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chartscharts 08-01-2006 05:38 PM

Keel Bolts Repair/replacement
Hi all,

I just bought a Cal 20. It has 6 keel bolts. The forward 2 are in good shape. The middle 2 are fairly bad (rusted). The aft 2 are awful rusted and are one is starting to look more like a rounded rust knob than a bolt/nut.

I believe this got this way due to water in the keel bolt area that the other owner didn't keep dry. There was a bit of water in there when I bought it.

I don't believe the keel bolts are leaking. After I dried it out, I've never seen water there in the few months I've had the boat.

So I'm thinking about budgeting for keel bolt replacement at the same time I haul/paint the bottom. I've talked to 2 boat yards who quoted between $1200 and $1800 to fix the keel bolts. Both proposed leaving the existing bolts in place and just drilling 4-6 new ones in the same area to hold the keel on. One called this the "catalina fix."

My questions are:

1. Does the fix sound right? Does the price sound right for the fix?

2. It will take me a while to save up for that. In the meantime, what can I do to keep the bolts from getting worse/mitigate the damage?

For question 2, I'm tempted to knock the rust off the bolts and paint them. That will work fine for 3-4 of them. However, 2 are so bad, I'd be afraid that I'd crack the nut/bolt right off if I scrubbed it too hard! What about covering the bolts up in something like sealent or a hard caulking? Something that might prevent further corrosion and keep the bad ones held together for whatever strength they might have left? Since it doesn't sound like we'll try to remove them as part of the fix, then covering the bolts in goo may not be a disadvantage to the permanent fix.

Thanks for the hints!


Hawkeye25 08-01-2006 08:17 PM

Check the size and thread count of the good nuts and get some replacement nuts that are identical to the originals. When the boat is hauled and resting on the keel, carefully slit one of the worst nuts (you can do this with patience and a dremel with slitting discs) and used a chisel and 2 pound hammer to split the nut. DO NOT SLIT THE NUT SO FAR AS TO DAMAGE THE THREADS ON THE BOLT. It will split without goint that far.

It is possible that the threads on the bolt that were covered by the nut are fine. Remove most of the top of the bolt, leaving only enough to rise 1/4" above the new nut. Clean up everything else, including the threads at the top of the bolt, and carefully install the new nut, torquing to factory specs. Do the same to the other bad nuts.

Then, make a decision to have the yard strengthen the hull/keel joint by adding several more bolts.

One of the real problems with these keel bolts isn't the corrosion in the bilge, which is a problem, but the corrosive 'necking down' of the bolts directly in the joint between the keel and the fiberglass. For some reason, I have found far too many of these keel bolts withered to less than half their original diameter.

If torquing the original bolt you fix doesn't snap it off, then you might assume yours are OK. If it does, then you know you must have the yard do the "fix" you described.

Don't feel bad if you have to do it - once it's fixed, it will be fine.


Gary M 08-01-2006 09:34 PM

I have a similar problem but with a 30 footer. In my case and likeley in yours the bolts will be stainless steel but the nuts are carbon steel and so rust rather badly. I my case I am going to try to get all 8 nuts of and clean up the threads. then install new SS nuts with a good thread lubricant and torque them. Hoping that will seal up the small leak into the bilge.

If not I will have to drop the keel and recaulk it.


pigslo 08-01-2006 09:43 PM

you can also tap the top of the bolts with a ballpeen hammer and listen to the sound (hollow or dull).


sailingdog 08-01-2006 10:50 PM

I'd recommend Lanocote as a good anti-seizing compound for the keel bolts and nuts. I'd coat the entire keel bolt, at least as far as you can reach it, as it will help prevent crevice and galvanic corrosion from occuring. It will also prevent the stainless steel nuts and bolts from seizing or galling.

chartscharts 08-01-2006 10:51 PM

Thanks for the info! This is exactly the kind of helpful hints I was hoping for.

I hope you'll pardon my ignorance (new boat owner). I'm assuming that taking one of those nuts off in the manner described is something you'd only want to do when the boat is hauled? Is this because without the nut, the bolt will drop right out the bottom, through the keel and you'll have a nice new thru-hull to the sea?

Or are the keel bolts "imbedded" in the keel and you can remove one nut at a time without fear of the bolt dropping and flooding the boat?

Part of my problem is that I don't have a trailor for it. So I'll have to rely on a boat yard to haul my boat for me. I've heard, but haven't yet verified, that they don't let you do your own work on the boat after they've hauled it (liability in their yard, plus they want the biz).

Thanks again for all the replies!


Blue Eagle 08-01-2006 11:44 PM


Originally Posted by chartscharts
I've heard, but haven't yet verified, that they don't let you do your own work on the boat after they've hauled it (liability in their yard, plus they want the biz).

I don't know whether it's a practical option, but I'd give serious thought to finding an alternative yard if this is their attitude. What additional liability are they worried about? the boat falling over while you're working on it? I know that in the US of A the frequency of mischievous litigation frequently makes people over-cautious, but this seems ridiculous - mind you, here in hong kong we have the opposite problem! lol.

Good luck!

Blue Eagle

pigslo 08-02-2006 04:11 PM

The keel bolts on my boat are imbedded in the lead.


chartscharts 08-07-2006 12:40 PM

Thanks for the replies everyone.

What do you think about covering the tops of the worst bolts in 3m 5200 adhesive/sealant? Since the repair options seem to be to either destroy the worst nuts or add new bolts, I'm not sure there'd be a disadvantage to covering it up with 5200.

My goal would be to prevent further corresion, and perhaps help hold what's left of the nuts together to keep whatever strength is left.

Lastly, does anyone know where I can find out if my keel bolts are imbedded in the keel or go through to the water? I'm trying to figure out if I take one nut off, if the bolt will drop out and flood my boat or if I can take one off at a time while it's in the water? I have a cal-20.

Jeff_H 08-07-2006 02:44 PM

You might contact the Cal 20 racing association. This is a common problem. If I remember correctly, I believe that the Cal 20's have a cast iron keel with a flange that is bolted with galv. iron bolts through the flange and bottom. With the keel dropped off the boat, the bolts are pretty easy to remove and replace (if I remember correctly, the heads are countersunk into the flange but are not welded or otherwise connected. If you use liquid wrench or PB Blaster you should be able to remove the nuts. This is a actually a very easy and routine repair job compared to the so called 'Catalina Method', which is necessary on boats that have the keel bolts cast into the ballast keel, and which is not a very good way to make the repair lasting.

As to gooping up the bolts with 5200, that is a bad idea. It will not help and may cause crevice corrosion and will make the ultimate repair much harder. I would suggest cleaning the bolts with naval jelly or ospho and then painting with a zinc rich epoxy primer. Because of the way that the Cal 20's keel is bolted on, you cannot undue the nut while the boat is in the water.


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