Suitable metal for replacement keel bolt in cast iron keel?

[Sandero]

Ocean Girl,

Of course keels have fallen off. I am curious as to how common this is. When i look at the tens of thousands of sailboats in LIS for example each season... not being aware of and dropped keels... I am wondering how common this is? It seems like a very very rare occurrence. So I phrased the question poorly.

Is this something that boaters should be concerned about and think about preventative maintenance?

I think about this possibility but would never consider opening and replacing 16 keel bolts on my boat without a symptom.

I have to say that my Contest keel has a very wide flange, 16 well space athwart ship bolts running from the mast to the companionway. I can't imagine the keel dropping or being ripped off. The hull to keel design is well engineered and not likely to fall off. I think the Pearson of the OP is similar, not quite as good... easier to service and more exposed to corrosion from the bilge side.

Interesting thread never the less. When designers push the limits of engineering to gain speed they are tossing away safety factors for speed.

[OrangeCrush]

Something like this... (only not with Crayola clay)

There is no need for the top of the bolt head to sit flush, since the recess in the iron is deep enough to cover the hex head as well. It just needs to be tapered for the purposes of distributing load and filling up gaps.

I don't really see the need to bond the epoxy to the iron first, since it will be held in place by the tightened bolt, and the any gaps will be filled by the caulk. (I am still planning on using lifecalk unless somebody has a better idea. The stuff that was in there originally was white but a bit harder than caulk I think. Anybody willing to second the tuf-fil suggestion?)

I'm also going to coat epoxy/filler over the head of the bolt (on the bottom), then use faring compound, then another layer of epoxy before the bottom paint, as well as coating the nut/bolt end (inside the hull) for extra sealing.

Could this approach work? I like it because it uses the most corrosion resistent steel of all my choices (I think) and because I have everything I need already. But if there is a reason this is a bad idea I really want to know!

Thanks!

Jack

[roverhi]

Manitu, think your chart is way way off where they placed 304/316 stainless. 304/316 should be lumped in with stainless steel much farther up the list and acceptably close to steel/aluminum, etc to use in a marine environment.

Go with SS bolts for the keel. 316 if you can find it. Try and buy from a US manufacturer as the Chinese stuff is questionable alloy. Seal the bolts in place with LifeCaulk or 4200/5200 and they should do just fine for another 35 years. As long as the bolts are sealed well and saltwater doesn't intrude, there is no problem with crevice corrosion. Even if water does intrude, they will last a long long long time. Annual retorqueing should tell you if any of the bolts has been compromized. With that many bolts, you'd need to lose more than 1 bolt and probably 2 on the same side for it to become a problem needing immediate attention.

[OrangeCrush]

For everybody's info, I found this article from Don Casey informative regarding keel bolt maintenance and stainless v. galvanized

Keel Bolt Concerns - SailNet Community

[barnakiel]

I would not trust epoxy / solids (e.g. silica) only. If building beds, jackets for bolts, etc., I would go the grp way.

In our boat, the bolts go from the top (a single huge washer with two holes for each pair of bolts here) and the end of each goes out into a pocket in the keel - there goes a huge (bolt dia fit hole) washer, then the nut. The pocket is filled with epoxy putty (possibly talcum or other white stuff) flush. Very neat and easy to control.

b.

[Anonymous7500]

Originally Posted by OrangeCrush

Could this approach work? I like it because it uses the most corrosion resistent steel of all my choices (I think) and because I have everything I need already. But if there is a reason this is a bad idea I really want to know!

Thanks!

Jack

No.

There are a couple serious problems with the approach that you are presenting.

First of all, you are not going to be able to match the angle of the hole with the the build up that you are putting on the bottom of the bolt. The angle is most likely between 80 and 82 degrees. What you are doing is not going to create a consistent mating surface.

