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Iron keel - white, acidic liquid?

Apr 23, 2018
6
Allegro 27 Gålö
Jan 19, 2010
10,009
Hunter 26 Charleston
Nice boat! Those full keels must make for a steady ride.

Since it is not encased, I'd simply grind out the strange spot and inspect it., then seal it back up with some barrier coat and a fresh touch up of bottom paint.

How do you know it is acidic? Metal oxides are acidic so if you have some pH paper or such, that would be a real clue.

I'm thinking you must have gotten some water between the paint and iron and it is oozing out but why it is white in color is confusing to me. Tin(IV) oxide is white but tin-based bottom-paints were banned almost 30 years ago. Maybe you have a very old layer of tin bottom paint buried under that copper paint. That is the only think I can think of. If that is the case, you might not want to know the answer.
 
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Apr 23, 2018
6
Allegro 27 Gålö
Hi agranger!

Thanks for your help! I determined it as acidic based of the smell, will go at it with lacmus paper this Saturday to confirm.

If it’s a tin paint layer I guess I won’t be sailing much this year. Will look in to how to confirm or rule this out!

Thank for your help once again!
 
Apr 23, 2018
6
Allegro 27 Gålö
Hi Gunni!

Ok, the boats were all built with cast iron keels. I doubt that it has been replaced, since measurements add up to schematics. Not impossible thugh, will test for this as well this Saturday.

Thank you!
 
Jan 19, 2010
10,009
Hunter 26 Charleston
Gunni might be right. It is more likely to be lead oxide (also white) than tin oxide. Lead is more common than tin these days. Even without a lead stub...you might have an old layer of lead based paint under that newer bottom paint.. Grind it out, seal it up and go sailing. You won't be polluting the environment unless you plan on removing it in an irresponsible manner. Leave it alone and it is stable. Unfortunately, a flame test for lead or tin both give you a blue/white flame. So no quick test there.

If you need to know, do a google for "Home Lead Test Kit". They are less than $15. There is also a company called Osumex that sells test kits for tin.

Both tin and lead are toxic so don't breath the dust (just in case) as you repair this spot.
 
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Apr 23, 2018
6
Allegro 27 Gålö
Hmm, it seems as if blastering and repainting is due regardless of TBT or lead. Will get a professional to look at it, I don’t believe I can handle the procedure in a safe manner.

Big thanks you guys, you’ve been extreamly helpful! Some day I will become wise and pay it forward!
 
Apr 23, 2018
6
Allegro 27 Gålö
True that, I tend to assume the worst sometimes :/

Haven’t found any similar pictures online. Am I compleatly off the wagon if I reason that if this was a sign of TBT environmental agencies would post similar pictures as a sign of TBT?
 

Gunni

.
Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
Take a nail punch and hammer, see if you can easily dent the keel in that spot. Yes, lead. No, iron.
 
Jan 19, 2010
10,009
Hunter 26 Charleston
Man that could be a hundred different things. Can you peel the paint back with the flat end of a screwdriver? And then just seal it up with some quality oil based enamel?

THEN GO SAILING :)
 
Oct 22, 2014
16,137
CAL 35 Cruiser moored EVERETT WA
@BrolleSenior
@Gunni and @rgranger, as usual, have you on the right path.

Look at the discoloration of the paint around the weeping. It is the sign of water getting under the paint.
Way to address it is to chip or grind the paint back to solidly attached paint. Smooth the area. If you find a depression fill it with some thickened epoxy. Then smooth again (grinder). Once you are back to a smooth contoured surface then give it a couple of coats of Interlux barrier paint. This will seal the area of the repair. You are now ready to bottom coat the area. If the bottom needs a whole paint job go at the whole thing with a sander (preferably a sander that captures the dust with a vacuum as you sand).
0E324CCC-BD97-4A55-A4F4-3346744B16E4.jpeg
Then wipe down (clean all the dust away) and paint. There are some great YouTube videos and instructions online or from paint manufactures. This is not a rocket science job. It is just manual labor. If you do not have the time and money give it to the yard to do the work.
Precautions are recommended. Mask up, preferablely with a good paint mask.
6E8DE8FC-895D-4C2C-8D09-FB2220DD24C2.jpeg
Cover your eyes and a tyveck suit is cheap insurance from the itch of fiberglass.
F09A32C2-4D0E-4A3A-9376-76EB04B2A00F.jpeg
Put a drop cloth down to capture the paint dust/chips that fall from your work.
31679EDB-5A36-4C6F-8248-3D6F3D523206.jpeg
You should be all good.

I had water blisters. Here are three pictures.
First the boat side with the blisters, E25E2ABE-330E-42F8-8A8A-BCB88364A953.jpeg
then the boat bottom blisters ground out. C9CD3C51-61E1-47E4-B84B-612C9701CBA1.jpeg
Finally the finished job about to be splashed,BC30D4A5-9DCE-432B-820F-5C5A6C2BD1DF.jpeg
following the same procedure identified above.
 
Sep 20, 2014
1,282
Rob Legg RL24 Chain O'Lakes
I would recommend a sandblaster, rather than grinding. Grinding takes off way too much metal, especially if it is pitted.
 
Apr 23, 2018
6
Allegro 27 Gålö
Thanks jjsailem and daveinet!

While I do love manual labour I’m short on tools and experience so I think the yard is the way to go.

With all your help I now believe I have solved the mystery! It does look quite similar to jjsailems blisters. Looking back to pictures when I bought the boat a year ago it was freashly painted. The paint shifts colour when wet, as seen were the rain has poured down on the sides.

However, water shouldn’t be trapped in iron, so atm I’m guessing there is an old cavity filled with epoxy that was not done tight. The truth will be in grinding :)
 

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