Permanent Solution For Rudder Cavitation Damage

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  • Seaspan has, to date, applied Ecoshield to rudders and other running gear on over 65 vessels in their fleet.
  • Over the last several years, the containership industry has focused on maximizing economies of scale by building larger and more efficient ships.
  • Ecoshield has a companion product, Ecofix, designed to fill pitted and corroded steel and other materials easily, quickly and smoothly prior to the application of Ecoshield.

Seaspan finds a permanent solution for rudder cavitation damage across its fleet of container ships. An interview with Mr. Emilian Jianu, Coating Performance Specialist for Seaspan, says an article published on subsea industries website. 

Seaspan finds permanent solution

Seaspan has, to date, applied Ecoshield to rudders and other running gear on over 65 vessels in their fleet with such success that they plan to continue using the specialized protective coating on newbuilds and on existing vessels. 

Subsea Industries asked Mr. Emilian Jianu, who is in charge of all paint selection and application for Seaspan, for his insight and experience with Ecoshield.

Seaspan is the largest independent owner of containerships in the world, with twice the capacity of their next competitor, and the third largest owner overall. The company has grown steadily since its first ship was delivered in 2001, following a successful strategy of signing long-term chartering contracts with strong liner companies in tandem with shipbuilding contracts. 

Seaspan has built lasting partnerships with a diverse, best-in-class group of charterers, including COSCO Shipping, Hapag-Lloyd, Maersk, ONE, Yang Ming, MSC, CMA CGM and others. The company now has 112 ships in service with newbuilds being delivered regularly.

Shipbuilding quality

Seaspan’s ships are built to the highest quality standards at shipyards such as Samsung Heavy Industries (SHI) and Hyundai Heavy Industries (HHI) in South Korea, Jiangsu Yangzijiang Shipyards (YZJ) in China and CSBC Corporation (CSBC) in Taiwan.

Over the last several years, the containership industry has focused on maximizing economies of scale by building larger and more efficient ships. Responding to industry demand, Seaspan’s 10,000 and 14,000 TEU SAVER vessel series incorporate the latest technological and environmental advancements while maintaining their commitment to quality: “We use only the finest manufacturing partners in the construction of our vessels,” is one of the company’s strengths.

According to Seaspan, “Recent ship modification projects carried out in drydock make our vessels more useful and cost-competitive for customers.”

Rudders and running gear

Among these modifications has been the ongoing protection of the vessels’ rudders and running gear with Ecoshield, one by one as they come into drydock, as well as applying this permanent solution to recent newbuilds.

Ecoshield, from Subsea Industries, is an extremely tough, resin-based, glass platelet composite protection for steel, aluminum, and GRP, which puts an end to cavitation damage and corrosion on the parts of the ship such as the rudders, nozzles, thruster tunnels and other running gear, which are most prone to these effects. Applied once, Ecoshield is designed to last the life of the ship with only minor touch-ups required in drydock in the case of mechanical damage.

Emilian Jianu – Seaspan Coating Performance Specialist

We spoke to Emilian Jianu, Coating Performance Specialist for Seaspan, who is in charge of everything to do with marine paint for the Seaspan fleet. Mr. Jianu began his career as a seaman and went on to become a paint inspector (NACE 3 and FROSIO 3). For many years Mr. Jianu oversaw painting on newbuilds and on ships in drydock for Seaspan. 

He therefore has a practical view of ships, their construction and maintenance and the coatings that are used to protect them from the harsh sea environment, and a great deal of experience in this field. His duties have expanded to include Paint Specification Plan Approval at New Building and Dry Docking, as well as paint selection and application.

Serious rudder cavitation damage

“I encountered Ecoshield many years ago,” Mr. Jianu recalls. “I was contacted by our top management. They had heard about Ecospeed at that time and asked me to research it. We were then interested in repair of the rudder blades of the ships in drydock.”

Recalling the extent of the problems that Seaspan was encountering before they began using Ecoshield, Mr. Jianu says, “Most of our problem was with really huge cavitation damage. Huge! To the point of completely penetrated steel, making a hole so the rudder would even fill up with water. So when it came to drydock, we were not just blasting and painting and letting the ship go. It was necessary to replace the steel plate.  You can imagine the delays. There was a plan for drydock with a calculation of the number of days off-charter. 

Then suddenly we see the state of the rudder, and realize we have to remove many square meters of steel plate and weld in replacement steel. It created problems with delivering the ship back to the charterer in time. In those days, drydock was normally 10-12 days. In some circumstances we had to delay another 1-2 days just because of the rudder damage.”

The company was ready to test Ecoshield to see if it would help.

Ecoshield in 2010

The first ship to have its rudder protected with Ecoshield was the container ship Seaspan Vancouver in January 2010, followed closely by seven other vessels, all of which received the same treatment in the same month. “Of course, we were following the progress of the first few ships very closely during underwater surveys to see what was going on,” Mr. Jianu continues. “The results were quite amazing.”

“Then at the first drydock we were able to see that the coating was completely intact and there were no signs of the damage that we had grown so used to and were trying to solve,” he continues. “Since then, our company maintained a cooperation with Subsea Industries and Hydrex [sister company that handles underwater ship repair.]”

