On Jun 10, 7:02 pm, RichH wrote:
All metal has a service life based on fatigue. ...

Rich,

No argument there. But, failure after, say, 10 million cycles doesn't
seem to fit the profile of most of the keel failures that I know of.
There is a theory that suggests that many of the racing boat keel
failures are preceded by a hard grounding that leaves no immediate
signs of harm but weakens the system. There may be something in that,
but the problem I have with it is that racing boats go to ground all
the time (as a class they are deep) and while many of them will have
had a hard grounding in the recent past few of them will drop their
keels. In any case, all of the keel failures I know of that have not
happened at the moment of going aground have happened in pretty new
boats. I do know of cases where people have removed the keels of
older boats, inspected the bolts, found signs of corrosion and
replaced them but I don't know of any actual failures underway. To be
sure this is just hear-say, but I've been aboard or near bunches of
boats that have had rig failure and many boats that have broken their
rudders (including the entire Hawaii J/24 fleet and three time on a J/
29) but no keel failures except for grounding and accompanied by major
structural failures...

-- Tom.