# Replacing lead Keel bolts



## cousineddy (Nov 27, 2011)

The Keel bolts looked good, but when I went to check the torque, all but two twisted off with little effort. Kinda scary. Anyway, its a lead keel, probably has the studs casted in. I would like to replace, or add new bolts next to the failed ones with out fully removing the keel. I heard that some have used lag bolts. Has anyone tried anchor bolts? Like for concrete? Or, I wonder if setting a helicoil into the lead would be strong enough? Or maybe some other type of blind insert?


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## Gene T (May 23, 2006)

I believe I would drill a new hole for the new stud. Then drill a large hole in the side of the keel to meet the end of the first hole to put a nut/washer on. Drop in some threaded rod, put a nut on the bottom, one on the top and torque it down. I would probably try to remove the old ones first but that may be more trouble than it is worth.

Gene


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## misfits (Dec 9, 2011)

It's a good thing you torqued them down, sounds like there's not much holding that keel to the boat. No matter how you decide to fix it, you should really drop that keel enough so it can be cleaned out & rebeded.

You may want to check these guys out. 
Keel Bolt Replacement | MarsKeel


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## kd3pc (Oct 19, 2006)

on a 30+ year old boat, I certainly would not use some threaded rod and a few nuts....were it an iron keel you may have gotten away with "unscrewing" them and replacing with the correct pitch bolts

IMHO this is a wake up call to have the keel repaired or replaced by a reputable mechanic or yard with experience. The threaded rod generally available today is junk, not coated or strong enough for your task. The original bolts were likely "L" or "J" shaped and quite stout stainless or coated steel and cast in place as the keel was poured. If you do drill holes be aware that hitting that hidden stainless will likely walk the bit around and out where you really don't want it to...that assumes you can find a decent bit long enough.

Same with any blind insert that will be inserted from the top, If two were bad, you can be assured the others are not too far behind.

For your safety, get it fixed correctly


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## Gene T (May 23, 2006)

I think the solution here is not to spend $3,000+ to repair a 33 year old 25 foot boat. That is why doing it yourself is appealing. What really is a viable alternative?

Gene


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## cousineddy (Nov 27, 2011)

Well, drilling the hole the side of the keel is an excellent idea. I dont see how that would be any less strong then the boat yard method. I believe they sink new J or T bolds, then melt lead in to fill the gap. I think drilling a hole then inserting a circular stainless plug, with a radial tapped hole is the ticket. I think I will use good quality bolts instead of all-thread. I should have thought of that. Kudos!


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## Stumble (Feb 2, 2012)

Most cast in place bolts are just threaded rod, with different designers preferring stainless others like hss steel, and there is a small faction switching to other more exotic materials. For replacement though there really isn't a good option except melting the lead away from the old bolts, and replacing them with new. Frankly a hex head bolt cast in place is a pretty poor option. The head has pretty minimal surface area compared to T or J rod, which increases the problems of point loading. 

As for material, it really depends on what you are looking for. A quick cheap fix to get back on the water, go with steel.

Arguably better is stainless, but in keel bolts it has a lot of problems.

If you want to fix it once and never worry about it again, titanium.


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## misfits (Dec 9, 2011)

Some people will grind out a pocket on one side of the keel so you can put a bigass washer & nut on a piece of s.s. rod & crank it down from inside the bilge. Then you just fill & fair the keel pocket you created with epoxy. 

This works if you need to repair a keel bolt or two. Sounds like in your case the only thing holding the keel on is the 5200 it got bedded in 33 years ago.


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## SloopJonB (Jun 6, 2011)

GeneT has the best advice here IMHO but I'd add one other choice. Your keel is only 1200 Lbs or so - not a huge lump. There is a type of fastener called a "Hanger Bolt" that has conventional threads on 1/2 of it and lag type threads on the other 1/2. If you got some good big ones in good metal, carefully drilled new boltholes, no larger than the minor axis of the lag threads and wrenched them down into the lead it should be adequate.

I believe Catalina advises this type of repair on one or more of their smaller boats. It's called "sistering" the bolts.


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## cousineddy (Nov 27, 2011)

I am familiar with hanger bolts. That sistering Idea sounds easy. Hmmmmmm. I could add a couple extra bolts too.

...And it is for sure hanging by the 5200 like a dingle berry, lol. All the nuts are loose or broke. Thats strong stuff.


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## mitiempo (Sep 19, 2008)

I would drop the keel if you are able to. The water that destroyed the bolts got there somehow and decades old bedding, even 5200, is well overdue for replacement.


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## eherlihy (Jan 2, 2007)

My post from another thread;



eherlihy said:


> (Ya, I know it's an old thread...)
> 
> I thought that I should share a couple of pictures that Illustrate this point.
> 
> ...


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## SloopJonB (Jun 6, 2011)

The attached is an example of what was holding the keel on, on my Columbia 43 when I bought it and what I replaced it with. The bilge was dusty dry but obviously wasn't always that way. The fasteners were steel tapped into an iron keel so it was an easy fix. Other than the heavy equipment needed to remove & reinstall the keel, it only cost a few $hundred for the stainless pieces.

