Reposted from ROF to ROFF

[Bob La Londe]

Physics of fishing
at http://www.washtimes.com/metro/20050907-090210-5222r.htm


--
Bob La Londe

Win a Spinnerbait Tackle Kit

Spinnerbait Tips & Tricks Contest
Through the Month of September 2005

http://www.YumaBassMan.com

[Frank Reid]

Tungsten coated lines fishing at 60 foot depths? Okay, I'll bite. Anyone
else seen this?

--
Frank Reid
Euthanize to respond

[rw]

Frank Reid wrote:

> Tungsten coated lines fishing at 60 foot depths? Okay, I'll bite. Anyone
> else seen this?
>

Scientific Anglers uses tungsten powder in the coatings of its
fast-sinking lines:

http://www.3m.com/us/home_leisure/scianglers/about_lines_superior.jhtml

--
Cut "to the chase" for my email address.

[vincent p. norris]

>Physics of fishing
>at http://www.washtimes.com/metro/20050907-090210-5222r.htm

" Ideally, the energy directs the fly to the target, he says. The
most efficient way to accomplish that goal is through a straight line
path of the rod tip.

"If the rod tip doesn't travel in a straight line path during the
cast, it either becomes convex or concave. A convex path of the rod
tip creates a wide, inefficient loop."

The rod tip becomes convex or concave? Wow!

Aside from that second paragraph's being an example of damn poor
writing (not extraordinary for the DC Times), the whole quotation is
nonsense.

I'll wager that there is no one in the entire world whose rod tip
describes a straight line when he or she casts.

Assuming the rod maintains a constant length during the cast, which is
the case with most rods I've seen, the tip follows an arc, not a
straight line.

vince

[Mike McGuire]

vincent p. norris wrote:
>>Physics of fishing
>>at http://www.washtimes.com/metro/20050907-090210-5222r.htm
>
>
> " Ideally, the energy directs the fly to the target, he says. The
> most efficient way to accomplish that goal is through a straight line
> path of the rod tip.
>
> "If the rod tip doesn't travel in a straight line path during the
> cast, it either becomes convex or concave. A convex path of the rod
> tip creates a wide, inefficient loop."
>
> The rod tip becomes convex or concave? Wow!
>
> Aside from that second paragraph's being an example of damn poor
> writing (not extraordinary for the DC Times), the whole quotation is
> nonsense.
>
> I'll wager that there is no one in the entire world whose rod tip
> describes a straight line when he or she casts.
>
> Assuming the rod maintains a constant length during the cast, which is
> the case with most rods I've seen, the tip follows an arc, not a
> straight line.
>
> vince

Indeed it is a badly written mish-mash of an explanation. However in the
casting stroke, backwards or forwards, the rod bends due to the mass of
the rod and the mass of the fly line attached to it being accelerated.
So the path of the tip is not a simple circular arc, but at a minimum
will be flattened towards straight from such an arc due to that bend in
the rod. All the well-known casting gurus, Lefty Kreh, Joan Wulff, Mel
Krieger will tell you that the optimum rod tip path is a straight line,
and there is plenty of video to back them up. If the cast is
overpowered, the path will be concave and usually results in a tailing
loop. If you try to cast a line that's too light for the rod you won't
bend the rod enough, and get the convex path. If the line is to heavy,
it will bend the rod too much during the stroke resulting in the concave
path. Within limits though, these effects can be controlled with technique.

But the worst thing about the article is that it dances around but
doesn't really get at the essential physics of what makes a fly cast
work. What it is, is that at the instant the loop is formed, the whole
line is in motion and has a certain amount of kinetic enery. As the line
rolls out, the energy that was in the part that goes static transfers to
the moving part. In the absence of air resistance the speed of the
moving part would continually increase due to this effect. It would
theoretically go infinite just as the end of the line is reached.
However among other things, the tensile strength of the line would be
exceeded, and it would break before this happened. With air resistance
there is a balance between the loss due to it and the transfer of energy
from the static part, and the line unrolls at more-or-less constant
speed. Narrow loops are preferred because less frontal area has less air
resistance.

