Well Scott,
For fishing in the salt I would not be without one. They work and that's the bottom line!!! Mine's a Scotty. What you say about a boat being to hot is entirely true, the range that attracts salmon runs from .6 to .75 volts positive depending on the species of salmon. If your boat has a ground from the battery connection, battery switch, or any other electrical source on the boat it will "blow off" the fish. The field is created by the difference of the nobility between the stainless steel wire on your downriggers and the zincs on your boat. If your boat is zinc'ed correctly the natural electrolosys field around your boat will be between .7 and .9 volts positive, the box allows you to control that voltage to get it in the right range. If there is a ton o' fish like in the ocean last year the box will not make much of a difference as I think everybody was gettin' em, box or no box, the edge comes when the fish are fewer and farther in between. For the $200 or so they cost it's worth every penny. For a lot more detailed explanation go to
http://www.scotty.com/scotty_blackbox.htm Hope this answers some of your questions.
Good luck and tight lines, Jeff :grin: :grin: