It is currently 28 Mar 2024, 06:59


New Topic Add Reply
Author Message
Post 13 Nov 2020, 14:59 • #1 
New Member
Joined: 08/15/05
Posts: 17
Location: Hudson Valley, NY
I hope all is well. I have some data on static load deflection curves for fly rods now and have a few wonderings. Of course most will come back to “cast the rod with different lines and see how it feels,” but I am still interested in this.

You know the “Common Cents” system uses a single point on the static load deflection curve (load to deflect 1/3 rod length) and uses that load to establish an “Effective Rod Number” (ERN). Many people have many opinions of this. Some say is absolute (ie ERN=ELN and an ERN of 5 should use a 5wt line), some say it is relative (for comparing different rods and you normally like line to be 1 or 2 above or below ERN), and some say it is garbage.

Of course all of this came about because fly line wts are standardized (ie the first 30 feet of a 5wt line is 140 grains +/- 6 grains) but fly rod weights are not. One manufacturer 7wt may be the same another’s 6wt or 5wt.

I have established the entire static load deflection curve for 10 rods (not all mine). Various wts, lengths, materials. I have removed all manufacturer’s names, but classify by length and marked weight and graphite or fiberglass. Below my code is 8-5 f is an 8’ rod, 5wt, fiberglass. 10-5 g is a 10’ rod, 5wt, graphite. You see there is lengths from 6.5 feet to 10 feet and line weights from 3 to 8 right now and half are graphite and half are fiberglass. Obviously there are some random errors but I think the trends are illustrative.

In figure 1, there is just the raw data. Load (measured in pennies) and deflection (measured in cm). In figure 2, the rod length is “normalized” by having deflection as % of rod length vs load (pennies). In figure 3, both are normalized. Same normalization for deflection, and the load is normalized for EACH rod, normalized to the load to deflect that rod 1/3.

You can clearly see in figure 3 that “all fly rods act like fly rods.” If a rod deviated from the trend, it probably would not be a good fly rod.

My couple wonderings. You see in figure 1 AND figure 2 that the “9-8 g” and the “9-7 g” are very similar rods. Makes sense. They are both actually about 9.5 ERN, and behave very similar on the graphs. Different manufacturers, but one marked 8wt and one marked 7wt. Seems they should both be marked the same with a standardized system. BUT, in figure 1 (no normalization), you also see that “9-5 g” and “10-5 g” seem to be similar. BUT, in figure 2 (deflection normalized), you see that “8-5 f” and “9-5 g” seem to be similar. Is one of the figures better to show similarities? Curves with actual data overlapping or curves with normalized data overlapping. My guess is the first (actual data overlapping) because when you normalize both the load and the deflection, then all the rods look similar to each other.

My second and more important wondering. If someone believes the common cents ERN (either absolute or relative), then would it be possible (better) to find percent deflection from a COMMON load? Instead of finding the load that makes a COMMON percent deflection. In my mind, then if you had that load (mass of 20 pennies or 30 pennies as in figure 2), then you could use that common load, determine what percent of the rod length it deflects the rod, and then have a “industry standard” that would make the fly rod weight scale the same across the board for all. You could also take that load to a fly rod shop and quickly do that test and determine if it is the “right weight” rod you are looking to buy.

Figures below.


Figure 1:



Figure 2:



Figure 3:


Top
  
Quote
Post 13 Nov 2020, 15:07 • #2 
Glass Fanatic
Joined: 04/20/07
Posts: 8920
Location: US-ME
Ambitious! I think for a more useful comparison, the rods compared must be the same length and the same basic material and construction. Then, the area swept by the rod flexed with X amount of weight gives a somewhat more meaningful comparison than the deflection of any one point on the rod. Still hard to interpret.


Top
  
Quote
Post 13 Nov 2020, 18:10 • #3 
Glass Fanatic
Joined: 12/05/06
Posts: 2086
Location: US-PA
My brain hurts...



Top
  
Quote
Post 13 Nov 2020, 19:55 • #4 
Master Guide
Joined: 06/07/12
Posts: 865
Location: US-CA
Bamboozle, I love it.

Ultimately, it’s about the dynamic coupling between your hand/arm and the fly line. This is a nice capture of one of the factors at one point - the static deflection under a specific tip load, which is sort of a (distributed) spring constant. You also have (distributed) mass, damping, and aerodynamic effects. All modeled with partial differential equations. Fun stuff.

