hull coatings for vessel performance

FATHOM FOCUSwww.fathomshipping.com

Hull Coatings for Vessel Performance

Information Specialists for Maritime Eco-Efficiency

FOCUSFathom

From the publishers of Ship Efficiency : The Guide


Published by

Information Specialists for Maritime Eco-Efficiency Fathom has developed a range of technical publications to serve the thirst for eco-efficiency knowledge in the industry. Titles include Ship Efficiency: The Guide Ballast water Management: The Guide The Step-By-Step SEEMP Manual and Emission Control Areas: The Guide amongst many others. Fathoms newest publication range is the Fathom FOCUS series. These in-depth guides to specific efficiency topics and market areas are available to the shipping community to use as a free reference source. The first edition was titled Choosing the Optimum Lubricant Solutions for your Operation

Email: [email protected]

Website: www.fathomshipping.com

Proud Sponsors of Hull Coatings for Vessel Performance

A Century of Pioneering Leadership Hempel was founded in Denmark in 1915 by Jrgen Christian Hempel. Driven by innovation and the vision of helping to protect man-made structures from corrosion and fouling, the company has developed and grown into a world-leading coatings supplier working in the decorative, protective, marine, container and yacht markets. In 1917, Hempel introduced the worlds first antifouling coating for ships hulls based on modern science and technology. Today, Hempel is among the world leaders within antifouling and fouling release technology, and retains a close bond with the scientific community. Hempel filed its first silicone patent in 1972 and the companys first commercial silicone-based coating, HEMPASIL, was introduced in 1999. This pioneering product created a smooth, non-stick surface on the hull, preventing marine organisms from attaching to it. The result was less drag in the water, lower fuel consumption and lower CO2 emissions. Over the years, Hempels research and development lab continued to improve this technology by optimizing its long-term stability and mechanical properties, leading to HEMPASIL X3, Hempels flagship fouling release product with a fuel saving guarantee. Hempel is committed to constant improvement of its performance with regard to energy efficiency and environmental impact. The development of ActiGuard technology arose out of a wish to pursue an entirely new concept that would set the bar way above current standards. Fouling control was no longer enough. The goal now was a Fouling Defence solution that effectively protects against fouling throughout the service interval. Hempels new patented ActiGuard technology introduces a new and unique way of producing an underwater hull coating containing a silicone-hydrogel that not only enables controlled biocide release, but also has the necessary long-term stability and mechanical properties. Hempels latest hull coating product, HEMPAGUARD, is the first to be based on this patented technology, offering substantial economic and environmental advantages. We are committed to remaining focused on our goals, adaptable in a fast-changing world and quick to implement new ideas. We will strive to increase our understanding of our markets and customers, and offer innovative solutions that add value to their business, Hempels Christian Ottosen concludes.


Contents

Chapter One The Important Role of the Hull in Ship Efficiency The Hull Roughness FactorThe Science of SmoothnessOptimisation of Hull SmoothnessHull ThreatsHull Bio-Fouling: A Deep DiveThe Scale of the ProblemEnvironmental Impact of Hull Fouling Chapter Two The Market Landscape A History of the Market: Key MilestonesRegulation of the Hull Coatings IndustryThe Future: Market Barriers and Drivers for Change Chapter Three - Choosing the Optimum Hull Coating The Ideal Coating Checklist Hull Coating ChemistryA Snapshot of the Market: Hull Coating Manufacturer Profiles

Chapter Four - Measuring Hull and Propeller Performance Hull Fouling and Performance: The RelationshipHow to Measure?What to Measure? Developing a Standard Method for Measuring Hull PerformanceKey Industry Studies A Snapshot of the Market: Hull Monitoring Software ProvidersA Snapshot of the Market: Class Society SolutionsA Snapshot of the Market: Hull Coating Provider SoftwareProvider Partnerships

Chapter Five Hull Cleaning for Optimal Performance

The Importance of Hull CleaningHull Cleaning MethodsUnderwater Cleaning MethodsA Snapshot of the Market: Hull Cleaning Service Providers

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Welcome! Following the success of the inaugural edition of Fathom FOCUS Choosing the Optimum Lubricant Solutions for your Operation Fathom is proud to bring you the second edition of Fathom FOCUS - Hull Coatings for Vessel Performance. As you may already know, this is just one of the technology areas covered in our flagship publication Ship Efficiency: The Guide. Ship Efficiency: The Guide maps out a litany of abatement technologies and ship efficiency techniques, and is comprehensive in focus. It was designed to be your road map for the labyrinth that is ship efficiency.

Our free Fathom FOCUS mini-guides give the reader the opportunity to have access to comprehensive information that is in much more depth and that has focus on a single technology area. What Information you Should Expect Our Fathom FOCUS series is reminiscent of our guides in that they offer a technically led, but easy to understand analysis of the solutions on offer, in addition to offering insight into the key issues affecting the market. This edition of the FOCUS series will shine a spotlight on the apparent lack of faith in the industry that has resulted from the clash between super slow steaming, laying up and foul release coatings, and the banning of tributyltin (TBT), in addition to a plethora of market influencing events that have occurred over the last few decades.

We discuss key emerging trends, including the legislative landscape, the development of solutions for Arctic conditions, and increased demand for more fuel economy, for example. In keeping with our usual structure, this publication offers broader market-based editorial and analysis, coupled with manufacturer profiles that offer in-depth technical detail on individual hull coatings solutions. In addition to the coatings themselves, Hull Coatings for Vessel Performance includes a chapter on monitoring hull performance and a chapter on hull cleaning, with profiles from hull cleaning service providers.

Why the Publication can Benefit Your Operations Biofouling can reduce ship efficiency by up to 40%, which results in massive fuel penalties that directly eat into the bottom line of your operations. Quite simply, an un-healthy hull can really adversely affect a healthy bank balance. The hull coatings sector is undergoing a period of change that posits exciting opportunities for the sector and is a key stepping stone to a sustainable and profitable industry. We hope that you find this publication useful and an interesting read! Warmest regards,

Catherine McMillanSEPTEMBER, 2013

From the E

ditor:

A Message F

rom Cather

ine McMilla

n


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The hull of a ship is a key piece of the ship efficiency puzzle. The physical ability of the ship to cut through the waves in a streamlined manner is of paramount importance to fuel economy.

Therefore, improving hull performance plays a pivotal role, because a smooth hull is an optimally hydrodynamic hull.

The Hull Roughness Factor The key factors that affect hull performance are the shape of the hull, the condition of the hull itself, the coating used on the hull and the nature and extent of fouling on the hull.

This edition of Fathom FOCUS looks at those factors that can vary during the vessel lifecycle the coating used on the hull and the nature and extent of the fouling. This publication also delves into the anti-fouling coatings market, the monitoring of the coatings results and also the hull cleaning market.

In this publication, when we talk about improving hull performance we are referring to taking those measures needed to make sure a ships hull is as smooth and friction-free as possible.

ABS comments in its publication Ship Energy Efficiency Measures: Status and Guidance: A tanker at its design speed will use the majority of its fuel overcoming frictional resistance in calm water..The size of frictional resistance is dramatically impacted by the roughness of the surface exposed to flow.

Each additional 10m to 20m of roughness, ABS estimates, can increase the total resistance experienced by the hull by 1% for full form ships such as tankers and carriers, and by 0.5% for ships at high speeds.

Ships are regularly delivered with a very low surface roughness at around 75m. ABS state that later in the ships life cycle, the very same vessel could enter a dry dock with a roughness of 250m, which would mean that by the time it is dry-docked the vessel will have been fighting against an increased resistance of up to 17%, leading to an increase in fuel consumption of 3 to 4% compared to when it first went into operation.

Historical records have shown that even with good maintenance practices average hull roughness can increase by 10 to 25 m per year, depending on the hull coating system, even when fouling is not included.

Image Courtesy of Micanti

CHAPTER 1

The Importa

nt Role of t

he Hull in S

hip Efficienc

y


The Science of Smoothness A hydrodynamic ship, able to cut through the waves with little resistance and drag to go further on less fuel.

In essence, creating a hydrodynamic ship is to create a shape and texture that is able to manipulate the flow of water around the vessel to allow for maximum ease of movement and maneuverability.

As mentioned there are two ways to do this:

- Hull form and dimension optimisation: The shape of the ship itself is arguably the most important element of ensuring the ships hydrodynamics because it is also one of the few choices that will stay with the ship for the duration of the ships life-cycle; once the ship has been built, whilst some parts of the ship can be integrated, automated and retrofitted for further efficiency savings, you cannot change the shape of your hull.

