They usually can only help with success. The biggest thing is making sure your boat doesn't have a "negative charge field". You can test this by connecting a volt meter positive lead to your downrigger cable and the negative lead to any good ground on your boat. You want to have at least .6 + volts on your cable. In order to ground your cable you have to isolate the weight from the cable with a non metal connector. I use either a piece of #150 mono line or a piece of white nylon cord. What the blackbox does is give you the ability to adjust that voltage up or down.