A comment or two regarding fatigue -- Most ferrous metals exhibit what is known as an endurance limit. This is a stress level below which the material is expected to survive infinite cycles. I have no detailed knowledge of the high strength stainless rod material fatigue properties, however I suspect stresses induced by boat rocking at the dock are below the endurance limit and therefore of no consequence.
Evaluation of fatigue life and accumulated fatigue damage is highly uncertain. The load history is often unavailable, certainly the case for a sailboat. Also, material resistance to fatigue is quite variable. So, in effect, both sides of the equation significant uncertainty. If an evaluation is conducted and 1.0 is the division between survival and failure, the actual failure can range from 0.3 to 10. Get Outlook for Android<https://aka.ms/AAb9ysg> ________________________________ From: Andrew Burton via CnC-List <cnc-list@cnc-list.com> Sent: Thursday, December 12, 2024 3:22:50 PM To: Stus-List <cnc-list@cnc-list.com> Cc: Joe Della Barba <joe.della.ba...@ssa.gov>; Stus-List <cnc-list@cnc-list.com>; Andrew Burton <a.burton.sai...@gmail.com> Subject: Stus-List Re: old rod rigging On both my C&C 40 and my current boat I took my rigging to a professional and had it inspected. He re-headed some pieces and on Masquerade, my current boat, replaced the turnbuckles. But the rod is still good. Andy Andrew Burton 26 Beacon Hill Newport, RI USA 02840 Www.burtonsailing.com http://sites.google.com/site/andrewburtonyachtservices/ +401 965-5260 On Dec 12, 2024, at 14:34, Rob Hamlin via CnC-List <cnc-list@cnc-list.com> wrote: I’m replacing the rod, turn buckles and furler on Sapphire 37+ this season, only because of piece of mind. The boat is a 1990 with 34 year old rigging always made me think, when I’m racing in 25kts of breeze hammering up hill. -Rob Sent from my iPhone On Dec 12, 2024, at 2:23 PM, Matthew Wolford via CnC-List <cnc-list@cnc-list.com> wrote: I believe I am sailing with original rod rigging (1975). I have been told by some that it needs to be replaced, and I have been told by others – including mechanical engineers – it probably does not. As I understand it, the issue is fatigue based on a number of “cycles” (pressure applied then relieved). A boat rocking in waves (even at the dock) adds to the number of cycles, but the fatigue point allows for millions of cycles. My boat is on the hard for over half the year, thereby limiting the number of cycles. Also, two big problems for rod rigging is nicks in the surface and the cracks in the balls joints at the mast (which should be inspected and possibly replaced). Perhaps my friend Bill Coleman will comment. He knows all about metal. Bill? From: Della Barba, Joe via CnC-List <cnc-list@cnc-list.com> Sent: Thursday, December 12, 2024 2:15 PM To: Stus-List <cnc-list@cnc-list.com> Cc: Della Barba, Joe <joe.della.ba...@ssa.gov> Subject: Stus-List old rod rigging Question for the collective knowledge base here: Would you sail a 1980s era boat with original rod rigging or is it going to fall on your head any second? Joe Della Barba Coquina Your contributions help pay the fees associated with this list and help to keep it active. Please help by making a small contribution using PayPal at: https://www.paypal.com/paypalme/stumurray All contributions are greatly appreciated. Your contributions help pay the fees associated with this list and help to keep it active. Please help by making a small contribution using PayPal at: https://www.paypal.com/paypalme/stumurray All contributions are greatly appreciated.
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