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What does it take to make a nymph float?

There are really two simple elements behind the science that explains why things float or appear to float.

The first part of the science is pretty simple and is down to Archimedes who worked out that for something to float it had to displace at least its own weight of the fluid it is in.

The second bit of science relates to surface tension of fluids which in our case is water. We have all seen insects walking on water. They don't stay above the surface of the water just because their weigh is less than the weight the water that their body displaces, they stay on top of the water because they have a big enough of a "foot print" in relation to their weight to avoid their foot print actually penetrating  the surface layer of the water. Dry flies utilize this principal and its the tail and the hackle that create the "foot print" and cause enough of the fly not to penetrate the surface tension of the water rather than the fly actually being in the water and relying solely on Archimedes principal to float.

This nymph applies elements of each of these two principals of science. The materials are all as buoyant as possible. This includes the tail which is deer hair and of course "hollow' and the closed cell foam which has tiny bubbles of air trapped within its membrane. It also has a reasonable "foot print" made up of the  tail, and teased out seals fur body and thorax. Seals further adds a further benefit to the fly in that with a couple of brisk false casts it easily sheds water.

Materials

Process

A	Wind thread along the hook shank in touching turns and return the thread half way up the hook shank. Understanding hooks Tie in a tail of  deer hair that extends behind the hook a distance equal to about half the length of  the shank of the hook and so that the butt ends are tied down as under-body. Deer hair - uses in fly tying

B	Using the single strand method of dubbing dub a cigar shaped body along the rear half of the hook shank. Single strand method of dubbing Cut a length of closed cell foam which is as wide as the gape of the hook with a sharp V at one end. For this #10 hook trout fly I have used 1 mm closed cell foam. For a size 1 or 2 bass fly I would use 2 mm closed cell foam.

C	Tie the closed cell foam in along the top of the hook shank.

D	Dub a thorax of seals fur that is thicker than the body on the front half of the hook shank.

E	Pull the closed cell foam over the top of the thorax and tie it off at the 95% position. Trim the excess closed cell foam. Build up a neat thread head. Neat thread heads Whip finish and varnish the head of the fly and trim the excess thread.

F	Using a strip of Velcro tease out both thorax and body fibres so as to increase the "foot print" of the fly.

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