PRODUCT OVERVIEW GALVANIC CORROSION CORROSION CONTROL Galvanic corrosion results whenever two or more dissimilar metals (like those found on the sail-drive) are submerged in a conductive solution, such as saltwater, polluted water or water with a high mineral content because a chemical reaction takes place causing electrical current to flow between the metals. The electrical current flow causes the metal that is most chemically active, or anodic, to erode. If not controlled, galvanic corrosion may corrode Sail-Drive components.
It is the boat designer’s responsibility and/or the re-powering engineer’s responsibility to design the proper systems and equipment to control and reduce the possibility of galvanic corrosion. However, it is essential that the owner/ operator frequently monitor the anodes for wear, inspect the sail-drive for corrosion and replace the anodes often enough to provide a sacrificial surface for the electrical current to attack. Galvanic isolators and isolation transformers are also available from the aftermarket (not supplied by Yanmar).
The Galvanic isolator is a device that is installed in series with the (AC) grounding (GREEN) conductor of the shore-power cable to effectively block low-voltage DC galvanic current flow but permit the passage of alternating current (AC) * . The rate of corrosion depends on numerous factors, such as: the number, size and location of sacrificial anodes on the sail-drive and vessel; the marina environment, such as stray current in the water, fresh or salt water and use and isolation of shore power; improper application of marine paint or antifouling paint; failure to repaint damaged areas; and how the vessel is bonded.
Please check with the boat builder, dealer or other professional to determine if your vessel and/or Sail-Drive is adequately protected from galvanic corrosion. NOTICE: The anode of the Sail-Drive is only calculated for the Sail-Drive. Changing the material of the propeller may require additional anodes to be installed on the Sail- Drive. * “The Boatowner's Guide to Corrosion”, by Everett Collier. SD Operation Manual 11 © 2009 Yanmar Marine International