When you hear the term "Speed Trolling" you may discount the idea as some kind of far fetched technique with very limited applications. In reality, it can be a productive way to catch walleyes in many types of water. A word of caution, trolling 4 to 6 mph is not for the "laid back sipping on a barley pop fisherman"! It is a fast paced, hands on method. You have to be ready to tend rods in a big hurry.
An example of where and when "Speed Trolling" worked very well was at the 1999 NAWA Championship tournament in Red Wing, MN. This is a section of the Mississippi River with many different types of water. There are so many ways to catch walleyes you could become a versatile angler fishing just this impoundment.
The setting is early fall. As the water slowly cools the walleyes start to move into the river channels following the baitfish. I was working an area of shallow water about 5 feet deep with a narrow 8 foot deep channel cut through it. The entire area is about 1/2 mile long with a 1 1/2 mph current. This is one of the routes used as the fish come out of Lake Pepin. Muddy water and current make the fish susceptible to a "reaction strike" presentation. They sense something and take a swipe at it. No finesse needed.
Trolling speeds up to 5 mph produce a unique vibration from the #5 shad raps. Try different speeds, the fish will show a preference. Our best action came at 3.5 to 4 mph. I used the "speed over ground" on my GPS which read 2.5 mph upstream and 5 mph downstream. Running a zig zag pattern over the entire area was another key to getting a lot of bites. Because of the speed not all of the bites were successful. But that is part of the game.
Rods, reels and line for trolling this fast can make the difference between fighting fish and frustration. I used long custom 11 1/2 foot trolling rods, Daiwa line counter reels and #10 fireline on the inside rods. With 90 feet of line out the #5 shad raps were touching the bottom but not digging into it. The outside St. Croix S-Glass rods had Line counter reels and #7 shad raps with 70 feet of #12 trilene XL line out. They were snapped to Offshore plainer boards running about 25 feet from the boat. This spread made tight turn arounds easy.
At these speeds the fish hit hard. Team work is a must. When a fish bites the boat must be slowed and the line kept tight by thumbing the spool. Once the fish is under control, tighten the drag. If you can, keep the boat moving while you bring in the fish. That helps maintain a tight line. If it's a big one you'll know when to stop the boat. Until you have tried trolling this fast it's hard to imagine things can happen this quickly.
When the water is dirty and the fish are shallow "Speed Trolling" can leave you tired, breathless and wanting more.