Funny you should ask - I lost a forestay ~3 years ago during an overnight race. Sailed for probably 9 hours in 15-20 and steep chop on starboard. Tacked over to port at dawn and about one minute later - BAM!
Luff rope (had a heavy sail on) kept the mast up while we secured it. The top swage fitting broke right in the middle. Got 100% new rigging at that time.
Rigger said LACK of toggle caused the failure. The break looked like someone cutting down a tree, like you were chopping at one side for an hour, then one whack on the other took it down.
-dan