Mike

[vincent p. norris]

>Indeed it is a badly written mish-mash of an explanation.

Your response, OTOH, is very lucid. Well done!

Not having seen any slo-mo films or videos of casting, I would guess,
and did guess, that the rod would have about the same amount of
bend--and thus effective length-- during most of the forward stroke.

> All the well-known casting gurus, Lefty Kreh, Joan Wulff, Mel
>Krieger will tell you that the optimum rod tip path is a straight line...

Never had the opportunity to hear them say that, but I can see the
logical reason for it.

>and there is plenty of video to back them up.

Do you mean their rod tips actually describe a straight line?

Seems to me, a priori, that with a given rod and line, only one length
of cast (and therefore amount of casting effort) would achieve that. A
longer cast, or a shorter cast, would produce different results.

vince

[rw]

vincent p. norris wrote:
>
> Do you mean their rod tips actually describe a straight line?
>
> Seems to me, a priori, that with a given rod and line, only one length
> of cast (and therefore amount of casting effort) would achieve that. A
> longer cast, or a shorter cast, would produce different results.

The resistance of the line will make the rod tip tend toward a straight
line. The more line is out, and the more mass is being accelerated, the
stronger the tendency. It's all according to the principle of least
action (which, by the way, is not the same "principle of least action"
that the Bush administration is following in the aftermath of Katrina).

--
Cut "to the chase" for my email address.

[vincent p. norris]

>> Seems to me, a priori, that with a given rod and line, only one length
>> of cast (and therefore amount of casting effort) would achieve that. A
>> longer cast, or a shorter cast, would produce different results.
>
>The resistance of the line will make the rod tip tend toward a straight
>line. The more line is out, and the more mass is being accelerated, the
>stronger the tendency.

Yes, that's what I was trying to say.

>It's all according to the principle of least action...

Never heard of that. Can you explain? That's not another name for
Newton's First Law of Motion, is it? ((:-))

>(which, by the way, is not the same "principle of least action"
>that the Bush administration is following in the aftermath of Katrina).

No need to explain that one.

vince

[rw]

vincent p. norris wrote:
>
>>It's all according to the principle of least action...
>
>
> Never heard of that. Can you explain? That's not another name for
> Newton's First Law of Motion, is it? ((:-))

The action principle in physics is independent of and far more general
than Newton's Laws. It finds application not only in mechanics, but also
in quantum field theory and general relativity. You can find many
explanations with a Google search. Once you understand it (and it's
subtle), Newton's Laws seem crude in comparison.

--
Cut "to the chase" for my email address.

[Mike McGuire]

rw wrote:
> vincent p. norris wrote:
>
>>
>>> It's all according to the principle of least action...
>>
>>
>>
>> Never heard of that. Can you explain? That's not another name for
>> Newton's First Law of Motion, is it? ((:-))
>
>
> The action principle in physics is independent of and far more general
> than Newton's Laws. It finds application not only in mechanics, but also
> in quantum field theory and general relativity. You can find many
> explanations with a Google search. Once you understand it (and it's
> subtle), Newton's Laws seem crude in comparison.
>
It's an elegant generalization but the concept wouldn't have arisen
without quite a few "crude" examples. In this particular instance, I
would say RW is talking about a different perspective on Newton's second
law.

Mike

[rw]

Mike McGuire wrote:
>
> It's an elegant generalization but the concept wouldn't have arisen
> without quite a few "crude" examples. In this particular instance, I
> would say RW is talking about a different perspective on Newton's second
> law.
>
> Mike

I'm not dissing the incredible genius Newton, but the action principle
is far more general than Newton's Second Law. All three of Newton's
laws of motion can be derived from it, and it applies to modern
physics, both in the small and the large, in ways that Newton never
dreamed of.