- Coatings and hull roughness: Hull coatings and the circumvention of hull roughness play a key role in ensuring optimal hydrodynamics of the hull and ship. The preservation of hull smoothness can represent significant fuel savings however, when comparing this figure to the fuel penalties involved when the hull becomes rough from either physical or biological fouling, the potential fuel savings become much, much more.

Optimisation of Hull Smoothness

For the purpose of this publication, we study two areas of hull smoothness optimisation; the first being the choice of an anti-fouling hull coating; and the second being the maintenance of that coating through hull cleaning.

Hull Coatings

The era of simply coating a ship with standard issue paint to protect it from corrosion and fouling has long passed, some of the options available on the market are highly complex and a vast amount of science and chemistry has gone into their development. A fast-growing technology in its own right, the latest hull coatings have shown considerable potential for substantial eco-efficiency savings over the past few years. Following the ban on TBT-based coatings in 2008, research into alternative options has increased tremendously. Hull coatings now aim to not just reduce fouling but make the hull surface as smooth as possible.

Most hull coatings today are designed to reduce hydrodynamic drag and to prevent the build-up of marine organisms. This also leads to a variety for fuel saving claims and the nature of these are addressed in Chapter Four but claims for the fuel savings they can deliver vary.

Coating systems usually consist of a primer, possibly a tie coat and then one or more coats of the product. Each product has its own role, the primer is the first barrier to corrosion, the tie coat bonds the primer and the final product coating delivers the protection that the system is designed for.

For the purpose of this publication we focus on the final product, in other words the anti-fouling product that delivers its specific type of protection.

Manufacturer and associated anti-fouling product profiles are provided along with product-specific technical data in Chapter Three.


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Hull Cleaning

It is inevitable that once a ship is in water bio-fouling will occur, it is therefore essential to keep the hull clear of all matter to ensure the safety and efficiency of the vessel. Despite the use of effective anti-fouling systems and operational practices, bio-fouling will still accumulate on the hull of the vessel.

To maintain a ship as free of bio-fouling as practical, it may be advisable for the ship to undertake in-water inspection, cleaning and maintenance.

Typically, every 5 years a ship will be inspected in dry dock, where a full clean is usually undertaken and new applications of anti-fouling paint can be applied where necessary. However the optimum interval between the periodic cleanings and inspections will vary with the type of vessel, the location of the vessel and its service profile (speed of operation, idle time, etc).

BIMCOs Framework A recently released BIMCO Circular has suggested a framework for the delegation of hull cleaning and hull maintenance responsibilities in the wake of slow-steaming and long periods of idleness in port, in particular in tropical waters where fouling has a tendency to be the most aggressive.

Whilst previously it would have undisputedly been the responsibility of the ship owner after a period of docking to clean the hull (failure to do so would result in the owner being liable to pay the operator the cost of the resulting fuel penalties), BIMCO has seen fit to respond to the new market trend that has seen extensive fouling on hulls due to periods of idleness a tactic selected by the operator and not the owner.

To ensure it is the decision-maker who reaps the consequences of the decisions taken, BIMCO suggests deciding the period of idleness in advance (the default is suggested at 14 days) after which point responsibility for the condition of the hull switches to the operator.

A full blast and re-application of anti-fouling can cost about US$10 per square metre, which would total at around US$300k for a typical VLCC, whilst just a clean will be about US$50k.

The cost of maintenance is a testament to how expensive fouling can be when maintenance still works out to be much cheaper. Cleaning a light slime results in 7 to 9% reduction in the fuel bill, whilst heavy slime means up to 18% less, and heavy macro fouling can offer a reduction of up to 30%.

Hull Threats

There are two key threats to hull integrity; physical threats and biological threats, both of which negatively impact the hull in a number of ways, but all with the same result: hull roughness.

Physical Threat: Corrosion

Corrosion is an incredibly common phenomenon.

Ships are made of metal and the sea is a mass of salty, moving water metals nemesis. To counteract the corrosive effect of sea water on a Ships metal hull, a hull coating forms a barrier between the metal and the water, thereby ensuring the Ships surface integrity is protected.

However, if for whatever reason the coating is damaged, corrosion becomes a very real prospect and the nature of corrosion means that any corrosion on the hull surface is difficult and expensive to rectify. Even following repairs, micro-pitting can be present in the repaired area, which weakens it and makes it a candidate for future damage or fouling.

Other macro physical symptoms of hull damage are plate laps, seams and butts, weld roughness, weld quality, and mechanical damage; however (aside from the obvious issue of coating condition) these types of hull threats are not linked to the hull coating and would have to be covered under specific hull maintenance and repair programmes that include but also go above and beyond just the issue of hull coatings.


Biological Threat: Fouling

Like physical hull threats, biological threats to the hull can be divided across the category of macro and micro, both of which wreak havoc on the integrity of the hull via attachment. The build of said attachment severely impacts the hydrodynamics of the ship.

Also, like physical threats, the relative seriousness and impact on the overall hulls health is also reflected in whether or not it is a micro or macro issue.

However, even minor bio-fouling has a significant impact on the overall profitability of the vessels operations when considered across a fleet and a vessels 25-30 year lifetime.

Roughness caused by micro bio-fouling is caused by slime, and results in an increase in fuel consumption between 1 to 2%. Macro bio-fouling refers to animals and plants, and its impact on fuel consumption greatly varies depending on the nature of the unwanted guest. Whilst seaweed will cause a fuel consumption increase of up to 10%, shells barnacles, oysters, and mussels for example can cause a massive increase of 40%.

In addition to fuel penalties in the short and long term, extensive bio-fouling will eventually lead to hull corrosion, which further compounds what was already a significant additional expense.

Hull Bio-Fouling: A Deep Dive

Whilst preventing corrosion is a relatively easy requirement of a hull coating, the prevention of bio-fouling build up is much more complex, especially in the advent of slow-steaming, long periods of idleness, and the banning of TBT-based paints.

Bio-fouling is especially aggressive in tropical and sub tropical waters, for example ships serving Europe/Latin America or Europe/Asia must have a coating that is able to function well in both environments.

Fouling refers to the accumulation of unwanted material on solid surfaces, most often in an aquatic environment. As further described below, the fouling material can consist of either living organisms (bio-fouling) or a non-living substance (inorganic or organic) and is often a combination of the two. Fouling is usually distinguished from other surface-growth phenomena in that it occurs on a surface of a component, system or plant performing a defined and useful function (such as a ship hull or propeller), and the fouling process impedes or interferes with this function.

Bio-fouling is not as simple a process as it sounds. Organisms do not usually simply suck onto a substrate. The complex process often begins with the production of a biofilm.

Contact and colonisation between the microorganism (biofilm actors) and the surface is promoted by the movement of water through Brownian motion, sedimentation and convective transport, although organisms can also actively seek out substrates due to propulsion using flagella. Bacteria and other colonising microorganisms secrete extracellular poly- meric substances (EPS) to envelope and anchor them to the substrate thereby altering the local surface chemistry which can stimulate further growth such as the recruitment and settlement of macroorganisms.

Biofilms do not have to contain living material; they may instead contain dead bacteria and/or secretions. The growth of a biofilm can progress to a point where it provides a foundation for the growth of seaweed, barnacles, and other organisms. They use this biofilm similar to an incubator. This is a process that constantly repeats itself, meaning that high concentrations of micro-organisms can be present in the affected water after a period of time. In other words, micro-organisms such as bacteria and algae form the primary slime film to which the macro-organisms such as mollusks and barnacles attach. If this biofilm is eliminated from the water, it becomes impossible for micro-organisms to reproduce.


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Biofilm is characterised by 5 stages of growth:

Stage 1 Initial attachment

Stage 2 Irreversible attachment

Stage 3 Growth I

Stage 4 Growth II

Stage 5 Outbreak

Micro Bio-Fouling

Bio-fouling starts with a biofilm, or slime layer. The most cost effective efficient option when it comes to bio-fouling treating or prevention is to catch it early so that the micro-fouling does not have a chance to progress on to attracting macro-bio-fouling.

A biofilm consists of bacteria that has accumulated on the surface of the hull. The layer can also consist of some types of seaweed, diatoms (which are a type of algae and a common phytoplankton), and secretions from marine organisms.

Diatoms attachment depends on the pH of the hull coating. The biofilm-causing bacteria Vibrio alginolyticus, for example, is sensitive to temperature changes and pH. Many innovative hull coatings, as profiled in Chapter 4, leverage organisms characteristics and preferences to create highly effective, targeted solutions, such as paint that change pH.

