DSK wrote:
OzOne wrote:
From the article.
The supplier of the hydraulic cylinders that controlled the canting
keel on Skandia in the 2004 Rolex Sydney Hobart Race was found to have
breached their contract and supplied inadequate hydraulic cylinders
for the duty specified by the yacht's designer.
IOW, the yacht designer did not have the necessary knowledge to design
the rams.
He instead gave a duty spec to the experts (the ram suppliers and
their engineers) who supplied rams that did not meet the duty spec.


Well, I'm not trying to be a jerk, but how did they know
that the spec was not exceeded by the stresses on the boat
in the storm?

Bingo. That's exactly my concern as well. Seems to be a case of 'oh,
the rams broke. Must have been defective/inadequate'. Now that might be
true, but it also might not.

If I was given a spec to build an instrumented sheave capable of
handling a SWL of 2 tonnes and somehow the cable hooked up on
something, had a breaking strain of 10 tonnes, and the block shattered
under the excess load, it's not the fault of the design *or* the
construction. The load is outside the spec.

How do Wharro et al know that the applied load at failure was within
design spec? If the yacht designer, naval architect etc didn't provide
a spec with numbers then IMO the hydraulics guy was foolish in
accepting the job. Hindsight is a wonderful thing of course.


The only way to be sure the rams were strong enough is if
the boat's hull broke around them.

Which is exactly what'll happen next time, I predict. Alternatively, no
ram supplier will touch the job unless the designer specs the rams &
hydraulics in detail.


This is a matter of professional interest for me.

Me, too. This reinforces my resolve to *never* do private jobs for
people, too.



Oh and it's not about deep pockets.
Skandia was built using Wharro's own money, he sold his house to
complete the yacht which was uninsured.

Yes, I understand that. But from an engineering POV it's irrelevant. I
regard racing as an inherently high risk activity. Nobody designs for
the worst case strains etc because if they did, they'd never win a
race. It's hardly surprising if something breaks in a storm.

PDW