Interestingly enough, 140 grains is only 1/3 or so of an ounce, and a typical 5wt rod might weigh >3 ounces. But it’s all suspended off the tip of the rod.

It’s not hopeless, though. Your method does seem like a good way to compare similar rods and identify ones that might be way out of standard compared to their peers. It would also be fun to find two rods with identical static deflection and see how different they feel - live vs dead, tip recovery speed, etc...


Top
  
Quote
Post 13 Nov 2020, 21:31 • #5 
New Member
Joined: 08/15/05
Posts: 17
Location: Hudson Valley, NY
Motosacto,
Good stuff in your reply which lines up with what I opened with that casting the rod with a few different lines is probably still best. But, I was trying to see if developing more of the static load deflection curve (instead of one point like CC system) would reveal anything interesting. I think the CC system is good for comparing and seeing if something is way out of line compared to peers and going from there with your test casting. Probably what I determined is confirmation of that, and that you could either find the load for a common deflection percentage (like the 1/3 that CC system uses) or you could find the deflection for a common load. I have been told that using a common load has some downfalls (especially that you probably need a load for rods 1-6 and a different load for rods 7-12.)
Whrlpool,
Interesting comment about the area. I will have to chat with some mechanical engineer friends, especially one who used to design piles to stop a ship (but not damage the ship). But what you talked about is along the lines of some of my desires. Another post I made today about having an Echo RG586 and thinking about an Orvis SFG686 and wondering if they are the "same" rod or is there is definitely a difference between the two with equal length and marked one line weight different by different manufacturers.

I am certainly overthinking all of it (and I agree with all of you who are saying in your heads "just go cast the rods with different lines.") But it is interesting to me and I enjoyed getting the data and seeing if I can make any sense of it.


Top
  
Quote
Post 13 Nov 2020, 22:49 • #6 
Master Guide
Joined: 02/22/07
Posts: 871
Location: Out West
No offense to anyone, but I have never been a fan of the “Common Cents” focus, because it really doesn’t help much in my opinion with evaluating the actual fishing and casting feel, not to mention the real fishability of a rod or blank. Tried it some with rod building, blank and rod purchasing, etc. for a while, but found little value with it especially with fiberglass and moderate carbon. At times it was in the ballpark, but when it’s all about the feel and fishability for me, it just didn’t work. I've seen examples of glass rods and blanks with an "ERN" in the 2wt to 3wt range that fish as 4, 5 and 6wt's. It’s all very subjective...just my 2 cents.


Top
  
Quote
Post 13 Nov 2020, 23:19 • #7 
Guide
Joined: 12/20/19
Posts: 101
Location: Christchurch, NZ
I’m with Bamboozle on this one. That was a great skit!


Top
  
Quote
Post 14 Nov 2020, 19:19 • #8 
Glass Fanatic
Joined: 06/23/05
Posts: 4966
Location: US-MT
You lost me the moment you started talking about the "common sense" system. Nothing about that system makes much common sense.

Glad you are having fun though, keep it up!


Top
  
Quote
Post 14 Nov 2020, 21:34 • #9 
Glass Fanatic
Joined: 06/11/05
Posts: 1008
Location: US-NY
I was initially intrigued by the Common Cents System when it was first introduced in Rodmaker Magazine. I remember having mixed feelings about it. On the one hand, I was happy to see an objective system for evaluating fly rod line ratings. But some of the author’s statements made him come off like a pompous ass. Many of the readers immediately praised him as some sort of genius, although I’m sure most did not have the technical background to make such a statement.

Nevertheless, I still find the system useful. I will usually use it to evaluate a totally unmarked rod. It gives me a starting point, and I usually assume that a good line weight will be within one line size of that which is predicted by CCS.

You will find that many people will just categorically dismiss any scientific method for evaluating anything. This is just dumb, IMO. Everett Garrison was often criticized for his approach to bamboo rod design, usually by people who had just enough engineering knowledge to be dangerous.


Top
  
Quote
Post 15 Nov 2020, 10:26 • #10 
Glass Fanatic
Joined: 06/23/05
Posts: 4966
Location: US-MT
Science is good at some things, others not so much. Pennys hanging from the end of a rod are not really science

A woman's beauty, for instance, how can you evaluate it to everyone's satisfaction??

