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Old 06-05-2018, 05:21   #76
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Keel bolts... is this the end?

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Originally Posted by jimbunyard View Post
The idea of modifying an existing corroded bolt seems far-fetched, not the least because of the reduction of the supporting glass around it required to affect the modification.

My initial reaction was similar but I was thinking about it and now I’m a little surprised I’ve never heard of anyone doing something like this. With the right (custom?) tools and parts it could be a very quick fix:

What if you bored around your bolt all the way down to the keel so you had eyes on the whole length of the bolt popping up out of the lead? Assuming you had plenty of sound stud (and this may be a big assumption) you could tap it and fit a (custom?) flanged nut that sits in your bore hole but has its flange resting on the untouched, surrounding solid glass. I’m imagining a custom nut that fills the bore hole diameter completely and has a really thick, broad flange?

Ultimately you’ve removed material from the stub so this isn’t with its drawbacks!! And if your stub has wood embedded in it (my 22 footer was like that, dunno if bigger boats ever have that kinda built in time bomb) forget it, you’ll be exposing it to possible leaks from below. Also wouldn’t be a good fix if the bore would end up close to the wall of your stub.

But ignoring all that, I could imagine someone with the right tool/jig/whatever for boring around the bolts (and a set of these custom flange nuts in assorted geometries) being able to bang out a repair like this in an afternoon.

???
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Old 06-05-2018, 06:54   #77
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Re: Keel bolts... is this the end?

The main problem is the unknown; one starts core drilling a hole in the already limited area of the keel stub, and then finds the bolt is beyond repair.

You now have a 2" (the minimum spacing needed to screw a coupling nut onto the shortened keelbolt) hole in the stub.

If you had to chase or rethread the stub you'd need even more clearance, probably on the order of 3 - 3 1/2 inches...

I have fairly recently actually done this, not on a keelbolt but on a 1" light pole anchor bolt in concrete that a worker snapped off below the surface while trying to straighten the bolt to fit the pole flange.

We had to remove about 3" of concrete to get the top surface of the coupling nut flush with the surface of the concrete the other anchor bolts were set in, and then chase the threads to be able to thread the coupling nut on. Fairly simple and effective, but we had a relatively open area to work in.

I can't imagine trying to do it in a keel sump, even if doing so didn't irreparably damage the structure holding the ballast on.

If one has the ballast off, then it is possible that it could work, but the proper repair would be to remove the bolt and install a new one.

As for using a 'flanged deep socket nut', the same uncertainty problems arise; how does one repair the threads if damaged?, how does one remove the lead in the bottom of the hole to give enough clearance to tighten the nut?, how does one cut the recessed bolt off if it's necessary to shorten it?

Given the restraints imposed by the the nature of the construction of this system, the possibilities for repair are realistically limited to standard construction practices. Attempting to reinvent the wheel here is likely to cost more in the long run.
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Old 06-05-2018, 11:06   #78
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Re: Keel bolts... is this the end?

Can't speak for the actual "best" repair method, lagscrews etc, but my prep approach would be to haul the boat and set it up with the ability to drop the keel. Then go to work on the keel nuts, loosen off, clean up rod and then retorque to factory specs. Best with new nuts and bearing plates fitted. If you have any failure along the way, so be it. Once you've gone end to end at least you'll know what you have that is still intact. If you have a dozen keel bolts and you lost say 3-4, then you can plan your fix, either the spare tire patch up to get you home or continue and drop the keel for repair. But at least you'll have a better assessment of the overall risk.

Speaking for myself only, I'd be inclined to sister up any bad bolts (if only a few) at a decent distance away, which may require rebuilding the bearing locations to be as solid as originals. I'd sister with stainless rod with coarse threads. I wouldn't use lag screws, as tightening them puts both tension and torsion into the screws, while threaded rod with well lubed threads is mainly tension loading and less likely to snap off the rod than a lag screw.
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Old 06-05-2018, 11:42   #79
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Re: Keel bolts... is this the end?

