Looking for a good depth finder to put at my console. One that will read when I'm running down the river. Tried a couple but couldn't get them to pick up. Don't want to break the wallet but want one that will work while running. I have an 18 foot aluminum boat with a 60 yamaha so won't be running fast. Mounted my eye on the right back of the boat but it was a hand me down. May have had the wrong eye. Any suggestions on a good depth finder?