My dad also anchors a cast above the dam. My dad has been fishing gills off of wingdams longer than anyone I know. He does not use a bobber. He uses a small long-shank hook with small smashed-up pieces of nightcrawler. He uses a split shot or two for weight. Barbless hooks work very well for bluegill. You do not lose many if any fish due to no barb and the fish are so much easier to unhook. With quicker unhooks you get to spend all that extra time catching more fish. Plus you are not taking as great a chance at injuring the fish you are throwing back.
My dad also targets dams with low current flow but I’ve found a few dams with higher current flow that the gillies like to hang on. When you find them on a dam with a little more current then the gills seem to be bigger.
Eyehunter