Slime in general like all bio-fouling is strongly impacted by the temperature of the waters. Once the biofilm is fully established, it will inevitably lead to macro bio-fouling as the underside of the hull has now become an attractive environment for a number of organisms.

Macro Bio-Fouling Macro bio-fouling can be divided into two categories.

The first, calcareous or hard fouling can include: barnacles, bryozoans (which look a bit like an underwater moss), mollusks, tube worms, and zebra mussels.

As the name may indicate, calcareous fouling can be difficult to remove without damaging the hull coating underneath as it requires more abrasive hull cleaning techniques than non-calcareous or soft fouling.

The second, non-calcareous fouling, includes: algae, slimes, hydroids, sponges, and seaweed.

Different fouling communities will develop depending on the type of environment the hull offers; this preference or distaste helps provide clues as to how to avoid the fouling. For example zebra mussels dislike aluminum-bronze for example. Cupronickels (copper-nickel alloys) have good bio-fouling and corrosion resistance, but may not be able to cope with the demands of a ship that spans continents involving oceans of varying salt levels and temperatures, as the changes may impact the coatings efficacy, or a particular species in a particular region may be more resistant.

This becomes an issue when the bio-fouling species are no longer content to ride on the underside of the hull but also become invasive species with wide-spread ecological and bio-fouling implications.


The Scale of the Problem

Economics

In the absence of hull fouling control systems, within six months of active service a vessel could have up to 150 kilograms of marine life per square metre attached to the hull. This obviously has huge fuel efficiency and bunker fuel cost implications.

Loss of speed from moderate fouling can range between 10% to 18%.

With hull resistance and drag having such an immense impact of bunker fuel consumption, ship owners and operators are looking for hull coatings and cleaning solutions that deliver the highest impact on drag reduction.

A study published by the United States Naval Academy, compiled by Dr Michael P Schultz, released in 2011 entitled Economic impact of bio-fouling on a naval surface ship estimated the overall economic impact of hull fouling on a mid-sized naval surface ship in which fuel, hull coatings, hull coating application and removal, and hull cleaning costs were analysed and assessed.

Following the reports release Schultz conveyed the message:

Ship owners: paint now, or pay later

Schultzs research quantified the economic consequences of drag from ship hull fouling.

The study looked at the hull fouling penalty for the U.S. Navys conventionally powered, mid-sized surface combatant: the Arleigh Burke-class destroyer (DDG-51). The study examined 320 actual individual inspection reports from Jan. 1, 2004, to Dec. 31, 2006.

It was found that resistance due to hull fouling amounted to US$56 million per year for the DDG-51 class destroyer fleet, and about US$1 billion over 15 years.

His conclusion from the studies was: The main cost associated with fouling is the increased fuel consumption from increased frictional drag.

The costs related to hull cleaning and painting are much lower than the fuel costs, Schultz reports in Economic Impact of Bio-fouling on a Naval Surface Ship, published in the journal Biofouling.

Furthermore, Schultz said, a hull neednt be fouled to drag. Even when the hull is free of fouling, frictional drag on some hull types can account for up to 90% of total drag, he reported.

According to a white paper released by Hydrex, entitled The Slime Factor published in 2010, uses the example of a cargo ship that requires 100 tonnes of fuel per day to maintain a cruising speed of 20 knots with a completely smooth and unfouled hull, the way it was at its first speed trials.

If that ship were to build up a thin layer of slime in a month and a thick layer of slime in two months, by the end of those two months of sailing, it would be requiring 110 tonnes of fuel per day to maintain the same cruising speed. Applying a fuel price of US$450 per tonne, which is majorly conservative in todays market, the slime build-up would cause a fuel penalty of an additional US$4,500 per day just to keep operating at the same service speed. Even if the fouling remained at that level, in a month it would have used US$135,000 more fuel than it would have if the hull were clean. In a year, at that same rate, it would have cost US$1.62 million more than if the hull had remained clean.

International Paint has also calculated the immense fuel penalties and savings that can be generated across various pieces of literature. An example of such is provided below.

A 5000 TEU containership that consumes 150 tonnes of fuel per day at US$500 per tonne, their annual fuel bill would amount to US$131,625,000. A saving of 9%, from the optimisation of hull smoothness through prevention of fouling build up would equal a saving of US$12million off the annual fuel bill.


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Environmental Impact of Hull Fouling

Emissions

The reduction in fuel burn and emissions is directly proportional.

The worse the fouling, the slower the ship will sail at a given RPM. Or in other words, more power will be required to keep the ship sailing at a given speed.

This results in higher fuel consumption and a higher fuel consumption results in a greater volume of greenhouse gases and other emissions being produced during the process of fuel combustion.

According to Bellona and the Clean Shipping Coalition (CSC), poor hull & propeller performance accounts for around 1/10 of world-fleet energy cost and greenhouse gas (GHG) emissions.

~ US$30 billion increase in energy cost and

~ 0.3% increase in man-made carbon emissions

The previous example of International Paints 5000 TEU containership that uses 150 tonnes of fuel per day as described in more depth in the previous section, would emit 77,000 tonnes less of CO2 as a byproduct of the anti-fouling coating application and associated fuel savings.

If the worlds fleet didnt have proper anti-fouling protection, International Paint estimates that an extra 72 million tonnes of fuel would be burned each year. If this scenario was flipped, and the savings were not realised, the increased fuel consumption would lead to the production and release into the environment of an estimated extra 210 million tonnes of carbon dioxide and 5.6 million tonnes of sulphur dioxide.

Invasive Species Widening the Bio-Fouling Boundaries

Whilst the problem of ballast water and invasive species has been widely recognised by both the media and regulatory bodies the issue of the transference of invasive species via other areas of ship have to date been relatively overlooked.

A noteworthy contributor to the issue of invasive species imported and exported across the world along with the worlds trade and goods is the presence of bio-fouling communities that establish themselves on the hull.

The zebra mussel for example has caused huge problems in the US Great Lakes because it is a voracious eater that has a devastating impact on other members of the ecosystem.

They also decimate native mussel populations by subjecting them to their own medicine through bio-fouling; they attach themselves to the hard outer shell of the native mussel, decimating the native carrier.

As this behaviour suggests, zebra mussels are aggressive bio-foulers and the species proliferates in a wide variety of environments, thereby exposing shipping communities to the threat of zebra mussel bio-fouling areas that were previously safe and therefore unprepared.

The zebra mussel, for obvious reasons, is in the top 10 of BIMCOs Most Unwanted list but only one of many invasive species that bio-fouling has helped to introduce to native ecosystems the world over.

However, it is only one example of many as invasive species brought over from far away is an endemic and systemic problem in shipping; hull coatings have a vital part to play in limiting the further spread of invasive species around the world.


The activity and interest in the marine coatings market has boomed in recent years. This is due to a number of factors but not least including ship owners searching for clean technology solutions that can offer technical maturity and proven fuel savings but also factors such as the decline in the ship newbuilding market and resultant increase in ship repair and maintenance have played a major part. There is of course also the growing urgency to minimise fuel consumption penalties wherever possible whilst a shift in the regulatory landscape is enforcing a movement towards reduced environmental impact. This change has meant that both industry and its technology providers, including the marine coatings sector, have had to respond and reconfigure how the current and future regulatory and market landscape can work best for business. Innovation within the marine coatings market is evolving at a rapid rate as companies compete to provide the best products. As a result of the intense competition, the market is growing and there are a greater number of high specification, innovative marine coatings solutions available on the market than ever before. There have also been numerous launches of low-cost solutions to respond to a financially troubled industry where minimising vessel maintenance cost, including paint investment, is a focus area. In many ways a polarised hull coatings market has emerged that has a product cost focus at one end and investment in vessel efficiency at the other.

A transition towards more premium solutions, offering significant savings in fuel consumption and carbon dioxide emissions compared to the current market average, is predicted by most of the major marine coatings companies. Also, the market is seeing a new driver emerge. In collaboration with the marine coatings industry marine coatings provider, Jotun is currently leading an initiative to establish reliable measurability of hull performance. This was spurred by a historical lack of accurate and reliable measurability on hull performance that has resulted in limited incentives to invest lifetime performance in both newbuilding and maintenance situations. Therefore, this initiative will be absolutely crucial to increase market awareness and contribute to growth in the marine coatings market.

