Good lures are great. Good lures with voltage is better. I stand by my guarantee. You put one of my 'voltage tuned' lures down there at any depth and fish it beside a plain comparable lure, within say 25 feet, and my 'tuned' lure will come out the winner, or I'll give you your money back.
As far as proper bonding on a boat, the boat's metals form one half of a cell and the stainless wire the other half. When done properly, the voltage travels to the full depth of the wire (not just 20 ft).
Us Canucks do fish deeper than 20 ft. When the killer whales would go through, I found that I could still catch spring salmon when I lowered my cannon balls down to 70 fathoms. There isn't much light down there and a little voltage helps the fish to find your tackle.