GUIDE SPACING FORMULAS – HOW & WHY THEY DO & DON'T WORK:

First of all, let the record show that I am mainly answering this question as an exercise in and an explanation of the mathematics involved. I am trying to discuss the mathematics of the question more than its power to provide a suitable guide spacing layout. (Which is subjective.) I am NOT really endorsing the use of these mathematical systems apart from an appropriate understanding of guide placement basics, or from the many assumptions latent in the use of these formulas. But I am responding so that Readers can learn the math and decide for themselves, based on their own applications and observations, if and when it is a suitable system for making a FIRST APPROXIMATION of placement for their guide layout. Formulas are not meant to be the final arbiter, nor were they ever intended to be (at least not in my book).

So, for the sake of proceeding with an orderly discussion, please spare me the outcry of comments suggesting how inferior these formula are for optimizing guide layout. I am by no means attempting to make a comprehensive discussion of this subject here at the RBO Forum. Been there, done that, ... WAWOT! You could say that this is mostly all academic at this point, which it is, because some other methods can more easily give guestimations that are at least as satisfactory as this one. I'll let the Reader decide that rather than the jeering gallery.

GEOMETRIC-PROGRESSIVE Spacing-Distance Method Guide Layout:
Available in Dale P. Clemens' book "Advanced Custom Rod Building", which was first published and copyrighted in 1978 (p.192-196). Also available in Clemens' "The NEW Advanced Custom Rod Building", copyright 1987 (p. 194-197). ...

[Trust me when I tell you that neither Dale Clemens or the RodCrafters in the book had anything to do with the derivation of these formulas. They merely made them available to the rod-building public. These formulas have been around for centuries before Isaak Walton wrote The Compleat Angler. They are routinely studied in any college level course in Calculus or Series or Sequence Theory. One famous variation is the Fibonacci Sequence, which is from the early 13th century. ... "What has been, will be again. What has been done, will be done again. There is nothing new under the sun." Ecclesiastes 1:9.]

GEOMETRIC-PROGRESSIVE Spacing-Distance Formula:

B = [N * T] + [N * (N-1) / 2] * D

where:
B = distance from the rod tip to the BUTT guide
T = distance from the rod tip to the FIRST guide
N = the total number of guides used, excluding the tip-top.
D = equals an incremental value of arbitrary value which is often
assigned the value of ONE for the units system you are using,
inches or centimeters. Using a value of D = 2.00 does simplify
the mathematics. D is usually not much greater than 2.00 inches
or 5.0 centimeters. In fact, for limber rods, like fly rods,
D may be less than 1.00, and approach 0.00 (zero).
* = multiply
/ = divide
+ = add

By this method, you must first decide an approximate value for B, the distance from your rod tip to your Butt Guide. This can be done by a Ratio Method (~ 65% of the distance from the rod tip to the spinning reel spool), or Free Flow Zone (a recommended range for the distance between the reel spool and the Butt or Stripper guide, often 18" - 24").

Then you must set a value for D or for T, and solve for the other. It is usually a little easier to set D = 2.00, which gives a more equal guide spacing than if D is larger. Then you must SOLVE this equation for T. Or you can set a value for T = 4" to 6", based on your experience. Then plug T into the original equation, which is: B = [N * T] + [N * (N-1) / 2] * D

B = [N * T] + [N * (N-1) / 2] * D

Perhaps the most important thing to realize about using this equation is that the second term in the equation is heavily dependent upon the value of D for how dramatically it effects the rate of geometric progression. The smaller the value of D, then the closer to an EQUAL INTERVALS method the spacing will be. The larger the value of D, then the more dramatic the expansion rate of the intervals. It is the coefficient of D, the product "N(N-1)" that makes this "Progression" a "Geometric" one. That is the rudimentary form of the equation, and variations on that theme are a natural corollary. And those variations have no further need to be based on a representative or theoretical model.

Suffice to say that you are free to alter the formula by changing the coefficient of D to reflect what you think is a better or more realistic progression than a geometric mathematical model. Instead of using N(N-1) for the coefficient of D, you could try N(N-2), which gives a slower expansion rate. Or N*N (N squared), which would be too rapid an expansion rate, but now I hope you get the idea of how YOU can alter and use the equation to control and discover the results you get, instead of feeling like the EQUATION is in control of you. YOU are the "Creator" of this microcosm - Don't be a "NOMAD" robot. Outsmart the equation. (Sorry if this reference to Star Trek escapes you, ... "Sterilize!")

