Is this Galvanic corrosion?

[gmakhs]

Hello ,
Recently I find this deposit around and near my shaft seal , normally the issue is bigger but I did the mistake to clean before the photo .
I tasted it and its not salty , my mind goes to galvanic corrosion since I am in the marina .
It happened during a period I was away from the boat ,so the boat wasn't connected to the shore power .
This white staff feels more like a powder and not like salt.

[Alan Mighty]

Originally Posted by gmakhs

This white staff feels more like a powder and not like salt.

My guess is cyrstals of hydrated calcium magnesium carbonate. That's the first chemical to precipitate out of seawater as the H2O evaporates. Sodium chloride only crystalises when 75% of the H2O has gone.

See more at: http://www.cruisersforum.com/forums/...ml#post2562827

Question is: if you rotate the prop shaft by hand, do you feel any resistance?

[Helia 44]

Yea,
What He said... Above...

That "Packing Gland" in the old language is adjustable and you tighten it down tow a drip only a few times a minute when running, just to cool and lube the packing material around the shaft... Sitting in the marina it has just gummed up and stopped leaking, and that is not galvanic corrosion but partially dried up sea water IMO..

Helia 44...

[gmakhs]

Thank you , i plan to change it at this year's haul out , the boat is sitting in the marina and won't move for the next 3 months when I plan to take it out of the water .