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/0B8pEh5lnvP1ySXFBdDhrX0ZaMzNna
> zViYkZzRVRoODlSSUd3/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
>> ~~~~~~~_/)~~~~~~
>>
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> _______________________________________________
>
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> and every one is greatly appreciated. If you want to support the list -
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>
_______________________________________________
Thanks everyone for supporting this list with your contributions. Each and
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