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

[Graeme Clark]

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