Zincs and the 'Hot' Marina

[Crazy Eight]

I had corrision problem that destroyed the nuts holding my starboard outdrive. At the end of six months in a salt water bay, the outdrive broke free and fractured the gimbal ring resulting in a $3,500 repair. My new mechanic swears the prior mechanic installed fresh water zincs as there was very little lose of material on the zincs. How can you distnguish between fresh and salt water zincs.

[hellosailor]

Fresh water zincs? Aren't those the ones that are sold next to the prop wash and striped paint in the chandlery?

[GordMay]

Fresh water zincs (sic: Anodes) are actually made from Aluminium or Magnesium alloys.
These are very "active", and care must be excercised when protecting aluminum outdrives.

When used in freshwater, a zinc anode forms a coating of zinc hydroxide, which passivates it.