Archimedes

[Larry L]

The floating materials thread has me thinking, indeed I woke up at 4 AM
trying to get some ideas straight in my sleepy head.

Seems to me that flies float from a combination of factors.

1) true "lighter than water" materials ... these displace more weight of
water than they weigh . One interesting thing the fly designer
should note is that such materials ABOVE the water do not help float the
fly, any more than the part of a ship above the water displaces water and
adds buoyancy. I suggested dense foam in the other thread not because it
is lighter, rather because it can be shaped better, trimmed from fat to
thin quickly to go from tie in point to "displacement" size in a very short
distance for small ties

2) surface tension ... something I don't "really" understand ... but we all
know that slightly heavier than water items can be made to float by placing
them gently on the film. My observations of the bugs indicates that they
rely heavily on the film for support, after surface emergence is well under
way, and as adults ... I'm betting our flies should, too, to look most real,
at least at times.


3) trapped air .... probably the reason most commonly used materials in #1
are lighter than water, but some tying styles use the idea too, such as a
loosely tied folded emerger wing. The bugs use this too, we're told. ( I've
spent hours trying to actually "see" a caddis emerge, without success, but
I've closely watched many mayflies and midges ... the 'bubbles" are there
but far less obvious than all the glitter in many patterns .... indeed I'm
inclined to belief that most caddis emerger patterns function as attractors
from the overuse of antron and z-lon, since I've never been able to see
anything nearly as bright in hours of trying ... ah, not that there is
anything wrong with attractors, they work, .... and some of my best friends
fish attractors, ... I even had a roommate that fished attractors ... I
wouldn't want my son to fish them, of course :-)

4) chemical help .... again, something I don't really understand .... but I
think most of the times this simply keeps materials from absorbing water,
gaining weight, and changing from type #1 to non-type #1 materials. But, I
think there are other factors, in the best chemicals ... a water repellency
that increases local surface tension, or something ... as I've seen emergers
with closed cell foam wings float better when JUST that foam was treated ...
hard to believe that is the result of stopping water uptake

5) Other factors ???
.............................................

Anyway, I think "float" is the most important part of fly design, and not
just "dry fly" ... a wet that won't sink isn't a good fly, either. By,
"float" I mean the "presentation" aspects of the design ... if it's supposed
to be "half in, half out" it needs to float that way every time, and gain
that float quickly after touch down ... if it's supposed to represent an
adult midge standing on the film on extra long legs, it has to stand on the
film, body raised, .... wets need to sink to the right depth, etc. etc.

Second place on my list of design criteria would be the practical
considerations ...durability and castability ( there is no such thing as a
"good fly" that uses stiff winging and twists my leader, for instance )

Once those two things are handled, then the more commonly discussed traits
of size, shape, outline, color cab v\be addressed

.................................................. .......

Anyone that really understands surface tension, and how the fly tier can use
it or the chemical and why the best work better .... please post the
knowledge ..... I think most of us would benefit, as we design our patterns
and fish them

[Mike Connor]

"Larry L" > schrieb im Newsbeitrag
...

Well, most chemical "floatants" are not floatants at all but waterproofing
agents. All dry material like feather, fur etc, floats when it is dry. It
is keeping it dry which is the problem.

There are no chemical treatments which will give a fly positive buoyancy.

Some of the newer chemicals are hydrophobic. Material treated with them
actually stays dry, and therefore floats.

Some "floatants", rely on the material being soaked with a hydrophobic
material, or at least a material which is immiscible with water. ( Gink,
Paraffin, silicone grease, wax dissolved in various solvents).

Others are hydrophobic in their dry state, ( Watershed etc). The material
thus does not soak up water. The principle is the same, but the dry
materilas don´t wash of as easily as the liquid ones.

Cohesive forces between liquid molecules are what cause the phenomenon known
as surface tension. Surface molecules do not have other molecules on all
sides of them, and consequently they cohere ( cohesion = "stciking
together"), more strongly to those with direct contact to them on the
surface. This effect forms a surface "film" which makes it more difficult to
move an object through the surface than to move it when it is completely
submerged.

Surface tension is typically measured in dynes/cm, the force in dynes
required to break a film of length 1 cm. Equivalently, it can be stated as
surface energy in ergs per square centimeter. Water at 20°C has a surface
tension of 72.8 dynes/cm compared to 22.3 for ethyl alcohol and 465 for
mercury.

If you wish to hold a fly ( or anything else) "in" , ( as opposed to "on")
the film, then it must have at two entirely separate properties. It
requires positive buoyancy to keep one end floating, and it must also sink
at the other end.

This is further complicated by surface tension. Surface tension in water is
caused as a result of hydrogen bonding. As stated above, water molecules at
the surface of water are surrounded partially by air and partially by water.
These surface molecules are more stable when they are completely surrounded
by liquid, as all their hydrogen bonds are then fullfilled (cohesion). This
is why water tends to have the smallest surface possible, i.e. it has a high
surface tension, in order to maintain the lowest energetic state.

