# Re-torquing Keel Bolts



## weephee (Oct 25, 2008)

I am finally coming down to the short strokes in restoring my Columbia 8.3 sailboat. One of the final tasks I wanted to do was to retorque the keel bolts. In searching Google I found an article that said you should never, ever retorque these bolts and if you do the bolts will need to be replaced. This makes no sense to me so I thought I'd ask the experts here what I should do. I also have never been able to find the specs on how tight these nuts should be. The nuts are 1 1/8 inches. I put a long wrench on one and with some effort I was able to tighten it a little. Two question then, should I retorque them and where can I find the torque specs. Thanks again
Larry


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## Gary M (May 9, 2006)

Yes you probably should re-torque, which means finding a suitable torque wrench. No way you can guess at it and you do not want to over torque. 

As to what they should be torque at there are standard tables for torquing SS rod that should be OK but if you can find the builders spec so much the better.


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## c40eb (Sep 12, 2002)

I have a 30' Sabre, and the manual states the keel bolts should be checked and torqued (to 90 foot pounds), as necessary.

From the manual:

"...Occasionally, water from the bilge may seep through this crack when boats are hauled. This would be due to a slight leak at a keel bolt, which can be readily be overcome by tightening the keel bolt nuts. As part of launching procedure, check all keel bolt nuts for tightness to 90 foot pounds before the boat is lifted out of the cradle."

Now...I don't know what you're boat manufacturer would say, but I can't see why you wouldn't want to check and tighten as needed.


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## weephee (Oct 25, 2008)

Thanks for the replies. I'd say they are certainly not at 90 ft lbs if I can tighten with a wrench. The Columbia boat is no longer made so there is no contacting the manufacturer but there is a site that has the original boat dwgs so I will order the one for the keel and hopefully it will tell me the torque. Would it be safe to say the torque would be at least 90 lbs. Thanks


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## c40eb (Sep 12, 2002)

I'd hesitate to say what to tighten your bolts to...as it most likely depends on the size. Hopefully, you can find out from someone who has your model, or at least more knowledge.

Sorry!


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## TommyD (Sep 16, 2005)

*Torquing Bolts*

First start with the bolt size.. typically manufacturers use a bolt size appropriate to the load they will encounter with some safety margin. You would be amazed by how much linear force a thread will transmit because of the mechanical efficiency. 90 ft-lbs is a literally a boat load of force.

Using the simple calculator here

http://www.engineersedge.com/calculators/torque_calc.htm

a 1" bolt @ 90 ft-lbs transmits 960 lbs of linear force. If you have a half dozen, that is close to 3 Tons of clamp.

Torque with caution, & not all at once.

TD


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## weephee (Oct 25, 2008)

Thanks C40EB. TommyD, there are 6, 3/4 inch bolts with 1 3/8 inch nuts. The lead keel weighs 3100 lbs. I just read in my manual that the bolts should be tightened every year but unfortunately doesn't say how tight.


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## Sabreman (Sep 23, 2006)

On my Sabre 28 and now on the 38, I apply a simple approach. With the boat hauled and blocked (i.e., resting on its keel), I use an appropriate socket with a 3/4" ratchet and a 12" extension pipe slipped over the handle. I then tighten the nuts as much as I am able while bracing my feet against the mast, seats, etc. The keel boats are at least 1" and I am not nearly strong enough to break them (perhaps others are more manly than I ). In 23 years of boat ownership, the best that I've been able to tighten a bolt was 1/16th to at most 1/8th of a turn. This spring, I was only able to move 1 bolt. Good enough.


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## RichH (Jul 10, 2000)

Proper torquing REQUIRES that the bolts be properly lubricated, and requires that the 'torquing' be done in increments and 'reverses'. .... Unless the manufacturer (now long out of business) listed otherwise.

If you dont lubricate, dont 'increment, loosen tighten - loosen tighten ... you usually wont atting the 'spec'd' torque values. 

If you dont have access to the OEM torque values/methods, do websearch for the values (principally from MECHANICAL ENGINEERING WEBSITES, etc.), choose the correct bolt materials, etc. "torque values" + bolts + (your choice of material). You will need to know bolt material, number of threads per inch, etc. 

;-)


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## Gary M (May 9, 2006)

Sabreman, you could well be over tightening them, I tried what you are talking about once with a long torgue wrench. Sitting on the floor and using one foot to push the torque wrench I was able to get close to 400 lbs of force. You really need to use a torque wrench.