At the least, spline plays a large part in how a rod deflects, though I have never done it, I would bet you can take a rod, do the "common cents" thing, turn rod 180deg and try again and get way different results. Maybe if I get bored this winter.

Most of us that have been around the block a few times can pick up a rod blank and guess within one size line what it will take.

If people enjoy the cents system more power to em, this is all about doing what makes you happy.


Top
  
Quote
Post 15 Nov 2020, 11:12 • #11 
Glass Fanatic
Joined: 09/18/09
Posts: 5561
Location: Relocated to the Drought Stricken West.
smalliefly, I appreciate someone taking this type of thing on again. Common internet wisdom from 10 years ago was that CCS was usefull for graphite rods, but once you got into slower rods, things were not directly comparable. And if you think that you're over thinking it, move over to www.sexyloops.com. They do high speed video of rods loading, unloading and loop unrolling.

The two things I see as missing to get a better characterization are: the length and mass or mass distribution of the rod.

This came across when trying to interpret the first graph and I realized a 60cm deflection on a 7' rod is different than a 60cm deflection on a 9' rod.

The mass of the rod is a big factor. I'm wondering if you can measure deflection under no load vs minimal deflection. And if you can find the nodal point (scientific wiggle test). How far from the tip (or butt) is the stable place when wiggling a rod, and what is the natural frequency. This would be a lot harder to measure than static deflection, but might capture a bit of the "action"


Top
  
Quote
Post 15 Nov 2020, 11:54 • #12 
Glass Fanatic
Joined: 06/11/05
Posts: 1008
Location: US-NY
majicwrench wrote:
.... Pennys hanging from the end of a rod are not really science
...


I beg to differ. The idea behind the pennies is that pennies minted after a certain date and that are still in new condition have a very accurately known weight. This gives everyone a readily available weight standard. That part of it is very much science.


Top
  
Quote
Post 15 Nov 2020, 12:28 • #13 
Guide
Joined: 08/19/16
Posts: 314
Location: Brazil
carlz wrote:
The two things I see as missing to get a better characterization are: the length and mass or mass distribution of the rod.

This came across when trying to interpret the first graph and I realized a 60cm deflection on a 7' rod is different than a 60cm deflection on a 9' rod.

The mass of the rod is a big factor.


In the Common Cents System, rod length is taken into account. “Loading” a rod is considered to be a deflection of 1/3 the rod length. But I certainly agree that rod mass must also be taken into account. If you use that method to test a blank when only the tiptop is in place, then test the same blank once all the guides are in place, wrapped and finished, the results will almost certainly be different. That’s also why we need to disregard the droopy tip when taking measurements.

What Majic said about the effect of spline is another thing that would be interesting to check into, at least with a rod that has an easily detectable spline (or spine?) or a rod that has already been completed.


Top
  
Quote
Post 15 Nov 2020, 12:32 • #14 
Glass Fanatic
Joined: 06/23/05
Posts: 4966
Location: US-MT
Hope everyone has a bunch of new pennies minted after a certain date. :)

Your opinion and mine differ on the definition of science, and that's fine with me.

Seriously though, have fun with it if you wish.


Top
  
Quote
Post 15 Nov 2020, 16:29 • #15 
Glass Fanatic
Joined: 04/20/07
Posts: 8920
Location: US-ME
Well it is science and it is objective, but only in one element of fly rod in a static mode, and only for rods of essentially similar material. We can note the time the sun rises and the time the sun sets objectively, but that doesn't tell much about the day. Fly rods are used in a dynamic mode, but we don't even know how long it took the bend to form or the deflection pattern as it did.

An experienced user--again, experienced with that material and length--can note the nodes, the frequency, and the flex pattern and damping about as objectively. In doing this, just as it is not hard to swing a hammer with a fairly consistent force, an experienced user will be consistent in the flex input, not only its resistance to bending, but its weight. Common cents is consistent in a much more precise way, sure, but in a much more limited way.
The sum of observations of a careful flex-in-hand test are individually less precise, but collectively more accurate. I think that is what Mag is describing--objectivity informed by judgment. I forget the the statistical (math-science) principal, but essentially that a series of reasoned estimates (as in a "wiggle test") tend to accumulate and center on an accurate outcome. So although each observation could be quantified, there really isn't any need to. It's easy to get within one line weight, just as Mag said, and then casting a couple lines tells the rest.

