ELECTROLYSIS AND GALVANIC PROTECTION
PAGE 32
Salt water allows electric current to flow from
anodic to cathodic material. For any two metals
from two components, their relative positions in
the galvanic rating table, will determine which
loses material (the anode) and which remains
largely undisturbed (the cathode). The distance
between the two metals on the galvanic table
determines the rate of wear. Thus a sacrificial
zinc anode is often fitted to the underwater
area of a boat to attract any destructive cur-
rents away from bronze or steel propeller
shafts, for example.
It is not enough to know that your boat does
not suffer from electrolysis; a newcomer in the
adjacent marina berth may start a too-friendly
association with metal components on it. An
easy place to fit an anode is on the propeller
shaft, or covering the propeller nut. The anode
should not be painted; this would render it inef-
fective.
To prevent electrolysis in seawater, the differ-
ence between the voltages of the two adjacent
metals should not exceed 0.20 V. For example,
zinc and carbon steel used together risk corro-
sion, while lead and active stainless steel are
compatible. Metals with a high voltage corrode
faster and need a larger area to diffuse the elec-
trochemical reaction.
Summary of Contents for HUNTER 25
Page 55: ...Power Squadron recommendations for maintenance and safe boating PAGE 13A 11...
Page 56: ...Local sailing club or marina s recommendations for maintenance and up keep PAGE 13A 12...
Page 58: ...Spare parts list PAGE 13A 14...
Page 59: ...Dates of practice drills and onboard safety inspections PAGE 13A 15...
Page 60: ...MY PERSONAL PREFERENCES FOR MAINTENANCE ITEMS SAFETY GEAR PAGE 13A 16...
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