White paper 14_Opmaak 1 3/10/14 15:07 Pagina 1
HYDREX WHITE PAPER N°14 Tackling the special coating requirementsTackling coating special the of the hulls and running gear of ice-going ice-going of gear running and hulls the of Hull Protection for Protection Hull Ice-going Vessels Ice-going ships and icebreakers and ships WHITE The Hydrex GroupHydrex The www.hydrex.be
PAPER White paper 14_Opmaak 1 3/10/14 15:07 Pagina 2
Copyright 2014 by Hydrex, nv. All rights reserved. White paper 14_Opmaak 1 3/10/14 15:07 Pagina 1
Hull Protection for Ice-going Vessels Part I: Introduction Part I. Introduction
ce represents a severe hazard to ships. reduction in the ship’s scantlings of up to IIcy waters, icebergs, packed ice, old 1 mm in thickness of steel plate. This can add ice, first year ice, lava- or gravel-laden up to a significant reduction of steel or other ice or any other form of ice are all substrate and in the overall weight of the significantly more challenging to a ship vessel. than water. More than in any other marine The fuel efficiency of the hull coating is application, choices regarding ships that also very important, especially when one will sail in ice can be a matter of life or considers current fuel prices. A hull coating A hull coating that death. that reduces friction and remains smooth reduces friction over the ship’s life cycle will result in and remains There are many ice-specific class regulations tremendous fuel savings for the operator. smooth over the ship’s life cycle intended to reduce the risk of that hazard and But this is not just a point of economy. will result in promote safety for ships sailing in such Reduced fuel consumption means fewer tremendous fuel conditions. noxious, harmful atmospheric emissions savings for the When it comes to choosing a hull coating such as CO2, NOx, SOx and Particulate operator. for icebreakers and ships that sail or trade in Matter including black carbon. Hull fuel icy waters and their rudders and running gear, efficiency comes down to two main factors: certain key factors must be looked for. 1) long-term hydrodynamic smoothness and The first and most important is protection. low friction of the hull; 2) freedom from The steel or other material from which the biofouling, either by repelling it or by hull is made must be protected from this removing it before it accumulates to any harshest of harsh environments. This means large degree. While not nearly as significant a really tough coating which is resistant to a factor in icy waters as in temperate or the abrasion of the ice, which will adhere tropical climes, the control of fouling must under the constant pounding and scraping still be taken into account when choosing the that accompany sea voyages through ice. It best hull coating for trading or sailing in ice. also means a coating that is not brittle or Low friction is a key property of a hull inflexible and therefore subject to cracking or coating for an ice-going vessel or icebreaker. disbonding when the panels that make up This permits the vessel to move through the hull flex and bend, even permanently ice more rapidly, or at least less slowly, denting, under the impact the ship receives especially when the ice friction is increased from the ice. As soon as the hull coating is by a covering of snow. It also makes it easier damaged, corrosion of the underlying hull for an icebreaker to ram onto and reverse off can set in and spread. There is an economic the ice during icebreaking operations. This factor here too. Certain ice abrasion resistant is an economic factor but also a safety hull coatings are certified as such by the factor. Less fuel will be consumed by a classification societies. This certification ship operating in ice which has a low friction includes the provision that the coating, if coating on its hull. The danger of running correctly applied to the ice belt, will permit a out of fuel or having to curtail a voyage is
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Hull Protection for Ice-going Vessels Part I: Introduction
reduced. application? How long will it last? Does it Environmental considerations are very need frequent and expensive repair or important. The Arctic, the Baltic, the Great replacement in dry-dock? If so, how difficult Lakes, the Antarctic, southern South America and/or expensive is it to repair/replace? Can and many other environments where ships it be safely cleaned in the water without operate in icy conditions tend to be relatively damage to the coating or harm to the marine pristine when compared to the much more environment? traveled sea routes and other waterways. These then are the main points which can Certain pollutants such as black carbon are be greatly influenced, for better or for worse, much more harmful in the same volume in by the choice of coating used on the hulls of polar waters than in tropical or temperate ice-going vessels and icebreakers: zones. These areas are particularly sensitive 1. Protection and safety. to the invasions of alien species and to the 2. Economy of operation and reduction of effects of heavy metals and other toxic total ownership costs. substances such as those leached by biocidal 3. Environmental sustainability. antifouling coatings and many foul-release 4. Ease of application. coatings. A further aspect which must be This White Paper examines the subject, considered when choosing a coating for the the types of coating available and the best hull of ice-going ships is the ease of applica- approach to choosing the right coating for the tion and maintenance of the coating. Does it hull and running gear of ice-going ships. require special conditions and equipment for
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Hull Protection for Ice-going Vessels Part II: Climate of change Part II. Climate of change
or icy waters, particularly the Arctic precautions specifically for vessels operating FOcean, shipping traffic is in a major in polar regions. A number of suggestions state of flux. This has been big news, were put forward, and preliminary work was attributed to climate change and receding done, concentrating more on the safety aspects summer ice, opening heretofore impass- than the environmental ones. These suggested able ship routes and making Arctic travel or desired requirements included the use of ice possible or easier. Reports are somewhat abrasion resistant, non-toxic hull coatings, and conflicting on the subject but in general measures for preventing hull-borne invasions the forecasts are for increased or greatly of non-indigenous species in the form of increased shipping in icy waters. biofouling, which would mean ships sailing into Polar regions having a macrofouling-free Offshore oil and gas exploration and produc- hull. While work on the Polar Code had not tion activities in Polar regions, particularly been completed at time of original publication the Arctic, are increasing. The reserves of oil of this White Paper, shipowners and operators and gas in Arctic regions are estimated to be planning to sail in these waters need to take about one quarter of the world’s proven the possibilities into consideration as they sources.1 The countries that border the Arctic build new vessels or replace the hull coating Ocean are all increasing or planning to on ships in service. increase their shipping activities in the icy If delays on developing an acceptable waters of the Arctic region. Remote offshore Polar Code continue, it is quite likely that vessels are expected to stay on station for individual ports and States affected will long periods of time without going to dry- develop and impose their own requirements. dock. This poses a challenge to hull coatings This is far from optimum since the various in that they need to protect the vessel from nations and authorities involved are unlikely corrosion and be cleanable for underwater to come up with the same set of regulations, inspections in lieu of dry-docking (UWILD) and ships traveling between and among the by classification societies. Toxic antifouling various ports and States will need to keep coatings and other soft coatings are not track of and follow different sets of rules. Far appropriate for ice-going vessels since they simpler would be a rapidly completed, IMO- are easily damaged or scraped off by contact led Polar Code which can be agreed on by all with the ice. The additional factor of not affected States. going to dry-dock as in the case of off-shore These various factors are all coming exploration, production and storage vessels together to pressure shipbuilders, shipyards, The question is, how does one imposes severe requirements for toughness shipowners and ship operators to make the choose the best and durability on the coating used to protect correct decisions concerning the application hull coating the hulls of such vessels. and repair of hull coatings on ice-going vessels. system for this Work was started by the IMO in 2009 on a The question is, how does one choose the harsh and Polar Code supposed to recommend or dictate best hull coating system for this harsh and unforgiving safety and environment-related conditions and unforgiving environment? environment?