Whenever N(N-X), where X is your choice for a modulator, attains a negative value, just Set N(N-X) = zero, and use an equal interval spacing for those first X number of guides.

Aah, if you are still paying attention, now you can see how this modification can eliminate one of the main drawbacks of the Geometric form of this Progression: "The guides start spreading out two early and too much". Now YOU can preserve a section of Equal Intervals for the first X number of guides AND control the rate of expansion in the Progression, by altering X.

AND you can even further control the rate of expansion by your choice for the value of D. Now you have at least 2 arbitrarily (designer) controlled variables that you can tweak here.

HINT: Higher X for uniform bending sections; Larger D for spinning rods, because they have the widest cone of flight and the largest angle between the line-guide path and the rod blank. These variables, X and D, have the capacity to represent a real & tangible aspect of the rod & reel geometry. IF you already know rod-building AND IF you know some math basics. Or IF you are at least willing to learn. Math can work FOR you instead of against you, if you work at it.
The next form of the Geometric Progression Formula is:

S(n) = [n * T] + [n * (n - 1) / 2] * D

where:
n = the ordinal number of the guide, for the 1st to the "N-th" guide.
S(n) = the distance of the "n-th" guide from the rod tip.
T = distance from the rod tip to the FIRST guide
D = equals an incremental value of arbitrary value which is often
assigned the value of ONE for the units system you are using,
inches or centimeters. Using a value of D = 2.00 does simplify
the mathematics. D is usually not much greater than 2.00 inches
or 5.0 centimeters. In fact, for limber rods, like fly rods, D may
be less than 1.00 and approach 0.00 (zero).
* = multiply
/ = divide
+ = add

I will now choose some values for these variables which allow a convenient calculation to be performed, hopefully in your head. Otherwise, grab your calculator, or pull up your PC's desktop calculator (which may be at Start-Button / Programs / Accessories / Calculator). The values selected below are realistic, but not necessarily optimal.

So, let's say that (for something like a 90" surf rod) you're using
N = 5 guides
B = 50 inches
T = 6 inches
D = 2 inch

Again: S(n) = [n * T] + [n * (n - 1) / 2] * D
Because ("D = 2" / 2), these "drop out" of the equation.

Now: S(n) = nT + n(n-1)

S(1) = 1(6) + 1(0) = 6 + 0 = 6 inches
S(2) = 2(6) + 2(1) = 12 + 2 = 14 inches
S(3) = 3(6) + 3(2) = 18 + 6 = 24 inches
S(4) = 4(6) + 4(3) = 24 + 12 = 36 inches
S(5) = 5(6) + 5(4) = 30 + 20 = 50 inches

You should notice that this formula gives the next guide position as simply the previous interval distance (I) plus the value of D.

I(0-1) = T = 6 inches. S(1) = S(0) + I(0-1) = 6 inches
I(1-2) = 6 + 2 = 8 inches. S(2) = S(1) + I(1-2) = 14 inches
I(2-3) = 8 + 2 = 10 inches. S(3) = S(2) + I(2-3) = 24 inches
I(3-4) = 10 + 2 = 12 inches. S(4) = S(3) + I(3-4) = 36 inches
I(4-5) = 12 + 2 = 14 inches. S(5) = S(4) + I(4-5) = 50 inches

Well now, aren't you glad you asked! If you pay attention to the rhythm of the pattern in the mathematics, it's almost like music. You can drum it out in your head faster than on the calculator. That really is the end of the discussion of the mathematics, per se.

It has a certain elegance to it on paper, but it may not give such great results on your fishing rod for a myriad of reasons. Not the least of which is that it describes an ideal geometrical system, which a fishing rod and its reel and guides are NOT. Nobody ever said they were! BUT such formulas CAN be used to describe a fishing rod IF you know BOTH rods AND math, ... which eliminates about 50% of the rod building population from the word "Go". About 33% of the remaining rod-builders couldn't care less. About 12% are too dang busy actually building fishing rods and making money at it to even bother reading a hypothetical Post like this one. And the last 5% of the rod builders are laughing so hard right now that they can't even read the computer screen, the tears are so bad. So, that means I may be left talking to myself again, ... LOL!

