Replacing lead Keel bolts

cousineddy · #1 10-13-2012

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?

Gene T · #2 10-13-2012

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

misfits · #3 10-13-2012

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

kd3pc · #4 10-13-2012

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

Gene T · #5 10-13-2012

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

cousineddy · #6 10-13-2012

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!

Stumble · #7 10-13-2012

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.

misfits · #8 10-13-2012

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.

SloopJonB · #9 10-13-2012

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.

cousineddy · #10 10-13-2012

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.