1Cambos, Philippe, et. al. “Technical Challenges Associated with Arctic LNG Developments: A Class Society Approach,” Bureau Veritas, Paris, (2013).
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Hull Protection for Ice-going Vessels Part III: Issues with Hull Coatings for Ice-going Ships Part III. Issues with Hull Coatings for Ice-going Ships
hat are the special requirements eats away at the hull which then becomes Wfor hull coatings on ice-going thinner and less able to withstand the forces ships? of sea and ice. It is a vicious circle which begins with the failure of the coating. This is The most important consideration is the an economic consideration as well as a point Ice damages and harshness of the environment. Ice damages of safety. A worn hull will more easily be destroys all but and destroys all but the toughest hull holed than one which had been well- the toughest hull coatings. This is clearly visible when the ship protected and has not lost its thickness. coatings. comes to dry-dock after a season in the ice. Collision with or pressure from ice also The hull paint, even dedicated, ice-class causes the plates that form the ship’s hull to paint, is usually badly depleted, damaged or flex and deform, at least temporarily. This worn away to bare steel. means that a coating which is brittle or
The hull of an ice-breaking Antarctic supply vessel after a single season in the ice with a specialized, industry standard, ice abrasion resistant coating.
As the coating is damaged or destroyed, inflexible or which is poorly bonded can the direct contact of seawater with steel disbond under the stress caused by contact begins the corrosion process. This corrosion with ice.
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Hull Protection for Ice-going Vessels Part III: Issues with Hull Coatings for Ice-going Ships
Some background information is useful generally not in contact with each other but before getting down to the specific have open water in between. Bergy water challenges that confront the hull coating has some ice of land origin but is freely when ships are trading in ice or breaking ice. navigable. The entire range is from 10/10 consolidated ice to 0/10 ice free water with Not all ice is created equal all stages in between. Ice of land origin Ice comes in different forms, shapes, sizes includes glacial ice, glaciers and ice shelves. and conditions. Some ice is more of a From these, icebergs and ice islands of challenge or threat than other ice. various types, sizes and denominations break The following information and definitions off. These can extend from 1 - 75 or more are taken from “Annex A Terminology for meters above the sea and can have an area as Ice, Navigation and Ship Design” of the small as 20 sq m or as large as 500 sq km or Canadian Coast Guard’s publication Ice more. Navigation in Canadian Waters.2 Sea ice ranges in its thickness and Some ice-related ship terms permanence, and therefore harshness to Technology has built up over the years with shipping, from new ice, recently formed, regard to making ships fit for sailing in icy which reaches thicknesses of 15 - 30 cm, to water. Nomenclature has been developed first-year ice which is of not more than a to describe the special measures taken to season’s growth but ranges from 30 to over strengthen ships and make them ice-worthy. 120 cm in thickness. Beyond that there is Some of these terms need to be explained for second- and multi-year ice which is thicker a full understanding of this White Paper in and stands higher out of the water than first- case the reader is not familiar with them. year ice. The ice belt is the area of the ship which In addition to varying in age and is strengthened to withstand ice loads at the thickness, ice comes in different forms: ice draft water line. pancake ice consists of small circular pieces Ice draft is the draft at which the ship of ice, 30 cm to 3 m in diameter and up to must be in order for the ice-strengthening of 10 cm thick. Ice cakes are relatively small the hull structure to be of value. pieces of ice up to 20 m across. Floes are An ice horn is a wedge-shaped structure fairly flat pieces of ice ranging from 20 m to placed above the rudder in order to protect it 10 km across. Fast ice is attached to and when the ship goes astern into ice. remains fast along the shore and can be first- Ice-strengthened is the term used to refer or multi-year ice extending for hundreds of to the added strength built into the hull of an kilometers along the coast. ice-going ship so that it can operate safely in Ice cover is a term used to indicate the ice-covered waters. ratio of the area of ice to the total area Ramming describes the action of driving of water, expressed in tenths. Thus the ship, usually an icebreaker, as far consolidated or compact ice would have a forwards into and onto the ice as possible and concentration of 10/10 with no water visible. then backing it out and repeating the process. Open ice would have a concentration of An icebreaker is driven forward up onto the between 4/10 and 6/10 where floes are ice and uses its weight to break the ice. This
2Canadian Coast Guard,Ice Navigation in Canadian Waters, (2012).
