Tightening Keel Bolts

[Tartan34C]

This is the information I have in my files accumulated from being in the repair business for thirty years and it says the keel bolts should be torqued to the following specification according to these manufactures:

George Gulden from Tartan Yachts, service bulletin I have from Tartan
1/2" 180 ft/lbs
3/4" 250 ft/lbs
1" 350 ft/lbs

C&C Yachts service bulletin
1/2" 180 ft/lbs
3/4" 250 ft/lbs
1" 350 ft/lbs
1 1/4" 450 ft/lbs

Bill Shaw, Person Yachts, from a letter I received from him and an owner’s
manual
5/8" 70 ft/lbs
3/4" 125 ft/lbs
1" 280 ft/lbs

All the best,
Robert Gainer

[sailingdog]

Why do the Pearson numbers look so low, when compared to the C&C/Tartan numbers? Is their keel attachment that radically different a design??

[hellosailor]

pigslo-
Remind me to let Charlie Morgan build my boats, but not work on my car. There have been major issues with brake rotors warping and failing because greasemonkeys were over-torquing lug nuts. There is no such thing as "as tight as a car wheel" because the proper torque ratings vary over a wide wide range, and using any one number for all lug nuts will leave some loose, and others creating damage.
Case in point, mine are spec'd to about 75 ft.lb. but most shops and dealers have set them to 125-150ft.lb., where even a breaker bar can barely budge them. This, despite express warnings from the car makers.

If the designer has done their job properly, there is a default SAE, ASTM, etc. torque rating for each size/grade of bolt, and that is the rating which "should" be used. If the designer took that into account and built the hull layup to match. If someone used generous bolts and intended them to be under-torqued..."properly" torquing them might damage the glass, I'd guess.

Kinda like going to a casino, no matter what you do, the odds are against you.

[Tartan34C]

Originally Posted by sailingdog

Why do the Pearson numbers look so low, when compared to the C&C/Tartan numbers? Is their keel attachment that radically different a design??

I don’t know Sailingdog but when I was in the business my interest was in doing it by the manufacturer’s book because we wanted the warranty work and I didn’t really care about some of the details at the time. Now I wish I could go back and ask about it but that feeling will pass after dinner and a drink.

By the way, to get 350 or 450 foot pounds we used a torque multiplier and 1 inch drive wrenches and sockets. Some of the sockets had the top cut off and a short pipe welded between the top and bottom pieces to get a socket deep enough for some of the keel bolts.
All the best,
Robert Gainer

[capngregg]

Depending on the type of material the bolt is manufactured from, the initial torque loading of the bolt may vary considerably. For instance some bolts aren't even set by a torque value necessarily, they are set by achieving a compression load on a rotating washer. Some bolts (depending on their material) will also tend to succcumb to intergranular corrosion when in tension at various torques.

The designer of the installation should be consulted to determine the correct values. The folks at Valiant Yachts said the keel bolts don't really matter that much once they have been installed and torqued up. (and the adhesive they use cures) As they explained to me the adhesive joint at that point is stronger than the bolts themselves.

[pigslo]

What Charlie Morgan e-mailed me specifically was that he designed the keel with rubber donuts that cushion the keel. I don't think many boats are built this way. Although my boat was designed and built by Mr. Morgan, nowhere on the boat is his name. She is a Heritage West Indies named after his entry into 1970 Americas Cup. I only point this out so no-one gets the impression that Morgans in general were spec'd this way.
pigslo

[sailaway21]

On reading the post originally I was struck by the thought as to why the keel bolts would need to be re-torqued. Other than the nuts backing off, which I fine unlikely, I would think that the need to re-torque them would be because something changed. Changed not for the good. If the bolts have stretched I would be asking why. Perhaps this is a regular maintenace item I am not familiar with. Over torqueing strained bolts is an iffy proposition at best. Maybe Tartan could expand on his experiences.

[hellosailor]

pigslo-
Rubber donuts?! Sheesh, suspension bushings on a boat, who'd a thought.

I suppose that means, like suspension bushings on a car, or the engine mounts on a boat, you really need to drop the keel and replace those bushings every decade or so in order to maintain the ride quality?

[sailingdog]

Nah, he doesn't sail fast enough to really put any wear on them... he is called pigslo for a reason.

[pigslo]

Actually, dog... with 700 sq ft of sail ( main and 100%jib) and a 32 foot waterline on a 36 foot boat, she will hold her own. Pigs are smarter than dogs..it's a fact.
pigslo