If one were manufacturing rods from the start, a scientific/measured way would be/is used to get close to a replicable desired action. Once that was done, you wouldn't need to hang pennies on the end of the rod to check if it were close. You would need to test cast/fish it to see if the predicted outcome was the perceived outcome. If it weren't, something was wrong with the formulae used, not the experienced caster.


Top
  
Quote
Post 16 Nov 2020, 21:31 • #16 
Master Guide
Joined: 06/07/12
Posts: 865
Location: US-CA
Here’s some modeling and measurement fun if you really want to melt your brain...

https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.504.3831&rep=rep1&type=pdf

https://core.ac.uk/download/pdf/207772614.pdf

https://www.ri.cmu.edu/pub_files/pub4/anderson_dean_2006_1/anderson_dean_2006_1.pdf

It’s a little dated, but kind of fun. A couple of the papers include experimental results compared to finite element models. You could argue whether a Euler-Bernoulli beam with just one mode is the best model for a fly rod, but that’s probably a topic for a different forum?


Top
  
Quote
Post 17 Nov 2020, 09:33 • #17 
Glass Fanatic
Joined: 12/27/14
Posts: 1501
Location: ON, Canada
We’re all so very nerdy. :)


Top
  
Quote
Post 17 Nov 2020, 11:27 • #18 
Master Guide
Joined: 07/27/18
Posts: 375
Location: Probably at a Diner in Eastern PA
I don't know if anyone else agrees, but it seems to me that the choice of fly line creates a bigger difference than the actual difference in Rods of the same material and basic length


Top
  
Quote
Post 17 Nov 2020, 16:53 • #19 
Master Guide
Joined: 05/16/10
Posts: 814
Location: South of Houston, TX
Fun charts. I figured if any of the rods I owned would be an outlier, it would be my noodliest rod, a "Norie-Like" rod that was built from a blank advertised as a 7 foot 3 wt. I thought I'd to a quick check to see where it would lie on the graph. I often fish them with a 2 or 3wt line, but they self load. The rod I measured at 85.5", so a 28.5" deflection is 1/3. With no weight at all I have 4.75" of deflection. 5 pennies and I have 17.25", 10 and I have 25.25" deflection, and at 13 pennies I'm up to 28.25" and at 14 I overshoot to 29.25". For a point on the graph I also measured 15 pennies and got 30.25" of deflection. So 13 pennies is an ERN of 0.89.

to make units match the first and second chart,
5 pennies, 43.8 cm, 20.2%
10 pennies, 64.13 cm 29.5%
15 pennies, 76.84 cm 35.4%

It would be the lowest line on the graph, as it's a sub 1wt by CCS. Also, it would be a bit of an outlier on the third chart, as with 0 load it's already at 6% deflection. Obviously at the .33 on the x axis and 1 on the Y they intercept, as 100% load is defined at 33% deflection.


Top
  
Quote
Post 17 Nov 2020, 20:14 • #20 
Guide
Joined: 08/19/16
Posts: 314
Location: Brazil
ColdPass, it looks as though it may be in order to try a 0- or 1-weight line on that little rod.


Top
  
Quote
Post 19 Nov 2020, 14:49 • #21 
Guide
Joined: 11/23/17
Posts: 314
Location: Lehigh Valley, PA
The intent of this post isn’t to promote the CCS, nor is it intended to condemn it. I won’t try to explain the developer’s method or his intent - plenty of literature is out there for those who want to give it a try. What I will say is that each individual who dabbles in CCS will come away with his/her own impression of its applicability, or lack of applicability. Below I provide some of my takeaways:

CCS data has been collected on all fly rods I’ve built since sometime in the early 1990’s, plus rods and blanks I’ve tested for others. One thing that has become very clear to me is that ERN will not precisely predict the line weight a rod will perform best with. To expect line weight prediction by deriving an ERN will be an exercise in futility in many cases.

