Lew Townshend identified my rams a #6...whatever that means. On Fri, Aug 3, 2018, 7:36 PM Gary Russell via CnC-List < cnc-list@cnc-list.com> wrote:
> Hi Josh, > Were you able to get the hydraulic ram displacement vs. back stay > load? That would help those of us who don't have a working pressure gauge. > > Gary > S/V Kaylarah > > ~~~~~~~_/)~~~~~~ > > > On Fri, Aug 3, 2018 at 5:28 PM, Josh Muckley via CnC-List < > cnc-list@cnc-list.com> wrote: > >> Here's the data guys. It looks like there is a loose corollary (in my >> case) between hydraulic psi and backstay lbs load. My hydraulic pump >> relief valve is seized and appently set at ~2600 psi. So I'm safe in that >> no matter how much I pump it will never exceed even 25% of the backstay >> load limit. As for the transom load limit...who knows. >> >> >> https://docs.google.com/spreadsheets/d/1B6F6OQU8b7L5tVgvvWKViQHS5UVL1Srx6HV7xPKRC40/edit?usp=sharing >> >> Josh Muckley >> S/V Sea Hawk >> 1989 C&C 37+ >> Solomons, MD >> >> >> >> On Fri, Aug 3, 2018 at 1:48 PM, Bruce Whitmore via CnC-List < >> cnc-list@cnc-list.com> wrote: >> >>> I'd love to see that as well Josh. >>> >>> Thanks! >>> >>> Bruce Whitmore >>> >>> (847) 404-5092 (mobile) >>> bwhitm...@sbcglobal.net >>> >>> >>> ------------------------------ >>> *From:* Josh Muckley via CnC-List <cnc-list@cnc-list.com> >>> *To:* C&C List <cnc-list@cnc-list.com> >>> *Cc:* Josh Muckley <muckl...@gmail.com> >>> *Sent:* Friday, August 3, 2018 10:22 AM >>> *Subject:* Re: Stus-List 37+ Backstay tension >>> >>> With that info I'll head down to my boat and apply various psi to the >>> hydraulics and then measure the tension with my loos gauge. >>> >>> Josh >>> >>> On Fri, Aug 3, 2018, 10:17 AM Gary Russell via CnC-List < >>> cnc-list@cnc-list.com> wrote: >>> >>> So... I went over to Kaylarah this morning and found the following: >>> >>> The back stay diagonals are 235" long >>> The spread between the attachments is 80" >>> Doing the math, that means if the maximum tension on the vertical rod is >>> 5000 lbs., then the tension on the diagonals is 2537 lbs. >>> From here you can apply any safety factor you like, just maintain the >>> ration of 2537 : 5000. >>> Because the angle between the diagonals is so small (smaller than I >>> thought), it is pretty close to 2:1. >>> >>> Personally, I'm going to try and keep the tension on the diagonals less >>> than 2000 lbs. which keeps the upper rod below 3942 lbs. (Now where did I >>> put that Loos gauge?) >>> >>> Gary >>> S/V Kaylarah >>> '90 C&C 37+ >>> East Greenwich, RI, USA >>> >>> >>> ~~~~~~~_/)~~~~~~ >>> >>> >>> On Thu, Aug 2, 2018 at 9:00 PM, Gary Russell <captnga...@gmail.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 >>> >>> _______________________________________________ >>> >>> 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 >>> >>> >>> >> >> >> -- >> When security matters. >> http://www.secure-my-email.com >> >> >> >> >> _______________________________________________ >> >> 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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