I've posted this before. I don't think it's great but I'll probably keep using it because it's easy to apply, relatively cheap, and very easy to clean up. It works fairly well as long as the boat is being used, By late August our boat tends to sit at the mooring seeing very occasional use on weekends until the mid-October haul out. In fairness to the product, our mooring is located near the head of the harbor in Freeport, ME in relatively warm, brackish waters and very close to the sewer plant outfall. This was what the bottom looked like at haul out last fall.