We tried trolling with big boards for a few years and had many issues with them. Including not having the rubber band break and dragging undetected fish. Had problems with the boards not running far enough to the side of boat and the board line interfering with the rods when we made turns. Took a long time to set out and bring in boards and gear too. We finally gave up and went back to my inline boards and have not looked back. We didn't have a problem with the board line having too much slack though. That slack would most likely be the board not pulling hard enough. One solution would be to add weight to bottom of board to have it run deeper and pull harder. Good luck perchin.