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The "F" Fly or the "F" word?

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The "F" fly is a very simple fly that is quick and easy to tie but it has all the right qualities needed by any artificial to be really successful. In this article, Terry Lawton explains something of its background, how to tie it and corrects some of the myths associated with CDC feathers.

One of Slovenia's
crystal clear rivers
The "F" fly is a very simple fly that is quick and easy to tie but it has all the right qualities needed by any artificial to be really successful. In this article, Terry Lawton explains something of its background, how to tie it and corrects some of the myths associated with CDC feathers.

One of the most inspiring fly tying books of recent times must be Leon Links' book Tying Flies with CDC, The Fisherman's Miracle Feather.(Read my review of this book) One of the flies featured in that book was the Slovenian, Marjan Fratnik's "F" fly. This is a fly that I have tied and used with great success.

Earlier this year I read an article, based on a meeting the writer had with Marjan Fratnik, in which he used the word croupion when referring to the CDC feathers that he used for his flies, and to cutting the feathers. I was intrigued because I had never heard the word croupion before - it is not used in Links' book - and I always understood that you should not cut CDC feathers, in the same way that you normally pinch marabou to length. Something else that I did not know was how these feathers are harvested. I have always plucked them from wild mallard shot during the wildfowling season.

I then made contact with Marjan who now lives in Italy. He very kindly sent me samples of his flies, croupion feathers and quite a lot of information about how exactly he ties his flies and how and why CDC feathers are so buoyant.

A selection of "F" flies tied
by Marjan Fratnik, with his
pink version for grayling
in the middle
Marjan's "F" fly was first publicised in the Slovenian flyfishing magazine Ribic in 1983, in an article written by his friend Dr Bozidar Voljc, followed in 1984 by an article in the German magazine Fliegenfischen, this time written by Marjan Fratnick himself. Marjan has been fishing since he was 16 - he is now 86 - mostly in Slovenia but all over the world as well. He now fishes "F" flies mostly tied on size 14 hooks with natural colour croupions.

In difficult light conditions he uses yellow or orange flies and has not noticed any reluctance of trout to take them. Yellow and white flies are good as dusk approaches. He told me that if a fish refuses a fly after a number of presentations, he will pull his fly underwater just in front of the fish. One version of his fly that would seem to depend on its colour is his pink grayling fly. Apparently this fly has a fatal attraction for grayling and is possibly the most effective grayling fly throughout Europe.

Commercial producers pluck the croupion feathers from live ducks - up to 40 or 50 feathers per duck. Apparently the name has been used by Maximillian Jost and Charles Bickel since the 1920s. They were two fly tiers in the south of France, working with CDC feathers without knowing each other. In France croupions are plucked from domestic ducks in January and they have a grey-khaki colour, are very transparent, strong and regular in shape which makes them easier to tie with. Once you know what a croupion looks like and if you have access to mallards, either dead or alive, then you can pluck your own. Failing that, it will be a question of buying bags of commercial CD feathers and sorting through them to find the croupions. Marjan has convinced himself that "F" flies tied with them kill better than the same fly tied with 'ordinary' CDC feathers!

Darrel Martin, in his very interesting and informative book Micropatterns, Tying & Fishing The Small Fly, first published in 1994 in the USA, referred to CDC feathers trapping a 'sheath' of air as a result of 'embedded oils' in the feathers so making them water repellent and buoyant, and that during preening a duck will transfer oil with its beak from its preen gland to the surrounding feathers. He also maintained that this preening process kept the feathers flexible and waterproof. He did refer to the special structure of CDC feathers but I don't think that I mis-understood what he wrote if I say that, in his opinion, it was the oil that was the primary reason for their superb natural buoyancy and water-shedding qualities.

 The Soca
The reason that CDC feathers float so well is not due to oil in them or on them that comes from the duck's preen gland which they surround, but their structure. The structure of a CDC croupion is very different from an ordinary feather. John B Randall wrote an interesting article, in 1995, for the magazine American Angler, on the structure of CDC feathers. When viewed under a microscope, the difference can be seen easily. Every barb of a CDC feather has many long barbules on it. These barbules project from the barb in every direction and they capture and retain air bubbles when the feather is submerged. Even the shape of the CDC barbule helps the feather to retain air bubbles. It is because it is the feather's structure that provides the incomparable floatability that allows these feathers to be dyed successfully, without destroying their floatability.

The "F" fly is a very simple fly as it is tied with tying thread and between one and three croupions, depending on the size of hook, usually 12, 14, 16 or 18. Thread colour can be black or any other dark colour including red, olive, green or brown, and pink for his pink version for grayling. Tie a very slim body - Marjan uses size six thread, except for size 18 hooks when he uses size eight - and then take the appropriate number of feathers depending on hook size, one or two for small hooks, three or four for the largest, and density. Pinch them together with your fingers and cut the thick ends neatly and cleanly with sharp scissors. Yes, cut them before tying them on top of the hook shank and complete with a neat whip finish. The other end of the feathers can be trimmed to length, directly over the bend of the hook for slow rivers and chalk streams, and two or three millimetres longer for faster rivers. Cut them on the long side rather than too short. The head can be finished with a drop of varnish. Leave to dry and then varnish again. In his book, Leon Links shows a slightly different way of tying the "F" fly which is not the way of its inventor.

CDC flies can be real 'killers' and I have fished "F" flies for a number of years with great success. As with many CDC flies, some last much longer than others. I think that it depends on how much of a mauling they get in a trout's mouth. A fly that is lightly hooked in the scissors will suffer less than one inside a fish's mouth. At the moment I would need convincing that this is the only dry fly that anyone would need, but it is without doubt a 'must have' fly in any fisherman's fly box.

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