unsure about what causes this corrosion

[cyrano138]

I looked at a Cape Dory 25d yesterday. In the engine compartment there were four or five bronze through holes with seacocks. They all had this bluish green patina or corrosion or whatever this is. I'm trying to decide whether or not to make an offer and if so how much, and that will depend on how much of a project something like this would be.


The smaller seacock handles turned easily enough but I could not get the larger ones to turn and I didn't want to force it. The wood mounting blocks were a little rotten but I assume they're original and I guess that's not too surprising.



Do they need to be repaired or replaced?