Paint protects against rudder cavitation damage

Among these are container vessels, bulk carriers and oil tankers, all of which were given the Ecospeed coating to protect against rudder cavitation and mechanical damage.

After cavitation damage had appeared on the rudders of several container vessels, the owner decided to have the rudders coated to prevent similar damage from occurring again. The rudders of these sister vessels were coated in Dubai and Shanghai where another customer also had Ecospeed applied on the rudder of his vessel. Further applications were performed in Rotterdam and Skaramanga, Greece.

After the required welding repairs were performed the cavitation pitting that was present on the rudders was filled with Ecospeed to regain a smooth surface. Once this was done the required two layers of the coating were applied, effectively providing the rudders with an impenetrable protective layer.

According to Ecospeed, a great deal of effort goes into the design and manufacturing of rudders, therefore they deserve adequate protection that will remain intact for the lifetime of the vessel. The company says its coating is both flexible and tough. It provides the ship with an impenetrable protective layer while its flexibility enables absorption of the forces that are produced by cavitation, thereby preventing the damage normally caused by this phenomenon.

Tests are said to have confirmed that Ecospeed performs well under severe cavitation. These flow chamber tests were divided into six stages during which the coating was exposed to an increasing pressure drop, leading to a growing cavitation force. After the last stage no erosion was present on the test patch coated with Ecospeed. The tests were sponsored by the French MOD/DGA and were carried out by DCNS at LEGI in Grenoble.

The company says that with the right planning, grit blasting and application of the two required layers can be performed in just one day.

Ecospeed is claimed to remain intact for the lifetime of the vessel and is guaranteed for ten years. The rudder will not have to be repainted during future drydockings and extensive repairs will not be needed. Planning the maintenance of the vessel’s stern area therefore becomes much easier. The smoothness attained by the coating is also said to provide optimum hydrodynamic conditions for rudders to operate at maximum efficiency. The ship’s performance remains stable and the owner’s investment is secured.