CHAPTER 2

The Market

Landscape


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412 BC: A translation from the Aramaic of a papyrus dated about 412 BC concerning boat repairs struck an optimistic note: And the arsenic and sulphur have been well mixed with Chian oil thou broughtest back on thy last voyage and the mixture evenly applied to the vessels sides that she may speed through the blue waters freely and without impediment. 16th century onwards: The main form of protection for wooden ships was copper sheathing or the use of a mixture containing sulphur and arsenic. It was not until the development of iron hulls that copper sheathing was abandoned.

17th century: In 1625 William Beale was the first to file a patent for a paint composition containing iron powder, copper and cement. In 1670, Philip Howard and Frances Watson patented a tar, resin and beeswax paint.

1854: James McInnes patented the first practical composition to come into widespread general use. It used copper sulphate as the biocide in a metallic soap composition, which was applied hot over a quick-drying priming paint of rosin varnish and iron oxide pigment. This was soon followed by a similar product known as Italian Moravian which was used well into the 20th century.

1881: Holzapfels Antifouling Compositions were introduced. The Holzapfel brothers were the Founding Fathers of International Coatings Ltd.

1926: The US Navy developed a hot plastic paint using coal tar or rosin as binder and copper or mercuric oxides as toxins. This was followed, later, by cold plastic paints which were easier to apply.

1960s: Contact leaching antifoulings are introduced, designed to increase antifouling lifetimes by increasing the biocide content.

3rd century: The Greeks were using tar and wax to coat ships bottoms.

13th to 15th centuries: By this time pitch, oil, resin and tallow were in use. The Chinese Admiral Cheng Ho had the hulls of his junks coated with lime mixed with poisonous oil to protect the wood from worms. Christopher Columbus was also familiar with the problem: All ships bottoms were covered with a mixture of tallow and pitch in the hope of discouraging barnacles and teredo, and every few months a vessel had to be hoved-down and graved on some convenient beach.

18th century: William Murdock patented a varnish mixed with iron sulphide and zinc powder, using arsenic as anti-foulant in 1791.

19th century: By 1870, more than 300 antifouling patents had been registered. Then as now, the basic principle of the majority of antifouling paints is to use biocide(s) to deter the settlement of fouling organisms through a leaching mechanism.

1863: James Tarr and Augustus Wonson were awarded a US patent for antifouling paint using copper oxide and tar.

1885: Zuisho Hotta was given the first Japanese patent for an antifouling paint made of lacquer, powdered iron, red lead, persimmon tannin and other ingredients.

1906: The US Navy began to manufacture its own antifouling coatings and tested shellac and hot plastic paints.

Late 1940s onwards: Major changes in paint technology resulted from a wide range of new industrial chemicals and the introduction of new surface preparation and prefabrication methods.

1974: International Paint introduces the first Self Polishing Copolymer (SPC) antifouling.

A History of the Market: Key MilestonesThe Fouling of Ships Hulls has Troubled Mankind for CenturiesTimeline courtesy of International Paint History of Fouling Control


1987: The first TBT-Free Controlled Depletion Polymer (CDP) polishing antifoulings are introduced globally. 1999: The first foul release system for Deep Sea Scheduled Ships. Revolutionary low surface energy coating technology controls fouling without the use of biocides.

2002: International Paint introduces the first self polishing antifouling system blending SPC and CDP technologies.

2013: Foul release coating technology evolves with the introduction of International Paints Intersleek1100SR product, the first micro fouling-focused fluoropolymer based slime release technology specifically designed to tackle the impact of slime.

1994: Introduction of Interspeed340, a controlled depletion polymer (CDP) antifouling suitable for use at Newbuilding or Maintenance & Repair.

2000: International Paint launch the first Linkcoat, Intersleek717 introduced, allowing direct conversion of biocidal SPC anti-foulings to foul release systems.

2007: The next generation foul release coating is launched by International Paint that is based on fluoropolymer technology, Intersleek900.

To understand the current trends and drivers influencing the market today, and the developments that could trigger expansion, an understanding of how the market has evolved is required. The need to keep a smooth hull and experimentation around the types of coatings that can be used is as old as the maritime industry itself. In the industrys infancy, various compounds were used to coat the hull in an attempt to dissuade marine life from becoming an attached pest. The first successful anti-fouling surface to receive general recognition was copper sheathing. William Beale filed the first coating patent in as early as 1625. This coating was surprisingly on the right track, containing iron powder, copper and cement. In 1670, a tar, resin and beeswax-based coating was then patented by Philip Howard and Frances Watson.

The historical market pathway has been littered with scientific discovery.

Naval institutions have spurred a great deal of ground-breaking research. Prompted by a desire to obtain more fundamental knowledge as to how to prevent fouling, various naval institutions arranged biological investigations which has been fundamental to shaping the evolution of the market. The work has supplied valuable information on the toxicity of potential paint ingredients to marine organisms, on the nature of the fouling population, its rate of growth, its seasonal and geographical incidence, and the relation of the service in which ships are employed to their tendency to foul. For example, an early proposal that identified that slimes produced by bacteria and diatoms on submerged surfaces had an important bearing on subsequent fouling aroused much interest, and has been a pillar for innovation throughout the development of anti-fouling coatings. Following much research into the occurrence of fouling and the development around hull coating options the problem of preventing the attachment of organisms became one of applied physical chemistry rather than a game of permutations and combinations.


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A more recent pivotal market-shaping event in recent times was the banning of TBT -based hull coatings. Its presence in hull coatings prevented marine growth to an unprecedented level and for the industry it was a revelation. However, TBT-based paint was also extremely toxic to non-target organisms. It is an endocrine-disrupting chemical, which means affected aquatic animals would have disruptions in reproduction; whelks would change sex and oysters became deformed. There was also the frightening possibility of the bioaccumulative aspect of the compound in some ducks, fish and seals, and the resultant threat of it eventually entering the food chain and appearing on peoples plates. In reaction to what was perceived as a fast approaching ecological disaster, the IMO passed the International Convention on the Control of Harmful Anti-fouling Systems on Ships (AFS Convention), which was adopted in October 2001 and came into force in September 2008. This Convention is discussed further in the next section. Following the ban of TBT-based paint, new paint formulations evolved which are discussed in great detail in Chapter Three and also below. New biocidal anti-fouling paints were rapidly developed in the wake of the ban, for example the coatings based on silyl-acrylates or copper, and foul-release solutions, based on self-polishing silicone types.

Regulation of the Hull Coatings Industry

As shipping is global in nature variations in regional and local environmental regulations have an industry-wide impact, and this is in addition to global regulations that govern all areas. Regulations are making it technically more challenging to deliver coatings that perform, however in the same breath, regulations are helping to increase the value add associated with higher levels of performance where the coatings have an impact on energy efficiency in particular. Many stakeholders within the industry regard environmental regulations as an important driver of innovation in the marine coatings market. It is a delicate balance however between the benefit to the environment, the economic impact, and the constraints of technology. As described in the previous section, the Anti-fouling Systems Convention (AFSC) outlawed the use of TBT-based paints. In response to the AFSC, the major hull coating manufacturers voluntarily decided to withdraw tin-containing anti-fouling hull coatings from the market before the IMO convention enters into force. The European Union (EU) also passed legislation that bans the application of tin-containing coatings and prohibits vessels with tin-based anti-foulings from entering EU ports. Whilst copper has been the go-to substance since the banning of TBT-based coatings, there are indications that its time is coming to a close. The reasoning behind this potential ban is that copper can interfere with photosynthesis and enzyme function in both plants and animals in very low concentrations as low as 4 g/l.

As a result of this some regional regulations are set to address the presence of copper in hull coatings. The U.S. State of Washington will be banning the use of copper with effect from 2018, and California looks set to do the same.


In addition to this, the 2013 Vessel General Permit (VGP) addresses the issue of copper a few paragraphs after addressing the issue of TBT-based coatings the unspoken message being that the Environmental Protection Agency (EPA) considers them to be part of the same family of undesirables. Some ports and harbors are impaired by copper, a biocide used commonly in anti-foulant paints. These waters include Shelter Island Yacht Basin in San Diego, California, and waters in and around the ports of Los Angeles/Long Beach, the VGP states.When vessels spend considerable time in these waters (defined as spending more than 30 days per year), or use these waters as their home port (i.e., house boats, ferries or rescue vessels), vessel owners/operators shall consider using anti-fouling coatings that rely on a rapidly biodegradable biocide or another alternative rather than copper-based coatings. If after consideration of alternative biocides, vessel operators continue to use copper-based anti-foulant paints, they must document in their recordkeeping documentation how this decision was reached the document continues. Another potentially impactful IMO Regulation is the Ballast Water Convention. Obviously this is not a coatings specific regulation. However, it does impinge on coating performance or lifetime. This convention aims to stop the transport of invasive marine species from one part of the globe to another in the ballast water by ensuring the water is treated before discharge into the sea or is discharged into fixed onshore facilities where it can be treated. Several onboard systems have been developed to date. However, a factor to consider for the hull coatings industry is: should these ballast water treatment processes be compatible with the prescribed coatings, or should coatings be compatible with the systems?


