Join Date: Dec 2011
Location: Ontario, Canada
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Re: Keel bolt torque values ????
Yes. Torque specs are merely a best effort substitute for the ideal method of tightening a bolt/nut, which is to measure the stretch of the bolt. Since measuring bolt stretch is difficult to impossible in many cases, torque values which equate closely are used instead.
Yes I am aware of this having been involved in studies on the elongation of rebar and bolts used in the containment areas of nuclear power stations. However we are talking about sailboat keels of say 2000 - 2500 lbs the weight of which is distributed over several bolts. The torque values most likely should be calculated per application and consider other factors such as crushing of fiberglass and other materials used. I am not questioning the tables showing the max torque values of bolts but would like to know the torque numbers the actual boat designers and builders suggest.
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