Interesting. All parts of our backstay are rod, the double lowers and the single upper. The upper is a larger diameter (as you would expect). Two hydraulic rams, one each side.
Some of you have wire for the lower section? Ken Heaton & Anne Tobin S/V Salazar - Can 54955 C&C 37/40 XL - Hull # 67 Cape Breton Island, Nova Scotia https://c-c-37-40.blogspot.ca/p/salazar.html On Thu, 2 Aug 2018 at 22:02, Gary Russell via CnC-List < cnc-list@cnc-list.com> wrote: > Actually, if you look closely at the manual, you will notice that the > 4125 lbs. refers to "wire limit", and 5000 lbs. refers to "rod limit". > Since the vertical part of the back stay assembly is rod, I will assume > that the 5000 lbs. refers to the vertical. I will go over to the boat > tomorrow and try to measure the back stay angle, to see which limit gets > exceeded first, the rod or the wire. C&C could have made this a lot > easier. I've got to believe the transom will fail before the wire, yet the > wire is all that is specified. > > Gary > > ~~~~~~~_/)~~~~~~ > > > On Thu, Aug 2, 2018 at 8:52 PM, Josh Muckley via CnC-List < > cnc-list@cnc-list.com> wrote: > >> Absolutely without any doubt in my mind the backstay tension of 4125 is >> to be measured on the mainline. This works in opposition to the head stay >> which is equally sized #12 rod. >> >> Josh >> >> On Thu, Aug 2, 2018, 8:41 PM Gary Russell via CnC-List < >> cnc-list@cnc-list.com> wrote: >> >>> Hi Josh, >>> Oops! I missed that. I looked in the chapter about rigging and >>> didn't find it there. Silly me! I even searched for the number 4125 and >>> found nothing. I guess the document is an image rather than text. Now the >>> question, is that the tension in the vertical part of the back stay? I >>> guess, the safest assumption is that it is. >>> >>> Gary >>> >>> >>> ~~~~~~~_/)~~~~~~ >>> >>> >>> On Thu, Aug 2, 2018 at 8:33 PM, Josh Muckley via CnC-List < >>> cnc-list@cnc-list.com> wrote: >>> >>>> Page 68 of the manual pdf file which I linked before has the pre-load >>>> and max load limits. >>>> >>>> Again I am corrected in my preconceived notions regarding the >>>> correlation between a hydraulic gauge and the tensile load on the back >>>> stay. >>>> >>>> Josh >>>> >>>> On Thu, Aug 2, 2018, 8:13 PM Gary Russell via CnC-List < >>>> cnc-list@cnc-list.com> wrote: >>>> >>>>> Hi Josh, >>>>> Where did you find the 4125 or 5000 lb. limit? I don't see that >>>>> in the Owners Manual? Is the 4125 lb. limit for the lower angled segments >>>>> of the the back stay or the upper vertical part. You can't simply measure >>>>> the port back stay tension and multiply by two, because of the angle >>>>> between the two. You would have to measure the angle and apply some trig >>>>> to get the right value. Mike Cotton's boat was the one I was referring to >>>>> in my email above. >>>>> >>>>> Gary >>>>> >>>>> ~~~~~~~_/)~~~~~~ >>>>> >>>>> >>>>> On Thu, Aug 2, 2018 at 6:31 PM, Josh Muckley via CnC-List < >>>>> cnc-list@cnc-list.com> wrote: >>>>> >>>>>> The manual says limit to 4125lbs and then says absolute max of >>>>>> 5000lbs. >>>>>> https://drive.google.com/file/d/0B8pEh5lnvP1ySXFBdDhrX0ZaMzNnazViYkZzRVRoODlSSUd3/view?usp=drivesdk >>>>>> >>>>>> I never considered that the hydraulic pressure psi could/would be >>>>>> independent of tensile load. When I had my hydraulic pump rebuilt by Lew >>>>>> Townsend he tried to adjust the relief valve but mine adjustment knob was >>>>>> seized. He gave up and just hydro-tested it anyway. He found that the >>>>>> relief was roughly 3500. I rarely go over 2500. Now that I have to >>>>>> consider the corollary between psi and lbs I'll be pulling out my Loose >>>>>> tension gauge and get back to