Your dad has described the "poor man's trolling rig". I've tried it and it does work. You take a weight and tie it to a line. Off of the weight you tie your downrigger release (have a couple feet of line connecting the release to the weight - don't tie the release right to the weight). You then attach you fishing line to the release like you would with a downrigger. Set the drag, put the rod in the rod holder and slowler lower the "downrigger" line into the water. I used water-proof marker and marked the line at 5 foot intervals. When you get to the depth you want, tighten your drag, secure the rigger line and you are fishing. Be sure to not get the rigger line all tangled when you pull it up. I wouldn't use much more than 5 pounds of weight. This set up works good for lake trolling and shallow salt water trolling.
Good luck!