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Old 20-04-2018, 15:04   #1
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Finishing Lead Keel?

My boat is out of the water for 10 days and I have organized quite a bit of labor.

My lead bulb keel has never held antifouling very well -- it bubbles and flakes off, and I just know that the resulting rough surface is slowing me down.

I've got enough labor now to spend some time stripping all the antifouling off it and making it smooth and fair.

What is the best way to prime a bare lead keel to take antifoul, not flake it off, and to stay smooth and sweet?

The shipwright leading the team thinks it should be epoxied, but admits that he doesn't really know -- he's from a family of Cowes boat builders specializing in wooden boats, and he doesn't have much experience with plastic boats.

What do you guys think?
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Old 20-04-2018, 15:09   #2
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Re: Finishing Lead Keel?

Iron putty then paint the putty cheap and easy.
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Old 20-04-2018, 16:03   #3
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Re: Finishing Lead Keel?

Interprotect 200E over the faired keel. Then bottom paint. That’s what I did when I raced. Plus don’t forget to sand the anti-fouling to 600 grit for the front third and 400 for the back two thirds.
Seriously the interprotect is basically a thin epoxy paint and provides a barrier between the lead and the copper based paint. Easy to apply too.
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Old 20-04-2018, 16:11   #4
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Re: Finishing Lead Keel?

I've had good luck with epoxy barrier coat on my lead keel. If you go that route, it's a good idea to use a barrier coat of the same brand as your anti-fouling for the best compatibility. Hot coat the first coat of anti-fouling on the barrier coat for best adhesion.
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Old 21-04-2018, 01:46   #5
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Re: Finishing Lead Keel?

OK, thanks. And what do I fair it with?
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Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
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Old 21-04-2018, 01:54   #6
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Re: Finishing Lead Keel?

I second the epoxy route. I used epoxy directly over well cleaned raw lead keel, then faired with epoxy and fairing compound (can't remember which one, probably micro balloons and fumed silica), then final epoxy coat followed by Interprotect and then CopperCote. More than ten years in the water and still going strong; can't tell where the lead / keel interface is .
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Old 21-04-2018, 02:47   #7
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Re: Finishing Lead Keel?

I VERY carefully sanded the lead with a good full face mask, full Tyvek and gloves and a vacuum attached to my sander on a slow speed with a coarse 40 grit paper then mixed up epoxy, painted it on and wet sanded by hand through the still wet epoxy into the lead with 80 grit paper to key the epoxy into fresh unoxidised lead.

The epoxy goes quite grey with lead dust, and after it tacks off a second coat is needed to encapsulate the lead powder/ epoxy slurry. Then it is just a case of fairing as normal over the epoxy, being very carefull not to sand back into the lead.

Watch the lead temperature, it stays cold for a long time so even on a warm day the lead keel may be much colder, giving the epoxy a hard time if it's near it's lower boundary temp wise.

I think this is the method described in the Gougeons excellent book availible as a Free PDF here.

https://www.westsystem.com/the-gouge...-construction/

So far mines been good for about 3 years, no problems on any of the areas I have patched up so far.
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Old 21-04-2018, 03:00   #8
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Re: Finishing Lead Keel?

"Pour the keel as soon as possible so that you will have plenty of time to prepare it for final installation.

Clean the casting and then rough up its surface with a wire brush to remove oxidation.

Coat the keel with epoxy and, while the epoxy is still wet, scrub it again with the wire brush.

WEST SYSTEM epoxy bonds well to clean lead surfaces. This coating will improve both paint adhesion and the interface between the high-density lead and lower density epoxy, and it will also reduce immediate oxidation."

Around Pg 150. Gougeon Brothers on Boatbuilding.

Come to think of it I also used the wire brush, but you basically have to throw away the wire brush after each use, the wet and dry paper also workedif I recall correctly.
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Old 21-04-2018, 03:24   #9
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Post Re: Finishing Lead Keel?

To pick up from Snowpetrel's cite of the Gougeon Bros' book: that procedure is for a lead keel that's new.

Lead is not unreactive. Shiny new lead quickly gets a surface layer of lead oxide. And you really need to remove that before coating with epoxy. The traditional way is to sand a small patch, then coat, then sand another patch, then coat, and repeat until finished.

Dockhead's keel has been in saltwater. So the surface is likely not just lead oxide but various other hydrated salts of lead.

For a quick job, sand blasting is one way to clean the surface, as long as you have the labour to fairly smartly coat with epoxy before the lead acquires an oxide surface layer.

Talking to one of the big chemical/paint companies, such as International, might be worth your while. When inquiring of them, be sure to note that the lead keel is not newly cast. That might, for instance, rule out just using an etch primer.

Then then next question is applying antifouling. Depending on the epoxy, the need to fair the keel, and any intermediate coats, you may need to be careful applying antifouling over the epoxy.

Should you not need to fair or use any other intermediate coat, you might need to apply the first coat of antifouling at a particular stage of the epoxy curing - e.g. while the epoxy is still not fully cured. Some epoxy, once cured, is so slippery that antifouling will not adhere.
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Old 21-04-2018, 03:38   #10
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Re: Finishing Lead Keel?

Thanks to everyone for the great answers. It's more complicated than I thought!
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Cushion me soft . . . . rock me in billowy drowse,
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Old 21-04-2018, 06:06   #11
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Re: Finishing Lead Keel?

I had my 45 year old keel sanded back to bare lead and i coated it in hempels epoxy primer called Hempadur 45182. It seals the keel very well.

Just out of interest? Who is the boat building family the guy stems from?
My boat was built by Sewters in Cowes 50 odd years ago.
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Old 21-04-2018, 07:48   #12
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Re: Finishing Lead Keel?

Would one use a belt sander for the rough sanding part of this, or better a big orbital sander?
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Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
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Old 21-04-2018, 08:11   #13
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Re: Finishing Lead Keel?

I used an orbital..
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Old 21-04-2018, 10:33   #14
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Re: Finishing Lead Keel?

Quote:
Originally Posted by Snowpetrel View Post
"Pour the keel as soon as possible so that you will have plenty of time to prepare it for final installation.

Clean the casting and then rough up its surface with a wire brush to remove oxidation.

Coat the keel with epoxy and, while the epoxy is still wet, scrub it again with the wire brush.

WEST SYSTEM epoxy bonds well to clean lead surfaces. This coating will improve both paint adhesion and the interface between the high-density lead and lower density epoxy, and it will also reduce immediate oxidation."

Around Pg 150. Gougeon Brothers on Boatbuilding.

Come to think of it I also used the wire brush, but you basically have to throw away the wire brush after each use, the wet and dry paper also workedif I recall correctly.
I was going to say the same thing about wire brushing the wet epoxy. Done a few boats as well as two of my own that way and no problems with adhesion
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Old 21-04-2018, 15:12   #15
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Re: Finishing Lead Keel?

Quote:
Originally Posted by Dockhead View Post
Would one use a belt sander for the rough sanding part of this, or better a big orbital sander?
Both plus an angle grinder (5") fitted with 36 grit (or coarser) fibre disc and at times, a cup wire brush.

Really depends on the existing condition of the lead. Mine was pretty good mostly, just a couple of areas that needed the angle grinder.

I concur with the wire brushing though the first coat of epoxy.

It's not a complicated job once you come to grips with the technique - like most things I suppose
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