you. Since it is split I'll remember to >>>>>> add >>>>>> together or double a single. >>>>>> >>>>>> As for the attachment to the transom, I agree it does seem slightly >>>>>> poor engineering. In fact when we were shopping around the first boat >>>>>> looked at wad named Blue Pearl and had been owned by Mike Cotton who was >>>>>> and may still be on this list. It was evident that some past event had >>>>>> caused the port aft attachment to separate the flat horizontal (cap) part >>>>>> of the fiberglass casting from the curved (body) potion. The hydraulic >>>>>> pump was a single piston and pump combo that attached between the port >>>>>> anchor amd the port side of the back stay. Evidently a sheave >>>>>> communicated >>>>>> the tension to the stbd size at the point where the single rod attached >>>>>> from the mast head. It seemed as though maybe the sheave didn't roll >>>>>> smoothly and failed to split the tension evenly between the port and stbd >>>>>> anchor on the transom. That of the fiberglass layup was uneven and the >>>>>> port side was just coincidentally weaker. >>>>>> >>>>>> I was attentive to this weakness when I continued shopping and found >>>>>> Sea Hawk. I discussed the issue with the PO and he showed his >>>>>> engineering >>>>>> answer. >>>>>> >>>>>> https://drive.google.com/folderview?id=0B8pEh5lnvP1ybDFIZ0ZZTU1XdHM >>>>>> >>>>>> I'm not convinced that it is "correct" but it is certainly better >>>>>> than nothing. I had decided years ago that I was going to engineer a >>>>>> reinforcement of my own with some G10 FPR. I still have the G10 but have >>>>>> never acted on the project. My idea was to back the entire corner of the >>>>>> transom with 1/2" G10 FRP by epoxying it in place and then fill the >>>>>> attachment cavity (the bump out) with epoxy. Longer u-bolts and a spade >>>>>> or >>>>>> mortise bit to countersink a flat load bearing "pad" for the washers and >>>>>> nuts to drive against and I would be done. >>>>>> >>>>>> Josh Muckley >>>>>> S/V Sea Hawk >>>>>> 1989 C&C 37+ >>>>>> Solomons, MD >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> On Thu, Aug 2, 2018, 5:53 PM Gary Russell via CnC-List < >>>>>> cnc-list@cnc-list.com> wrote: >>>>>> >>>>>>> Does anyone know the maximum back stay tension allowed on the >>>>>>> C&C 37+. My problem is the hydraulic back stay adjuster pressure gauge >>>>>>> has >>>>>>> failed and I don't even know what the maximum pressure spec allowed is, >>>>>>> anyway. I'm concerned that at least one owner has had the attachment >>>>>>> points on the transom fail presumably due to excessive tension/pressure. >>>>>>> Frankly, the attachment points don't instill a lot of confidence as >>>>>>> there >>>>>>> aren't any backing plate; just a couple of holes drilled in the hull. >>>>>>> I'd >>>>>>> feel more comfortable putting a Loos gauge on the wire and calibrate the >>>>>>> extension of the back stay adjuster to it. Any thoughts / ideas out >>>>>>> there? >>>>>>> >>>>>>> Live Slow / Sail Fast, >>>>>>> Gary >>>>>>> S/V Kaylarah >>>>>>> '90 C&C 37+ >>>>>>> East Greenwich, RI, USA >>>>>>> ~~~~~~~_/)~~~~~~ >>>>>>> >>>>>>> _______________________________________________ >>>>>>> >>>>>>> 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 >>>>>> >>>>>> >>>>>> >>>>> _______________________________________________ >>>>> >>>>> 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 >>>> >>>> >>>> >>> _______________________________________________ >>> >>> 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 >> >> >> > _______________________________________________ > > 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 > >
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