ClimateRight CR-2550 El manual del propietario descargar pdf (Pagina 272)

Cosmetic Care & Maintenance

7-27

Typically electrons ﬂ ow from the anode (the aluminum drive unit),via

the external conducting path to the cathode (stainless steel propel-

ler). If there is a very large anode connected to a small cathode, the

anode will corrode very slowly. If a very large cathode is connected

to a small anode, the anode will corrode very quickly. Obviously, if

you do not control galvanic corrosion, over time the aluminum will

corrode away.

The ﬁ rst sign of galvanic corrosion is paint blistering (starting on

sharp edges) below the water line- a white powdery substance forms

on the exposed metal areas. As the corrosion advances, the exposed

metal will become deeply pitted as the metal is actually eaten away.

Another condition which will increase galvanic corrosion is the re-

moval or reduction in surface area of the sacriﬁ cial anodes. Never add

aftermarket products that are connected to the engine ground such as

stainless steel steering aids and trim planes.

Zinc connected to aluminum will form a corrosion cell but the alumi-

num (drive) becomes the cathode and the zinc (anode) corrodes.

Even though your boat may not have shore power aboard current

from nearby vessels with shore power can produce stray current gal-

vanic corrosion. Stray current corrosion occurs when metal with an

electrical current ﬂ owing into it is immersed in water that is grounded

(lake, ocean, pond). The current can leave the metal and ﬂ ow through

the water to ground. This will cause rapid corrosion of the metal at

the point where the current leaves.

When a vessel nearby is plugged into shore power, they can poten-

tially tie your aluminum drive unit to their boat via the green ground-

ing shore power lead. Your aluminum drive unit could be the receiving

end of a large galvanic cell (a battery) interconnected with nearby ves-

sels or even through the marina’s metal structures via their electricial

system.