Several neighbors in my area have suggested that going out into our river and bay area would be insane without a depth reading (lots of mud, shallows, shoals). As I'm browsing through the WestMarine catalog, I'm trying to figure out why I would spend $150-$250 for a depth sounder, when I can buy a fish finder that will give me water depth with a shallow alarm for around $125... Is there some disadvantage to using a fish finder for depth? Not incidentally, we're talking about having to navigate through 2.5-3' of water in some places. Does anyone have any insight on using fishfinders for shallow depths? Also, FYI: I don't particularly care about the fish.<br />Thanks, Rich