Fishing: How To Fish: Basics

Gripping the rod: There are several ways to grip a fly rod, but only two of them give their wrist freedom you need for good fly casting. The grips I like are shown in the first two photos below.
The main difference in them is that in the first the thumb is extended along the top of the cork; whereas in the second it is curved around the cork.
I find this second hand position, with the thumb curved over to meet my forefinger, a bit more free and easy than the extended-thumb grip. It also helps put more power into a conventional overhead cast because it places the back of the hand in a position to exert more force on the rod.
The bottom photo shows how lightly the rod is held as it pivots in the hand during casting motion. The grip should be comfortable, natural. Pick the rod up between thumb and first finger and let it settle gently into place.

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