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The Maths: The Cost of Hull Roughness

According to the International Paint Hull Roughness Penalty Calculator model. This is a software programme that predicts the inevitable increase in underwater hull roughness during the specified in service period and combines this with the risk of fouling associated with different antifouling types. The model compares fuel usage and cost to the installation cost of different TBT free antifouling and foul release systems to derive potential net benefit. The model is also able to compare the exhaust emissions (CO2, SOX) associated with the additional fuel consumption for a particular vessel. The effect of coating roughness on ship performance can be calculated using the Townsin1 formulae below: Fractional Added Resistance ( R/R) for going from a smooth (AHR = k 1 ) to a rough (AHR = k 2 ) surface: R/R = C F /C T = 0.044[(k 2 /L) 1/3 (k 1 /L) 1/3 ]/C T Where: = Change in resistance, power, speed or propeller efficiency due to increased roughness C F = Frictional Resistance coefficient increaseC T = Total Resistance coefficient = ([Total Resistance]/0.5 S V 2 ) or very approx. = 0.018 L -1/3 (if C T value cannot be found otherwise, and where L is in metres) = Seawater densityS = Surface wetted area of vesselV = Speed of vesselL = Length between perpendiculars of vessel Hull roughness gauge in use Fractional Power increase ( P/P) at constant speed for going fr om a smooth (AHR=k 1 ) to rough (AHR=k 2 ) surface: 1+ P/P = (1 + R/R) (1+ / ) -1 Where:P = Shaft Power = Open water propeller efficiency For Ro-Ro ships: (1+ / ) -1 = 0.17 (1 + R/R) + 0.83 For Tankers: (1+ / ) -1 = 0.30 (1 + R/R) + 0.70 Fractional Speed Loss ( V/V) at constant power, for going from a smooth (AHR=k 1 ) to rough (AHR=k 2 ) surface: V/V = P/P (n + 1) -1 Where:n = speed index = ~2.15 for Tankers and Bulk Carrier


There are a number of key challenges and drivers that the industry is facing that will trigger change in the market. Firstly, declines in shipbuilding after many years of overhang and overtonnage will start to bite; for the hull coatings market this will mean a drop in the volume of newbuild hull coating application orders. With a lay-up of 10% worldwide, the coatings industry has also suffered from cancellations and delays in newbuildings and in maintenance work when operators have realised that losing their deposit and idling the ship would result in less losses than attempting to operate. Secondly, ship management companies, as a way of surviving during difficult economic times, will consolidate. This consolidation process will strengthen the buying power of individual clients, thereby putting pressure on coatings prices. The technical ramification of this future drop in pricing is that it will impair the ability of coatings companies to invest in R&D projects at a time when they are needed more than ever. An additional challenge, as Azko Nobel has pointed out in the past, is that hull coatings have a long development cycle due to the lack of reliable accelerated test methods and considerable formulation work required to meet anti-fouling performance, mechanical and application property requirements. The development cycle consists of laboratory and assay tests, field trials and test patching.

These factors will put pressure on the market whilst other trends will trigger further demand and development in the market. The preference for vessel lay-up and operating at lower loads requires new solutions, whilst increasing bunker prices makes the demand for an optimised hull condition all the more important.

The clock is ticking for coatings manufacturers to prove to operators that they can offer non TBT- based paints with pre-TBT performance. For that reason perhaps the current difficulty in the market would be more aptly described as growing pains than any more sinister a market trend. A study by Frost & Sullivan in 2011 estimated that the market earned revenues of over US$5bn in 2011, and estimated that figure to reach US$10.2bn by 2018. The need to lower fuel consumption is a strong market driver and antifouling coatings applied to ships hulls offer one way to combat emissions and reduce fuel consumption, explained Frost & Sullivan Research Director Dr Leonidas Dokos. Foul-release technology, which also results in substantial fuel savings, is particularly useful for large cargo ships, which consume a lot of fuel.

The Future: Challenges, Drivers for Change, and Market-Shaping Trends


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Market Barriers

When considering market barriers, the 2012 study published by the European Commission (EC) Analysis of market barriers to cost effective GHG emission reductions in the maritime transport sector. (Reference: CLIMA.B.3/SER/2011/0014) is useful to refer to in order to gain insight into the process and background of market barrier identification. In this section we identify the main market barriers to the uptake of hull coating technology solutions, split by technical limitations and non-technical limitations. Technical Limitations The technical limitations of a hull coating product is dependent on a number of factors:

The efficacy of the hull coating. The impact of slow-steaming. The technical maturity of the products. Differences in performance. The Efficacy of the Hull Coating Whereas TBT-based coatings dominated the market prior to the ban, it is not clear whether the new biocidal or foul-release coatings will evolve as the superior approach to hull coating, the EC study notes. The ability of some of the newer hull coatings to live up to their claims of extremely long life is a technical concern it admitted. However, the technical issues that surround the new coating products are not simply down to the mediocrity of the products; if anything, more research and precaution is going into the preparation of the coatings than ever before. It should also be noted that the technical performance of the coatings has been impacted by market conditions (e.g. widespread slow steaming and extended idle periods) that could not have been foreseen at the time of their development.

Slow-Steaming The ECs analysis reports that operating ships at lower speeds is the single best solution to reduce marine GHG emissions. However, as the study points out, operating vessels at lower speeds dramatically changes the economics of implementing other GHG solutions. This is inherently true for hull coatings. A key issue for foul-release coatings is the fact that they are dependent on the ships movement though the water to remove the bio-fouling from the hull. The EC study notes that certain types of new hull coatings may not be as effective at low engine loads. This is because during periods of no movement, or very slow movement due to slow-steaming, the natural cleaning effect from the waters circulation around the hull is minimised, which means that bio-fouling builds up. Once the bio-fouling has built up as a result of this reduced engine load, returning to usual speeds (which would be nonetheless extremely unlikely in current market conditions, and according to market forecasts, in the future) would not be enough to remove the biofouling, especially if the marine organisms have had a chance to develop into macro-organisms or even established a full-blown bio-fouling community on the side of the ship. As a result, the ship will have to be cleaned more often. To conclude, whilst slow-steaming is the number one tactic of offsetting fuel costs, it has triggered other unforeseen costs in other areas of the vessels operations.


Technical Maturity A fundamental market barrier to the uptake of hull coating solutions is the maturity of the technology, the relative number of installations and the proven delivery of promised savings. With most cutting-edge solutions naturally having a relatively short track record in the industry, ship owners and operators can naturally be wary of utilising them. However, it should be considered that particularly following the foul release coatings issue, the hull coatings industry has learnt valuable lesson on the research that needs to be carried out to ensure true market wide applicability and reliability. The newest generation of hull coatings have been tested under a far greater range of operating profiles and conditions than ever before

Non-Technical Barriers Non-technical barriers include: Lack of a market-wide performance measuring standard to allow for easy comparison between products, which exacerbates the technical barrier of possible product under-performance.

Lack of information or understanding of the economic returns relative to other coatings on the market.

Increased price of non TBT-based paints and possible need to re-coat more often.

Split incentives under term charters.

Patents that limit the flow of information between manufacturers and also of performance information into the market. The impact of non-technical market barriers could be mitigated by further investment in new technologies followed by the effective communication to industry stakeholders as to the benefits of this new technology.

The Good News The Changing of Market Barriers to Market Drivers Market barriers and drivers are sometimes two sides of the same coin. There are some market drivers that have spurred the hull coatings industry to develop best practices and be ahead of the regulatory curve. This has allowed the sector to cope with and further leverage market changes. The hull coatings sector excels in anticipating changes in regulation. They make tremendous investment and efforts in early R&D efforts to meet these anticipated changes. It is no quick process to develop and test coatings. They have also been good at adopting consistent and coherent regulation globally, with any potential market changes already identified and expected. This means that vessels tend not to suffer from restrictions in trading areas. Latterly, they have also started to offer performance guarantees to clients in order to allay concerns about the coatings not living up to the claims. It is a multi-billion dollar market and therefore it tends to swiftly address how to overcome the market barriers in order to open the opportunity that comes with their removal.