NOW, some of the other myriad of reasons why these formulas give imperfect results include, but are not limited to - regarding the:

ROD STYLE (N, D) - Spinning, Revolving Spool, Fly, Trolling, etc.
REEL - Spool Diameter, Height off the rod blank (D), Spool Width
ROD BLANK - Length (N), Power, Taper (X), material
GUIDES (B, T) - Style, Ring Diameter, Height off the rod blank (D)
LINE - material and pound test

(I have suggested which of the equation variables are affected by the various rod & reel variables by putting them together.)

And the personal preferences of the rod builder will also affect guide layout. So much for a short answer to a simple question! LOL! A set of correction factors would have to consider these variables as well. (Tom Kirkman said he once had about 20 different equations for all such differences and gave up.)

No formula for guide spacing is going to eliminate the need for or the usefulness of a Static Distribution Deflection Test or a Casting Test. Formulas must be used in concert with Testing to determine the proper placement and selection of line guides.

And the manufacturers of line guides will always incorporate certain assumptions and constraints into the geometries of their line guides. Ring sizes and heights off the blank will be offered only in certain quantum values, and that in & of itself will mean that certain patterns for guide layouts will naturally recur due to these mathematical and geometric commonalities. It is inevitable. And useful. But not always automatically reliable. If you change one thing in the system, it may affect the whole system, and throw all your pre-conceived selections across the threshold and into the next size or style category. And then all the formulas may have to be re-worked again. (Example: Building a 30-60# GUSA B-70-Monster-MAG. As a 30# rod, I may choose Fuji BHNLG casting guides. BUT as a 50# rod, I may choose the BLRLG Turbo guides. Same rod blank, different LOADS AND different GUIDES. A very different guide layout chart for the same rod blank and fish.)

And let's not forget to consider that progressive guide spacing seems to work better in the sections of the rod with the longest radius of curvature (toward the stiffer butt and mid-section). And the limber tip section may be better suited to an almost equal interval approach to guide spacing (equal arcs). So, this further limits the appropriateness of a formula where D is too large.

Basically, until you learn to discover and incorporate your own correction factors for these style variables, any formula will give a compromised result. Probably the spinning rods are best suited to the raw formula as discussed above, because they most closely resemble the geometrical representation of a sequence, which is some form of an acute triangle or cone. Fly rods are the least "cone-like", because their guide rings are too narrow. And fly rods traditionally use a very low height off the blank, which means the line-guide path and the rod blank are parallel. With fly rods, the guide spacing is 'TOTALLY' dependent on the rod bending (power and taper and curvature) and has virtually nothing to do with the geometry of the reel or line guides. For a fly rod, some mathematical model which sweeps out arcs may work, but that seems to degenerate to the trivial case of equal spacing.

In the NEW-ACRB, page 196-197, Clemens includes some Correction Factors & Table of Distances from the Reel to the Butt or Stripper Guide. You'll have to refer to them yourself, or generate your own values from your own observations. From what I can tell by reading this section myself, there is a lot of empiricism employed there. It is not based upon some underlying mathematical or engineering principle that the authors have discovered. Its the art of the rod-building craft. And until somebody gets it all figured out, that's the way it will be done. Because the incentives to computerize it are very small, and as some have suggested, "would take all the fun out of rod-building." ... Or reduce you to being a robot. ... For me, it puts some of the fun of discovery into rod-building. ... To each, his own, ...

Good luck with it. -Cliff Hall, Gainesville, FL-USA+++

Special Thanks to Justin Mitchell, whose recent Post
(below) inspired my cogitations on this subject:

"guide spacing" ... justin mitchell (HIDDEN)
October 18, 2005 01:09AM ... [www.rodbuilding.org]
"is there a math formula to dertermine guide spacing on
fly rods,casting rods,are they different?" -justin mitchell-

So what you're saying is... wing the mother? LOL

Either you are the definition of "Morning Person", or you've already had wayyyy too much coffee!

Good stuff, Cliff!

Cliff,

I appreciate The time, effort, and thoughfulness you put into your impressive post.

Mick,

I appreciate your sense of humor.

Cheers to both of you. You got my day off to a good start.

