Trolls are especially effective in deep, murky waters or on overcast days. The basic difference between lake trolls is in the number and the shape of the blades, and the length of the shaft or cable. The shape of a blade determines how fast it will rotate and the particular sound vibrations it will produce. A round or nearly round blade, such as the Colorado or Bear Valley, swings slow and wide from the shaft while narrow blades like the Willow Leaf spin fast and close to the shaft. Narrow bladed trolls are best suited for fast trolling as they have less water resistance.
Trolls appeal to several fish feeding instincts.
The troll consists of a rudder at the front end which prevents line twist, a series of free-swinging blades on a wire cable or shaft and a swivel to which you tie a leader. When trolled, the blades act as attractors, fish follow the flash and sound to the source, spot the trailing lure and go after it. Larger and more blades should be used for deep trolling or murky water. Clear water or depths of 10 to 20 feet require fewer, smaller blades. If you are going to use lures or trolls that have a tendency to spin in the water, a rudder is an essential piece of trolling equipment.