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Hull Protection for Ice-going Vessels Part III: Issues with Hull Coatings for Ice-going Ships
action can be repeated by going astern and The Finnish-Swedish Ice Class rules have a driving forward over and over again to break notation system of their own. These rules a path through the ice. were developed for merchant ships navi- gating in first-year ice in the Baltic. They Ice classes cover the ship’s ability to advance through Out of the need for strengthening ships for ice, and concern engine output and hull ice navigation have come a series of strength. The structural strength of the hull classifications or categories which are used and propulsive machinery of the ship need to by the classification societies to describe a be able to withstand expected ice loads with vessel’s suitability for traveling in ice- a margin of safety. covered waters. Unfortunately there is not The Swedish-Finnish ice class designa- just one system of such classification but tions are as follows: several issued by different classification societies or bodies. However, the correlation 1. ice class IA Super; ships with such between the various designations is not too structure, engine output and other complicated and the principles in use are properties that they are normally what is important here. capable of navigating in difficult ice The following table shows ice-class conditions without the assistance of notations as used by DNV classification icebreakers; society.3 2. ice class IA; ships with such structure,
3Morten Mejlænder-Larsen, “Role of IACS in Arctic Shipping,” (October 2008).
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Hull Protection for Ice-going Vessels Part III: Issues with Hull Coatings for Ice-going Ships
engine output and other properties or certification is not lightly given. The that they are capable of navigating in Swedish-Finnish rules state the following: difficult ice conditions, with the assistance of icebreakers when When considering the laboratory testing, necessary; the following testing procedure could be 3. ice class IB; ships with such structure, followed: engine output and other properties - Resistance to abrasion (Taber abraser that they are capable of navigating in test) moderate ice conditions, with the - Impact resistance assistance of icebreakers when - Adhesion strength necessary; - Extensibility (flexibility) e.g. according 4. ice class IC; ships with such structure, to ASTM D4145 engine output and other properties that they are capable of navigating in In addition, the following corrosion tests light ice conditions, with the could be considered: assistance of icebreakers when - Cyclic corrosion test or salt spray test - necessary; Water immersion test 5. ice class II; ships that have a steel hull - Cathodic disbondment test.6 and that are structurally fit for navigation in the open sea and that, Additional factors despite not being strengthened for In addition to frozen fresh or salt water, ice navigation in ice, are capable of can contain highly abrasive material and navigating in very light ice conditions particles such as, for example in the Antarctic with their own propulsion machinery; regions, volcanic lava, or gravel. This makes 6. ice class III; ships that do not belong to an already harsh environment for ship hulls the ice classes referred to in and their coatings into an even more extreme paragraphs 1-5.4 source of abrasion and potential damage. The ice can also be covered with snow of The classification society regulations require varying depth. This can greatly increase the a “corrosion allowance” for ice-class ships friction which the ship’s hull undergoes when which means added thickness to the in contact with ice. scantlings to compensate for wear from ice Friction is the force resisting the relative abrasion. Usually this is an additional 2 mm motion of solid surfaces, fluid layers and in thickness of the plates. Where a recog- material elements sliding against each other. nized ice abrasion resistant coating is used For a ship moving through water, the forces and on condition that the surface is of skin friction, also known as drag, are con- thoroughly and properly prepared and the sidered. For a ship moving through and in coating correctly applied, this corrosion contact with ice, dry friction applies since allowance can be reduced to 1 mm.5 This both objects are solid. Both skin friction and shows the importance of correct selection dry friction affect the hull of a vessel moving of coating and its standard application. through icy water. This ice abrasion resistance recognition Coefficient of friction is a numerical
4Finnish Transport Safety Agency, Maritime Safety Regulation, “Ice Class Regulations and the Application Thereof,” (23 Nov. 2010). 5TraFi Swedish Transport Agency, “Guidelines for the Application of the Swedish Finnish Ice Class Rules,” p. 20 (Dec. 2011). 6 Ibid.
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Hull Protection for Ice-going Vessels Part III: Issues with Hull Coatings for Ice-going Ships
value by which friction can be measured or between the hull and the ice is of value. In the indicated and compared. The coefficient of case of icebreaker which must ram the ice friction depends on the materials involved. and often reverse and ram again, a low For example, steel on ice has a relatively low friction hull enables this operation to be coefficient of friction whereas rubber on carried out with a lower output of power and concrete has a much higher coefficient of consumption of fuel than with a higher friction. The usual values for dry friction of friction hull. In the case of any ship traveling most common materials are between 0.3 and through ice covered waters, a low friction 0.6. A coefficient of friction of 0 would mean hull can greatly reduce the amount of fuel no friction at all. Rubber against other consumed to travel the same distance at the materials can have a coefficient of friction same speed. This has an additional value of between 1 and 2. creating fewer emissions of noxious gases Friction is a very Friction is a very important element in ice and particulate matter which are particularly important element navigation and icebreaking. unwanted in polar regions. Lower fuel in ice navigation Depending on how old the hull is, the consumption adds up to reduced atmospheric and icebreaking. coefficient of friction between ice and the emissions, all other factors being equal. A bare steel of uncoated hull platings is usually low friction hull depends mainly on the type between 0.2 and 0.3. The friction between ice of coating used and the state of that coating. and a low friction hull coating is more likely to be in the range of 0.05 - 0.17 which is Hull coating requirements considerably lower.7 The difference can be Thus the two key requirements for ice-class seen in the following example. The level of hull coatings are corrosion protection of the power needed to force a ship with an hull and a low friction surface. uncoated hull forward that was stationary in Corrosion must take into account ice, corresponds to a speed of advance of 3 adhesion and abrasion resistance. Basically knots. The power required for a ship with a the coating has to stay on the hull and low-friction coated hull in similar conditions withstand the onslaught of the ice without corresponds to a speed of 0.5 knots. disbonding or sustaining