Rich H there are tables for dry torquing which is most common or torquing with a lubricant.


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## RichH (Jul 10, 2000)

Gary M said:


> Rich H there are tables for dry torquing which is most common or torquing with a lubricant.


Dry torquing is usually wholly inaccurate and usually doesnt ultimately apply the correct torque. With dry torquing one never knows if the 'wrench values' are from the threads 'point/friction' welding together or if you are actually reaching full spec. torque. This is a REAL BIG difference, especially when torquing STAINLESS STEELS.


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## weephee (Oct 25, 2008)

What about compression of lead keel to fiberglass hull. Maybe in theory you can torque a nut to 120 ft lbs but might that not create too much compression on the fiberglass and crush it. Perhaps the spec would call for a less than theoretical value for this reason. Am I correct in thinking that that would be a factor to also consider. RichH, what would you use for a lubricant.


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## Sabreman (Sep 23, 2006)

> What about compression of lead keel to fiberglass hull


When a boat is blocked out of the water it rests on its keel. The jack stands are only used to keep it upright. If you have a 16000# boat with 8000# ballast, that means that 8000# is being exerted on the keel to hull joint. The design of the boat allows for that which is why the keel doesn't come through the floorboards when blocked.


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## olson34 (Oct 13, 2000)

There is a good table of keel bolt torque values on the C&C owners' site, and we have some stuff also on the Ericson owners' site as well.
Over the years, I have noticed that in the real world it all gets down to one boat yard guy, working in a confined space in the interior, with a 1" socket bar with a 3' cheater-pipe and putting a good bit of shoulder into it.

We had our keel dropped for rebedding due to a slow lead around one bolt and the concern that corrosion might be setting in where the ss threads are deprived of oxygen below the nut and washer...
We found only some surface rust and no structural problems. With the keel top and the hull cleaned up and thoroughly dewaxed it was all torqued up with new sealant/adhesive and has never leaked a drop since it was done in '02.

I just look at this as a preventative maintenance item every 15 or 20 years, or so.

Regards,
L

ps; echoing the information from Sabreman, our boat (and the smaller fin keel boat that preceded it, have always rested on their keels when in the yard, with multiple jackstands used to keep them upright.


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## RichH (Jul 10, 2000)

weephee said:


> RichH, what would you use for a lubricant.


30 wgt. oil is the 'usual' for plain vanilla torque applications.

Here's a typical torque value chart for common bolting materials: http://www.engineersedge.com/torque_table_sae.htm


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## weephee (Oct 25, 2008)

Thanks once again everyone for all the valuable information. If I am unable to find the manufacturers suggested torque, I will go with the above table. I will let you know how I make out.


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## RichH (Jul 10, 2000)

olson34 said:


> Over the years, I have noticed that in the real world it all gets down to one boat yard guy, working in a confined space in the interior, with a 1" socket bar with a 3' cheater-pipe and putting a good bit of shoulder into it.


Thats a damn good way to make the keel fall off unexpectedly later on !!!!!!

If the OEM manufacturer/designer really knew his/her engineering, he/she would design the bolt torquing so that the stress never or rarely exceeded 30% of the Ultimate Tensile Strength - UTS of the bolt (~90,000 psi for 'stainless'). If you go above this 1/3 UTS or 30,000 psi limit .... FATIGUE (FAILURE) will RAPIDLY occur due to load cycling of the keel and you can wind up with several unexpected 'water fountains' in the keel sump if the boat doesnt actually 'invert'. .... and thats the reason why a knowledgeable mechanical or structural engineer avoids a boat with bolt on keel unless he/she can validate what stress level design is in those bolts !!!!! Happily, most designers 'overbuild' such structurals to a 'safety factor' of 3 .... 90,000/3 = 30,000 psi which is the 'fatigue endurance limit' for most common stainless. A cheater bar and lots of 'shoulder' can EASILY exceed this LIMIT. 
USE a TORQUE WRENCH, leave the '500 lb. gorilla mechanics' for someone elses boat. 
;-)


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## olson34 (Oct 13, 2000)

RichH said:


> USE a TORQUE WRENCH, leave the '500 lb. gorilla mechanics' for someone elses boat.
> ;-)


I agree about the need for correct torque, but after observing boat yard workers for three decades, I would observe that the initial tightening gets done with a "breaker bar" followed by a long bar and _hopefully_.... finished off with a torque wrench. 

L


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