On Thu, 10 Jun 2010 18:02:29 -0700 (PDT), Tim
wrote:

As far as I know, there's not really any to speak of on the Ohio and
Cumberland rivers, but the northern Illinois river is infested with
'em!

I'm fairly sure there are tugs and barges on the Ohio, at least in
some parts. Don't forget that radar reflector! It will make your
return echo look like a 100 footer. A short pole mount in a rod
holder will do the trick.