Help ! Coating on Prop Shaft

[99Chances]

When I hauled my boat this fall (Lake Ontario - fresh water) I had a sandy coating on my shaft and prop. (See pictures). Can anyone please tell me what causes this ? It rubs off easily and leaves no apparent damage. No one else at our club has it. Someone suggested electrolysis but does electrolysis attract sand ? There is no pitting. I have slid the shaft back an inch and there is nothing in the cutlass bearing. This is the second year in a row.
Help. Please

[99Chances]

When I hauled my boat this fall (Lake Ontario - fresh water) I had a sandy coating on my shaft and prop. (See pictures). Can anyone please tell me what causes this ? It rubs off easily and leaves no apparent damage. No one else at our club has it. Someone suggested electrolysis but does electrolysis attract sand ? There is no pitting. I have slid the shaft back an inch and there is nothing in the cutlass bearing. This is the second year in a row.
Help. Please

[zeehag]

looks like dried marine slime.

[Sailor g]

From what I remember from growing up in the area it might be snow! Could it be calcium or other mineral build up? Lots of minerals in the water around there?

[99Chances]

Originally Posted by zeehag

looks like dried marine slime.

Right. That is what it looks like except when dry it is a sandy substance. And none of the other 120 boats have it. I'm afraid it is working its way up into to my dripless bearing.

[zeehag]

do you keep your boat in exactly the same place the others do?

[fstbttms]

It is scale deposited by your anodes as they deplete.

[fstbttms]

http://www.cruisersforum.com/forums/...tml#post813937

[99Chances]

The boat is kept in an assigned slip at a yacht club. No other boats have this deposit.
I know what it is; it's a gritty, sandy coating.
What I am looking for is to find out what is causing it; on only my shaft and prop.

[GordMay]

Greetings and welcome aboard the CF, 99Chances.

As fstbttms notes, it’s the result of the electrolytic corrosion of your zinc anode.

[99Chances]

I believe you are right. Thanks.
Now I need to find out why me and no one else?
I've had the boat batteries (cable, isolater,fuses etc.) rewired, a new charger and off switches. Could there be a problem there?
The guy who did the work is an electrical engineer and is meticulous. He tested for stray current. My anodes don't seem to be disappearing any faster than anyone elses.
And they don't get the sandy slime!

[fstbttms]

This is not indicative of a problem and is a very common occurance. I wouldn't waste another second worrying about it.

[99Chances]

OK. Thanks Fstbttms.
The only reason I was even concerned was that the same sandy slime appeared to be getting to my Lasdrop dripless bearing and causing it to leak. Once wiped clen the drip would stop.
Just annoying. That's all. Thanks for your help. Appreciated.

[SabreKai]

Not to worry mate, you aren't the only one. I'm at the bottom of Kipling Avenue at Lake Shore Yacht Club in Etobicoke, and I have the same stuff on my shaft as well. It comes off easily and there is no damage to the shaft.

As a matter of fact I pulled my shaft yesterday and between the gritty scale, slopped over bottom paint and some epoxy and other gunk, the only clean spots are where the prop was pulled, the area inside the cutless and the area under the stuffing box packing. Yuck.