When I tightened my keel bolts 3 years ago, I also found this discrepancy in torque values and went with the lower numbers rather than the C&C numbers. I figured it would do little harm having them lower than too high and also went with dry as opposed to lubricated. I haven’t checked them since as I don’t own the tools and was borrowing them from the yard. I haven’t noticed the smile since then, so I feel fairly confident in things. I also addressed the smile with G flex epoxy on the exterior at the time.
On the 2 aft bolts, the original fibreglass and filler under it was crushed/depressed by the washer and nuts. I dug out the filler and replaced it with ren modelling board (dense waterproof urethane foam) and epoxy before reglassing over the whole area. I also made a level/perpendicular bed for the new backing plates with thickened epoxy. So the load from the nuts is distributed over a much larger area now. Derek McLeod 1983 C&C 29-2, Aileron Toronto > On Jan 2, 2018, at 9:16 PM, Josh Muckley <[email protected]> wrote: > > Ok so now I'm confused and concerned. Neil Schiller got me thinking about > the science and standardization of the torque specs. Wet, dry, tension, > yield strength... So I did some investigating. I expected that the specs on > the c&c photo album would loosely correlate to those in a standard > engineering document. Boy was I wrong! > > I don't know where the torque specs on the c&c photo album came from. It > looks like the values for my largest 2 bolts consevatively correlate with the > wet/lubricated specs from a general online chart. The rest of the smaller > bolts are progressively less conservative. In fact the rating on the photo > album page is almost twice that of the online chart! Wet or dry, 80 vs 45 - > Quite concerning. > > Thoughts? > > http://www.cncphotoalbum.com/doityourself/torquebolts/torquebolts.htm > > https://www.fastenal.com/content/feds/pdf/Torque%20of%20Stainless%20Steel,%20Non%20ferrous%20Torque.pdf > > Josh > > > >> On Jan 2, 2018 3:18 PM, "Josh Muckley via CnC-List" <[email protected]> >> wrote: >> Ok Guys, >> Since I have the mast out, this provides the rare opportunity to access ALL >> of the keel bolts. I've measured each of the bolt and nut diameters and >> checked the archives for torque specs. I intend to buy a toque multiplier >> and the appropriate sized sockets. I think I can do it for less than the >> yard is going to charge and I'll come out of it with some tools. I'll also >> be able to tell myself that it was done correctly. >> >> That being said it sounds like the best practices are are follows: >> - be on the hard >> - loosen the bolts one at a time, clean, and lubricate with tef-gel >> - reinstall and torque at progressively higher levels. >> >> I was unable to find the torque spec for my 1.5" bolt in the website but Ken >> Heaton cited 600lbs in one of his past responses. >> >> Keel bolts (fwd to aft): >> Nut stud torque >> 1 - 1 1/2 (38mm) 1 (25mm) 350 >> 2 - 2 3/16 (56mm) 1 1/2 (38mm) 600? >> 3 - 2 3/16 (56mm) 1 1/2 (38mm) 600? >> 4 - 2 3/16 (56mm) 1 1/2 (38mm) 600? >> 5 - 1 7/8 (47.5mm)1 1/4 (32mm) 450 >> 6 - 2 3/16 (56mm) 1 1/2 (38mm) 600? >> 7 - 1 1/2 (38mm) 1 (25mm) 350 >> 8 - 3/4 (19.5mm) 1/2 (13mm) 80 >> >> >> Anything I'm missing? >> >> >> Thanks, >> >> Josh Muckley >> S/V Sea Hawk >> 1989 C&C 37+ >> Solomons, MD >> >> _______________________________________________ >> >> Thanks everyone for supporting this list with your contributions. Each and >> every one is greatly appreciated. If you want to support the list - use >> PayPal to send contribution -- https://www.paypal.me/stumurray >> >>
_______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
