,287 79,599 203 457 812 1270 1830 3250
41,127 27,752 67,121 171 385 685 1070 1540 2740
51,500 28,900 68,664 175 394 701 1090 1590 2800
57,000 49,700 105,199 268 604 1070 1680 2420 4290
Energy Absorption of Fishing Vessels at ¼ point Berthing (kJ)

Table (vii) Energy Absorption of Fishing Vessels at ¼ point Berthing (kJ)

Type G/T Assumed Weight ( t ) Approaching velocity ( m/s )
0.20 0.25 0.30 0.35 0.40 0.50 0.60
Whale

factory

ship

10,000

17,000

20,000

34,058

53,494

66,217

348

546

676

543

853

1060

782

1230

1520

1060

1670

2070

1390

2180

2700

2170

3410

4220

3130

4910

6080

Whale ship 400

800

1,000

1,797

3,263

3,950

18.0

33.0

40.0

29.0

52.0

63.0

41.0

75.0

91.0

56.0

102

123

73.0

133

161

115

208

252

165

300

363

Trawler

Vessel

400

800

1,000

2,000

3,000

2,297

3,693

4,458

7,173

9,863

23.0

38.0

45.0

73.0

101

37.0

59.0

71.0

114

157

53.0

85.0

102

165

226

72.0

115

139

224

308

94.0

151

182

293

403

146

236

284

457

629

211

339

409

659

906

Skipjack

vessel

20

50

100

200

126

202

390

779

1.3

2.1

4.0

7.9

2.0

3.2

6.2

12.0

2.9

4.6

9.0

18.0

3.9

6.3

12.0

24.0

5.1

8.2

16.0

32.0

8.0

12.9

25.0

50.0

12.0

19.0

36.0

72.0

Mackerel

vessel

20

50

100

112

266

525

1.1

2.7

5.4

1.8

4.2

8.4

2.6

6.1

12.0

3.5

8.3

16.0

4.6

11.0

21.0

7.1

17.0

33.0

10.0

24.0

48.0

Tuna

long-liner

150

200

400

590

780

1,681

6.0

8.0

17.0

9.4

12.0

27.0

14.0

18.0

39.0

18.0

24.0

53.0

24.0

32.0

69.0

38.0

50.0

107

54.0

72.0

154

Round

Haul netter

20

50

100

75

191

377

0.8

1.9

3.8

1.1

3.0

6.0

1.7

4.4

8.7

2.3

6.0

12.0

3.1

7.8

15.0

4.8

12.0

24.0

6.9

18.0

35.0

Towing

net vessel

20

50

100

300

500

99

204

361

1,138

1,838

1.0

2.1

3.7

12.0

19.0

1.6

3.3

5.8

18.0

29.0

2.3

4.7

8.3

26.0

42.0

3.1

6.4

11.0

36.0

57.0

4.0

8.3

15.0

46.0

75.0

6.3

13.0

23.0

73.0

117

9.1

19.0

33.0

105

169

General

fishing

vessel

20

50

100

150

77

195

350

500

0.8

2.0

3.6

5.1

1.2

3.1

5.6

8.0

1.8

4.5

8.0

11.0

2.4

6.1

11.0

16.0

3.1

8.0

14.0

20.0

4.9

12.0

22.0

32.0

7.1

18.0

32.0

46.0

Energy Absorption of Ferry Boats at ¼ point Berthing (kJ)

Table (viii) Energy Absorption of Ferry Boats at ¼ point Berthing (KJ)

G/T Assumed Weight (t) Approaching velocity ( m/s )
0.20 0.25 0.30 0.35 0.40 0.50 0.60
50 124 1.3 2.0 2.8 3.8 5.1 7.9 11.0
100 246 2.5 3.9 5.6 7.7 10.0 16.0 23.0
200 430 4.4 6.9 9.9 13.0 18.0 27.0 39.0
300 664 6.8 11.0 15.0 21.0 27.0 42.0 61.0
500 1,012 10.0 16.0 23.0 32.0 41.0 65.0 93.0
1,000 1,796 18.0 29.0 41.0 56.0 73.0 115 165

After having the effective berthing energy value, one can then choose the suitable type of marine fender design / system. Performance has to be compared in order to design the most suitable system. For example, deflection curve, energy absorption and reaction of a cylindrical fender is different from an arch-shaped fender. One has to compare alternatives and then determine which one is more suitable for use. This is when previous records of fender systems deployed play a big role in advising the suitability for the particular marine condition.

Energy Absorption:

The obvious factor in designing a fender system. This value has to be higher than the effective impacting energy of ships.

Reaction Force:

This value has to be less than the vessel’s allowable reaction force to prevent damage to the hull surface (or in extreme cases, the structure as a whole).

Environmental Condition:

It is vital to determine how harsh the working conditions for the fenders will be. One will have to choose accordingly its durability to handle strong waves, winds, or extreme weather. If the working condition is very demanding, it is possible you will have to replace the fenders quite often.