If a solid material, more dense than water is placed on the surface of
water, then what happens, depends on the nature of that material. If the
material is hydrophilic ("water loving") water is attracted to its surface.
This adhesion of water, to the material´s surface, reduces the surface
tension, and causes the object to sink.

If the solid object is hydrophobic ("water fearing"), then water is unable
to coat the surface. Two distinct forces now come into play -- the energy
required to overcome this repulsion, and gravity. If the force of gravity is
strong enough, it will prevail and the object will sink (assuming that the
object has a density greater than water). If gravitational force is less
than the surface tension. then the object will float on the surface of the
water.

Surface tension is what allows insects to walk across the surface, and
enables a needle to float. The critical feature, is is the amount of force
per unit area. If you put a needle into water end-on , instead of sideways,
then the needle will immediately sink

Adding detergents and other things to water changes these properties
radically. One hundred years ago, it was much easier to float a fly, as
there were many streams which contained no detergents, road run-off., etc
etc.

Displacement is another problem. A material which is less dense than water
( Cork, wood etc etc) displaces it´s weight in water, but continues to
float.

A material which is denser than water, once it has penetrated the film,
displaces its volume! in water, not its weight!

For instance, say you have a concrete bucket anchor in your boat. You throw
the anchor over the side, what happens? The boat rises in the water, as it
is now carrying less weight. The water in the lake ( although of course you
wont notice this ) actually goes down, because the concrete is more dense
than water, and is now displacing its volume, and not its weight.

Hope this helps!

TL
MC

[Willi]

Larry L wrote:


> 2) surface tension ... something I don't "really" understand ... but we all
> know that slightly heavier than water items can be made to float by placing
> them gently on the film. My observations of the bugs indicates that they
> rely heavily on the film for support, after surface emergence is well under
> way, and as adults ... I'm betting our flies should, too, to look most real,
> at least at times.

I think that's why it is often difficult to take fish when they are
feeding on small insects. Their orientation in/on the film are hard to
consistently reproduce with an artificial fly.


>
>
> 3) trapped air .... probably the reason most commonly used materials in #1
> are lighter than water, but some tying styles use the idea too, such as a
> loosely tied folded emerger wing. The bugs use this too, we're told. ( I've
> spent hours trying to actually "see" a caddis emerge, without success, but
> I've closely watched many mayflies and midges ... the 'bubbles" are there
> but far less obvious than all the glitter in many patterns .... indeed I'm
> inclined to belief that most caddis emerger patterns function as attractors
> from the overuse of antron and z-lon, since I've never been able to see
> anything nearly as bright in hours of trying ... ah, not that there is
> anything wrong with attractors, they work, .... and some of my best friends
> fish attractors, ... I even had a roommate that fished attractors ... I
> wouldn't want my son to fish them, of course :-)

Below is a link to a MPG of an emerging Mayfly. The film was taken by a
guy that was raising nymphs in an aquarium. Fast and silvery.

http://www.njflyfishing.com/vbportal/photopost/data/509/1Fuscom.mpg



> 5) Other factors ???
> ............................................
>
> Anyway, I think "float" is the most important part of fly design, and not
> just "dry fly" ... a wet that won't sink isn't a good fly, either. By,
> "float" I mean the "presentation" aspects of the design ... if it's supposed
> to be "half in, half out" it needs to float that way every time, and gain
> that float quickly after touch down ... if it's supposed to represent an
> adult midge standing on the film on extra long legs, it has to stand on the
> film, body raised, .... wets need to sink to the right depth, etc. etc.


I'm a "presentation" man too.


>
> Second place on my list of design criteria would be the practical
> considerations ...durability and castability ( there is no such thing as a
> "good fly" that uses stiff winging and twists my leader, for instance )
>
> Once those two things are handled, then the more commonly discussed traits
> of size, shape, outline, color cab v\be addressed


Although I agree that the "how" is most important, size is also often
critical. The rest, far less important.


Willi

[Larry L]

"Willi" > wrote in message


> http://www.njflyfishing.com/vbportal/photopost/data/509/1Fuscom.mpg
>
>


WAY cool, thanks Willi. I love things like that, and it can be so much
harder to see, on the stream, than one would think. I've watched many
mayflies free themselves from the shuck and more than a few nymphs swim/
float the last inch or two to the surface to do so, but I've never had that
much of a "silvery" impression from ABOVE ... the only view I've had

Where did I put my Antron ??? <G>

[Larry L]

"Mike Connor" > wrote in


>
> Hope this helps!
>


You might consider hiring yourself out as an encyclopedia, Mike <g>

Thanks buddy

[John Lindsey]

Great post Larry! It's posts like these that make reading through all the
off topic BS worthwhile. May I add two categories?

