[C320-list] Check your stem fitting - near catastrophic failure to C320

[Marko Jamnik]

Hello Graeme

Since my sail number is 304 and built in '95. I will check my situation and take a picture. Once again it could be just that one but worth while having  an overall inspection.
Thanks for the heads up

MarkoJamnik
Marquesas 304 Lake Ontario



On 2015-08-04, at 11:17 AM, Graeme Clark <cg at skyflyer.co.uk> wrote:

> Or try this link
> 
> http://oi58.tinypic.com/t8lwz9.jpg
> 
> G
> 
> Sent from mobile: please excuse typos etc.!
> 
> 
>> On 4 Aug 2015, at 15:55, Daryl Hunt <drhunt at rochester.rr.com> wrote:
>> 
>> Hi Graeme,
>>   FYI, when I click on the tinypic link I don't see the image.
>> 
>> /Best regards,
>> /
>> 
>> /Daryl
>> '99 C320 #660 Believe
>> /
>> 
>> 
>>> On 8/04/15 10:15 AM, Graeme Clark wrote:
>>> 
>>> Just to correct my own post!
>>> 
>>> The perspective of the picture I posted made me wrongly state there was a backing plate, I can now see that it is in fact looking at the entire broken cross-section of the vertical bar to which the forestay (headstay?) connects.
>>> 
>>> You can see a tiny rusty part, which someone with better engineering knowledge may confirm to be crevice corrosion -  almost certainly starting from a tiny pit where the  triangular gussets are welded in place?
>>> 
>>> Still very tricky to spot and worth a good look at your own boat to check for a similar issue maybe?
>>> 
>>> Graeme
>>> 
>>>> On 4 Aug 2015, at 13:12, Graeme Clark <cg at skyflyer.co.uk> wrote:
>>>> 
>>>> The C320 that I used to share before buying my own, suffered a near catastrophic failure of the stem fitting that attaches the forestay to the bow, last week;
>>>> 
>>>> How they didn't lose the mast I don't know
>>>> 
>>>> The boat is  serial no 303 built in 1996
>>>> 
>>>> This link, pasted into your browser, will show the failure, the red arrow is the fractured surface
>>>> http://tinypic.com/r/t8lwz9/8
>>>> (by the way, the halyard you see is the jury-rig to keep the mast up!)
>>>> 
>>>> For interest you may wish to see the current design of replacement offered by CD
>>>> http://www.catalinadirect.com/index.cfm/product/2573_699/stem-fitting-c-320-c-34-c-36.cfm
>>>> 
>>>> Note that CD state they have removed the unnecessary and non structural triangular gussets that are clearly visible on the part that failed.
>>>> 
>>>> But you will also note that there is a ‘backing plate’ joining those two gussets that is located close to and to the rear of the part that failed.
>>>> 
>>>> My guess is that a small defect or other stress concentration was present on the rear of the vertical bar and over the years repeated flexing has caused a fatigue crack to develop and propagate.
>>>> 
>>>> The point is that it is very difficult to see this area, and I think any crack would be very unlikely to be spotted with a routine cursory inspection.
>>>> 
>>>> I have no idea if there’s any history of these parts failing, but If so I was not aware of it.
>>>> 
>>>> I would strongly recommend a careful  inspection of your own boat to make sure that no crack is developing in the same area.
>>>> 
>>>> I hope the above description is clear, but if I have confused you, please ask away and I will try and  explain further
>>>> 
>>>> Regards
>>>> 
>>>> Graeme
>>>> #366, Jaskar
>> 
>> 
>> 
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