Lead keels are not better than iron keels in EVERY way.


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## BELLATRIX1965 (Jan 2, 2007)

Plus 1 for Gene T's idea. Windows in the keel allow for through-bolting - MUCH stronger than threading into lead (very soft - not much tensile strength). Hinckley attaches lead keel ballast that way.


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## cousineddy (Nov 27, 2011)

Wowsa Eherlihy! What a surprise? How would you ever know there was a problem? Those bolts look fine!! I would have chalked that seem up to normal flexing!

I cut the 5200 away, the keel dropped a bit. See Pics. I am thinking that I will install 8 stainless 1/2-13 hanger bolts. Currently, there are six 1/2-13 studs. I was thinking maybe I should add two 5/8 window bolts in addition. Not really sure if that is necessary. Clamp force on these hangers is 9600 lbs.

It looks like the studs are in good shape up to the bilge. In the bilge is where the corrosion occured. This boat must have had a wet bilge most of its life.


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## cousineddy (Nov 27, 2011)

Just calculated the max torque for these hanger bolts in lead. 35 ft lbs. That equates to a 5700 clamp force. So, I think I will add some window bolts too. Maybe a couple 3/4 bolts.


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## eherlihy (Jan 2, 2007)

cousineddy said:


> Wowsa Eherlihy! What a surprise? How would you ever know there was a problem? Those bolts look fine!! I would have chalked that seem up to normal flexing!
> 
> I cut the 5200 away, the keel dropped a bit. See Pics. I am thinking that I will install 8 stainless 1/2-13 hanger bolts. Currently, there are six 1/2-13 studs. I was thinking maybe I should add two 5/8 window bolts in addition. Not really sure if that is necessary. Clamp force on these hangers is 9600 lbs.
> 
> It looks like the studs are in good shape up to the bilge. In the bilge is where the corrosion occured. This boat must have had a wet bilge most of its life.


Those pics are from September 2010.

When she was hauled for survey, I looked at the boat from directly off the bow. IIRC the boat was not perfectly level in the slings, but the keel pointed straight down. Regardless of my failing memory, I do recall that the keel did not appear symmetrical with the hull. It was not off a lot, perhaps ½ to 2º. The yard manager, and the broker, felt that the boat came off the production line like that. The surveyor was quiet.

I kept expressing my concern, because it just didn't look right to me. Finally, the surveyor crawled under the hull, and looked up at the joint. As he was crawling under the keel, he pulled on the keel, and *it moved*. He quickly got up from under the hull, and told me that I was right, and the keel was loose. The keel would flex about ¼" port to starboard at the bottom of the keel.

Here is a pic taken immediately after the keel was repaired. You can see that the keel and the hull appear symmetrical.








(I forgot how bad her gelcoat looked when I first bought her... Sheeesh!)

Left unchecked, this would have only become worse as the boat was tacked. I don't get what you mean by "normal flexing."

I had the hull sodablasted and barrier coated this year. Here is what the keel joint looked like after it was stripped in April, 2012;








(Thanks to Maine Sail for his tips on Compounding and Waxing. This boat was not compounded or waxed this year before the pics were taken, or at all this year, because I could not get clear access to work on the boat in the yard that I stored her last winter. The hull was last compounded by me 1 year before this pic was taken. She _will _look better next year.)



















THERE SHOULD BE NO MOVEMENT OF THE KEEL - PERIOD.


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## GaryHLucas (Mar 24, 2008)

So, you say your boat won't point well? My Hunter 27 pointing ability was very poor, then the keel nearly fell off, came down about 2" when they lifted her to go in the water the next season! I fixed it, and the difference in pointing ability was astonishing. Apparently you DO need a keel to sail upwind!

Gary H. Lucas


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## Plumbean (Dec 17, 2009)

While probably most boats are made with "j" bolts for their keel bolts, there are plenty that used the pocket method, mine included. Here is what they looked like when we dropped the keel and replaced them all with silicon bronze.


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## cousineddy (Nov 27, 2011)

Sweet! I have been thinking about this. 

I dont think I will be able to drill perpindicular, intersecting holes precise enough to do the window method. I will end up with over sized holes to get my studs to thread into dowel nuts.

There are currently six 1/2-13 studs casted into the keel which weighs 1400 lbs about.

The largest hanger studs I can find are 1/2-13, 6 in long, with the lag portion 3 inches long. According to my calcs, the pullout strength in pure lead is about 6000 lbs. With the boat at a 90 degree heel, the tensile load on the 2 out board bolts is about 7000 lbs. That ignores the fore and aft single bolts. So thats 3500 per bolt. If you want the preload to be higher than the joint separation load, we exceed the pull out strength in lead (conservsative). 

