I've experienced both in use, for me it's a drift sock. Trolling plates are good if you're only trolling forward, a drift sock can be used in both directions, especially good when back trolling. If you're drift fishing for walleye, then the trolling plate is useless, the sock on the other hand can be hung off the side of the boat. I made my own from the top 3 inches of a 5 gallon bucket leaving the rim edges on. Then out with the sewing machine and made a long tapered cone from nylon with about a 4 inch hole. The upper edge doubled over with a 550 cord drawsting tight around the top of the bucket. It can 't collapse. I use it mostly for slow salmon trolling in the spring or when I'm alone in the boat downrigging, keeps me in a straight line.