Some Basic Information
about Sacrificial Anodes and Boats
Cont'd:
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Types of Anodes
The main anode
types are described below. The majority of these anodes are made from zinc.
Anodes for the corrosion-prone sterndrives and outboards should be made from
aluminum. Zinc will not fully protect these units!
Shaft
Clamped to the propeller
shaft – usually made in two halves.
Usually made from zinc. Performance Metals is the only company supplying these
in aluminum.
Rudder/Trim Tab
Round or streamlined in shape.
Bolted in two halves through the rudder or trim tab.
Hull
Larger rectangular anodes bolted to the hull. These provide general protection
for the boat through the grounding system. Zinc versions should NOT be used with
sterndrive boats, otherwise the aluminum anodes on the sterndrive protect the
zinc hull anode. Performance Metals offers aluminum versions to overcome this
problem.
Engine
Screwed into the engine to protect internal cooling system parts from corrosion.
They are always made from zinc, which is quite acceptable.
An example of a set of anodes for a MerCruiser Bravo unit is shown below:
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