The end of cavitation damage on running gear

Over the last few months a large number of vessels belonging to eight different owners received Ecoshield protection for their rudders, bow thruster (tunnels) and nozzles. The applications were carried out in shipyards in Turkey, the Netherlands, Singapore, Hong Kong and China on a wide range of ships. These included vehicle carriers, tankers, yachts and container ships. The running gear of all of these ships will be protected against cavitation and corrosion damage for the rest of their service lives.

Ecoshield offers permanent protection against cavitation damage for rudders. The coating protects the rudder for the service life of the ship without need for recoating or major repair. Ecoshield is also suitable for bulbous bows, stabilizer fins, nozzles and other underwater ship gear which needs special protection from corrosion.

Until now the problem of cavitation damage to rudders remained unsolved. This caused erosion, pitting and sometimes complete failure, necessitating very expensive repairs or replacement. The need for repairs to rudders, involving welding and resurfacing in drydock has been almost universal. The cost of rudder maintenance and the safety hazards connected with worn and failing rudders are out of proportion to the relatively small surface area involved. Efforts to solve this problem have taken the form of redesigning the rudder, changing its position relative to the propeller, trying various materials including stainless steel, metal facing the surface, cathodic protection and a variety of coatings. But the problem has persisted.

Groundbreaking protection

Ecoshield puts an end to these problems. The coating is a specifically reinforced version of the well-known Ecospeed non-toxic underwater ship hull coating which is designed for the entire underwater hull of any ship. Small but significant variations of the Ecospeed formula have been tested on rudders since 2002 with extraordinary results. Ships that were experiencing heavy cavitation damage to their rudders have seen no further cavitation damage erosion for over ten years and counting after application of Ecoshield. They show no sign that the coating will need replacement during the life of the ship.

Suited for newbuilds and existing vessels

Protection of the running gear of your ships is best begun at the newbuild phase. When a ship comes into drydock, maintenance of its stern area, especially cavitation and corrosion damage repair, can take a long time. There are strict procedures concerning blasting, painting, welding and propeller and stern tube seal work. Painting is then assigned to the end of the schedule. As a consequence it may be rushed or not done at all or else may prolong the stay in drydock. With Ecoshield this is avoided from day one.

The newbuild phase is the perfect time to apply Ecoshield. However, the coating can also be used to protect vessels that have been in service for some time and are already facing cavitation and corrosion damage. Such was the case with the rudders coated over the last months.

Ecoshield’s flexibility makes it easy to adapt the application schedule to the rest of the activities at the shipyard or drydock in a way which does not interfere with them. Overcoating time can be as short as three hours. This means that for smaller surfaces such as rudders or bow thrusters the two required coats can usually be applied in one single day.

Ecoshield insulates the rudder or other running gear and makes cathodic protection systems, including sacrificial anodes, unnecessary. This is evidenced by the very little wear on the anodes when a rudder coated with Ecoshield is inspected in drydock and by the fact that an impressed current can be turned right down with no ill effect.

Evidence of the success of the coating is the number of companies that began by coating one rudder experimentally and have ordered Ecoshield for the running gear on other ships after seeing the results in service. Most have plans to convert their entire fleet. Shipowners who have previously applied Ecoshield to rudders on ships in service are specifying the coating for the rudders and other underwater gear on their newbuilds.

Ecoshield comes with a ten year guarantee. It is the only coating known to fully protect a rudder from all cavitation damage.