...My only problem is the speed sensor, can't get it dialed in correctly...
Use the brand the commercial guys use...................http://www.boatersland.com/ls4100.htmlhttp://www.practical-sailor.com/sample/Fishfinder.html
uh, just to update you on my experience with the fishmark480: i don't like it any more. it lasted maybe two full seasons and then started failing to read consistently deeper then thirty feet. it seems like maybe an electrical problem, as it is acting like it isn't getting enough power, but it also seems like these things should be made to last a little longer. but i guess that's what i get for going the cheap route.