5) Lighter than Air. In order to offset hook and overall bug weight, I've
often thought of reducing bug weight by substituting trapped hydrogen,
helium, methane and/or other gasses in lieu of trapped air to make bugs
float higher. I've experimented with using these gasses in foam for bugs
but found it difficult to work with. Guess I need to find a plastics
injection engineer who fly fishes - LOL! Foam problems include: Too hard,
too soft, hard to color, hard to drill, hard to glue, hard to shape, hard to
remove from molds, etc. Also I frequently embed plastic or glass rattles in
my cork popping bugs. I've injected helium in plastic straws with BBs to
offset weight but found them hard to work with.

With all the bass tournament boys experimenting with various materials
making worms, grubs, minnows, crawfish, etc., in the future expect to see
lighter than air injections in their innovations. I expect to see frogs and
snakes included in this technology in the future.

6) Mechanical devices. Floating lures can be made to dive when retrieving
by using a scoop on the front. The reverse can also be used to keep them on
the surface. I scoop a 15 degree (top to bottom) slope on my Chug Bug
popping bugs to provide motion during retrieval but it also helps keep them
on the surface. This approach presents many difficulties when working with
unruly materials. My pathetic attempts to trim hair into a reverse slope
come to mind . <g> A major limitation of this approach is that it only
works while the bug is being retrieved. When not being retrieved, it
provides no flotation capability.

Anyone having any thoughts on how to make any of the 6 categories "work"
better will surely be appreciated.

Thanks again Larry. Good luck.
John


"Larry L" > wrote in message
...
> The floating materials thread has me thinking, indeed I woke up at 4 AM
> trying to get some ideas straight in my sleepy head.
>
> Seems to me that flies float from a combination of factors.
>
> 1) true "lighter than water" materials ... these displace more weight of
> water than they weigh . One interesting thing the fly designer
> should note is that such materials ABOVE the water do not help float the
> fly, any more than the part of a ship above the water displaces water and
> adds buoyancy. I suggested dense foam in the other thread not because it
> is lighter, rather because it can be shaped better, trimmed from fat to
> thin quickly to go from tie in point to "displacement" size in a very
short
> distance for small ties
>
> 2) surface tension ... something I don't "really" understand ... but we
all
> know that slightly heavier than water items can be made to float by
placing
> them gently on the film. My observations of the bugs indicates that
they
> rely heavily on the film for support, after surface emergence is well
under
> way, and as adults ... I'm betting our flies should, too, to look most
real,
> at least at times.
>
>
> 3) trapped air .... probably the reason most commonly used materials in
#1
> are lighter than water, but some tying styles use the idea too, such as a
> loosely tied folded emerger wing. The bugs use this too, we're told. (
I've
> spent hours trying to actually "see" a caddis emerge, without success, but
> I've closely watched many mayflies and midges ... the 'bubbles" are there
> but far less obvious than all the glitter in many patterns .... indeed I'm
> inclined to belief that most caddis emerger patterns function as
attractors
> from the overuse of antron and z-lon, since I've never been able to see
> anything nearly as bright in hours of trying ... ah, not that there is
> anything wrong with attractors, they work, .... and some of my best
friends
> fish attractors, ... I even had a roommate that fished attractors ... I
> wouldn't want my son to fish them, of course :-)
>
> 4) chemical help .... again, something I don't really understand .... but
I
> think most of the times this simply keeps materials from absorbing water,
> gaining weight, and changing from type #1 to non-type #1 materials. But,
I
> think there are other factors, in the best chemicals ... a water
repellency
> that increases local surface tension, or something ... as I've seen
emergers
> with closed cell foam wings float better when JUST that foam was treated
....
> hard to believe that is the result of stopping water uptake
>
> 5) Other factors ???
> ............................................
>
> Anyway, I think "float" is the most important part of fly design, and not
> just "dry fly" ... a wet that won't sink isn't a good fly, either. By,
> "float" I mean the "presentation" aspects of the design ... if it's
supposed
> to be "half in, half out" it needs to float that way every time, and gain
> that float quickly after touch down ... if it's supposed to represent an
> adult midge standing on the film on extra long legs, it has to stand on
the
> film, body raised, .... wets need to sink to the right depth, etc. etc.
>
> Second place on my list of design criteria would be the practical
> considerations ...durability and castability ( there is no such thing as a
> "good fly" that uses stiff winging and twists my leader, for instance )
>
> Once those two things are handled, then the more commonly discussed traits
> of size, shape, outline, color cab v\be addressed
>
> .................................................. ......
>
> Anyone that really understands surface tension, and how the fly tier can
use
> it or the chemical and why the best work better .... please post the
> knowledge ..... I think most of us would benefit, as we design our
patterns
> and fish them
>
>
>
>
>
>
>
>
>
>
>
>