Hi all, IIRC, Our boat has a -10 rod capable of 10,000# load. The owners manual states not to exceed 40% of rod strength on the backstay hydraulic ram so our setup relieves around 3500 and we stay below that. We have a remote pump panel and the relief is adjustable. I set it myself after I had mine rebuilt by a local Ram shop. I believe excessive pressure will initially stretch the rod and more pressure will cause it to break. On board the boat, we adjust backstay by looking at the sails and only use the gauge as a safety reference. A batten is taped to the ram to indicate repeatable settings.
FWIW, Something I keep experimenting with: It's important to set the headstay and backstay length properly so the backstay works the way you want. It's part of tuning and done after the mast is centered and the shrouds are tensioned fully. In lighter air, you may want to bend the mast a little and flatten the mainsail before tightening the headstay excessively. In stronger winds, you may want the headstay to tighten before flattening the main. The PO used to add a 2" toggle to the headstay for light winds to lengthen the headstay and remove it for winds over 15 knots. This reduces the rake slightly and gives the backstay slightly more leverage and quicker response in higher winds and you get the right shape before bottoming out or exceeding thresholds. Chuck Scheaffer 1989 C&C 34R, Pasadena Md > On 04/19/2021 11:06 AM Jeffrey A. Laman via CnC-List > <cnc-list@cnc-list.com> wrote: > > > Hi All. Also wanted to comment on the pressure question. As I noted in > my post about the NavTec - 10 failure, I have been examining all the issues > that I more or less ignored or was happily ignorant of till now. One item > was to determine the yield and breaking load on my backstay and correlating > backstay shortening to load. If you do a little geometry and have knowledge > of stress/force/strain/elongation, it is a fairly simple determination (I am > a structural engineer). Others have provided photos of simple shortening > measure devices, which I now intend to make and install. If others have > photos, please share! But, one comment on pressure and force -- the pressure > on the hydraulic backstay is directly related to force. So, if I trouble > myself to read it, I will pay much more attention to the pressure on the > gauge right in front of my face. At the moment, I don't recall what I read > -- either NavTec or SailTec, or maybe both, 1000 psi = 1000 lbs force. The > NavTec - 10 ha s a relief valve set to 4000 lbs. SailTec - 10 is 4750 lbs. Others with more knowledge may have more definitive information. Long story but I received the wrong SailTec - 10 the first time -- a custom unit for J105s that has a pressure relief at 3000 lbs. > > Excellent discussion, btw everybody! > > Jeff L. > > > > --------------------------------------------- > From: Edd Schillay via CnC-List <cnc-list@cnc-list.com> > Sent: Sunday, April 18, 2021 3:04 PM > To: Stus-List <cnc-list@cnc-list.com> > Cc: Edd Schillay <e...@schillay.com> > Subject: Stus-List Re: Hydraulic backstay adjuster pressure? > > Bruce, > > You may find this article interesting: > https://www.sailingworld.com/getting-most-from-your-backstay/ > https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.sailingworld.com%2Fgetting-most-from-your-backstay%2F&data=04%7C01%7C%7Cd3bfbd243ace446e7faa08d9029cd2fa%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637543694834999454%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=smkRPe%2FC7SoZvMsQlt7WcZs5QqU7SNdPAHUnv0jHi2A%3D&reserved=0 > > > All the best, > > Edd > > > Edd M. Schillay > Captain of the Starship Enterprise > C&C 37+ | Sail No: NCC-1701-B > Venice Yacht Club | Venice Island, FL > > > > > > > > > > > > On Apr 18, 2021, at 2:05 PM, Bruce Whitmore via CnC-List < > cnc-list@cnc-list.com mailto:cnc-list@cnc-list.com > wrote: > > Hello all > > With all of the discussions about hydraulic backstay adjusters, and mine > being fixed (finally), where do most of you keep and use the pressure? At > the dock vs. sailing and under what conditions? > > Thanks! > > Bruce Whitmore > 1994 C&C 37/40+ > Thanks to all of the subscribers that contributed to the list to help > with the costs involved. If you want to show your support to the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray > https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.paypal.me%2Fstumurray&data=04%7C01%7C%7Cd3bfbd243ace446e7faa08d9029cd2fa%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637543694834999454%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=FQbJL0AbzD%2FsK2R9lqD%2Bsmu7EGNJGm7cTKs7uo6UfRY%3D&reserved=0 > Thanks - Stu > Thanks to all of the subscribers that contributed to the list to help > with the costs involved. If you want to show your support to the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray Thanks - Stu >
Thanks to all of the subscribers that contributed to the list to help with the costs involved. If you want to show your support to the list - use PayPal to send contribution -- https://www.paypal.me/stumurray Thanks - Stu