damage. An added Prior to the 1970s there were no suitable factor of corrosion protection is undercreep coatings for the hulls ice-going ships and and how to prevent it. If a coating permits coatings that were used would wear off undercreep, then when it is damaged the within a few days of deployment in ice- resulting area of corrosion spreads to covered waters. Thus the tendency was to adjacent areas under the coating. With the leave hulls uncoated and increase the best corrosion protection undercreep is thickness of the plates to allow for wear and almost entirely eliminated. This results from corrosion. The bare steel corroded rapidly their high adhesion to the substrate so that a and the hulls became quite rough, increasing scratch or chip does not result in corrosion friction considerably. Thus low friction, ice spreading underneath the coating to adjacent abrasion resistant coatings were a boon to areas. any ships operating in icy waters, helping Low friction needs to be measured over reduce fuel costs. the life of the coating and the hull, not simply Anything which reduces the friction when the ship is launched. A short-lived
7 Sodhi, D. S., Northern Sea Route Reconnaissance Study – A Summary of Icebreaking Technology,” CRREL, (June 1995)
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Hull Protection for Ice-going Vessels Part III: Issues with Hull Coatings for Ice-going Ships
coating, even if initially low friction, may be requirements for ice-going ship hull coatings fine for weeks or months but will be damaged on all major points. and need to be patched or repaired, thus Mäkinen et al. (1994) listed the require- degrading over time and becoming rougher ments of a good, low-friction coating. Their and rougher until eventually the only answer list is quoted in full here: is to blast the hull back to bare steel and reapply the full coating. But during the time 3. SEARCH OF NEW COATING MATERIALS that the ship is continuing to sail with a 3.1 Requirements of Low-Friction damaged and roughly repaired hull coating, Coating of Icebreaking Ships the power and therefore fuel required to The requirements for a good, low-friction propel it through ice-covered waters will be coating on an icebreaking ship can be much more than with a smooth hull. Thus a grouped into three categories: low friction coating can be defeated if it is relatively easily damaged by the ice, I: Requirements for low friction: requiring frequent spot blasting and repair or -The coating must be smooth, in other even replacement. words its surface roughness must be From an environmental point of view, any small with a low R value. coating used on a ship which travels in ice -The coating must have a large contact covered waters needs to be non-toxic. With angle with the water. toxic coatings, heavy deposits of highly toxic -The surface must have low surface material are simply scraped off onto the ice, conductivity, specific heat capacity posing an environmental hazard. These and density. substances are already hazardous when leached at their normal rate. But when II: Other requirements for a good ice- scraped off in concentrated amounts, this breaker coating: hazard is multiplied. -The coating must have good wear The only hull coatings which are really resistance. suitable for protecting the hulls of ice-going -The coating must have good bond vessels including icebreakers are hard, strength with the base material, i.e. resilient coatings certified as ice-abrasion steel in the shell plating. The best hull resistant. The best hull coatings for ice-going - The coating must sustain high normal coatings for ice- ships are also low friction coatings which pressures. going ships are remain smooth for their entire service life. - The coating must stand the deforma- also low friction The reason is quite simple. Soft coatings tion of the base material. coatings which such as biocidal antifouling coatings or -The coating must stand low tempera- remain smooth foul-release coatings cannot withstand the tures and temperature changes. for their entire service life. abrasion of the ice and are scraped off. Their -The coating must maintain its pro- protective powers are severely limited. When perties in water. damaged and patched they leave a very rough -The price of the coating must be hull. They do not protect against corrosion reasonable. and they also have high friction. When soft -The anti-fouling properties are desir- coatings are also toxic they fail to meet the able, but the coating must not pollute
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Hull Protection for Ice-going Vessels Part III: Issues with Hull Coatings for Ice-going Ships
the environment. yards the specialized equipment and the personnel trained in its use are simply not III: General requirements for the coating available. Economically, it adds up to greater method: expense in the application which raises the -The coating method must be appli- cost of such coatings considerably. cable in large (ship) scales. -The coating method must be appli- Cost of frequent replacement cable in shipyard conditions. A drive towards false economy can lead A drive towards -The coating method must allow pre- shortsighted shipowners/operators to apply false economy paration of smaller, damaged areas the cheapest available coating to an ice-going can lead short- afterwards.8 ship and then replace the coating on an sighted ship- owners/operators annual basis to try to prevent corrosion from to apply the Ease of Application taking too heavy a toll on the hull. Often this cheapest coating There are some other factors which must be is simply a general purpose epoxy coating. possible to an taken into account even with a tough, low It doesn’t take many seasons of dry-dock ice-going ship…. friction coating. There are a few coatings for and coating repair and replacement to catch ice-going ships which are hard and smooth up and make this cheap solution a very and even have fair longevity but which are expensive one. difficult to apply, require special conditions From the point of view of longevity and or equipment and therefore add time and total ownership cost, the least expensive expense in the new build phase and during solution would be a coating which could be dry-dock application, repair or reapplication. applied once and which would then last the This can be quite a drawback. life of the hull without the need for any The special requirements often include extensive repair or for full replacement of the dual feed spray equipment which is designed coating. Assuming that such a coating is to cope with the very short pot life that some reasonably priced, even if much more of these two-part paints suffer from. The expensive than the cheap paint designed to be special conditions often include tenting the replaced every year, the initial investment hull and heating it and the environment to would rapidly pay off and soon become far make application of the paint possible. This more economical. In terms of asset protection is, understandably, quite an expensive, time- and total ownership cost, the more effective consuming and difficult procedure. In many coating has many advantages.
8Mäkinen et al., “Friction and hull coatings in ice operations,” IceTech ’94 5th Intl Conf on Ships and Marine Structures in Cold Regions; 16-19 March 1994; Calgary, Canada. Pprs. Pub by SNAME, Arctic Section, Calgary, Canada. Ppr E [22 p, 27 ref, 5 tab, 22 fig].
