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/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
>>>> ~~~~~~~_/)~~~~~~
>>>>
>>>> _______________________________________________
>>>>
>>>> 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
