[Sonar] The powerboats strike back

[Shaina A Brown]

Precisely my thoughts, thanks Ernie. 

Shaina



On 4 May 2006, Ernest Brody wrote:
> I get to put my oar in also.  I suspect that whereas if you mixed it all
up
> you would not see any significant difference, the pH and oxidation
potential
> of the water at the first foot of water in the lake is more corrosive
than
> the general mixture.  This would be caused by the sunlight promoting
> photosynthesis of algae in that first foot as well as oxygen mixed in by
> wave action.  (I see this in another way, the sunward side of my boat has
> more blistering at the waterline than the shadeward side.)  This would
cause
> more corrosion at the top of the chain and calamitous loss of holding
power.
> 
> Ernest
> 
> -----Original Message-----
> From: sonar-bounces at lists.wyc.org [mailto:sonar-bounces at lists.wyc.org]On
> Behalf Of Shaina A Brown
> Sent: Thursday, May 04, 2006 11:18 AM
> To: Mark Kochendorfer; Thomas_M_Brown at bluecrossmn.com
> Cc: sonar at lists.wyc.org
> 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 strength of
> 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
> 
> _______________________________________________
> Sonar mailing list
> Sonar at lists.wyc.org
> http://lists.wyc.org/mailman/listinfo/sonar
> 
> 
Shaina A Brown 
brow1134 at umn.edu