Best way to prevent winter keel damage like this

[Chris & Lenore]

This past winter was especially cold and left a "reminder" on our keel.
Water froze at the keel bolt head and ruptured the lead. You can see the location in the first pic and a close up of the damage in the second.

The repair will be to sledge the lead back into place and fair over the cracks (possibly thinned epoxy first to prevent water entry).
The keel bolts and nuts look like new - no corrosion or damage.

But how to prevent the same thing happening next winter?

The previous owner just faired over the "smile" each year but of course it reappears after the first sail.
I go round out a furrow exposing the lead and FG and filled this with 5200 (the typical repair).
Possibly this is where water was getting in?

Should I also be removing the keel nuts (one at a time) and seating with 4000? There is usually always some water in the bilge - comes in via the keel stepped mast.
If I dry out the bilge it does stay dry until the next rain - so nothing is coming "in".

Oh, this could have been happening every year. The keel had a fresh fairing and bottom coat when we saw the boat. The PO "doesn't remember"...

Chris

 

[victorhoisington]

You say this happens every year. So taking the obvious route, water is getting into the bolt either through the bilge or via cracks in the lead. I'm not a metal engineer but here are some thoughts - Just to make sure nothing is coming in from the top, reseal the keel bolts. Now to the blow out section. just pounding it back in and trying to seal with epoxy probably won't solve the problem. You'll get some water back in and it will blow-out next winter. Can you get someone who works with lead to clean out the section completely and then "repour" that part of the keel. I would think you could completely remove the lead in the bad section, make sure it is completely dry, then craft a temporary form to the keel and repour the lead back into place. You may need to preheat the lead keel so that it bonds with the existing lead and you probably will have to do some fairing to get the final shape perfect but lead is easy to shape so that shouldn't be a problem.

Again I'm not an expert but trying to "patch" this with epoxy or some other covering isn't going to solve the problem for long and constantly trying to pound the blow-out back into place may lead to metal fatigue which could cause the whole section to eventually fail.

Just some ideas, good luck and fair winds.

 

[Chris & Lenore]

You say this happens every year. So taking the obvious route, water is getting into the bolt either through the bilge or via cracks in the lead. I'm not a metal engineer but here are some thoughts - Just to make sure nothing is coming in from the top, reseal the keel bolts. Now to the blow out section. just pounding it back in and trying to seal with epoxy probably won't solve the problem. You'll get some water back in and it will blow-out next winter. Can you get someone who works with lead to clean out the section completely and then "repour" that part of the keel. I would think you could completely remove the lead in the bad section, make sure it is completely dry, then craft a temporary form to the keel and repour the lead back into place. You may need to preheat the lead keel so that it bonds with the existing lead and you probably will have to do some fairing to get the final shape perfect but lead is easy to shape so that shouldn't be a problem.

Again I'm not an expert but trying to "patch" this with epoxy or some other covering isn't going to solve the problem for long and constantly trying to pound the blow-out back into place may lead to metal fatigue which could cause the whole section to eventually fail.

Just some ideas, good luck and fair winds.

I don't know if this has happened in the past (first winter for us with this boat). I'm told no, but there have been a few surprises from the PO. A surveyor (his, for insurance valuation) did look at it last spring and said the bottom was in perfect condition.

Regardless, I'm curious where the water could come from. If the keel is cast around the bolts, then how would it get to bolt head?

Hopefully the "smile repair" and resealing the nuts in the bilge will take care of it.

Just "one more thing to fix" - part of boat ownership...

Chris

 

[Meriachee]

Water can wick in from any place. If you're looking for a crack, it may not be obvious, and worse, the water might have been in there a long time, and only this year froze to that degree. If there was water in the bilge that wicked down the bolt(s) it could have been in there for a very long time.
Water: 1.0002 cm³/g
Ice: 1.0909 cm³/g
Just over 9% expansion.
It wouldn't take very much to cause a lot of damage in a tight space.

 

[dlochner]

While the boat is out of the water, you should re-torque each of the keelbolts. One at a time, remove the bolt and washer, clean out around the bolt and seal again with 4000 or another caulk that can be used below the waterline. If you are really fancy, get rid of the SS nuts and replace with bronze or monel. They are less likely to gall and become one with the bolt.

While the nuts are off, closely inspect the bolt where it enters the keel sump. Is there any indication of corrosion? That area is prime spot for crevice corrosion.

As for the the repair, don't worry about the lead. Clean the area. Perhaps drill a weep hole to let any remaining water out and then fill with epoxy. Bring the metal to bright and shiny and quickly coat with unthickened epoxy. Use a small wire brush to brush the epoxy into the lead. Once the expoxy has begun to set up a bit, in an hour or so, fill the void with thickened epoxy. When cured fair it, put a barrier coat on it and bottom paint.

The epoxy solution will weigh less than the lead, but the difference will be negligible, a few once perhaps. Not enough to worry about. If you wanted to make it heavier, you could add some lead flakes to the thickened epoxy, but I probably wouldn't.