Yes, they do have to be in water or at least on a wet surface to work properly.  If you use it ice fishing, bring a bottle of water to squirt the ice surface prior to taking a reading.

Thanks PJ. I wondered about that because I read about using it for ice fishing and that it had to touch water (the transducer end) to work. Wondered if water-in-the-bottom of the hull would work as well? Good to know. Can't wait to try it out. Appreciate the info. up

Those units were designed for ice fishing and finding depth through the ice without drilling a hole.  Put a small pool of water on the bottom of your canoe and it will read depth through the hull well enough but not particularly helpful for anything else.  They are handy for ice fishing though when all you really need to know is depth (or specifically, where the thermocline is.)

You're both helpful on this one and thanks. I mostly wanted something lightweight that would give me an idea of depth. I also did some research and found a pdf online with a 2-page instruction list. Evidently this LPS-1 is a fairly uncomplicated depth finder that you just dip into the water, push the switch and hold to get a depth. The screen displays the depth for 10 seconds after you lift it from the water. Probably just fine for what I need but not as useful as say a PiranhaMax 150 or something similar.

I'll work my way up to a more expensive model probably one of these days but for now this will work. Thanks gents! up

While I can't speak to your unit, the things I want from my unit are: depth & bottom type (sand, mud, rock, weeds, etc). Mine will even show underwater springs. When it shows fish, that's a bonus. I really look for fish holding structure. I turn off all the bells & whistles as they just drain power. Color also drains power so avoid it. Hope this helps.

I went to Amazon and found some info/reviews.
From what I can tell the unit is strictly for measuring the depth in feet. For that purpose it got good reviews. I didn't see anything in it's description that it has a "fish finder" function?

I did see this similar product, which does have a "fish ID".

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Hey fishing experts,

I got a "deal" on (You need to Login or Register to view media files and links). 

Now that I've entered the world of fish finders, anyone ever use on of these and what are the pros/cons. For instance, I love the lightweigth of the unit.....any other insights on this to consider?