A friend from the Great Lakes area turned me on to these trolling divers last year. I have since switched to using them exclusively. They are steerable, like the dipsy-divers, but the sliding feature allows me to reel closer to the fish for better control during netting - this has greatly reduced the number of boat-side losses and netting mishaps. These things are awesome!
http://www.slidediver.com/
Slide Divers
Linear Mode