Why can’t ERN always predict best line weight? IMO, the ERN table doesn’t contemplate enough variables about a fly rod/blank. Type of material, weight of material, and “action” of the rod/blank play a large role in determining ERN vs Effective Line relationship. Throw in individual casting styles and line styles and this discussion gets even more complicated. Without going into too many details, here are my general learnings about ERN values.

Very fast graphite rods (think Dan Craft FT - Action Angle of 75) fish best with fly lines that are 2.5 to 3.5 points below measured ERN’s. Why? This blank is very stiff through the bottom 2/3’s. Takes a lot of pennies to overcome this attribute.

Slower graphite rods (think Winston IBIS - AA of 55) through medium graphite rods (think AA’s in the low to mid 60’s) fish well with fly lines +/-1.0 point vs their ERN. Why? My opinion: These were fairly common actions while the CCS “Rosetta Stone” table was being developed.

Bamboo rods I’ve tested have fished well with fly lines that are two points above the rod’s ERN. Why? These are generally slow action rods, and the weight of the blank material alone flexes the rod considerably when held horizontally. An example is an 8’0” Orvis Model 99 which is believed by some to be a 6wt or 7wt rod. Its measured ERN is 4.31. I fish it with a DT5 line. Haven’t tried a DT6.

Slower modern fiberglass blanks I’ve tested and fished perform best with line weights above their measured ERN’s (slower being AA’s of 56-61). I’ve tested around twenty. On average, line weights around 1.25 to 2.0 points above ERN work best. Why? Depending on their construct even modern glass blanks are heavier (and usually slower) than graphite. An example is Chris Barkley’s 7’10” brown ale five weight. This rod fishes nicely with my DT5 line. ERN for this rod is 3.57. Another is Dusty’s 8’6” Western Series 4wt. ERN of the measured blank is 2.23 (I measured two of this blank and the ERN’s were identical) and it fishes nicely with my DT4.

A Fast modern fiberglass blank I have (AA of 70) requires a line 1.25 points above its ERN. Only one data point with this action in fiberglass.

So, why do I continue to collect CCS data? There are unique situations where I get my hands on half a dozen fiberglass blanks (blems and prototypes) for consideration. Using ERN/AA for each blank I can form my own impression of the line weight I might pair with the blank. There are also cases where I don’t have CCS data on an ordered blank. Upon receipt I can determine whether the designer of the blank and I are on the same page about line weight, followed with mock-up lawn casting to confirm. How many times have you purchased a fly rod that needs a higher line weight to fish effectively? And wish you didn’t have to?

I hope this type of information is helpful to others who are already using, or are considering use of, the Common Cent System.

Jeff


Top
  
Quote
Post 19 Nov 2020, 19:55 • #22 
Sport
Joined: 12/27/16
Posts: 52
Location: US-CT
I will add a slightly different variable to the mix that I think matters in the 1/3 bend which is where the rod beds.

Because I am a nerdy rod guy, I recently put a deflection table on the wall of my garage that holds two rods. As I was playing with Rosa I compared two 8 1/2 foot 4 wgts (label). Beige comparing them I would have guessed their deflection would be quite different with one too well lower than the other because from casting it, it seemed way softer with a SA Trout line while the other rod felt faster, with a Rio Gold. Using an SA Trout on the faster rod felt underlined.

Low and behold the deflection chart says that with the same weight, the tips are in almost exactly the same place! The difference is the faster rod is progressive while the one that felt slower has a softer mid section but stiffer tip.

So I am all for playing with rods and measuring them but it seems to me comparing the whole curve is helpful to compare rods and I for one have not figured out a way to effectively compare two of different lengths other than very generally.


Top
  
Quote
Post 19 Nov 2020, 20:06 • #23 
Glass Fanatic
Joined: 12/31/15
Posts: 1238
Location: Northern Rockies
Thanks for the deflection information. It's an interesting experiment, and I'm always interested in looking at more data points and comparing them to my own.

I would also say that Jeff (PENZZZ) mirrors my thoughts very closely on CCS and deflection analysis in general. He also managed to say it much better than I could. The data points are interesting, but there are too many assumptions buried in the system that only fit a certain range of rods in term of action, material of construction, and so on.


Top
  
Display posts from previous:  Sort by  

New Topic Add Reply



Who is online

Users browsing this forum: No registered users and 8 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Jump to:  
Google
Powered by phpBB® Forum Software © phpBB Group