[Sonar] The powerboats strike back

[Dallas]

It would have been nice to seem some of that corrosion on my 30 year old Shorestation lift that I had to cut up last weekend.

dj

-----Original message-----
From: Shaina A Brown brow1134 at umn.edu
Date: Thu, 4 May 2006 11:17:46 -0500
To: Mark Kochendorfer markoch at gmail.com
Subject: [Sonar] The powerboats strike back


Yet another thanks to all who helped to save Tally Ho! from certain death. 

  In terms of material failure, Im sure there was some wear and fatigue
occuring on the bouy and pennant that contributed greatly to the failure.
But as I talked about with Steve this morning, I think the larger problem
is that the water is so diluted with fuel from powerboats that its
basically like puting a chunk of metal into a solvent bath...and this
speeds up the crack propagation and failure process ten fold. Any presence
of tramp ions in a metal grain boundary is devastating to the strengthof
the metal. I bet that a simple pH test of Minnetonka water would scare most
of us off from swimming ever again. Fortuneately, we can all learn from
this mishap, and that Tally Ho! foundered into the safest place in the bay
that it could have.  In terms of a solution...I guess we will all have to
keep a closer eye and check on the corrosion and wear of each bouy
frequently. And for all those times that the powerboaters couldnt zip
through the channel at 50mph because of sailboats, the powerboats are
striking back...see you all at the club. Thanks,

Shaina 

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