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Hull Protection for Ice-going Vessels Part IV: Past and Present Solutions Part IV. Past and Present Solutions
Following is a brief history of ice coatings up ment efforts of Wärtsilä Shipbuilding until 1995, taken from the same paper quoted Division were fully reported at the first above. SNAME Icetech Symposium in Montreal Prior to the early ‘70s, no surface in April, 1975. The paper, entitled material was available which could “Influence of Friction on ice Resistance. withstand interaction with ice, partic- Search for Low Friction Surfaces”, ularly heavy ice. Thus, the practice was comprehensively describes all the to apply only anti-fouling paint to work carried out until that time. The icebreaking hulls to minimize/eliminate experiments formed a credible basis for biological growth on the hull surface. the assessment of the importance of the Such a paint application would be worn ice/ship’s hull/friction phenomenon and off during the first few days of heavy ice also established a basis for further operations. Thus, in ice, and from the development of the subject. point of view of ice-ship hull friction, a Since the mid-70s research has bare steel plate was accepted as the continued. The two-component, solvent- surface quality of a ship’s hull. It was free epoxy, Inerta 160, was extensively understood that, when a ship was adopted after the tests carried out in the relatively new and the shell plates were early ‘70s. That paint has proved to be a not badly corroded, the friction between practical and relatively good solution the ice and the ship’s surface was for all ships operating in ice. Further relatively low, but increased consid- developments were undertaken to erably for older vessels with corroded assure proper application methods for shell plates. the paint. The few competing paints Intensified research on the ship hull/ introduced into the market failed to ice friction phenomenon was initiated in obtain acceptance due to a lack of the early ‘70s. Tests conducted by Oy demonstrated capability or impractical Wärtsilä Ab Shipbuilding Division (the application methods. predecessor of Kvaener Mass-Yards Inc.) Inerta 160 is currently by far the most clearly demonstrated the importance of widely used exterior hull paint on ice- friction on ice resistance. These exper- going vessels. The product and its iments led to further investigation on the application methods have been compre- qualities of different materials, aimed at hensively developed, resulting in con- discovering and developing a material fident use and risk free application of which would exhibit higher ice resis- Inerta 160. It was realized, however, that tance capabilities than those of the for heavy arctic ice operations a better conventional paints used on a ship’s hull. solution should be adopted, although the These tests and the resulting develop- application of Inerta 160 was a definite
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Hull Protection for Ice-going Vessels Part IV: Past and Present Solutions
improvement compared to the previous recognized abrasion resistant ice coatings method, which was no special paint dated July 2013 lists a total of eight different application at all. coatings from six manufacturers. This led to a continuation of the Cargo ships that trade in ice in winter, search for other improved materials. The such as in the Baltic, still often use a fairly research concentrated particularly on inexpensive epoxy coating, knowing that it the use of stainless steel.9 will mostly be removed by one season in the ice and that it will have to be replaced the That was the state of hull coatings for ice- following spring or summer. As already going ships in 1995. A great deal of fruitful covered, the economic wisdom of this research in the intervening years has resulted approach does not usually stand up to close in great advances in this field, in particular scrutiny. Nevertheless, the appeal of a lower the development of glassflake technology initial cash outlay, uncertainty of the future and the use of different resin matrices. This business climate, short life expectancy of will be covered fully in Part V of this White the ship and other factors often lead to this Paper. approach to protecting, or at least covering, Today there are several options on the the hull of ice-going vessels. market when it comes to hull coatings for Other vessels such as cruise ships which ice-going ships. In general, ships that are tend to meet icy water only occasionally, built as icebreakers or which are designed to often take no special precaution when it break heavy ice or which sail in ice all year comes to hull coatings but simply continue to round, tend to have special ice-class coatings use the biocidal antifouling, foul-release or applied. There are a relatively small number even hard coatings which they have applied of these coatings and each major paint for more temperate waters. As has been manufacturer tends to offer at least one such discussed, all these coating types, with the specialized ice paint. exception of hard coatings, are quite unsuited As an example, a Lloyd’s Register list of to icy conditions.
9 Ibid. 10 Lloyd’s Register Group, “Lloyd’s Register Recognised Abrasion Resistant Ice Coatings,” (July 2013).
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Hull Protection for Ice-going Vessels Part V: Best available technology Part V. Best available technology
or reasons covered in great detail in passage through ice. FHydrex White Paper 13 Conquering Most of the certified ice coatings are Corrosion in Offshore Vessels, the best glassflake reinforced. However, it must be possible corrosion protection of hulls in noted that not all glass flakes are created …not all glass water is a combination of a tough, flexible, equal. This is again covered in detail in flakes are durable resin with large aspect ratio glass Hydrex White Paper 13 Conquering Corro- created equal. flakes. When the correct formulation is sion in Offshore Vessels and can be used, this type of coating is impenetrable summarized simply here. The best glass and impermeable and also stands up flakes for coating reinforcement are large better than any other to impact and aspect ratio (large ratio of area to thickness), abrasion such as that experienced by ice- C or ECR type glass, manufactured by going vessels. the spun method. The simple statement “glass reinforced” covers a wide range of With in-water conditioning using the right possibilities, some much more effective than equipment and tools, this type of coating can others. be made very smooth as more of the glass is Thickness varies among the certified exposed. The result is a coating which falls coatings but many of them are applied to a well within the requirements for a low dry film thickness (DFT) of 500 µm or less, friction ice coating. which is not very thick when long-term Of the eight coatings listed in Lloyd’s resistance to ice abrasion and damage is the Register Abrasion Resistant Ice Coatings, six prime concern. In general, the thinner the are based on epoxy resins, some glassflake coating, the more frequently it will need to be reinforced and some not. Epoxy resins can repaired or replaced. provide a low friction coating and generally The certified coatings vary in application perform well, but the epoxy tends to continue requirements. Some require dual-feed, hot the curing process indefinitely and thus airless spray equipment and demanding eventually becomes brittle and inflexible. environmental conditions whereas others can Over time this makes it easier for the coating be applied under normal conditions using to crack, chip and become disbonded with the single-feed airless spray equipment. This flexing of the steel plates of the hull. It tends can be an important consideration in making not to last as long as other types of resin such a final choice of coating. as polyester or vinylester. In general terms, the best all around Thus, if an ice coating is intended to last abrasion resistant ice coating for icebreakers many years without damage, without and ice-going vessels would have all the chipping or becoming rough due to mechan- following features and properties: ical damage and ice impact, it is necessary to 1. Abrasion resistant ice coating certifica- use a base resin which has excellent adhesion tion from the major classification but remains flexible even when fully cured societies. and does not disbond under the stresses of 2. A base consisting of a resin which cures
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Hull Protection for Ice-going Vessels Part V: Best available technology
fully without becoming brittle or in- flexible and has superior adhesion In use, this best available technology for properties. abrasion resistant, low friction ice coatings 3. Glassflake reinforced with large aspect will give the following benefits: ratio, C or ECR type spun glassflakes. 1. The coating will last intact and smooth The glass flake content should be as for many years in the harshest of icy high as possible within the bounds of waters. The currently inevitable exten- maintaining flexibility and toughness sive spot repairs and coating replace- of the coating. This is a key factor ment at each dry-docking will be in the mix. The best coatings contain unnecessary. a number of additives to improve 2. The hull will remain smooth and retain bonding and other qualities. its low friction properties, saving fuel 4. Low friction (a coefficient of friction and reducing emissions. with ice of less than 0.17 is considered 3. The ship using such a coating will low friction). Low friction must deposit no toxic substances either in continue to be low friction over the the ice or in the water column or years that the coating is in use before it sediment of sensitive areas. In other is fully replaced. words, the hull will be environmentally 5. A DFT of at least 1000 µm for high sustainable. impact resistance, superior corrosion 4. The coating will lend itself to in-water protection and adequate longevity. cleaning to remove biofouling when- 6. Completely non-toxic. ever this builds up and cleaning in 7. Application with normal airless spray drydock is impractical. equipment and under normal envi- 5. Any mechanical damage will be easy ronmental conditions, not requiring to patch and the resulting repair will specialized equipment such as dual- leave the hull as smooth as on initial feed airless hot spray equipment and application of the coating. restrictive environmental conditions in 6. Newbuilds will be able to take ad- terms of temperature and humidity. vantage of reduced scantlings, less 8. Requires adequate preparation of steel and a lighter ship. substrate which includes at least grit blasting to create a profile of at least 75 µm and a cleanliness of SA 2.5 or better.