Image Courtesy of HYDREX


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The Ideal Coating Checklist There are a number of high level factors which must be taken into consideration when evaluating which coating system to deploy onto a ship, either at newbuild stage or during routine maintenance of the hull and its coating.

The different factors listed below are a checklist of the essentials that should be considered when evaluating and selecting a hull coating system. For the purpose of this table, anti-fouling paints are the focus. However, it must be noted that, a system must also be put in place for corrosion protection.

Factors Questions to ask Why? Check forLongevity What is the lifespan of

the coating? Will the coating remain active 5-7 years in-between dry docking periods?

Varying systems have a varying lifespan. Some systems are designed to last 3 - 5 years. Some will aim to last the lifetime of the vessel. This will vary on type of product chosen.The lifespan of the coating can make a real variance in total ownership cost of the vessel, factoring in dry docking time, cost of materials and labour, and off-hire time.

Product specific lifespan information and case studies of longevity from manufacturer.

Suitability Will the coating system suit the needs of a particular vessel or fleet?e.g. Is the hull coating suitable for use on ships with lay-up times of any length?

Different ships, fleets, routes, activities operate under different conditions, therefore will demand varying aspects from a hull coating product.

The vessels trade route or voyage path, frequency of port calls, lay up periods. Ask for specific evidence that the product is suitable for that type of route. It may not be available but should be asked.

Chapter 3

Choosing Th

e Optimum

Hull Coati

ng


Maintenance Cleaning (hard coatings)

How frequently must the hull be cleaned to maintain coating performance? How suitable is the hull coating suitable for cleaning, in dry dock and/or underwater?

It is important to ascertain how often the hull will require maintenance and what impact this will have on the coating.In the absence of regular dry docking, in-water cleaning is a necessity if a ship is to run at optimum performance.

The following points need to be considered:- Does routine underwater cleaning damage the coating? - Can the coating be cleaned without damage to it?-Will in-water cleaning of the hull pose and environmental hazard, such as a pulse release of biocides, silicone oils or other substances? How can this be mitigated?

Factors Questions to ask Why? Check forProduct Features

How thick is the coating? How abrasive resistant? How flexible or brittle? Is it completely impermeable?

The answers to these questions have much to do with how well the coating will survive under harsh or varying conditions.

The challenges a vessel may face on specific trade routes, such as mechanical force, bumps and scrapes, ice and other challenges, varying water temperate etc.

Regulatory Demands

Will the coating have to be replaced in the future due to regulations or legislation?

Although there is nothing immediately in the pipeline, in the wake of the IMO ban on TBT, biocidal paints are continually under scrutiny. The future potential demands on the hull coatings market from regulation should at least be thought of with ships in the newbuild stage or requiring a full repaint.

Is there any likelihood that the paint compounds could be banned within the lifespan of that coating?

Condition How smooth will the hull be after coating? What rate of fouling should you expect with the coating?

Different hull coatings will cause different levels of hull resistance due to skin friction even when no fouling is present.More skin friction means higher fuel consumption.Another key consideration after basic protection has been established, is how the coating system deals with marine fouling.

Case studies from manufacturer.


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Factors Questions to ask Why? Check forMaintenance Repainting/Repairing

How often does the coating system require major repair or reapplication? Does the coating have any special application requirements?

How easy is the coating to repair or touch up if it is damaged?

This can be a major cost.Surface preparation plus application of paint can vary from 5 or 6 days for some coatings to as much as 17 or 18 days for others.

How many coats need to be applied and how long does this take in dry dock? Are there any special precautions or requirements for correct application or to obtain claimed savings?

Fuel-Saving Does the manufacturer guarantee performance? Does the hull coating system lead to greater fuel efficiency and therefore reduced GHG and other emissions?

The type of hull coating product and system can make a big difference to the ships fuel efficiency.Great care must be taken to understand exactly HOW any fuel savings are calculated.Note: It is actually reduced loss in performance that claims are made on not active savings themselves i.e. paint will degrade in performance less than another.

Third party verification? Is there an associated monitoring software package offered with the product to measure the fuel saving?

Environmental Concerns

Is the coating system toxic or not toxic to the oceans and waterways? Does the in-water cleaning of the coating present any additional environmental hazard? Does the application or removal of the coating constitute an environmental hazard? Does the hull coating system help or inhibit the translocation of hull-borne, non-indigenous, invasive marine species?

The coating system used on a ship can have a negative impact on the environment.Therefore the decision should include the environmental consequences of its use. It may be that corporate social responsibility concerns are a factor in the decision process.

Does the product contain: -Heavy metals-Biocides-VOCs-Toxic waste-Silicone or fluropolymer oils


Factors Questions to ask Why? Check forCost How much does the paint

cost? What surface preparation is required and what does that cost? How much does it cost to apply the coating? How many times can one expect to have to repaint in the ships lifetime? What frequency of in-water cleaning is required for a particular system and how much will this cost? How much will the fuel penalty incurred by a particular coating system add to the total ownership cost of hull?

Cost is a vital consideration in choosing a hull coating system for a new vessel or for repainting an existing vessel. However, prices per litre of paint can be misleading, as can cost of surface preparation.

There are a number of factors which contribute to the real cost of a hull coating system and they must all be taken into account for a total ownership cost assessment.

Beware of solely looking at price per litre. What are the total costs of materials for coating the entire hull?Some hull coating systems require five or more coats with lengthy curing times in between, stretching a full painting job out to as much as 17 days or more.Others can be applied in just two coats with a few hours between coats and can be fully prepared and painted in under a week, ready for launching or re-launching. The costs involved include labour, dry dock time and off-hire time.

Ensure you understand the whole cost cycle.


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Hull Coating Chemistry Due to the penalties associated with and the severe impact of the unwanted colonisation of a hull surface by marine organisms, primarily through negative impact on hydrodynamics via increased drag, anti-fouling systems are in great use across the maritime industry.

The principle mitigation tactic for reducing the impact of hull fouling is through preventing the attachment of fouling, and therefore minimising drag.

Therefore, there have been great advancements in the manipulation of the chemistry that sits behind anti-fouling products to prevent the attachment of fouling.

It must also be noted that although hull cleaning measures such as under water scrubbing can be deployed to mitigate hull fouling. Thus far the use of under water scrubbing as the sole method for complete hull fouling mitigation has not been proven to be viable for the vast majority of the worlds fleet.

There are four main tributyltin TBT-free fouling control technologies currently available:

Biocidal- Self-Polishing Copolymer (SPC)- Contact Leaching Systems- Controlled Depletion Polymer (CDP)

Foul Release

Biocidal Anti-Fouling Coatings

Biocidal anti-fouling coatings function by creating a microlayer of biocide rich environment at the paint surface, which prevents marine organisms from attaching. These coatings also contain active ingredients, which prevent or slow marine growth. There are currently only three main forms of biocides that can be used in anti-fouling systems: Metallic Organometallic Organic Few biocides have had the necessary combination of characteristics to make them safe, yet effective antifouling agents. Mercury, arsenic and their compounds, and also now the organotins, are examples of effective antifouling agents that have been deemed unacceptable due to adverse environmental or human health risks. TBT-based coatings were introduced in the mid-1960s and were common in the latter half of the 20th century as an effective anti-fouling solution. However, their acute toxicity to non-target marine organisms had severe environmental impacts and a complete ban on TBT paints entered into force on 17th September 2008. Copper-based biocides are the most commonly used, and often in combination with organic biocides in order to achieve a wider spectrum of activity.


Releasing Biocidal Agents

For biocidal anti-fouling coatings to be effective, the biocides have to be released into the sea. The most common method of releasing biocidal agents is through a combined leaching/polishing process. Seawater first diffuses into the coating and then the biocide leaches out. As each new layer of paint is exposed and then worn away, new layers come into contact with the water and the process repeats. Sea water is alkaline (pH ~ 8) and biocidal anti-foulings work by having an acidic binder component that can dissolve in sea water, thus releasing biocides. The method behind biocidal release is that the surface will not foul provided that the release rate of the biocide(s) is above a critical release rate threshold value (CRTV). Therefore, the objective is to control and maintain the release rate above the CRTV for as long as possible. To address this the market hosts Controlled Release technologies that are used to give maximum performance and enhanced lifetimes of the anti-fouling coating. Modern anti-foul coatings use a binder, which is partially soluble in seawater, hence allowing the steady release of sufficient amounts of biocide and, thereby, extending the active lifetime of the coating. The two main variations of self-polishing coatings are controlled depletion polymers (CDP) and self-polishing copolymers (SPC). Both require a current of water to wash away the coating layers at the required rate, so are not suitable for vessels that spend long periods of time laid up.

