Help identifying white fluffy rust on keel bolts

[Andycbriggs]

Hi all,

I have rather badly rusted keel bolts and looking to clean them up or replace.

One in particular is quite bad and seems to be “shedding” rust and has an odd white crystal/fluffy ness to it.

I wondered if someone could help explain the process that is going on here, doesn’t seem to be happening to the others.

Pic attached.

Andy

[GordMay]

Greetings and welcome aboard the CF, Andy.

White rust is a white, chalky substance, that can form on the surface of zinc materials, like galvanized steel, when the zinc is exposed to hydrogen and oxygen. This combination creates a zinc hydroxide (as opposed to the iron oxide, which is the common form of rust). While it can form on any zinc material (like sacrificial anodes) or zinc-coated material, white rust is a frequent problem for galvanized steel, especially in wet conditions with inadequate air circulation (bilges?).