Keel bolt torque values ????

anerussis · #1 10-05-2012

After reading some postings suggesting that the keel bolts should occasionally be re-torqued I decided to do just that on my recently acquired 1977 C&C 26.

There are several 1/2" nuts and 1- 1/2" nuts on the keel bolts.

I used my breaker bar on the 1/2" nut expecting a battle but was able to quite easily tighten it at least 1/2 a turn. I did not attempt to tighten the rest fearing that I may cause more damage then good and possibly break the seals causing leaks.
Does anyone know the torque values for these 1/2" and 1 1/2" nuts or does one just tighten by feel which would of-course very by the size and strength of the individual.

RobGallagher · #2 10-05-2012

Quote:

Originally Posted by anerussis

After reading some postings suggesting that the keel bolts should occasionally be re-torqued I decided to do just that on my recently acquired 1977 C&C 26.

There are several 1/2" bolts and 1 1/2" keel bolts.

I used my breaker bar on the 1/2" bolt expecting a battle but was able to quite easily tighten it at least 1/2 a turn. I did not attempt to tighten the rest fearing that I may cause more damage then good and possibly break the seals causing leaks.
Does anyone know the torque values for these 1/2" and 1 1/2" bolts or does one just tighten by feel which would of-course very by the size and strength of the individual.

CNCphotoalbum.com has torque values listed by bolt size.

anerussis · #3 10-05-2012

Quote:

Originally Posted by RobGallagher

CNCphotoalbum.com has torque values listed by bolt size.

Yes I saw that but it does not list 1-1/2 " bolts --- It show 80 lbs for 1/2" and 450 lbs for 1 1/4 bolts - but would that apply to all keel boats large and small - 18 ft to 40 ft + boats?

Feel a bit dumb but just realized the nut size is 1- 1/2" and not the bolt size. I measured the nut in order to buy the socket - bought a 38mm socket which fits fine. The 1 1/2" nut / 1"bolt size to be torqued to 350 lbs -- and the 1/2" nut 5/16 bolt to 80 lbs right?

Sabreman · #4 10-05-2012

One of the routine maintenance chores that I do in spring is to tighten keel bolts. I use a 3/4" socket wrench with a 1 1/2" socket and a pipe extender. Then I torque as much as I can. It's a keel. They're big honkin' bolts. As much torque as I can apply is what I want.

With that said, Sabre recommends 90 ft lbs torque.

anerussis · #5 10-05-2012

Quote:

Originally Posted by Sabreman

One of the routine maintenance chores that I do in spring is to tighten keel bolts. I use a 3/4" socket wrench with a 1 1/2" socket and a pipe extender. Then I torque as much as I can. It's a keel. They're big honkin' bolts. As much torque as I can apply is what I want.

With that said, Sabre recommends 90 ft lbs torque.

According to the chart 1 1/2" socket is for a 1" bolt - torque to 350 ft lbs - if you tighten past that would there not be a danger of pulling the bolts from the keel or crushing the fiberglass?

RobGallagher · #6 10-05-2012

I can only tell you that I rented a large (monster) torque wrench and sockets from a tool rental joint and followed the chart for 1" bolt w/ 1.5" nut. There where no disasters that followed. If memory serves me...

Sabreman · #7 10-05-2012

Sabre recommends 90 ft lbs for a 6,800# keel. I'm pretty sure that it's a 1 1/2" nut on the bolt, but either way, I tighten as much as I can by hand while the boat is blocked. Close enough. On both my Sabres, I was able to get about 1/8 a turn on some of the bolts the first time that I did it. Thereafter, they've never budged.

If the bolt breaks from hand tightening using a standard socket wrench, then the bolt was going to let go anyway. The keel area is one of the most heavily reinforced areas on all boats. If the fiberglass crushed on a hand tighten, then the keel bed was degraded anyway and it's a blessing that you found out sooner rather than later.

SloopJonB · #8 10-05-2012

Quote:

Originally Posted by Sabreman

One of the routine maintenance chores that I do in spring is to tighten keel bolts. I use a 3/4" socket wrench with a 1 1/2" socket and a pipe extender. Then I torque as much as I can. It's a keel. They're big honkin' bolts. As much torque as I can apply is what I want.

With that said, Sabre recommends 90 ft lbs torque.

"Give me a lever and a place to stand and I will move the world".

There is a reason torque wrenches were invented - you can exert a HUGE amount of force when you put a pipe extension on a wrench, enough to shear the threads or snap the stud. Stainless steel is also easily galled when too much torque is applied. I can quite easily apply over 100 Ft. Lbs with one hand and a 1/2" drive torque wrench.

Use a torque wrench and tighten the nuts to the torque specified for that size stud. Even a cheap torque wrench is going to be a LOT more accurate than "a piece of pipe and as hard as I can".

Sabreman · #9 10-06-2012

SloopJon- you are correct and I don't do that any longer, just tightening by hand with a regular socket wrench. I should have been more clear in my explanation. Thanks for pointing that out. I should buy a torque wrench, and this may be my impetus.

jgeissinger · #10 10-06-2012

I am glad SloopJonB made his response. Re-torqueing keel bolts (actually you are torqueing the nuts, not bolts) is a subject that comes up periodically, and almost always with bad advice. He is absolutely correct in that it is not that hard to break perfectly good bolts by over tightening. It should also be noted that torque values are given for clean and lubricated fasteners, which keel bolts and nuts usually are not. Just my two cents.