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-   -   barnacles on prop, shaft (http://www.sailnet.com/forums/gear-maintenance/59873-barnacles-prop-shaft.html)

pegasus1457 11-16-2009 04:24 PM

barnacles on prop, shaft
 
I neglected to protect the prop shaft with antifouling paint and now that the boat is on the hard, I see it is covered with barnacle skeletons.

I have knocked off as much as I can, but would like some advice on the best way to rid the shaft of what is left.

On/Off? Is it safe to use on bronze? How badly does it attack the cutlass bearing if I get a few drops in it?

Sandpaper?

thanks,
pegasus

JimsCAL 11-16-2009 04:35 PM

Scrape them off. Don't use ON&OFF as its a strong acid.

Vasco 11-16-2009 04:42 PM

Scrape and then buff with a wire wheel or one of those 3M wheels.

tager 11-16-2009 04:45 PM

Be careful. You don't want to have to get your prop balanced.

jjablonowski 11-16-2009 05:37 PM

Why NOT to paint your prop with bottom paint
 
Our friend Maine Sail says it better than I can:
Why Not To Paint Your Prop (with copper based paint) - SailboatOwners.com

TaylorC 11-16-2009 05:52 PM

I never see painted shafts, so I don't think you forgot to do anything. You should also have zinc collars on your shaft. Yeah - I get barnacles on my shaft also, I knock the big parts off with something hard like a scraper, and finish with scotch bright or a wire brush. They come off easier if you get them when they are wet, and don't let them dry out.

I've used Petttit Prop-Koat on my propeller with some success, but its very expensive and application is a two step process (primer and clear coat finish). I might be tempted to try it on my shaft but I would be careful to avoid coating where the zincs were going, you want a good electrical contact between the zinc and the shaft.

GaryHLucas 11-16-2009 09:22 PM

I must be missing something here. My aluminum rudder shaft was badly damaged by copper bottom paint. I know it because the only place eaten away is right at the bottom paint line, nothing above or below. However I fail to see how copper bottom paint could damage a copper alloy! I'd have to believe it was electrolytic action from stray currents, and no zincs.

Gary H. Lucas

KeelHaulin 11-17-2009 11:41 AM

May I ask why it makes a difference to not paint your prop; while most people paint their thru-hull, stanchion and skeg? These items had 30 years of paint on them on my boat; and none had the de-zincification that was shown in the pictures of the props over on that thread.

I don't discount the possibility that the paint causes galvanic corrosion; but I am wondering why it would be different for a prop than a thru-hull.

T37Chef 11-17-2009 12:01 PM

After you get it clean, try protecting it with Zinc spray by Pettit. I have used it for years with much success.

See here: http://www.pettitpaint.com/fileshare...ds/1179320.pdf

http://www.getaprop.com/images/produ...%5D%5B1%5D.jpg

pegasus1457 11-17-2009 12:11 PM

Quote:

Originally Posted by TaylorC (Post 542583)
I never see painted shafts, so I don't think you forgot to do anything. You should also have zinc collars on your shaft.

I've used Petttit Prop-Koat on my propeller with some success, but its very expensive and application is a two step process (primer and clear coat finish). I might be tempted to try it on my shaft but I would be careful to avoid coating where the zincs were going, you want a good electrical contact between the zinc and the shaft.

I am not that ignorant :) I have zincs on my shaft and I wouldn't dream of putting anything between them and the shaft.

Someone in my boatyard said that he had sprayed his shaft with a product from WM [I do not recall the name] and it kept the marine growth off his shaft and prop. I will have to ask him what he used.

"Expensive" is a polite way of characterizing the Pettit-Koat. But I guess for $175 you get 10 yrs use out of a quart.


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