Just some facts on aluminum corrosion and why boats have many aluminum parts.
Aluminum has a much greater resistance to corrosion than does iron or steel. A steel ship must be protected from the salt water or the corrosion of the steel is destructively rapid. Many ships are built of aluminum and, while they are painted for protection primarily against the growth of marine life, they are, on the whole, more resistant than steel to the action of salt water. Currently many large ships and tankers are built of aluminum. The Coast Guard is replacing its steel buoys with aluminum buoys. However, aluminum, like iron or steel, should be protected if it is exposed to salt water and salt air. The normal paint which a USEM motor or component receives is ample for all but the most unusual conditions. Outboard and inboard stern driver units are aluminum and enjoy long service life.
Question: Why do some people still believe aluminum corrodes more than iron or steel?
Answer: Prejudice and/or lack of accurate information. The following is from "Kent's Handbook" on the "Corrosion of Iron Alloys", and under "The Mechanism of Corrosion".
"SURFACE FILMS - Clean metallic surfaces exposed to air quickly acquire a film of oxide, which, at ordinary temperature, is thin and invisible. At higher temperatures it is thick enough to give well known characteristic colors - rust. The nature and properties of the film depend upon the composition of the metal itself and its environment. Aluminum and stainless steel, for instance, owe their high durability to the formation of a continuous and permanent file that is stable under most conditions of exposure". In general terms, aluminum is more resistant to corrosion by most common materials and atmospheres than cast iron, and far more resistant to corrosion than is carbon steel.
The Hummer might be around longer than some posting on this board.
AmbergrisCaye.com 