So, I am going to use six 3/4 dia by 6" stainless Lag bolts. Pull out strength on each one is 13700 lbs in pure lead with 4 inches of thread engagement. This will allow my preload to be 2x the joint sep load and still have a large margin of safety. I will torque these to 100 ft lb, and use Bellville spring washers under the head that flatten out at 5100 lb of preload, so I have a visual indication of adequate preload.

These will also be easy to install. So, I think this is the best approach. Catalina should have hired me.


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## Stumble (Feb 2, 2012)

Cousin,

The generally recommend design spec for keeps is that each bolt should be able to support the entire keel alone, at a minimum of a 5 times safety factor.

If you are really ok with that safety margin you might as well go down to 1/4" bolts. There is no reason to use anything close to the size you are currently planning on, and 1/4 will give you about the same strength as your design.


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## cousineddy (Nov 27, 2011)

Actually, that 5 times safety factor works for the 1/2 hanger bolts. 1400 x 5 = 7000 per bolt, which is about what i calculated was required for a 1x safety factor. So, having a 13700 lb holding capacity gives me an over all safety factor of 2x. I get a warm fuzzy with that margin.


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## casey1999 (Oct 18, 2010)

Plumbean said:


> While probably most boats are made with "j" bolts for their keel bolts, there are plenty that used the pocket method, mine included. Here is what they looked like when we dropped the keel and replaced them all with silicon bronze.


My lead keel attachment is just like yours (windows). My original keel bolts are stainless steel and appear ok (34 years old), but maybe one day I will need to replace.

Would silicon bronze be preferred over stainless? Titanium is also becoming available at a resonable price, any thoughts?

What is your boat make?
Regards


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## Stumble (Feb 2, 2012)

cousineddy said:


> Actually, that 5 times safety factor works for the 1/2 hanger bolts. 1400 x 5 = 7000 per bolt, which is about what i calculated was required for a 1x safety factor. So, having a 13700 lb holding capacity gives me an over all safety factor of 2x. I get a warm fuzzy with that margin.


I think you misunderstand. Each bolt assembly however anchored should have at least a 5 times safety margin.

Your assembly's week point is the attachment mechanism. So you have to design to that. If the max load the keel will generate is 7,000lbs, then you need an attachment mechanism, and bolts rated to 35,000lbs. Your design is woefully undersized.


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## cousineddy (Nov 27, 2011)

The 13700 holding capacity is per bolt. There are 6 bolts. Total holding capacity is 82200 lbs. That oughtta do er.


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## Plumbean (Dec 17, 2009)

casey1999 said:


> My lead keel attachment is just like yours (windows). My original keel bolts are stainless steel and appear ok (34 years old), but maybe one day I will need to replace.
> 
> Would silicon bronze be preferred over stainless? Titanium is also becoming available at a resonable price, any thoughts?
> 
> ...


Casey: Looks the same because it is the same boat! Aquafibre built S&S34. Someone had encapsulated the bolt heads in the bilge and they had corroded due to the lack of oxygen. On some there were only 3 full turns of the threads left on the bolt in the bilge. The rest of the bolt looked fine, just the part in the bilge was corroded. Silicon Bronze is more expensive but won't corrode like stainless. I only wanted to do this job once, so decided to spring for the silicon bronze.


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## cousineddy (Nov 27, 2011)

Titanium is the best choice. It will never corrode in salt water. The only substance that can penetrate its protective oxide coating is a strong acid, like hydroflouric. 

Silicon Bronze is more corrossion resistant than stainless, both 18-8 and 316 in salt water. No advantage in fresh water. Just gotta make sure you get good quality bolts. We tested silicon bronze against brass at work for a non-magnetic application. They were only half as strong as they were supposed to be. So, we abandoned them.


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## Brewgyver (Dec 31, 2011)

Eherlihy, I'm wondering if the root cause of the damage to those bolts is more stretching than corrosion? Anybody?


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## Stumble (Feb 2, 2012)

cousineddy said:


> The 13700 holding capacity is per bolt. There are 6 bolts. Total holding capacity is 82200 lbs. That oughtta do er.


As I said above the 5:1 safety margin is per bolt. Assuming each bolt alone is holding the entire keel. The justification for this is that when the boat is rolled onto it's side, and being slapped by waves, there is no telling how unequal the forces are going to be applied. It very well may be that just the front bolt will have to briefly hold the entire weight of the keel, plus it's momentum on the boat, even if everything else is in good shape.


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## Stumble (Feb 2, 2012)

Brewgyver said:


> Eherlihy, I'm wondering if the root cause of the damage to those bolts is more stretching than corrosion? Anybody?


It's a pretty easy check, just try and thread a nut down on the existing threads. But I don't see anything that looks like elongation. The pictures are pretty typical of general corrosion eating away at the bolts.


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## eherlihy (Jan 2, 2007)

Brewgyver said:


> Eherlihy, I'm wondering if the root cause of the damage to those bolts is more stretching than corrosion? Anybody?


I can't speak to that, as I did not build the boat, and she was not mine when those pictures were taken.

I believe that what you are looking at is simple crevice corrosion. Those lines in the metal are simply the way that the corrosion traveled through the steel.


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