Yeah, side-planers spread away from the path of the boat...I think it's one reason they are so effective is because they travel a line outside that of the boat...we use them w/live herring easing along w/electric trolling motor so can pull 4 lines...two on planers and two straight off the transom..they're also effective w/lures when trolling w/gas motor...lure or bait can be way behind the planer or close to it...I've seen stripers actually strike the planer-board itself!!...
One thing about planers...since the line goes out to the board and then straight back, this can sometimes diminish the pressure of the line's hook-setting ability...so when a fish hits a planer line, I always wind down and SET it hard w/a little heavier drag...
