Robert He used an example that if one held a fly rod rod truly
Robert horiz., and gave the handle a very quick upward (I think he
Robert means backwards; toward ones head) pure rotation, the tip
Robert momentarily goes Downward.

Robert Does it ?

According to Don Phillips' "The Technology of Fly Rods" (page 87), yes
it does. He says that he demonstrates this by having someone hold a
piece of paper rear of the stroke direction and then initiating a cast
with a rapid pulse (it does not have to be up, sideways will do as
well). If you are interested in this, I think it is relatively easy to
make a convincing experiment to confirm this.

Phillips also says that this phenomenon has practical importance: if
you initiate a cast too quickly, it will cause slack.

Robert Why does it, if so ?

I have some guesses, but since I am not a physicist I will pass and
leave this issue to be resolved by someone more educated.

--
Jarmo Hurri

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