Mike wrote:......
"Spider" flies, /( Soft hackled wet flies, wingless wets, etc) rely for their success more or less entirely on the relatively mobile hackles used. Most people who use them know this, but most don't know how it occurs. If you want to know how to move these flies correctly, then you must know how it occurs. Contrary to popular opinion there are no intrinsically mobile hackles! Regardless of what you use or how you apply it, all these things rely on water pressure to move them. A static fly in static water does not move at all. A fly moving dead drift downstream in any particular "block" of water remains completely static relative to that water. Hackle movement ONLY occurs as the result of drag external to the fly. This is a simple fact which is easily checked, but many people simply refuse to believe it.
Later...............
Im still on page 2
Just so I understand this correctly. I think I understand the principle that a fly will be static relative to the block of water that contains it.
This is speculation on my part based on limited knowledge but I reckon it may well be important to understand the behavior of the fly before we try any manipulation. Certain things we know to work, understanding the why would be a great bonus.
I cast a single spider and it enters the water.
On entry
- the hackle will not be in the nice umbrella shape that we see on the vice when it hits the water - for want of better words its not in its natural position.
- The hackle will try and flex back to its natural state following entry, it will always try to flex back.
Directly following entry the only external forces acting on the fly within its cushion of water will be Gravity and minimal but exponentially increasing forces created by the leader.
- the initial sinking of the fly will cause an upward push on the hackle, which will act against the hackle recovering to its natural position – the hackle movement will stop after this initial movement .
- the weight of the hook will determine how quickly the hackles attain their position on the drop – this may be important - but would have to be considered in juncture with the leader.
At some point soon after entry the pull of the leader will counteract the effects of gravity and the hackle will find its natural position or at least quite close to it.
Its well known that many takes do occur on or just after entry.
If my understanding of the physics of all of this is close to the truth then the weight of the hook, the design of the fly relative to the type of water and the diameter of the leader will all have a strong bearing on the initial behavior of the fly for that very crucial moment following entry and subsequently as well.
So “in theory” for a fly to be a good imitation , how it is dressed, what weight and style of hook it is dressed on, what leader it is tied to and how it is fished , and the type of water it is fished in are all intrinsically linked to its behavior and off course we assume the trouts reaction to it.
Another factor which I guess is obvious , but must be considered is how dry or damp the fly is as it enters the water - that too will effect the immediate behavior. So a load of false casts apart from scaring the trout also affects the behavior of my spider.
Once equilibrium has been achieved and the hackle is in its natural state, the leader then starts to exert a greater force - and if not controlled correctly by the angler will cause the fly to loose shape and speed up relative to the cushion of water that contains it. I know that some takes may occur at this point just before everything goes out of control - movement has occurred and has attracted a trout but it is a lucky strike. I guess the task in some cases is to try replicate this throughout the drift in a controlled manner that is pertinent to what we are imitating.
Interesting stuff to contemplate and working out what facts are the most relevant may indeed be some or all.
).
I prefer to grab a stick and go 'beat up a tree' ... provided I recognise it before 
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