It does look like a crack had developed that slowly propagated over some time as the initial break shows tarnishing. Eventually the remaining cross-sectional area was not enough to support the load and shows necking down due to ductile elongation and failure. Maybe the crack could have been discovered earlier before the catastrophic failure. Its hard to say. I'm pretty remiss about looking at much other than the swages at the deck level. I'm glad you didn't lose your rig like some friends of mine did exactly 2 years ago on their Hylas in exactly the same spot (Hurricane Gulch) as you were. We're coming back to Loch Lomond tomorrow from Petaluma and back to Alameda Thursday. First, I'm not going via Sausalito and second, I'll give my rigging a look over (especially those U shaped toggles).
Thanks for posting the pictures. They are very informative and gives reason to be vigilant.
Dave,
I read your .pdf file. Excellent analysis. That's the problem with these kinds of failures..the part may be big enough to normally support the load but flexing and fatigue or stress concentration at a very small defect eventually leads to failure.
