Discussion on quiz answers.

Gordy,

Everytime I see one of your quizzes I realize how far I have to go before I even consider taking a Master's Examination. I finally summoned the courage (and the time) to send in my answers to his last quiz on overhang. I guess I'm having 'quiz taker's remorse' as I review my answers.

There was a lot to think about there and because I'm still unsure with some of my answers.

My basic question is this: does a tapered line/leader speed up or slow down the unfurling of the fly line? An unrolling loop is really just a wave on a string. I know that from a physics point of view, the velocity of a wave on a string is proportional to the tension in the string (sidenote - a reason you definitely want to avoid slack in the line) and inversely proportional to the mass/length. This makes physical sense to me since it would take more energy to turn over heavier line and thus slow down the rate of the loop if the line was getting continuously heavier. Using this argument a tapered line (let's say the front of a TT type line) reduces the mass per unit length as it unrolls toward the target, and thus I would assume that it's velocity increases and the presentation would be more forceful, yet I know this seems to be incorrect from practice.

Further, in the continuing ed class at Marlborough, Topher Browne discussed the reason to use a scandinavian type head on a spey outfit (as opposed to a skagit) since it lengthens the unrolling period and allows for more flight time. Since a scandinavian head is just a TT line, he's saying that a TT line unfurls more slowly.

Something doesn't make sense to me.

Dan

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Dan...

I ran your last question on the Spey lines past Ally Gowens. Here is the string of messages on that subject:

Ally....

I've been away from my MailList Controller and so have not sent any Group messages for the last few days..... however, I'm composing them for later posting.

QUESTION: On your last sentence: "generally speaking, Spey casting is easier to accomplish with a longer belly lie and the belly somewhere within the rod whilst casting."................................

Now, as a non-Spey expert, I found the same thing while actually fishing. However: Is it not true that the expert can attain greater ultimate distance with a long shooting head and some shooting line of thin diameter and lower mass / length in the rod tip ?

Ally's answer:

Hi Gordy,

Re your question. It is true that a perfectly executed cast with a long belly head (75ft +?) and running line outside the tip ring should attain greater distance. The problem is that it is not easy (or at least much less easy) to cast consistently well with as little disturbance as possible at various wading depths whilst changing angles by at least 45 degrees (ie during practical fishing). There are comfort limits for all casts, they depend on tackle, weather conditions, physical situation and angler skill and so they vary a lot as well we know! With Spey casts the Single Spey can produce larger D loops than other methods but there are limits to this loop and even in ankle depth water for a tall and highly skilled person it is very difficult to support six times the rod length of fly line out of the water with a taught “anchor”. Therefore a loop size of between 4 and 5 times the rod length is more realistic in practice. I think that there are two reasons why bringing the belly (or at least some of the thicker back taper) is helpful. The stiffer line appears to offer more support and hence control for the loop (in addition to reducing loop size) and rods appear to load more evenly when some of the heavier line is in the guides. In practice the benefit of making a perfect D loop far outweighs trying to make a larger but defective D loop with increased water contact which robs the “shoot”.

Best wishes,

Ally Gowans

Now, back to your other questions, Dan.

Your description of the unrolling loop is correct, as far as it goes.

With a tapered line, as the loop unfurls, the mass of the extending line decreases. The energy stays the same, so as this mass decreases, the velocity increases.

However, the loop doesn't travel with anywhere near the increased velocity that one might calculate for the reason that it is doing so against atmospheric resistance as well as the resistance of the rod leg of the loop to the fly rod tip, even when shooting line.

Simply put, as the tapered loop unfurls, we are trading mass for velocity minus the resistance of air plus that of line-rod resistance.

If we were casting on the Moon with little gravity and no atmosphere, theoretically the pure physics of the unrolling loop would prevail and that loop would go faster and faster until gravity took over or the loop energy dissipated completely.

If casting from a satellite in space, the gravity of the satellite would be negligible, so the unrolling loop would travel ever faster, diminished only by the resistance of the line to the rod tip, until it completely unrolled.

Theoretically, in outer space, if you cut that fly line and let it sail off, you would have no resistance of the rod leg of the loop to the rod tip. The loop would never unroll and the darned thing would just keep going to Kingdom Come !!!

