That looks like a textbook case of fatigue failure: a local
discontinuity causes high stresses and starts a tiny crack, over time
the cracks expand in size, causing the "beach" marks, finally what's
left isn't strong enough to carry the load and the whole thing breaks.
Looking at a larger copy of the photo on the Web, I'm guessing the crack
started on the left side where there appears to be some corrosion, and
this is right at the point where the shaft exits the hull - which is
where the bending load is at the maximum. The crack worked its way
across to the right where you see the final fracture marks.
I have to wonder about the material, doesn't really look like stainless.
Neil Gallagher
Weatherly, 35-1
Glen Cove, NY
On 11/25/2013 5:06 PM, Rick Taillieu wrote:
Joe,
By the pictures the shaft sheared off right where it exits the hull.
http://translate.google.com/translate?hl=en&sl=ru&tl=en&u=http%3A%2F%2Fnavigatorpirate.livejournal.com%2F%3Fskip%3D10&sandbox=1
It looks like the shaft was cracked about 1/3 through the shaft for a
while.
Rick Taillieu
Nemesis
----- Original Message -----
*From:* Della Barba, Joe <mailto:joe.della.ba...@ssa.gov>
*To:* cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>
*Sent:* Monday, November 25, 2013 11:09 AM
*Subject:* Re: Stus-List 35-1 rudder drawings for stranded sailor
and NOW how to improve the 35 rudder
I would love to know what happened to the original!
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