The drydock affair simplified

Drydocking is necessary, evidently, for inspection purposes, replacement of certain parts and any necessary repair. In most cases, however, the time spent in drydock is substantially lengthened as a result of the replacement or repair of the hull coatings. The solution is very simple: Choosing the right type of coating system can drastically reduce the length of the visit.

Most of the time and effort spent in drydock goes to the maintenance or replacement of the coating system. This usually consists of five or six layers with application intervals of 24 hours in between. The required surface preparation alone will add several days to the visit. Three to seven days extra is not unusual. Adverse weather conditions will increase this number.

A substantial reduction of time and effort in drydock can be obtained by using a hard coating system like Ecospeed. Usually drydocking an Ecospeed ship can turn into a simple wash-and-go operation. This is due to the fact that the coating will withstand almost all impacts during its time at sea. Seawater, corrosion or marine fouling simply do not have an influence. The hull is usually in the same condition as it was when it was coated during newbuilding or the previous drydocking. The same goes for the rudder, bow thrusters and other running gear.

If no paintwork is required then it is obvious that the days in drydock can be more than halved. What this yields in terms of savings depends on the type and size of the ship. For a cruise ship fleet of 25 vessels this could result into 125-175 days saved per 2,5 year drydock interval. This   amounts to 500-700 days on a 10-year cycle. We have many cases in operation right now that prove this and we would be perfectly happy to discuss our technology with any interested party.

Corrosion simplified and solved

We are so used to corrosion on ships that no-one raises an eyebrow at the rust-stained hulls in any port or dock. It is, apparently, considered to be the way of things.


It is true that steel will rust. But with the knowledge and resources at our disposal we have long passed the point when we should have recognized that this is a problem, and solved it.

Corrosion on ships is rarely recognized as a failure of the coating, but that is precisely what it is. The first job of a hull coating is to prevent the gradual weakening and destruction of marine assets that is caused by corrosion. It remains a massive problem for shipping despite coating repairs every few years, eating up valuable days in drydock. Not only that, but current coating compounds also leak a million ton of toxic material into our oceans every year.

Corrosion is not some unavoidable fact of life. The basics of the subject have been well known for centuries, but they are worth reiterating. The iron in a steel hull is, effectively, trying to return to the state in which it was taken as an oxidised ore. Three things are needed for rust to form: metal, water, and oxygen. Energy, the galvanic difference between metals, stimulates the process, and impurities in the metal, seawater, water vapor, acids, salts, carbon dioxide and stresses hasten it.

While cathodic protection slows the corrosion on a ship, total prevention is only achieved by preventing metal, water and oxygen from coming into contact with eachother. That is the primary job of a coating. The problem is simply that most coatings fail poorly in that task.

One reason for their failure is the permeability of zinc primers, epoxies and antifouling coatings usually used. Water can get through and behind the layers of coating where it can start the corrosion process while accelerating it by causing coating delamination. This is the sequence of coating degradation which opens the door for further corrosion.

A second reason is the use of heavy metals in coating systems such as copper. These have a high galvanic differential with the steel of the hull. In practice we see copper-based coatings degrade very quickly – their difference in potential is the highest we encounter on ships. The fact that zinc, epoxy and antifouling, all of which have different surface tensions, are used together, further aggravates the problem.

Permeability, different surface tensions, poor adhesion and heavy metals are the four main factors that lead to an inferior protection on the ship hull.

It is not difficult to see that if a coating has no heavy metal content and therefore can avoid potential differential, is impermeable to water and achieves superior adhesion, the problem is solved. If the steel hull is isolated from its surroundings, then galvanic activity and corrosion are canceled.

Our range of coating systems has achieved this.

Observation over twenty years on hundreds of ships protected with our coating systems, reveals a distinct absence of hull corrosion on any of them. We do not find corrosion on these hulls.

With our glass-flake coating systems we have the solution. Their superior adhesion, impermeability and toughness fully isolate the steel hull. Even heavy corrosive environments in port or in seawater fail to touch the anodes or the steel surface of the hull. In fact, anodes become superfluous on an Ecospeed hull.

Environmentally our coatings are a vital solution because they contain no heavy metals, no zinc and no pesticides or other biocides. Extremely high concentrations of these elements are already found in the sediments around ports, estuaries and even far out at sea. It is clear that using them on ship hulls is not sustainable.

The subject of hull fouling is dealt with in a previous article – but it should be mentioned here that anti-fouling coatings have already caused one international marine catastrophe with the extensive use of TBT, and are creating further catastrophes if their use is continued. The attachment of marine organisms to ship hulls seems to be little affected by the currently available anti-fouling materials, but the marine environment suffers severely from their accumulating toxicity.

Simple mechanical removal of these organisms from a hard, non-toxic surface is the obvious and most workable solution, provided the coating is designed to withstand this.

We have seen more than 20,000 ships  over the last fifty years – after some time they all have corroded, rough, degraded and inefficient hulls.

An amazing discovery we frequently make is that, on inspection of ships coated with our systems, we never see corrosion of any significance, even when there has been small impact damage. Not after two years, not after five years, not even after ten years. This proves that with an inert coating there is no influence on the steel, even when exposed to seawater.

The conclusion is simple: the majority of the coating systems in general use today do not protect the hull sufficiently. They should be replaced with coatings that can do the job.

How ice-going vessels can benefit from using Ecospeed.

We have been coating ice-going ships for the last 16 years. The technical, economic and ecological results we have witnessed are nothing less than spectacular.


