- Dec 28, 2015
Did both failures coincide with the haulout? Maybe they contributed to the issue?
My misunderstanding.I did not say galling was a part of the bronze thread failure. I was responding to a failed SS bolt photo and sayingthat I did not thing it was mismatched threads. That is all I said.
There are two types of fatigue - looks like you are talking about low stress - high cycle fatigue. I would agree with you on that. But there is also high stress - low cycle fatigue. I think that is the more likely cause. Now, what causes the high stress - low cycle fatigue would require a lot more information than we have. The damage you describe of spinning up the turnbuckles too quickly could be part of this.Galling would be very unusual with bronze, which is the reason it is used for turnbuckles. Without a really close examination, this is a mystery. That fact that he said this had also happened a "a few years back" is interesting, suggesting a common factor. Fatigue seems unlikely. The boat is only sailed summers, probably not hard, and I assume the rig was professionally tuned (not slack). This makes fatigue seem unlikely. That the mechanic mentioned the lack lube is interesting. Also though t damamge is not galling, I'm wondering if the last mechanic spun the turnbuckle right up to tension, too fast (there is a LOT of heat generated if the threads are dry) and without lube, doing damamge at that time. Turnbuckles need to be tightened VERY slowly under load. Doing this fast is common, and often unnoticed error, because the damamge is hidden.