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Hull Protection for Ice-going Vessels Part VI: Case Studies - Ecospeed/Ecoshield Part VI. Case Studies - Ecospeed/Ecoshield
cospeed® is a glassflake reinforced Ecospeed and Ecoshield, will demonstrate Eabrasion resistant certified, low the performance of the coating in the real friction ice coating that meets all the world. specifications covered above in section V. Best Available Technology. Ecoshield® is Case Study 1: Case Study 1: an even stronger version of Ecospeed RRS Ernest Shackleton RRS Ernest which is designed to protect the ship’s The British Antarctic Survey’s (BAS) Royal Shackleton. rudder and running gear which are more Research Ship (RRS) Ernest Shackleton is susceptible to wear from cavitation and ice strengthened and capable of a wide range corrosion damage. The best practice is to of logistic tasks as well as having a scientific apply Ecospeed to the entire hull except capability. It is primarily a logistics ship, for the rudder, thruster tunnel, nozzles used for the resupply of the BAS’s stations, and other parts of the underwater hull with occasional scientific and specialist where Ecoshield would be used for tasking. Shackleton spends much of every maximum protection. The two are entirely year in the Antarctic where it frequently has compatible and each can be applied over to break through ice up to 2.5m thick, often or under the other. with a high content of lava and gravel which which is especially abrasive and harsh. Two case studies, one of an Antarctic Shackleton was initially coated with an icebreaker/supply vessel and one of a Baltic industry standard, epoxy-based specialized trading general cargo fleet, both converted to ice paint in 1995, at build. BAS took over the
RRS Ernest Shackleton routinely has to force its way through ice up to 2.5 meters thick. Antarctic ice additionally carries lava and gravel making it even more abrasive.
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Hull Protection for Ice-going Vessels Part VI: Case Studies - Ecospeed/Ecoshield
Typical state of Shackleton’s hull after a single season in the ice using a conventional, industry standard, specialized ice coating.
operation of the Shackleton in 1999. The world a paint contractor would be able to harsh conditions in which the Shackleton apply it without having to rent in expensive operates seriously damaged the coating with equipment or shielding to ensure application the result that each season the coating had to could continue. We also wanted to be able to be renewed or extensively repaired. Only the conduct minor repairs either by the yard paint recommended coating repair product was contractor or our own crews. Ecospeed gives used. The photos above show the typical us this capability. Application of some of the state of the hull in drydock after a single more traditional icebreaker paint requires a season in Antarctic ice, despite this annual twin feed paint system which means a great coating repair or renewal. deal more care during the application process A variety of problems with the existing as well as ensuring all the environmentals are coating system led to the search for a better correct which can include tenting up space solution which culminated in switching to heaters around the area that is going to be Ecospeed in 2009. The selection criteria used painted. Comparing the other paints with in choosing the new hull coating for the Ecospeed they’re very comparable as far as Shackleton are given here by Stephen Lee, purchase price and performance generally in then Senior Marine Engineer for BAS. “We the broadest of terms, but the main, huge looked at all the alternatives including the difference is the actual cost and complexity glassflake STC [Ecospeed] we eventually of application of the paint. The preparation chose. There were a lot of comparisons is the same, 2.5 Sa over the hull, but the between all of the products. Because of the actual application, not having to get the nature of our business and where we operate environmentals right, not having to tent up we also required a paint system that would the area if it’s slightly cool, not requiring have significant environmental benefits as space heaters, if the area is gingered slightly well as conforming to the Polar Code and which may or may not require a sweep blast latest classification societies regulations. We before you can put the primer on – there’s a required a paint system which was cost- huge amount of preparation and logistics that effective in purchase, application and have to go into getting the initial coat of maintenance. We wanted a simplified paint traditional ice-going paint onto the hull, system that no matter where you went in the whereas with Ecospeed it’s minimal as long
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Hull Protection for Ice-going Vessels Part VI: Case Studies - Ecospeed/Ecoshield
as you have a good paint inspector, and only most people understand works in conjunction minimum environmentals are needed.” with the paint. ICCP has never given “One of the inquiries I made before we complete hull protection but with a good put Ecospeed on the first time in 2009 was to paint system it will. Effectively a common see how compatible it was with the ICCP ratio I use is 80% protection from paint and system that the vessel had, because the ship 20% protection from ICCP. A failure in one was suffering from the ICCP system not or the other will quickly see a deterioration in functioning properly. The main problem the paint system. With Shackleton’s hull the was not having an adequate paint system. ICCP continued to be ineffective simply Cathodic protection works best when the because there was no complete paint system hull is undamaged and has a complete and therefore the ICCP system produced paint system covering the hull, unlike in eddy currents around the hull, which resulted Shackleton’s case. Cathodic protection as in the ICCP continually tripping, rendering
Ecospeed application to RRS Ernest Shackleton’s hull in Denmark in 2009.