If you can snap off a 3/4" lag screw, you're a better man than Superman
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Old 06-05-2018, 12:09   #80
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Re: Keel bolts... is this the end?

But if Superman's lag screw hasn't pulled down tightly because it's galled up and jammed, how will the keel actually be supported? Plus the original specs for torquing down a keel bolt are based on a threaded nut being torqued down, not a lag screw into a hole. Not trying to be silly, it's just that the words lag screw and high quality precision part don't jive in my mind. I agree with you BTW, but it's the cost difference, suitability and durabilty of the fix over the long term I'd be balancing out. I will admit to having driven my old beetle home once using vice grips for a steering wheel.... Cheers
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Old 06-05-2018, 12:20   #81
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Re: Keel bolts... is this the end?

A few observations:
1. To answer the title question, in my opinion, YES, but....
2. I would not sell a boat with any such repair without disclosure. Nor would I buy one if the repair were disclosed.
3. Depending upon cost and your personal pucker factor, make the repair and either head back during a really great weather window or see if the boat can be sold there.
4. There are several more of less possible and appealing solutions suggested in the thread, although I, as a non-engineer/marine architect/expert, have doubts that all of the applicable forces/stresses have been properly considered and applied.
Caveat: I've never lost a keel, but from what I've read recently (in newer boats) the result can be deadly, and here the knowledge, risk, and all the rest are in your possession, so there ain't no one else to blame. Whatever you do, may the force be with you.
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Old 06-05-2018, 16:37   #82
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Re: Keel bolts... is this the end?

I wish Motown would come back and tell us what he's done.
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Old 06-05-2018, 20:12   #83
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Re: Keel bolts... is this the end?

Lot of nonsense here.

The trepanning tool only needs to have an OD sufficient to allow minimal clearance for the re-threading tool. Off the top of my head I'd say a 3/4"bolt needs an internally threaded sleeve of sat 1 1/8" (assuming a 3/4 UNF thread) The sleeve would need to be a maximum of 2" long with a stud Locktited into the top and double nuts to screw it on properly.

The rethreading tool could be manufactured from a die nut tig welded onto a piece of tube with a T handle on top. Grind off the hex back to the OD of the tube. So cheap it would probably be prudent to knock up a couple.

Once the tools and parts are sourced it's about a 2 - 2 1/2 hour repair and just as strong as a complete new bolt provided the bolt has not corroded down into the lead keel.
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Old 06-05-2018, 22:48   #84
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Re: Keel bolts... is this the end?

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Originally Posted by RaymondR View Post
Lot of nonsense here.

The trepanning tool only needs to have an OD sufficient to allow minimal clearance for the re-threading tool. Off the top of my head I'd say a 3/4"bolt needs an internally threaded sleeve of sat 1 1/8" (assuming a 3/4 UNF thread) The sleeve would need to be a maximum of 2" long with a stud Locktited into the top and double nuts to screw it on properly.

The rethreading tool could be manufactured from a die nut tig welded onto a piece of tube with a T handle on top. Grind off the hex back to the OD of the tube. So cheap it would probably be prudent to knock up a couple.

Once the tools and parts are sourced it's about a 2 - 2 1/2 hour repair and just as strong as a complete new bolt provided the bolt has not corroded down into the lead keel.
Indeed, mostly from people making dangerous suggestions about something that they apparently haven't fully considered or don't understand; the mechanism securing the ballast to the stub or hull. And/or that have an unrealistic view of the scope (in either execution, longevity or reliability) of the operation(s) they're suggesting, and likely their own abilities. Or the potential of making the problem worse, or potentially almost irreparable (within the scope of value that is; anything can be repaired), when the almost inevitable surprises are found.

By the way, a standard 3/4 die is 1 7/16" across the flats, which would make it about 1 11/16" across the corners; the minimum 'trepanned' hole (to allow for "treppanning eccentricity' around the bolt) would have to be at least 1 3/4"" for a 3/4" bolt.
But I guess you can turn down the (hardened) die while you're making your (dangerously thin walled in this application) 1 1/8" sleeves...