New Build application

“Later, in 2012, when our company started a huge project here in China with 10,400 TEU ships, we decided to apply Ecoshield on the rudder blade and the energy saving device, Becker Twisted Fins, at newbuild,” Mr. Jianu continues. “We also applied it to the scrubber area of some vessels as well as the outlet pipes. Due to the product quality, we were very satisfied with Ecoshield.”

At time of writing, Seaspan has applied Ecoshield on a total of 66 vessels. On all of these the rudder has been protected. Additionally, many of them have had the same treatment on twisted fins, nozzles and thruster tunnels and on the scrubber outlet area. The highly corrosive chemicals emitted by the scrubber make short work of conventional coatings and begin to corrode the steel. Ecoshield and Ecospeed (a sister product to Ecoshield, usually used to coat the entire hull) are not affected.

Seaspan has already contracted with Subsea Industries for 13 more ships. Seven of these are for rudder, twisted fins, thruster tunnel and scrubber area applications and the other six are for the scrubber outlets on ships that have not previously had this area properly protected. 

For the scrubber area, usually Ecospeed is sufficient to offer the protection required as it has the same chemical corrosion resistance as Ecoshield. The latter is designed primarily to withstand the additional forces of cavitation.

Mr. Jianu explains, “Our company point of view is that we try to implement Ecoshield on each of our very large number of ships, on the same areas: bow thruster tunnel, scrubber overboard outlet pipes, energy saving device or BTF, and rudder blade. Different shipyards want to use other kinds of paints, so when you upgrade the product, as with Ecoshield, everything is carried out at extra cost. The fact that our company is willing to pay that extra cost shows how much we value the performance of this product.”

Seaspan’s Coating Performance Specialist recalls that the company had previously tried a silicone coating from a well-known paint manufacturer, but the results were not really satisfactory. They also tried stainless steel plates, especially on areas that were heavily affected by cavitation. The plates themselves worked but then the welds were suffering from the cavitation damage. And the stainless steel was very expensive. During his experience in another project, Mr. Jianu has also tried another product, but it was very difficult to apply, requiring a special gun and equipment for application that is not available worldwide and is expensive. And after application the surface was not smooth and had to be ground smooth before the next coating was applied. “It cannot achieve the performance of Ecoshield,” concludes Mr. Jianu.

Ecoshield has a companion product, Ecofix, designed to fill pitted and corroded steel and other materials easily, quickly and smoothly prior to the application of Ecoshield, where needed. Mr. Jianu has had good experience with this product as well. “It cures quickly, can easily be made smooth, zero level, and of course it is compatible with Ecoshield.”

Subsea Industries How easy is Ecoshield to apply? 

“Ecoshield is easy to apply as long as all the manufacturer’s instructions are followed exactly – if you prepare well and if the shipyard listens and follows all the instructions. We also have a second pump, hose and gun as standby, in case anything happens with the previous pump.”

“At newbuilding it is easier to follow the instructions and we usually allow extra time between coats. When ships are in drydock everything is under pressure, and in some situations, we have followed the minimum overcoat time required by Subsea. I can say that after five years we have never seen any bad consequences. That was something which gave us certainty to use this product. We found we can follow the Technical Data Sheet exactly per the maker’s requirements.”

How is Ecoshield performing over time?

“Last year I had a chance to see the rudders that were coated in 2012 or 2013,” says Mr. Jianu. “After high pressure washing we saw that no repair of Ecoshield was needed. In some cases on the whole rudder blade there was perhaps 15cm of damage, clearly from mechanical impact. I have seen two or three ships after 10 years and it was the same story. Follow the instructions, prepare well before starting the job, and you won’t have any unpleasant surprises, not in the near future or even the distant future.”

How has Ecoshield affected time in drydock? 

“So far we have mainly applied Ecoshield to the rudder blade and bow thruster tunnel which are usually left till the end of the drydocking,” says Mr. Jianu. “Compared to conventional coatings, due to not needing repairs, and due to curing times and other factors, we save somewhere between one and three days in drydock per ship.”

Future plans

“We are planning to apply Ecoshield on the rudder blade, bow thruster tunnel, energy saver and also the scrubber outlet on all our upcoming newbuilds,” says Mr. Jianu.

Any thoughts on the Subsea Industries service? “My contact has been with the office in Belgium and the service has always been fast and helpful and we are satisfied with it,” he said. “Also the representative in China, Raul Yu, is an amazing guy. Not only professional but also a very hard worker.”

Conclusions

“As a long time field inspector I am not only looking for quality of product. I am looking for applicability and quality. With Ecoshield I have that. I have had a situation where another company’s product was not bad, but due to using two or three kinds of accelerators, the coating failed on the spot. This is a terrible situation – to have to remove the coating and start all over again. I have never had this situation with Ecoshield.”

“The fact that we keep using Ecoshield means we are satisfied. Sometimes we have to fight with the shipyard because they want us to use the product of some manufacturer, they have an agreement with. Even though they are pushing these other products, we insist on Ecoshield. You can come to your own conclusions.  The product is its own best advertising.”

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Source: subsea industries