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Hull Protection for Ice-going Vessels Part VI: Case Studies - Ecospeed/Ecoshield
the system inoperative most of the time. specialists there to check the condition of the Once we knew what type of paint system we hull paint were amazed. After two seasons of were looking for, we checked into its battering its way through ice up to 2.5 meters compatibility with the cathodic system and thick with a high content of gravel and realized that the actual paint system would volcanic lava adding to its abrasiveness, act as a dielectric, so we’ve gone to 2000 the hull coating was virtually intact and microns around the anodes.” undamaged. This was in strong contrast to In 2009, the Shackleton was dry-docked the Shackleton’s previous drydockings, when in Denmark prior to its annual trek to the almost the entire hull was practically stripped Antarctic. The hull was grit blasted and two to bare, unprotected steel. coats of Ecospeed were applied, to a total The condition of the paint was carefully DFT of 1000 µm. The areas around the inspected. A professional, independent paint anodes were given a thicker coating of 2000 inspector took dry film thickness measure- µm as a means of ensuring maximum ments around the hull and found the DFT to efficiency of the ship’s ICCP. The rudder was be around 970-1000 microns on average. not coated at that time. Nor was the area Very little thickness had been lost. Some above the waterline. minor mechanical damage had occurred to After two seasons in the ice, the the coating but this amounted to some chips Shackleton was drydocked again in Den- and scrapes totaling less than 0.1% of the mark; the superintendent, engineers and paint total surface area. Compared to the virtual
Shackleton’s hull after two seasons in heavy ice. The coating is virtually intact with a few very minor scrapes and scratches (bottom right). Note that the boot top area above the water line and the rudder were not coated with Ecospeed in 2009 when the rest of the hull was converted to Ecospeed. They continued with the original coating. Thus the damage to the areas not protected with Ecospeed is quite severe. This omission was rectified during the 2011 docking.
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Hull Protection for Ice-going Vessels Part VI: Case Studies - Ecospeed/Ecoshield
total removal of all the paint which the crew in particular that there was negligible damage “All of us there of Shackleton had become used to before the at the bows, merely some scratch marks. commented on application of Ecospeed, the damage was None of us there would have predicted this. I the condition of the hull and in negligible and easily repaired. Only very then jokingly asked the question, ‘Are you particular that minor touch-ups were required in drydock. sure you’ve taken this ship to the ice?’” there was negli- Stephen Lee, then Senior Marine Engin- According to Stephen Lee, the crew of the gible damage at eer for British Antarctic Survey, the BAS’s Shackleton reported that they had been push- the bows, merely equivalent of a Technical Superintendent, ing into 2 - 2.5 meter thick ice, “...and it’s just some scratch and the Antarctic Marine Engineering (AME) not touched it – just not touched it at all.” marks. None of department were instrumental in the initial It was seeing the results after two seasons us there would research which led to replacing the under- in the ice that led BAS to go up another level have predicted water hull coating in 2009. He recalls the and have Ecospeed applied to the boot top this. I then jokingly asked reaction of those present when the Ernest area above the waterline so that it covers all the question, ‘Are Shackleton was first pulled out of the water at the ice belt where mechanical damage you sure you’ve Frederikshaven drydock in early 2011. “The normally occurs. The rudder was coated with taken this ship biggest thing was the surprise at seeing the Ecoshield during the 2011 drydocking so that to the ice?’” areas where you’d expect it to have taken a it too could benefit from the same protection lot of damage...when she first came out of the as the hull. water and onto the blocks it was a complete Two more seasons in the ice showed the shock to all those present. All of us there coating to still be in excellent condition. commented on the condition of the hull and When the ship was dry-docked in 2013, the
During the 2011 dry-docking the area above the water line was coated with Ecospeed since it is an area much affected by ice abrasion and subject to damage. The rudder was coated with Ecoshield as it had not been repainted when the rest of the hull was painted in 2009.
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Hull Protection for Ice-going Vessels Part VI: Case Studies - Ecospeed/Ecoshield
amount of repair work due to mechanical damage was again minimal. The ship had been cleaned inexpertly between dryockings so that, even though the barnacles were removed, the plates where the tenacious crustaceans had been attached were not cleaned off. Ecospeed is strong enough to withstand very aggressive cleaning if needed without suffering any damage. The barnacle plates would not wash off with pressure
washing but were subsequently removed The hull coating on the Shackleton after four seasons with standardly executed in-water cleaning in heavy ice is still in excellent condition, in strong contrast to how the hull looked after even a single leaving the coating in pristine condition. season in ice with the previous coating system.
BAS’s RRS James Clark Ross in typical Antarctic conditions (top), state of hull after a season in the ice with industry standard specialized ice coating (above left) and newly coated with Ecospeed in 2014, ready for relaunching.
