Originally Posted by silver creek
This is a casting fault that used to happen to me also. Now it almost never does.
The reason that this happens is that your line hand is too close to the fly rod when you release the line to shoot it on a longer cast. When you release the loose line, the line is pulled toward the stripping guide on the reel. If the line hand is close to and/or behind the reel or the rod but, the line may loop around the rod butt.
Note that you said it happens on longer casts and this problem typical occurs when shooting line. Sometimes the line will also loop around the reel.
Remember that the loose line is drooping down from your line hand so it it must fly up in a loop toward the elevated rod once you release the line. Keep your line hand and rod hand apart as you cast. That will cure the fouling of the line.
Glad I could help.
I would say this is the best explanation.
And i will add that instead of totally letting go of the line, just release it while maintaining a hold of it if this makes sense.
Imagine if your right handed, casting the rod with your right hand, and releasing the line with your left hand. As you shoot the final cast, instead of totally letting go of the line, keep your fingers curled around the line to maintain some control of it, but not holding it tight.
Imagine your left hand, palm up, with your fingers curled back toward your wrist, but not clenched in a fist. Your fingers form a reverse 'C', and thus prevent the line from looping round the reel and butt, but still free to fly out the guides.
This looks WAY better looking at my hand than it does written out.
I'll draw a pic and see if i can upload it.