In article ,
says...

On Mon, 5 Dec 2011 16:05:23 -0800, "Steve B" wrote:

Will these locate and identify thermoclines? I have read the manual, but
can't find anything about it.

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I have never heard of a product in the recreational boating market
that claimed they could do that with any degree of precision but who
knows.

Interesting discussion he

http://www.bobberstop.com/thermocline.html

I don't know about the Cuda, they are lower end units, but my Garmin
color will show thermoclines very nicely. It has to do with the sound
speed gradient.

http://en.wikipedia.org/wiki/Sound_speed_gradient