I'm still curious how the bolt is going to be shortened the at least 3/4" minimum required, down in your 1 1/8" hole; I suppose a die grinder?
Or would you suggest some kind of 'cup washer' to go over the spliced stud to provide the necessary clamping pressure? Imagine the localized compression force that's going to put on the weakened glass around the 'trepanned' (wallowed out?) hole around the spliced stud from that bit of jury-rigging...certainly conducive to a balanced structure.

Just for grins, stolen from http://www.cruisersforum.com/forums/...ir-164093.html ... that's a similarly sized boat, 42', with what appear to be 10 one inch and 2 three-quarter inch bolts holding the ballast on...

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Old 06-05-2018, 23:53   #85
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Re: Keel bolts... is this the end?

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Originally Posted by Motown View Post
First boat, been though a lot learning exactly what the hell sailing is all about.. got the 1982 39' o'day from Norfolk to rock harbor eleuthra Bahamas

Looks like he already got a fair way with the corroded bolts

and found that two keel bolts were so corroded that I was able to knock em over with a ball peen hammer

and has already shortened them

, the chips in the new bottom paint around the keel tipped me off to start tapping around the bilge, and eventually led me to the bad news.

Lead keel, so j bolts, found the company in Rhode Island that'll replace each bolt for about $700.. lookin at four minimum I'd say. I wouldn't be surprised if this fix started getting close to $10k with the haul out, storage fee, keel removal, shipping, bolts replaced, keel rebed..

and from the look of it would have to sail the boat back to Rhode Island

Tell you what guys, Im damn close to packin' my bags and shipping them back to the states, get some work and find another boat in a year or two.

Any and all advice, fixed a lot of things recently but this one got me outta left field not really sure what to do.

and is looking for any advice in order that he might salvage the boat
Like I said "off the top of my head" but even so trepanning/extending appears a viable solution.

He only needs to go down into the hull material slightly more than one bolt diameter and can use a spacer block and heavy washer to allow tensioning.

I wouldn't own a boat which had a keel fitted like the one in the video. Structure wise it's a disaster waiting to happen and the long front bolts on the forward end lead one to the suspicion that the designer is relying on these bolts to support lateral moments ie. they are being used as cantilever beams.

No wonder the damned things fall off.
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Old 07-05-2018, 05:15   #86
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Re: Keel bolts... is this the end?

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Originally Posted by jimbunyard View Post
I'm still curious how the bolt is going to be shortened the at least 3/4" minimum required, down in your 1 1/8" hole; I suppose a die grinder?
Or would you suggest some kind of 'cup washer' to go over the spliced stud to provide the necessary clamping pressure? Imagine the localized compression force that's going to put on the weakened glass around the 'trepanned' (wallowed out?) hole around the spliced stud from that bit of jury-rigging...certainly conducive to a balanced structure.

First, i agree with an earlier statement about not reinventing the wheel here. I certainly wouldn’t want to be a pioneer in keel fastening.

Second, does anyone know what ‘trepanning’ is? I googled it, gross.

Ok but back on topic, I’m not clear on everything you are saying here. Say the studs are 3/4” diameter, and the hull is an inch thick here. So you bore a nice wide hole (1.5” dia?) around the bolt right down to the lead, then stop. Or perhaps before you even get to the lead. Hopefully (you had your fingers crossed, right?) you have revealed about an inch of good stud that used to be buried in hull. Googling, looks like all you need is a sound 41/64” of length for engaging the 3/4” stud.

Now you tap that 41/64”, screw in a custom, round collar nut that fills your 1.5” bore and has a big wide flange to mate with hull around your hole, err on the ‘nut’ being too long and make up the difference between flange underside and keel with G10/etc.

