Proper drag settings are crucial for catching fish consistently. While you may get away with winching in a small fish with a nearly locked-down drag on heavy gear, you'd be hard pressed to stop a strong fish from breaking the line on its initial run with a similar setting. Conversely, if your drag is too light, it will be tough to set the hook or keep pressure on the fish.
Questions and theories abound on how to set a drag on a reel. However, as a guideline, the drag should be set at 25 percent of the line's rated breaking strength. That is, if you're using 20-pound-test line, the drag should be set at five pounds; 30-pound-test line at 7.5 pounds; 50-pound test at 12.5 pounds; 80-pound test at 20 pounds, etc.
Always set your drag using a scale and with the rod arched as if it is fast to a fish. Drag pressure is greatest at this angle, and it's where that 25-percent rule should come into play. When the rod is aimed directly at the fish, the drag pressure will likely be less than the 25-percent setting. That's why savvy anglers will often point the rod directly at a hot-running fish.
As a fish continues to run off line, the diameter of the line on the spool decreases, which, in turn, increases drag. Also, more line pulled through the water creates more pressure. When in this situation, slowly back off the drag as the fish runs, to alleviate the tension on your outfit. There will be enough drag from all the line in the water to keep the hook in a fish. Never tighten the drag if a fish is taking a lot of line. Drags should be checked before leaving the the dock and after each big catch.