Full disclosure, we didn't invent this tactic. Not sure who actually did, and it was likely by accident....but this is probably one of the more deadly large bottom dwelling predator producing tactics we have utilized in the past few years. It's called "mining".
The mining concept is simple, create as much constant contact and commotion on the bottom while trolling. Even more productive (and less work than constantly working your downriggers or divers) is simply dragging a much longer than needed segment of copper trolling wire in various water depths to create a condition where at least 30-70 feet of copper is dragging on the bottom while trolling.
This snaking copper trolling wire is super durable, and provides an extended and constant stream of sand and debris being kicked up off the bottom, not to mention stirring up baitfish and predators.
The snaking copper ahead of your bait presentation creates the perfect amount of turbulence and commotion to draw attention to the lure or bait.
Slow, like 2.0 slow or slower, seems to be the most effective "mining" speed. The faster you troll, the more copper is required to keep enough copper on the bottom to create the required commotion. Copper lifts considerably at higher speeds. The slower you troll, the less copper you need.
Think of running a 350' of copper in 50 feet of water, or running a 450' in 70-80 feet of water, or a 600' copper segment in 100 feet of water. The point of return is somewhere around an estimated 70 feet of copper fishing wire dragging on the bottom.
For additional reference on copper dive curves at 2.0 gps speeds, please view the charts here.