The three main soluble acid binder options to enable biocide release in sea water are: - Controlled Depletion Polymer (CDP)- Hybrid SPC- Self-Polishing Copolymer (SPC)

The so-called Self-polishing coatings use a binder, which is partially soluble in seawater, meaning that as biocide is released the coating also becomes smoother over time. The two main variations of self-polishing coatings are controlled depletion polymers (CDP) and self-polishing copolymers (SPC). Both require a current of water to wash away the coating layers, so are not suitable for vessels that spend long periods of time laid up.

Clarity of Terms Used

Note to the reader: The descriptions Self-polishing and Self-polishing Copolymer (SPC) are not the same.

The term self-polishing refers to the effect obtained with an anti-fouling coating in which the coating has a controlled decrease in its thickness.

The term Self-polishing Copolymer refers to a type of polymers that fulfill the requirement of Self-Polishing, for example CDP.

BIOCIDE (DISPERSED IN A RESINOUS MATRIX)


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Biocide Release: Self-Polishing Copolymer (SPC)

Self-Polishing Copolymer (SPC) anti-foulings release biocides via the hydrolysis or ion exchange reaction of an acrylic polymer with seawater, to form an acid polymer, which is then soluble in seawater. This results in thinner leached layers and thus much better control of biocide release.

SPC coatings require the binder to react with seawater first before it becomes soluble. This happens via hydrolysis the breaking of chemical bonds by the addition of water. The process results in thinner leached layers than CDP coatings and so better control of biocide release over time and self-smoothening. These paints are claimed to be higher performance although more expensive.

The main types of SPC polymer are nanocapsule acrylates, metal acrylate and silyl acrylate. Silyl acrylate coatings have a slow initial rate of polishing, while metal acrylate coatings have a fast initial rate of polishing however both demonstrate a steady rate of polishing over time. Nanocapsule acrylates have a more balanced behaviour. All are long-lasting and easy to re-coat.

SPC coatings can also be formulated with some co-binders such as rosin or derivatives, to improve the properties of the film. The combination of SPC coatings plus co-binder are often referred to as Hybrid SPC coatings.

In terms of chemistry, hybrid SPC technology are formulated via a mixture of hydrolysis and hydration mechanisms, combining SPC acrylic polymers with a certain amount of co-binder.

SPC Features:- Controlled, chemical dissolution of the paint film, capable of giving long dry dock intervals- Predictable polishing, enabling tailor-made specifications by vessel type/operation- Thin Leached Layers = simple cleaning and re- coating- Ideal for newbuildings- Excellent weatherability- Good mechanical properties

Hybrid SPC Features:- High volume solids content- Polishing control- Surface tolerant- Good film properties- Control of biocide release- Good anti-fouling performance

Biocide Release: Contact Leaching

Contact leaching anti-foulings were introduced in the 1960s and were designed to increase antifouling lifetimes by increasing the biocide content.

Also known as hard racing or long life paints, contact leaching paints have an insoluble matrix and continuous biocide release if generated by the high biocide concentration ensuring that biocide particles contact each other through the paint film. As surface biocide is released, microchannels are created which permit release of biocide from deeper in the coating. Biocide release rates decrease exponentially with time and effective life is again limited to periods rarely exceeding 18 months.


Biocide Release: Controlled Depletion Polymer (CDP) CDP coatings have rosin-derivatives as the main polishing-inducing binder.

The soluble binder, natural rosin contains around 90% abietic acid and has been used for over 100 years in antifouling paints.

Rosin, as a soluble binder has a low mechanical strength. As a general rule; the higher the solubility of the coating, the lower the mechanical strength, so there is a necessary trade-off in order for the coating to resist abrasion and damage. Leached layers of paint can build up, which slows biocide release down and inhibits smoothing.

Rosin has some disadvantages:- it is a brittle material, and can cause cracking and detachment;- it reacts with oxygen and has to be immersed relatively quickly;- it does not prevent water going into the depth of the antifouling paint film. Rosin can be used at low level to form hard Insoluble Matrix anti-foulings, or high level to form soft Soluble Matrix anti-foulings. It is the modern Soluble Matrix anti-foulings are now commonly referred to as CDP anti-foulings. CDP coating exhibit slow dissolution of the paint film in sea-water, this dissolution gradually slows down over time, due to the formation of insoluble materials at the surface. Also, leached layers can become thick, suppressing biocide release and increasing roughness.

CDP Features: - CDP anti-foulings have thick leached layers, which limit performance and negatively affect re-coatability.- CDP anti-foulings are claimed to be not as effective as SPC systems- CDP products are the lowest cost per sq. m value for money anti-foulings, and are suitable for use in lower fouling areas or for vessels with short dry-dock intervals

Biocide Release: Hybrid SPC

Hybrid SPC coatings are a combination of CDP and SPC technology. Hybrid SPC technology works by a mixture of hydrolysis and hydration mechanisms, combining SPC acrylic polymers with a certain amount of Rosin.

In terms of performance and price, they are mid-way between the two. Copper pyrithione is commonly used as a co-biocide.

Hybrid SPC Features:

- High volume solids content- Polishing control- Surface tolerant- Good film properties- Control of biocide release- Good anti-fouling performance


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Foul Release Coatings

Foul release coatings (FRCs) function by preventing or reducing the adhesion (non-stick) of fouling organisms to vessel hulls. The flora and fauna species that colonise on the hull, which contribute to marine fouling, typically attach to hull surfaces by exuding special glues, with the strength of the glue dependent on the glues ability to spread over the surface and bind to it.

In terms of chemistry, foul release coatings typically have low surface energy, which is a measure of the way they bind with other substances.

This low surface energy degrades an organisms ability to generate a strong interfacial bond with the surface via the aforementioned glues. The smoothness Non Stick properties of the coating at the molecular level allows for organisms to be dislodged once the vessel is moving beyond a critical velocity.

As a general rule, substances with a low surface energy are harder to wet (i.e. harder for a liquid to spread across), and so harder for adhesives to stick to.

To work effectively, foul release coatings need to have a minimum thickness in order to have the required flexibility and assist in the self-cleaning of any weakly-attached fouling that manages to settle on the coating. This thickness is always lower than that of biocide-based anti-foul coatings. All commercial foul release coatings contain oils, which migrate to the surface and improve their overall effectiveness.

There are three main ways of modifying the surface of silicone-based coatings: modified silicone oils, fluoropolymers and hydrogels.

Foul Release: Silicone

Silicone coatings are the oldest type of foul release coatings and are still the foundation over which all modern fouling release coatings have been built on.

Silicone coatings are still the most common type of foul release coatings.

Traditional silicone-based coatings foul relatively fast, so they require that the vessel stays sailing most of the time and preferably at high speeds (i.e. above 15 knots). Silicone coatings have several other properties that distinguish them from other anti-fouling coatings. They are generally smoother and have a higher volume of solids, which reduces their solvent emissions when applied.

Silicone-based technology relies on the unique surface chemistry of siloxanes to which fouling cannot easily adhere. These formulations are typically comprised of a silanol (SiOH) functional polydimethylsiloxane, silica, catalysts and an alkoxy functional silane or silicate crosslinker.


Foul Release: Fluoropolymer

Polymers containing fluorine can also be used to create a low energy surface with non-stick properties designed to prevent adhesion of marine fouling.

A Fluoropolymer is a polymer, with multiple strong carbon fluorine bonds, with the consumer product Teflon being the most commonly recognised example (but which unfortunately has poor fouling prevention properties).

Fluoropolymer based fouling release stands for silicone coatings, which are modified by small amounts of fluorinated oils.

Fluoropolymer chemistry represents the very latest advances in foul release technology, significantly improving upon the performance of the best silicone based systems as they provide an ultra-smooth surface.

Fluoropolymer systems provide an amphiphilic surface. It has been established that marine fouling organisms secrete an adhesive, either of a hydrophobic or hydrophilic nature depending on the fouling species. By having a balanced amphiphilic surface fluoropolymers can minimise the chemical and electrostatic adhesion between the surface and a wide range of fouling organisms. The amphiphilic surface physically deters the settlement of organisms simply by nature of the surface.

