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-   -   keel bolt torque (https://www.sailnet.com/forums/gear-maintenance/330660-keel-bolt-torque.html)

David Spear 07-19-2019 01:58 PM

keel bolt torque
 
I have a 1981 CS36T. During a recent haulout I saw that there's a hairline crack at the keel/hull joint at the front of the keel. I've owned the boat for close to 10 years and can guarantee that the keel has never hit anything, anyone have ideas as to if I should be worried? I've put a wrench on the keel bolts I can get at - there are 13 of them and at least 2 are underneath the mast step so... tough to access. They are quite large - 1-1/2" nuts - so I doubt I'm getting much torque to them with an 18" long 3/4" drive ratchet. At any rate none of them budged. Is there a method to torquing them that does not involve pulling all floorboards and the mast and hitting them with an industrial-sized air ratchet?

Thanks for any help.

Minnewaska 07-19-2019 04:47 PM

Re: keel bolt torque
 
Sometimes the nuts are stuck by the adhesive below them. Not a job for a hand ratchet. Get the specs and a large torque wrench. Use a long pipe as extension. You’ll need a helper to hold steady. If you need a torque multiplier, you’ll need two helpers.

Ninefingers 07-19-2019 05:57 PM

Re: keel bolt torque
 
Quote:

Originally Posted by David Spear (Post 2051615808)
I have a 1981 CS36T. During a recent haulout I saw that there's a hairline crack at the keel/hull joint at the front of the keel. I've owned the boat for close to 10 years and can guarantee that the keel has never hit anything, anyone have ideas as to if I should be worried? I've put a wrench on the keel bolts I can get at - there are 13 of them and at least 2 are underneath the mast step so... tough to access. They are quite large - 1-1/2" nuts - so I doubt I'm getting much torque to them with an 18" long 3/4" drive ratchet. At any rate none of them budged. Is there a method to torquing them that does not involve pulling all floorboards and the mast and hitting them with an industrial-sized air ratchet?

Thanks for any help.

Is the 36t a lead keel? I torqued the bolts on my CS27 a couple years ago. I managed to get a 1/4 turn out of a couple of them. It did it on the hard though, with the boats weight resting on the keel, so I wasn't lifting the keel with the bolt.

My keel is lead, and I had the same small crack in the same spot as you. I think the lead holding the j bolts gets compacted over time from having to suspend the weight. But I will defer to someone with more knowledge, because I am just assuming that is how they are constructed. But in my case my theory appeared to be true and the problem was solved.

eherlihy 07-19-2019 06:04 PM

Re: keel bolt torque
 
Note that fiberglass has a finite compressive modulus. While it is higher depending on how much fiber is in the mix, you still need to be careful not to overtorque the nuts, thereby crushing (and weakening) the layup. I regularly remove the nuts, washers, and backing plates on my keel bolts and retorque them to the limit of my strength while using a 25" breaker bar. My guess is that my limit is somewhere around 200 ft/lbs which is more than good enough!

Removing the bolts takes patience because I have to find the spot where the socket grabs the bolt, and I can engage the breaker bar with the socket and still have room to move the breaker bar... and I have to do all of this blind on one of the bolts because it is about 18" under the cabin soule.

David Spear 07-19-2019 06:50 PM

Re: keel bolt torque
 
Good info, thank you guys. I could probably remove all but 2 of the bolts if I was lucky. I have a 3/4" drive ratchet with some extensions, but the ratchet is like 12º per click so not much room as you describe. Next time I have the boat on the hard I'll try removing some pairs of bolts and re-torquing with a snipe bar, I believe there's a backing plate per pair of bolts the middle. My bolt pattern from aft to forward is 1-1-2-2-2-2-1-1, the forward 2 bolts are under the mast step and there's not enough clearance on top of them to get a socket on.

roverhi 07-19-2019 09:29 PM

Re: keel bolt torque
 
If it's only a hairline crack probably not a problem. Normal for the unyielding metal of the keel to work against the more flexible fiberglass. It's especially evident if someone tried to glass over the join or used a not flexible sealing compound. Fill with Lifecaulk or 4200, smooth out and paint over.

David Spear 07-20-2019 10:39 AM

Re: keel bolt torque
 
Quote:

Originally Posted by roverhi (Post 2051615898)
If it's only a hairline crack probably not a problem. Normal for the unyielding metal of the keel to work against the more flexible fiberglass. It's especially evident if someone tried to glass over the join or used a not flexible sealing compound. Fill with Lifecaulk or 4200, smooth out and paint over.

I like this answer. Yes it's just a hairline crack. The boat gets a coat of ablative paint at the end of every summer, I'll see how much paint I have to remove to get to the glass to fill it in. I just really wanted to know if periodic torquing of the bolts is a routine maintenance task that I should have been doing all along which may have prevented this. It feels more like normal wear and tear, but it's a bit nerve wracking to see cracks on the bottom.

Thanks for everybody's replies.


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