No. They usually do well at 2-6 MPH. Now Humminbird has their 360 deal now and that is a REALLY cool deal. It's like a radar that sweeps below the boat all the way around to give a full 360 view under behind and in front of the boat. The beam sweeps so you could be standing still and get a good 360 view under the boat. Here's a link to their 360 page..

Humminbird: America?s favorite Fishfinder ? the leading innovator of Side Imaging technology