Therefore, the basic concept behind this is to provide an amphiphilic surface with both hydrophobic (water-hating) and hydrophilic (water loving) areas

Fluoropolymer oils also are also leached into the water to increase the effectiveness of these fouling release coating systems.

Foul Release: Hydrogel

Hydrogel-based fouling release coatings move the concept of fouling release to the opposite extreme, hydrophilic surfaces. Inspired by advanced biomedical research, these coatings contain a hydrophilic modified silicone polymer that migrates to the surface upon immersion and creates a hydrogel layer at the outermost surface of the coating. Water trapped in this layer presents the biofouling organisms with a surface unlike other surfaces in the marine environment. Abundant research show that this chemistry provides upgraded fouling protection, and these coatings claim to release fouling down to 8 knots of speed and down to 50% of activity.

Foul Release Coatings Features:

Foul Release coatings are durable fouling control systems for Scheduled Ships Foul Release coatings give equivalent performance to SPC systems without the use of biocides. Foul Release coatings generally have an average hull roughness (AHR) under 100 microns, which is smoother than most biocidal anti-foulings Foul Release coatings are based on silicone chemistry, and are thus very Durable, both above and below water They retain their gloss and do not change colour, even after prolonged immersion periods, in contrast to biocidal anti-foulings Costs at Maintenance & Repair can be lower with FRCs because:

Only touch up is required at dry docking(s) up to 60 months. After 60 months only a single full re-coat (100 microns) of finish is required. Washing is easy & quick. There is reduced waste during paint application (fewer cans). Draft marks do not need to be re-painted.


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Therefore:

Potentially less time in dry dock. Intervals between dry dock can be flexible, up to 60 months. No expensive treatment of the wash water or abrasive is needed.

Advantages of Foul Release Systems:

No release of biocide in to the environment. Unlikely to be affected by future environmental legislation. Reduced paint volume (and solvent emitted) on first application. Good anti-fouling performance on a range of vessel types. Good resistance to mechanical damage. Reduced hull roughness giving improvements in vessel performance and reducing emissions. Less time in dock, paint required and application costs at future dockings. Keeps fouling off the propellers. Disadvantages of Foul Release Coatings:

Higher initial cost of paint and application. Quality of application is very important Masking and dedicated equipment required. As product is biocide-free, resistance to slime for silicone foul release systems are lower than some biocidal anti-foulings.

Hard Coatings

Hard coatings are a third type of marine coating which, like fouling release coatings, are not reactive with seawater and do not contain biocides. They have the advantage of not gradually dissolving and also provide very good mechanical resistance and anticorrosive properties.

However, to be truly effective against marine fouling, use of these coatings needs to be combined with a regular method for hull cleaning. Such coatings also need to be able to flex with a vessels hull, so the best coatings will combine extreme hardness with flexibility.

Alternative Coatings

A number of alternative and innovative approaches to hull fouling prevention have come onto the market or are currently in development. A selection of alternative coating solutions and innovative approaches to combatting hull fouling are profiled below.

Microfibre foils consist of a film of tiny fibres that are applied to vessel hulls.

These can prevent microorganisms from settling via the density of the foil and the swaying motion of individual fibres. For single cell organisms that form chains, such as micro-algae, the swaying motion damages the cell structure, which causes the threads of organisms to eventually be cut off rather than staying attached. This can also prevent algae spores from sticking and from finding their way to the hull surface.

Stimulated Release coatings use periodic stimulus to change the shape of the hull surface and knock any attached organisms off. This technology is currently in development by Duke University, with the stimulus in question being an electric current, although the technology does not yet have a commercial application.

Water Encapsulation is a new technology that Nippon Paint claims to employ. This enhances the self-polishing properties of an SDP coating by trapping water in bumps in the hull coating, creating a smoother surface than the paint alone.

However, the mechanism behind this effect is not clear; whether it is a function of the polymer being used or another technology has not been specified.


Natural Product Anti-Foulants have been the centre of much research over the last 20 years.

For example, materials harnessed from terrestrial trees & plants such as tea-tree oil and capsaicin and materials harnessed from marine organisms & plants such as furanones, zosteric acid have been widely used. In August 2013, Pettit announced the launch of Hydrocoat Eco, a self-polishing ablative coating with naturally-derived biocide. Hydrocoat Eco consists of self-polishing, water-based, ablative technology that has as its active ingredient the organic biocide Econea. The company claims that tests show that antifoulants made with 6% Econea are as effective as those made with 50% copper. Natural product anti-foulants features: Positive Perceived as an environmentally acceptable solution . Data exists that demonstrates the efficacy of some natural products. Negative Natural product anti-foulants are natural biocides, and in many cases very little data exists with regard to their toxicity and/or degradation in the environment. In many cases the materials are complex organic molecules that are very costly to synthesise.

Biomimetics is defined as the study of the structure and function of biological systems and processes as models or inspiration for the sustainable design and engineering of materials and machines. A number of technologies inspired by nature are worth considering as antifouling strategies such as surface texture, mucus and secondary metabolites. For example, one strategy is inspired by the low-drag performance of sharkskin surfaces made to mimic their grooved scales (placoid scales, which resemble tiny spines that protrude from the surface). These scales are almost parallel to the longitudinal body axis of the shark and their presence has been shown to reduce drag by 510%.

Surface Technology or Nanotechnology is defined as the manipulation of matter on an atomic and molecular scale. In essence, nanotechnology can be described as the science of molecular engineering, and is currently changing the way many industries think of surface coatings. Nanomaterials are finding applications in marine antifouling. The inherently small size of nanoparticles means they remain in the lattice of the antifoul coating. Although they do not readily leach out, they slowly release ions to provide long-term antifouling performance.

An example of nanotechnology innovation within for hull coatings application is described in the academic paper: Natalio et al, 2012 Inspired by nature: Paints and coatings containing bactericidal agent nanoparticles combat marine fouling

It makes use of tiny vanadium pentoxide nanowires and is inspired by one of natures own defense mechanisms in which so-called vanadium haloperoxidase enzymes play a crucial role.


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Advanced Marine Coatings

Advanced Marine Coatings (AMC) is a specialist manufacturer of marine coatings headquartered in Norway. Their product range applies to decks, cargo holds, ballast tanks and underwater hulls, having been tested both in laboratories since 2006 and on commercial vessels since 2008.

In 2006, the company experimented with a nano-modified epoxy coating formulation applied on a speed boat. Preliminary tests showed that the coating made a difference of several knots in terms of the speed, compared to traditional anti-fouling paints. Over the next three years, AMC continued to improve the formula. Subsequent tests on different types of boats with depths of up to 40 metres demonstrated an increase in speed of 6 to 10%, or a corresponding reduction in fuel consumption.

The foremost feature of AMC products is their use of carbon nano-tubes in epoxy-based coatings. Preliminary tests showed that the coating made a difference of several knots in terms of the speed, compared to traditional anti-fouling paints. Over the next three years, AMC continued to improve the formula. Subsequent tests on different types of boats with drafts of up to 40 metres demonstrated an increase in speed of 6 to 10%, or a corresponding reduction in fuel consumption. The use of carbon nano-tubes is also said to provide a stable, flexible coating surface without leading to compromises on other key mechanical properties such as adhesion and resistance to wear.

AMC also has a heavy involvement in cooperative research and development initiatives around the use of nano-technology. They hold partnerships with a wide range of institutes including SINTEF, the Max Planck Institute, EADS, Daimler, the YKI Institute for Surface Chemistry, SP, VTT, SAAB, and Vattenfall.

Premium Anti-Fouling Products:

Advanced Marine Coatings Antifoul, Super Sleek

An anti-foul system based on copper oxide slowly leaking through the coating during a span of several years. The pore free coating film has proved to be extremely hydrophobic and water repellent. The coating remains very smooth and has low friction against water. In addition the nano reinforcement ensures that the coating does not lift from the steel surface if washed by high pressure water cleaners.

Type of Coating: Biocidal

Known Ship Types: Particularly suitable for vessels involved in washing regimes and high speed ferries or catamarans.

Savings: Speed trials have proven that it is possible to increase speed up 10% compared to alternative anti-foulings.

Manufacturer Application Guidance: It is applied with roller, brush or spray and without added solvents (VOC).

Recent Vessels/Clients: AMC states that their AFS Hybrid coating has been applied on the bulb of a cruise vessel owned by a leading cruise operator since October 2011. Further details of

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