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7.3.6 Anodes
General points
- The sacrificial anodes protect the boat's metal components from electrolysis.
- A sacrificial anode is an expendable part, that by eroding (oxydisation), allows the current to
flow. The anodes used are made of a metal that is more readily reductive than the metal they
are protecting.
- On a new boat, all the underwater metallic components try to be at the same electric
potential, which leads to the rapid deterioration of the anodes in the first few weeks in the water.
- You can put several anodes on the hull.
Maintenance
- At least 2 times a year, check the corrosion on all of the anodes. Change the anode if
necessary (Before it lost 50% of its weight).
- Use the appropriate anodes for the cruising area: fresh water/magnesium anodes ; Sea
water/zinc anodes.
- When the boat is stored at a dry dock, the corrosion protection is not as effective due to
oxidation of the anodes: even the new anodes oxidize the surface. Before returning the boat
into the water, clean the anodes.
Cleaning anodes
- Use sandpaper. Do not use metal brushes or steel tools to clean the boat, it may damage
the galvanic protection.
Replacing the anodes
- The anodes are fastened with screws and nuts. First, remove the screws and nuts that hold
the anode, then clean the contact surface. Press the new anode to obtain a good electrical
contact.
- Never cover the anodes in antifoul.
- During the first few weeks that the boat is in the water, check the anodes
and if necessary replace them: they erode very rapidly during this period.
7
AC SYSTEM
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