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 > >
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