I use my finder (an Eagle Claw Barracuda or Pirhanna, can't remember which) quite often when traveling from one spot to another so that I can see what kind of water depth I'm over. You'll notice that I call it a finder, not a fish finder, because I never have the fish finding feature turned on. The fish ID sensitivity is too whacky and unreliable, but the information that I get in terms of bottom composition (hard or soft), contour, and depth are worth the effort of the installation. It's useless in water less than two or three feet deep, but then again who needs a finder then?
It's particularly good on new waters, or during tidal stages in that I rarely fish in well-known areas.
My finder is powered by eight AA batteries in series, which can provide 18 hours of use when fully charged. If you'd like install details, I can direct you to some via PM. Just let me know.