Technical

The first thing you look for in an ice-going coating is a resistance to the ice. The reason why Ecospeed is such a success in ice is because of the adhesion to the steel. In itself the coating is not flexible, but due to its superior adhesion the coating flexes with the steel. There is no delamination and no detachment from the substrate.

Economica
l

Ecospeed ships do not have to be recoated. Ice-breaking (and other) ships save an enormous time in drydock. Instead of twelve days you only have to spend four or five days in dock because only small touch-ups are required. These are very easy to do, even in bad weather and any repair done to an Ecospeed coating will have the same qualities and strength as the original layers. This is even the case if they have been applied 10 or 15 years before.

A combination of the corrugation of the coating and the absence of marine growth in ice results in a proven reduction of consumption. Depending on the size of the ship, the engines used and other specifications these fuel savings can go from 10%, 20% or even 30%.

The smoothness of the coating also provides for easier breaking of the ice. The ship slices through the ice because hull friction is substantially reduced.

We have been recognized as an abrasion resistant ice coating by Lloyd’s Register. Using Ecospeed allows the plate thickness to be reduced by 1 mm. Ships can be build with less material and will be less expensive to build and lighter to use.

Ecological


With Ecospeed on the underwater hull there is no loss of coating. There is no disbondment, no detachment and no delamination caused by ice impact. Our coating systems leave no paint behind. There is no spreading of anti-fouling toxic particles and heavy metals, because they are simply not used in our coating. Ships can safely be taken to the Polar regions without having a damaging effect on the environment or coloring the ice.

Because of the quality of the coating Ecospeed requires no use of anodes. As a result there is no loss of zinc materials in the Polar or other regions. No corrosion takes place on ships coated with Ecospeed.

When the cleaning effect of the ice is not sufficient all animal growth can be removed easily with intermediate underwater cleaning. There is no detrimental effect on the marine life. There is no chemical influence. The problem of biofouling is therefore completely handled. The animals are removed and left behind in their native environmental zone. They are not transported to another environmental zone. We promote this as a total solution because achieving this only depends on the cleaning of the ship.

Conclusion


We have well over a hundred applications of ice-going ships. RRS Ernest Shackleton and RRS James Clark Ross  of British Antarctic Survey, have been coated with our products with great and conclusive results. Our Ecospeed coating was also selected for the newbuild research vessel RRS Sir David Attenborough, the biggest commercial shipbuilding contract in Britain for 30 years.

Over a period of fifteen years these have shown that Ecospeed can withstand the impact of ice for many years. It is not a coating system that you get for one or two years, it is a system that you get for twenty years and longer.

The Matter of Biofouling

Recently there has been a lot of discussion about biofouling. A word coined to describe marine life attached to ship hulls, it is seen as a ship speed breaker, a destructive factor to hull coatings and a cause of alien invasive species. To call it fouling is in fact a misnomer. It is marine life and it was there first, long before any ship or boat had entered any water.

The situation with marine invasive species is twofold being carried around the globe in ballast tanks on the one hand and riding on the outside of ship hulls on the other.

In ballast tanks the problem comes down to any life that exists in water. From bacteria to larvae to small fish and anything in between. Because it is traveling in dark conditions with zinc anodes present, this problem is much smaller than the real problem posed by the ship hull.

Allegedly around 600-700 species are traveling on the outside of ship hulls. Six years ago we published a White Paper on the subject titled: Invasive Aquatic Species – A proposed alternative solution. In it we gave a summation of the problem and how to correctly deal with it. The basic viewpoint is simple: we do not want to handle this with a toxic solution. There are very good reasons for this.

A very negative and toxic influence is exercised on marine life traveling on the hulls. It is proven by various publications that animal life and algae are influenced by the many varied toxins in the coating. The continued toxic presence on and around the hull, from pesticides to heavy metals to pharmaceutical derivatives, have a detrimental effect.

By traveling on a toxic ship hull the animals become more resistant. In our white paper we called these gladiator species because they have become chemically stronger than the marine life of the different environmental zones they arrive in. The local populations are less adapted and give in to the newcomers. This alone is reason enough to look for other solutions.

Our viewpoint is that there is no such thing as a toxic solution for the mitigation of invasive species. As we do not know exactly what we are doing to marine life, we cannot see this as a responsible action. We have no idea how much and how many we are thus influencing. There is no control on the process.

What needs to be considered is the toughness and tenacity of marine life. Amongst the oldest species on this planet, they have developed an exceptional resistance to external factors and that does include chemicals and heavy metals.

With toxins we either kill the marine life or render it sick. This biomatter will then enter the food chain to a greater or lesser degree.

The situation thus created requires a lot more attention and a much closer look from all the players involved: authorities, scientists, technology developers, manufacturers and regulators.

From our side and as a group that has pioneered a totally non-toxic approach, we have firmly established that with our solution we have no influence whatsoever on marine life.

To achieve an environmentally safe solution for ship hulls, we have looked at how to safely wash ships before they leave port.

A full washdown of the ships is the best solution. It requires a system that allows to clean any size ship in less than an hour on a coating that will not emit particles.

Sister company  Hydrex (www.hydrex.be) is now working on underwater hull cleaning technology that will produce cleaning rates of 100.000 m² per hour or more. It does not require divers or visibility and can be used in a current.

This means that even the biggest ships can be cleaned in a very short time. They can be washed before they leave port and sail to a different environmental zone free of biofouling. When they arrive they can discharge and load again and when they leave they can be cleaned in the same fashion. During continued sailing, no marine growth is acquired on the hull as this only happens during stops.

This process also considerably optimizes the speed of the ships. Fuel consumption will be at its best attainable level and large fuel savings are thus achieved. These alone will pay for the effort many times over.

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