Wednesday, 28 October 2015

Re: {Tidal Potomac Fly Rodders} Noob Question: Line Choice

Look at the BIG BRAIN on BRAD!




Richard Farino

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From: Tidal Potomac Fly Rodders <tidal-potomac-fly-rodders@googlegroups.com> on behalf of Tidal Potomac Fly Rodders <tidal-potomac-fly-rodders@googlegroups.com>
Reply-To: Tidal Potomac Fly Rodders <tidal-potomac-fly-rodders@googlegroups.com>
Date: Wednesday, October 28, 2015 at 2:34 PM
To: Tidal Potomac Fly Rodders <tidal-potomac-fly-rodders@googlegroups.com>
Subject: Re: {Tidal Potomac Fly Rodders} Noob Question: Line Choice

I hate to say it, but Gene is right. The logic applied to the lighter line is better is flawed. 

The momentum (mass*velocity) of the line carries the fly. A heavier line results in more momentum. Drag, caused by wind, is proportional to the cross sectional area that faces the flow, which would be the diameter of the fly line times the height of the loop. Making the assumption that a 6 wt and an 8 wt fly line have the same density and length and are cylindrical in shape, the change in mass is proportional to the diameter squared. A hypothetical example, where the diameter of the fly line doubles the mass would actually increase by 4. So at the same velocity the momentum would be 4 times greater while the drag only doubles (if the loops are the same height).

The actual ratios for the mass of a 6 and 8 wt line will not be 4, but the ratio of the diameters would be the square root of the mass ratio, making the heavier line easier to cast. 

As for loop height, I also agree with Gene that the casting stroke can be adjusted regardless of line size to make the loop tighter, which as the above implies would also decrease drag.  Also, in windy conditions carrying extra line when casting a 6 wt as suggested would be counter intuitive to me as it would make the casting more difficult. Extending this further using a heavier line would allow you to load the rod with less line outside the rod tip, which would make casting easier. But that is just my opinion.

Howard

On Wednesday, October 28, 2015 at 12:02:11 PM UTC-4, TurbineBlade wrote:
I disagree, with respect!  ;) 

Sure, a heavier fly line will make the same rod load as though it has more line out of the tip, that's not in dispute.  What he's saying though is that this "hampers" making the cast in wind because it results in bigger loops....which is totally untrue.  A good caster will compensate for having more line out of the tip (or overlining) without thinking about it.  I can throw very tight loops with my old, slow action fenwick ff80 (7wt) loaded with a 8.5 weight fly line and do so regularly.  I'll post a video if anyone doubts it -- you adjust your cast naturally, it's simple.  I guarantee I can cast that rod further and more easily in wind using an 8-weight line than I can that same rod underlined with a 6-weight (thinner) fly line. 

Why not take his advice further and take the same rod he's talking about and drop to a much, much thinner 3-weight line in the wind?  Just keep extending 10 feet and another 10 feet until the rod thinks it is casting a 6-weight line up close, and you'll be the king of the SW flats fly fishing! 

His argument includes ideas that make sense, but the overall logic just isn't there.... 

None of this is a big deal, but if you have your entire life to think about fly casting you should get it right.  ;) 

Gene

On Wednesday, October 28, 2015 at 10:38:09 AM UTC-4, Dave J wrote:
This article? - http://www.scientificanglers.com/choose-right-fly-line-weight/. This actually makes sense...

"There is a second situation where a lighter than normal line will help you if you are a fairly good caster. The wind is blowing and you need to reach out to a distant target. Many try to solve this common problem by using a line one size heavier. The usual thinking is that a heavier line allows them to throw more weight and, they hope, get more distance. Actually, going to a heavier line means that they complicate the problem.

On a cast, the line unrolls toward the target in a loop form. The larger the loop, the more energy is thrown in a direction that is not at the target. When fishermen overload a fly rod with a line heavier than the manufacturer calls for, they cause the rod to flex more deeply, which creates larger loops on longer casts. Overloading the rod wastes casting energy by not directing it at the target.

If you switch to a lighter line, you may not have enough weight outside the rod tip to cause the rod to load or flex properly — if you hold the normal amount of line outside the rod during casting. But if you extend this lighter line about 10 feet or a little more outside the rod than you normally would for this cast under calm conditions, you can cast a greater distance into the wind. By extending the additional amount of lighter line outside the rod, you cause it to flex as if you were false casting the normal length of the recommended line size.

Since the rod is now flexing properly, it will deliver tight loops, but the lighter line is thinner. This means that there will be less air resistance encountered on the cast."

On Tuesday, October 27, 2015 at 12:34:33 PM UTC-4, TurbineBlade wrote:
I read some Lefty article where he was saying that it is better to "underline" a rod by a weight for windy conditions because the smaller diameter of lighter weight fly lines "cuts the wind" better. 

Of course, physics says that this is indeed true, but is more than compensated for by the increase in mass that you get with heavier fly lines.  Go stand on a windy SW flat with a 6-weight and an 8-weight and let me know how it goes. 

I stopped reading his articles after that. 

Gene

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