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The end of cavitation damage on running gear


In the last few months a large number of vessels belonging to seven different owners  received Ecoshield protection for their rudders, bow thruster (tunnels) and nozzles. The applications were carried out on a wide range of ships including several container vessels, ferries, oil tankers and a navy vessel. The running gear of these ships will be protected against cavitation and corrosion damage for the rest of their service lives. Rudders, thrusters, nozzles and other underwater running gear are exceptionally prone to corrosion and cavitation damage. Cavitation is caused by the spinning of propeller blades. If running gear is not given the proper protection against this the damage can be severe.

    

                                       Application of the first of two Ecoshield layers on a rudder.

This leads to expensive and time-consuming repairs in drydock at the least or malfunctioning of the running gear at worst. A rudder has been found missing in its entirety on more than a few occasions, unfortunately. This will have substantial financial consequences for a shipowner.

Ecoshield was designed to protect all running gear for the lifetime of the vessel. This coating system is applied only once. No repaint will be needed during future drydocking. Only small touch-ups to repair mechanical damage will be required.

Applying Ecoshield is a fast and easy to learn process. As a result an application is very flexible  and can easily be scheduled around the planning of the yard. Only two layers are required. The minimum overcoating time between these layers is only three hours. This means that most running gear can be coated in a single day.

Newbuild ships benefit the most from Ecoshield. Applying the coating during building means a vessel’s running gear will be protected from the moment the ship leaves the shipyard until the end of its service life. A shipowner will not have to worry about repainting during any of the scheduled dockings.

An existing ship can also be protected with Ecoshield. If for instance a rudder has already suffered corrosion damage, the coating can prevent any further damage from occurring. In such case Ecoshield can be used in combination with another product in the Subsea Industries family: Ecofix.Ecofix is a superior, tested and proven filler that restores the steel to its original shape with a smooth surface prior to recoating. Because it Uses the same basic resin, Ecoshield can be applied just one hour after the filler.


From one rudder to an entire fleet’s running gear

Since the original application, over 500 rudders have been coated on a wide variety of ships: cruise ships, cargo vessels, container carriers, ro-ro cargo ships, cable layers, dredgers, crude oil tankers, research vessels, ice-going ships and icebreakers, tugboats, reefers, passenger ferries, bulkers, navy vessels and others. These applications were performed in shipyards across the globe. Shipowners that started with a single rudder as a test have since then ordered the same protection for the running gear of their entire fleet. Several have included the coating in the newbuild specs to make sure cavitation and corrosion cannot touch the steel of their ship’s running gear. Even after years of service these owners are experiencing zero cavitation damage and failure.

 

 

 

  LMB-BML 2007 Webmaster & designer: Cmdt. André Jehaes - email andre.jehaes@lmb-bml.be