sun E sailor wrote:
You guys had me concerned that I was neglectful about maintaining my boat... So I checked all the nuts, bolts, and screws and found that everything was indeed still tight. Which means, at least to me, that I broke it by sailing it.
I'm just wondering exactly which conditions were to much...
Also, does the old x bar get returned to hobie? If not, I might make a TI3. All I would need are the clamps that hold the x bar down.
If everything was tight that's good to know.
At this point I don't believe we have a definitive explanation as to what exactly causes the weld on the bearing plate to break. Hobie has since corrected this problem with their new design and that's what is most important.
What I've been trying to establish is how the average person can determine beforehand, if their old style crossbar is about to fail. I should think Hobie would be interested to have your crossbar to see if this "grey line" is actually a crack in the weld or not.
However, you did not break it by sailing it; it broke because somethings wrong, it's not your fault. As for "which conditions are too much..." I believe the general rule of thumb is when one begins to see the whole ama a couple of inches under water. It's also been well discussed about the benefit of when to reef your sail. Again, I wish for all of us to be as safe as possible on the water and proactive through these continuing discussions.
If I had a thin enough feeler gauge, I could push it though the crack. The camera I used isn't high enough quality to show it but there is definitely a crack.
The physics of the x bar suggest to me that there is some deflection of the bearing ring, that repeated high loads stress these welds and they begin to fail where the load is the highest, at the edges.
The new x bar design is much stronger, likely many times stronger, because it has a much longer lever arm with which it distributes the load over.
Welds generally fail for two reasons; most likely is poor craftsmanship, less common but what is likely happening here, is when the metal is welded, it's crystalline structure changes slightly and becomes less able to deal with flexing. After thousands of flexing cycles, the metal begins to fail, progressively getting weaker, and at an increasing rate, till it fails completely. It could even be hundreds of thousands or millions of cycles, but every second we sail, every wave we hit, every minute change in wind, is another cycle on that weld, another step towards it's failure.
Just my humble opinion but....