Secondly, and in my opinion the more critical, the original bolt has a much higher surface area of contact with the keel material. If you have a standard 3/8" hex and 3/8" flat head, the hex head has .164" square of surface outside of the body of the bolt and the flat head has .293" square of surface outside of the body of the bolt. The flat head is bearing on 80% more surface than the hex head.

[OrangeCrush]

Points well taken, A7500.

As for the angle issue, since these replacement bolts are so hard to find, I'm gonna have to go with whatever angle they come with. If the Grade-8 bolts I get are a little off of the original angle, the mating surface could be just as bad as if I eyeballed it with the epoxy. To solve this problem, I could actually use the keel holes as a mold for the epoxy buildup. That is, I could grease up the hole, and while the epoxy is still soft on the bolt, push in the bolt gently to make it take the shape of the tapered iron hole. Then I would take it out and let it fully harden before installing it again permanently.

As for the surface area, I get what you mean, but if the epoxy is there and has strong compressive strength, doesn't it transfer the downward (or in this case upward) force of the hex head out sideways? And since the bolts are many times stronger than they need to be, isn't this less of an issue as long as they don't get too corroded?

Barnakiel, what is the grp way?

[Anonymous7500]

Originally Posted by OrangeCrush

As for the angle issue, since these replacement bolts are so hard to find, I'm gonna have to go with whatever angle they come with. The angle of 80-82 degrees has been around for a very long time.

To solve this problem, I could actually use the keel holes as a mold for the epoxy buildup. That is, I could grease up the hole, and while the epoxy is still soft on the bolt, push in the bolt gently to make it take the shape of the tapered iron hole. Then I would take it out and let it fully harden before installing it again permanently. That would seem to produce an accurate surface.

As for the surface area, I get what you mean, but if the epoxy is there and has strong compressive strength, doesn't it transfer the downward (or in this case upward) force of the hex head out sideways? I can't speak to the strength of this method.

One other thing, you know that the correct bolt will potentially last at least 35 years. You don't know if a hex/epoxy hybrid will last for any length of time.

Good luck.

[Searchh2o]

What did you end up doing and what was your final torque?

[GordMay]

Greetings and welcome aboard the CF, Searchh2o.

[boatpoker]

How about having the bevel machined onto the hex heads, would that leave enough head for the socket ?

[Dymaxion]

Maybe try Grade 12 Allen head bolts and have a machine shop cut the conical faces in at correct angle. Won't solve your corrosion concerns however, but a lot higher strength steel.

[OrangeCrush]

I wrote this in a message but figured it belonged here too:

Hi yes the project went well and I do believe I chose the right bolts. I used an anti-sieze around the tapered head. And yes I used about 70lbs of torque as was recommended to me.

Don't know if you got the old ones out yet... As soon as you start pounding, the round filler material pops out of the bottom, no need to dig it out or anything first. To pound them all the way out is a workout. Be careful because if they splinter or mushroom out badly you'll never get them through. One bolt started to expand but luckily it started moving down before it got too bad.

All of my bolts except one came out looking pretty much like new. The rust I had seen on top was only coming from the washers. The one bad bolt actually was from a factory error. as they had drilled one of the holes a half inch off and redrilled it overlapping the other hole. So there was a cavity holding water there against the bolt for decades. It lost a bit of surface material but even that was still looked pretty solid. I stopped after that because I didn't see the need to do the rest. The one with the messed up hole had been weeping rusty water from below, so that was my only real suspect anyway. What I'm saying is I replaced the other 3 without really needing to, so if you're doing the job as a precaution you might try one or two first and see how they look before taking them all out.

I coated the bolts/washers/nuts with west system epoxy with hardener and barrier coat additive. Before I did I took a small section of stainless bar and drilled a hole in it for a lighting ground, which I held on the top of one of the bolts with an extra nut, then coated everything well. The 4 bolts I replaced came out looking great and still looked perfect about 3 years later when I sold the boat.

Hope that helps!

Jack

[OrangeCrush]

I used the bolts linked from Dan Pfeiffer's site and I had them hot dipped galvanized.