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Hull Protection for Ice-going Vessels Part VI: Case Studies - Ecospeed/Ecoshield
Five years of continued success with gement (ISM) and International Ship and Ecospeed on Shackleton led BAS to switch in Port Facility Security (ISPS) certification. 2014 to the same coating for their advanced Until 2005, all those ships trading in ice in polar research ship, RRS James Clark Ross. the Baltic region went through a cycle of having all their underwater hull paint scraped Case Study 2: Case Study 2: Baltic trading – off by the ice each winter and having to Baltic trading – Interscan Cargo fleet drydock to repaint every spring. The paint Interscan Cargo Interscan Schiffahrt is a family owned used was a standard epoxy coating. Fleet. shipping company based in Hamburg, In 2005 the then superintendent engineer Germany. Founded in 1973, Interscan has a decided to test the environmental and fuel fleet of 23 container and multipurpose cargo saving benefits of a then novel, environmen- ships ranging in size from 1,723 to 11,800 tally benign, hard, glassflake reinforced TDW. The larger container ships (6,288 surface treated composite (STC) coating TDW Karin, 8,201 TDW Paphos, Pandora, system, Ecospeed. MV Patriot was the first Pioneer, and 11,800 TDW Elena, Pauline, ship coated. The Patriot was in need of a full Colleen) are chartered worldwide. The reblast at the time due to the build-up of smaller vessels, up to 3,500 tonnes, trade in multiple layers of epoxy, so the time was northern Europe, generally in the Baltic, right to prepare the hull fully and apply either on time charter or operated directly Ecospeed. The Patriot is an 82.3 m LOA, by Interscan. All Interscan owned or oper- 12.5 m beam, 3000 DWT, ice class ated vessels carry International Safety Mana- E2/Finnish 1B general cargo vessel with a
MV Patriot before Ecospeed (top) showing the condition of the hull after each year of trading in ice using a conventional epoxy coating. This type of coating hd to be replaced annually after being virtually entirely removed during the winter. The hull was grit blasted (bottom left) and then given two coats of Ecospeed to a DFT of 1000 µm.
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Hull Protection for Ice-going Vessels Part VI: Case Studies - Ecospeed/Ecoshield
4.95 m draft and a design speed of 11.5 knots. Seven years after Ecospeed was applied In June 2005 in drydock in Klaipeda, Michael Tensing, in charge of Interscan’s Lithuania, the underwater hull of Interscan’s charter operations, said, “Now we are in MV Patriot was blasted down to nearly white 2012, she was here recently and the paint still steel and was then given two coats of the looks good. That’s the best advertisement STC, each about 500 µm DFT. you can have. For sure you don’t have to do Two other Interscan vessels were recoated that much to the paint. It’s only a bucket of in the following two years. The first was the paint for touch-ups, just cosmetics at the Karin, a 6,288 DWT, 100 m LOA ice class anchor or if you have mechanical damage or E3/Finnish 1A general cargo vessel. The sec- something.” As he points out, there really is ond was the Phantom, the 3,220 DWT 82 m, no other coating that could stand up to seven ice class E3/Finnish 1A general cargo vessel. years of trading in ice and still remain intact The Patriot was docked in November and not in any need of repainting or repair 2006 and after a year of trading in ice it was beyond very minor touch-ups. found that there was virtually no damage The success with the first three ships led whatsoever to the coating, in strong contrast to the further application of Ecospeed to four to Interscan’s previous experience with newbuilds in 2008 and 2009 in Gdansk, underwater hull coatings. Poland: the Paivi, February 2008, the Tim, Docked again in 2010, the coating was June 2008, the Pernille, October 2008 and still found to be in excellent condition and the Widor, January 2009. All these ships are needing almost no repair or touch-up. in the 3,000 - 3,500 DWT range, all ice class
MV Patriot after the first year of trading in ice with Ecospeed on the hull. The coating is virtually undamaged.
MV Patriot again in drydock after five years of trading in Baltic ice with Ecospeed on the hull. Minor mechanical damage requiring only very small touch-ups.
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Hull Protection for Ice-going Vessels Part VI: Case Studies - Ecospeed/Ecoshield
MV Paivi ready for launching, with Ecospeed on the hull.
E1, 2 or 3/Finnish 1A or 1B, all just over 82 exceeded for the first three vessels and will m LOA general cargo vessels. soon have been reached for all seven. So far All these ships were coated with the STC all the ships have kept their coating in at newbuild stage which is the ideal time to excellent condition. apply the coating, giving Interscan a total of The Patriot and the Karin have both had seven ships using Ecospeed on their in-water cleaning since the coating was underwater hull. applied. In the case of the Baltic, very little Michael Tensing who ultimately took the fouling is seen to attach and this is cleaned decision to apply Ecospeed to the Interscan off when the ship sails in ice in winter. The ships, has no regrets about his decision: “We Karin was trading in tropical waters, how- had a special survey at Frederikshaven on the ever, and the hull became quite badly fouled, Phantom, 3,000 tonner, last year after the as is expected with a non-toxic coating. She winter. I can tell you that was quite a surprise was allowed to go too long without cleaning to the shipyard at Frederikshaven. We were and lost 3 knots. The hull was eventually the worst client the shipyard ever had! All cleaned in Trinidad and she immediately that was required was simply cleaning. The went back to her design speed of 15 knots. paint job consisted only of one bucket for “To my mind anyway another major touch-ups. To my mind, for the Baltic it’s the benefit is that when you go into drydock you best product I have ever seen.” That was after don’t have to rely on the weather any more four years of trading in ice every winter. which sometimes holds you in the dock,” When the first Ecospeed application was says Michael Tensing. “If it’s raining for two done in 2005, Interscan crunched some weeks or so then you cannot leave due only numbers and worked out that if the Ecospeed to this point of repainting, because you coating lasted more than 3.8 years without completed all the other work. It makes less needing replacement, the company would than no sense. From that respect alone I have made the payback and be making would always do it again.” money. That time period has been greatly
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Hull Protection for Ice-going Vessels Part VII: Conclusion Part VII: Conclusion
hen considering the best possible may or may not bear out in the real world. Wprotection for the hull and running The real test is when the hull meets the ice gear of an ice-going vessel, there are a and, not only that, when the hull continues to number of factors which must be taken meet the ice over a period of years. Then the into consideration, including tough true picture emerges. corrosion protection, low friction, longev- Ecospeed has been tested and proven to ity, ease of application, toxicity and others. outlast and remain smoother than even These have been well covered above. leading, industry standard certified ice coatings when used in the harshest of Specifications and claims made on paper environments.
To find out more about Ecospeed, visit the following websites:
www.ecospeed.be www.ecospeed.us
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