Thats the picture perfect scenario for this repair (if there is such a thing), but I’m realizing I’m picturing my own lump of lead which offers almost 2 feet of width, this is significantly different than a skinny fin keel, so in that case maybe theres not enough room to do what I’m talking about. And its probably a pipe dream that the studs would be in good shape where they were passing through the hull, as I recall thats actually where the bolts on my P22 were at their worst.

Another problem is the tapping tool bottoming out. I wonder, do they make progressive tap sets to get around that problem? Whereas the typical tap will cut more and more over its length until it gradually gets to the intended thread geometry, i wonder if there are sets where you progress from a first pass cut, to a new tap thats cutting a little deeper, to another thats cutting a little deeper, etc. This could get around the ‘bottoming out’ problem.
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Old 07-05-2018, 07:56   #87
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Re: Keel bolts... is this the end?

Trepanning in machinist lingo is cutting a groove in a face basically. Requires a specific grind to the tool so that the relief of tool isn't bound as the workpiece spins in the lathe.



I guess I don't totally follow how this would help the OP, but I gather it involves using the existing keel bolt to act as a concentric guide and a custom tool would be made to rotate around that? I read that comment quickly and didn't really think it through.
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Old 07-05-2018, 08:02   #88
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Re: Keel bolts... is this the end?

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Originally Posted by sailah View Post
but I gather it involves using the existing keel bolt to act as a concentric guide and a custom tool would be made to rotate around that?
Ah that makes sense, thanks!
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Old 07-05-2018, 15:02   #89
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Re: Keel bolts... is this the end?

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Originally Posted by wyb2 View Post
I wouldn't use anything intended for concrete in lead without serious confirmation that it will work. They are very different materials.

In the case of epoxy-set anchors, in concrete the epoxy has a rough porous surface grab onto, which means even if the epoxy had no adhesive properties at all it will still resist pullout. Imagine trying to slide 2 sheets of sandpaper against each other. In lead, it will be relying almost entirely on adhering to the relatively smooth inner surface of the hole.
Duh, what does sandpaper have to do with epoxy strength on different materials???? And why does it matter if the material is porous? The epoxy binds to the material it is placed upon. Kinda how 5200 will hold two pieces of fiberglass to each other. Here is how it works to bond two smooth steel plates together


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Old 07-05-2018, 17:36   #90
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Re: Keel bolts... is this the end?

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Duh, what does sandpaper have to do with epoxy strength on different materials???? And why does it matter if the material is porous? The epoxy binds to the material it is placed upon. Kinda how 5200 will hold two pieces of fiberglass to each other. Here is how it works to bond two smooth steel plates together
It was an analogy intended to communicate the concept of mechanical interference vs adhesion without too many words. Here are the rest of the words:

Adhesion-
This is how glues work. Epoxy is a pretty darn good adhesive, so is 5200. But all adhesives are dependant on the properties of the surface they are bonding to. Epoxy adheres well to fiberglass or marine ply, or a bunch of other materials, but try to use it on a smooth piece of polypropylene or polyethylene and you will likely be able to pull the result apart by hand. That's why you can knock cured pucks of epoxy out of the bottom of a mixing cup (usually polypropylene).

Mechanical interference-
This is how threaded fasteners (among other things) work. No surface is adhering to any other surface, but geometry dictates that something has to deform to allow movement. Because cured epoxy has decent strength, it can be used as a mechanical part as well as an adhesive. If you applied wax to a threaded rod, then set it into epoxy, you would have a hard time pulling the rod straight out, but you could easily turn it out. The epoxy didn't adhere to the rod at all, but it did form functional threads when in cured. Well, it does a very similar thing in a porous material like concrete. Even if the dusty, dirty surface of the concrete makes for a very poor adhesion surface, the epoxy will flow into all the small nooks and crannies, forming an opposing rough surface. When cured, pulling the epoxy "puck" out of the hole requires these 2 rough surfaces to slide past each other, much like 2 opposing sheets of sandpaper.
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