Slack in your tippet:
When fly fishing, especially with a dead drift dry fly, we are supposed to copy the natural movement of the live insects we are trying to emulate.
The only way an artificial fly can possibly move, twist and turn as well as move downstream at the rate of speed of the natural is to move freely with each little micro-eddy created by the stream obstructions and substrate.
This demands a “detached “appearance to the waiting fish.
BUT, Wait! How am I supposed to be able to hook the fish before he spits out the unnatural-feeling imitation fly?
The answer lies on keen observation and meticulous planning. Your tippet slackness will disappear after only a short drift on the stream and the fish will refuse it as unnatural. You must plan on where the fish is taking his food and planning on having just enough line out to reach him, but no more. This is particularly critical when fishing downstream in heavy cover.
In my many years of experience, I have never had a fish take a dead drift surface fly that has travelled more than three feet! By this time the fly has begun to move in an unnatural straight line and the fish is uncomfortably moved a long way from his hard earned feeding lie. He must now use a lot of energy to return to that spot to watch for food. Each inch he moves reduces the equation of “calories captured vs calories expended”. He is in a “lose-lose” situation and will refuse to act.
The best action is to roll cast the fly off the water quietly, recast above where the fish holds and STOP the rod tip to create a rebound of the fly, creating a small amount of slack in the tippet so the fly can “wiggle” like the real ones being eaten. The key to hooking any fish on slack line or tippet is to employ the “Gaspereau Twitch”, by snapping the rod against the water surface in a sideways motion.
If you miss the fish, at least you won’t have your fly caught in a tree! The method sets the hook by the surface tension and a missed fish is not a catastrophe. Practice this method all the time to become proficient.
Your movement pulses instantly to the fly and will hook any trout effectively.
Remember, the fish sees your fly from a distance of less than three inches and sees tiny movements which you and I cannot. Feeding hundreds of times a day creates a robotic-like action dependent on complete realism of MOTION, not accuracy of imitation! All predators seek out motion in their prey.