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Go Back   SailNet Community > On Board > Gear & Maintenance > Keel Fix help
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Thread: Keel Fix help Reply to Thread
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Topic Review (Newest First)
11-14-2012 10:54 PM
DrB
Thanks everyone

Based on the responses, my original approach appears sound. Rough up the exposed lead well (bright surface), coat it with unfilled epoxy, let it set some (tacky),and coat it with filled epoxy, full cure and the feather contour blend into remaining keel.

And yes, I do know that lead oxidizes as does aluminum and most metals. Little tidbit I learned in PhD Materials Eng school. And as you pointed out, bonding to some of these fast forming metal oxides can be an issue.

Thanks all for the advice.

DrB
11-14-2012 06:00 PM
SloopJonB
Re: Keel Fix help

Hello's method sounds pretty effective but I'd change one thing - the first "scrubbing layer" would be a lot easier if it was epoxy resin instead of filler. It would give the same, or better bond for subsequent layers.

Alternatively, going over the keel with a wire cup brush in a small grinder would clean off the oxide layer - lead stays "bright" for quite a while, unlike iron & aluminium so you'd have time to roll on a coat of resin to seal it before a problematic oxide layer formed.
11-14-2012 05:42 PM
hellosailor
Re: Keel Fix help

DrB, one doesn't apply a barrier coat over a lead keel, since there is nothing to "barrier". The lead doesn't give a damn what kind of water it is immersed in.

OTOH one certainly would apply a fairing coat over a lead keel, to provide a smooth surface. And antifouling paint over that. But then you'd be looking for a FAIRING product, not anything sold as a barrier coat.

Lead forms a thin skin of lead oxide upon exposure to air, and that thin layer of lead oxide is what comes apart and lets the coatings peel off. The trick to good adhesion is a somewhat messy process, you want to clean the lead, and then as you apply the next layer of epoxy fairing compound, scrub it in with a wire brush or metal mesh pads, so that you are scraping away at the oxide coating and allowing the bare lead to bond with what you are applying.

That may take four hands, i.e. yours to apply the goo and scrub it in, and someone else following you to smooth it off. But if you get that first coat scrubbed in so it has bonded with bare lead instead of an oxide coating, it should stick very nicely. Especially if it is an epoxy.

How much fairing you decide to do on the lead, rather than on the filling/fairing layers over it, is something else again.
11-14-2012 04:18 PM
misfits
Re: Keel Fix help

Quote:
Originally Posted by msmith10 View Post
Excuse me if it's a dumb question, but why barrier coat a lead keel? Why not take it down to clean lead and apply bottom paint?
My understanding was it gave the filler something to stick to.
11-13-2012 09:45 PM
RobGallagher
Re: Keel Fix help

I can only tell you what I did.

Strip the keel to bare lead.
Prime it with two part medal primer.
Apply X amounts of two part barrier coat.
Bottom paint.

Never had another problem. Careful in subsequent seasons to stop sanding bottom paint if I could start to see the grey barrier coat.

YMMV.
11-13-2012 09:31 PM
SloopJonB
Re: Keel Fix help

Looks to me like it was faired with Bondo, not filled epoxy. Polyester filler will always fail on a boat eventually. Clean everything off the keel and if required, do it again with thickened epoxy. Since the keel is lead, keep the filler to an absolute minimum thickness.

Edit: Don't put glass fabric on it - just thickened resin.
11-13-2012 09:29 PM
msmith10
Re: Keel Fix help

Excuse me if it's a dumb question, but why barrier coat a lead keel? Why not take it down to clean lead and apply bottom paint?
11-13-2012 08:20 PM
misfits
Re: Keel Fix help

I wouldn't glass it. Remove the loose portions, clean up the lead, seal with a barrier coat, fill & fair it
11-13-2012 07:20 PM
Faster
Re: Keel Fix help

Hmmm... I wonder where/when the 'chipping off loose bits' will stop? Once you've gotten under whatever that is I suspect you can just keep going.

Which may be as good a way to go as any.. get rid of all of whatever's there, and start over with your basic plan listed above. I don't think you want to suddenly 'patch' selected areas with cloth and epoxy, I think you'd want a uniform, homogenous coating if that's the way you want to go. The lead looks pretty fair, though, and maybe you just want to prep and paint it.
11-13-2012 06:43 PM
DrB
Pictures should work now.

Try these. Also I fixed the link.





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