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gmakhs 18-06-2018 17:43

Is this Galvanic corrosion?
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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 18-06-2018 18:35

Re: Is this Galvanic corrosion?

Originally Posted by gmakhs (Post 2654829)
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:

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

Helia 44 18-06-2018 19:24

Re: Is this Galvanic corrosion?
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 20-06-2018 07:01

Re: Is this Galvanic corrosion?
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 .

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