Berthing Angle:

A fender that can accept a situation’s angular compression has to be considered. An angular compression does not result in a simplistic linear energy absorption curve so this has to be a main priority when choosing a rubber fender design.

Fender (or Panel) Surface Pressure

Surface pressure value of fender has to be less than the vessel’s allowable hull surface pressure. For certain fenders like super cell type and cone type, they most commonly come with frontal frames/panels that distributes the pressure. So to decrease surface pressure value, one can increase the surface area of the panel.

Trustworthy Supplier

Choose a quality rubber fender manufacturer. Some people always assume that prices and quality can not come together but it is possible in today’s manufacturing innovation and high tech automation processes. Manufacturers are spending less time doing low importance repetitive work and focusing on Quality Control (QC) processes assisted by great process flow.

port-fender-distance

Fender Arrangement and Spacing In Between

After choosing what type and size of fenders to use, the next step is determining the number of fenders. To do that, one has to take into consideration fender spacing. The spacing between fenders play a very important role in determining a fender system’s success. Should one opt to save cost and have too great a spacing between fenders, accidents might happen where vessel berthing might hit the dock structure. British Standards recommend that for a continuous quay, the installation pitch is recommended to be less than 15% of the vessel.

The maximum spacing between fenders (S) can be calculated with this equation:

Maximum Spacing between Fenders, Space

Note:

RB = Bow Radius of Board Side of Vessel (m, ft).

If radius info is not available, one can use this estimation to find out the info:

Radius Calculation

PU = Uncompressed Height of Fender incl. Panel (m, ft)

C = Fender Height in Rated Compression.

deflection = Fender Deflection (m, ft)

For arrangement consideration especially distance between fenders, it is important to keep in mind that one should not only have the largest vessel type in mind. As smaller vessel might face problems berthing if one only design for large vessels.

This shows an improper design as smaller vessels berthing at the dock would crash into the wall:

fender design failure 1

This might be a possible solution for this situation:

fender design solution

Of course, aside from fender spacing, all aspects from angular compression energy absorption to hull pressure per unit needs to be considered as well. If a particular type does not satisfy requirement, one should consider other options.

Choosing a Suitable Frontal Panel

To choose a suitable panel, one has to consider hull pressures allowed for the berthing vessels. The following table shows a rough guide of allowable hull pressures of certain popular type of vessels. (just for reference):

Allowable Hull Pressures

Vessel Type Hull Pressure KN/m2
Tankers 150~250
ULCC & VLCC(Coastal Tankers) 250~350
Product & Chemical Tankers 300~400
Bulk Carriers 150~250
Post-Panamax Container Ships 200~300
Panamax Container Ships 300~400
Sub-Panamax Container Ships 400~500
General Cargo 300~600
Gas Carriers 100~200

Calculation:

vessel hull pressure calculation
PHull Pressure(N/m2, psi)
ΣRCombined Reaction Forces of all rubber fenders
A1: Valid Panel Width excluding lead-in chamfers(m)
B1: Valid Panel Height excluding lead-in chamfers(m)
PP: Permissible hull pressure(N/m2, psi)

Another option: WITHOUT frontal frames.

Rubber fenders like arch fenders and cylindrical fenders do not come with frontal frames. The fender body itself comes into contact with the vessel’s hull during berthing. One has to carefully consider the hull pressure exerted.

Selecting the Chains

cone fender installation

A common fender system with frontal frame usually involve a Weight Chain, Tension Chain and Shear Chain.

Chain Function
Weight Chain Normally installed at a static angle of 15 – 25° to the vertical, its main function is to sustain the weight of the entire frame panel structure
Tension Chain Protect the fender against damage when compressed
Shear Chain Fixed at 20 – 30° to the horizontal, shear chain exists to avoid damage while the fender is in shear deformation

Some installation do not involve shear chain, but a fender system would definitely be more resistant to shear damage with them.

chain selection equationchain selection

h1Static offset between brackets(m, ft)
Ф2:
 Dynamic Angle of Chain(°)
h2
Dynamic offset between brackets at F(m, ft)
D: 
Fender compression(m, ft)
R
Reaction Force of rubber units behind the frontal panel(N, Lbs)
WWeight of the panel face(N, Lbs)
FLSafe working Load of chain(N, Lbs)
L: Bearing length of chain(m, ft)
n: number of chains acting together
μ: Friction coefficient of face pad. Usually equals 0.15 for UHMW-PE facings.
FM: Minimum Breaking Load(N, Lbs)
FS: Safety Factor(2~3 times)

Tips on choosing suitable chains:

  • Chain sizes should be as exact as possible. An overly tight chain or an overly loose chain would fail the system.
  • Safety factor has to be considered. At least 2 to 3 times of the work load.
  • Open link type is more preferable.

Installation tips:

  • One must consider installation during the early design process and not after choosing the fenders and finalising the purchase as the maintenance, wear allowances and protective nets/coatings will affect their useful life.
  • Chains should not be installed twisted. They might break due to a reduction in load capacity.

A small tip after preliminary choosing the type of fenders to use, make sure you do not make these 5 top mistakes that causes structural failures for marine fenders.

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