I'll share your other thoughts about the quiz along with my comments in text in bold red italics.

Gordy

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Gordy,

Thank you for the insight. I found myself chuckling as I went through the mental experiment, and it makes perfect sense to me. I was going to attempt an 'earlth limited' version by simply casting a short fly line not attached to backing, and just let it slip through the guides on the delivery. Once airborne, the loop should halt unrolling until it hits the ground. I will try it someday.

I've already done that. It started as a practical joke which one of my casting buddies pulled one day on another buddy. When the caster was false casting with loops of line on the deck to be shot on the final delivery cast, he leaned forward and ,unnoticed by the caster, snipped the running line. On the final shoot, the whole thing shot though the guides and just kept going with the loop not unfurling much until gravity took over and the loop and line behind it fell to the water.

For a long time, I kept that old divided fly line for any doubter to try.      G.

This whole discussion leads to the fact that 'shot' line should unroll more slowly than if the line were pinched against the rod at the delivery. Thus as the friction of the line against the rod guides is lessened (by either cleaning the line or buying a new line, or buying a sharkskin) it increases distance by 2 mechanisms: 1) just allows the line to flow more freely out of the rod guides (the obvious one), and 2 allows the loop to unroll more slowly to increase flight time.  Does this make sense?   yes.

This then leads to my second thought:

I understood fully that the fly line will only continue forward as long as the loop is unfurling and thus the more line a caster can carry (and hence the more 'unrolling time' they'll have), the further the distance they can cast.

True. ..... however, with some tapers and leader designs, all of the energy is not expended at the point of complete loop unrolling. When that is the case, there is a small amount of momentum which can carry the line a bit farther ...... for practical purposes, it isn't much.       G.

I guess my question was geared towards how to slow down that process of unfurling to maximize flight time for a given length of carried line. Particularly I was keying off Topher's comment during the class where he mentioned the 'slow unfurling of the scandinavian head maximizes flight time compared to a skagit head'. This is why I asked about the taper. Compared to the amount of line a caster can carry, I'm sure this becomes a 2nd order issue, but nonetheless, it has an effect, no? It seems to me that although air resistance is present, the tapering will also cause the effect of said air resistance to drop off as the loop unrolls, aiding the increase in velocity of the unfurling loop.

Now we have a bit of a brain teaser. My thoughts:

# I think you may be right about the decrease in air resistance to the traveling loop due to the lessened diameter of the tapered line as unrolling occurs. I really don't know how much of an effect this would have.

# If we carry a given amount of line when false casting and hold tight with the line hand, thus shooting no line on the delivery cast, then I don't see how one can gain more distance even if there were a move by which the unrolling of the loop is slowed down.

# If we do shoot line, then the prime way of having the loop unroll for a greater length of time is to cast with increased overhang.

# I'm no expert on Spey casting or Spey lines, though I do think that the differences in the rate of turnover of these heads has to do with the relative lengths & design of their tapers.        G.

Finally, why does having excessive counterflex by keeping the last few feet of head in the rod guides result in poor performance? Certainly loop size should not be effected as the additional radius the counterflex first introduces is pulled out during the rebound. Is the concern that it adds shockwaves to the rod leg?

If you have thick/heavy line in the rod guides and tip top, you have greater resistance to the shoot. However, I think that the main reason for increased counterflex is that the rod tip is bending down more because of the increased mass of this heavier line allowing gravity to help pull the tip down.

With increased counterflex, the rod leg of the loop is temporarily deformed. As the loop travels forward and unrolls, however, this "bump" in the line irons out straighter, but as the deformity is "sucked up" (to use Paul Arden's term) a slight amount of increase in resistance to the shoot must occur which will use up a little of the energy.    This can happen even if the size of the loop has not changed.

(Now, if the counterflex is extreme, then it can tear open the loop.)

By decreasing the velocity of the shooting rod leg of the loop, we slow down the forward velocity of the loop itself by virtue of the formula:

        Velocity of the leading edge of the loop = Velocity of the fly leg + velocity of the rod leg

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Gordy

Dan