Steve

No coffee. Just LOTS of insertions, finalizing and proof-reading last night, after a day of letting the first draft simmer for ~ 24 hours. Then it gets released. Then we can all wing it, fling it or sing it, whatever floats your boat. Just so long as it there is a thorough and realistic analysis of the subject, and a fair-minded review by you all. Then we can take it or leave it, as time and inclinations allow. But I or we can’t get any synergy here until it gets out for review. The idea of how X or D correlate realistically to actual rod parameters didn’t fully occur to me until I had to write about it and articulate it. Now I can see how the discovery is as important as the results, because the discovery can give me (and hopefully others) more insight into more ways to improve our results. … And any good designer or engineer knows how to wing it or find another “fudge” factor to make the theory and the practice come to a “flush”-fit meeting somewhere in the middle. That’s where the floor boards come together – not where all the “fudge” gets flushed. LOL, Cliff Hall+++

The factors that most affect casting are not found in any of the equations I'm aware of. Because of this, charts and equations are only useful as starting points after which you must alter the spacing to suit the line, reel, etc., at hand. For this reason, I see no point in starting with something that you won't be able to use anyway, or which must be manually changed or altered before you arrive at more optimum guide sizing and spacing.

This in no way is meant to undermine the well researched and thoughtful post Cliff has made. But generally, with just a little experience, most builders can set up an optimum guide system in less time than it would take to plug in the numbers for any equation and then place those guides, test and alter the set up to fit the particular blank. For me personally, mathematical equations are an additional and uneccesary step that only slows down what is actually a very quick, easy and straightforward process.

I would not, however, underestimate the value of such mathematical systems for builders who are just starting out and don't yet really have a feel for the criteria that determine good static distribution or good casting qualities. Along that line they may be very helpful.

.........

Tom,

I have an idea. Why not have a floor demo at the next Rod Builder's Show given by someone who is comfortable with optimum guide spacing methodology. This would alleviate the anxiety shared by many who like spacing charts and formulas. I believe what you are saying, however, a demo would help my confidence immeasurably.

Thanks,

BOB

Rod building for me is just a hobby, I build only for myself and family. I was always looking for an easier way to determine guide placement other than the static test since it does take time and can be more tedious. But what made me a believer in it was seeing the difference in the tip action on a Gloomis GLX and my recent Sage XP blank. With the upper section stressed, the GLX exibited an even round bend in the upper section and required guide spacing a consistant and even manner. However, my Sage XP (which supposedly has the same type of action) had more of an oval curve to it. In fact, the major "bend" in the tip section was about 12"-14" from the tip. Between this and the tip was reletively straight even under load and I was able to spread the first couple of guides a bit further than normal. And lo and behold, this 10' long rod came out balancing perfectly - no butt weight needed - DUH.

I would much rather use a formula for guide spacings since it's a lot easier but from what I've experienced - especially because of unique differences between various blank manufactures, the static test is really the only way to go if you want to optimize rod performance. I guess I've been converted!

Cliff's mathematical tretise and the responses beg an issue that has made me wonder every time I read a post and responses on "proper" guide spacing, and even after I've read and re-read the two articles in the library on static testing and the new concept primer. Every presentation on guide spacing ends with "test casting" to verify good placement of guides -- and there's where my questions lie. Cliff's variety of mathematics provide objective spacing related to a blank configuration that is increasingly stiffening from tip to butt, but there are still some subjective decisions to be made before applying these mathematics -- position of the butt guide and either that of the first guide from the tip or the number of guides. Guide placement by static testing and/or the new concept primer in the library is entirely subjective -- everything's up for grabs from the start, but there are certainly relatively straightforward guidelines given to follow to start the process. At the end of the day though, either approach goes to test casting, which as I see it is perhaps the most subjective step of all steps. So I'm wondering, what do different folks see or feel when they're test casting after placing guides with whatever method they choose? And more to the point, specifically what in their initial guide placement ends up being altered as a result of a "bad" test cast? I can see one obvious problem revealed by test casting might be improper butt guide size and/or placement resulting in the line not coming off the reel properly; here I'm thinking mostly in the spinning reel arena. But beyond that, what other significant adjustments do folks feel they need to make after test casting? If the butt guide is moved, are the adjustments simply related to repositioning all guides to make things look smooth, or are there other problems to be found.

To boil this all down to couple of questions: 1) If a group of test casters were blindfolded and supplied with a variety of rods built on the same blank but with guides set up by a mathematical approach, the "book" values from published charts, and subjective spacing by a number of builders, would they really be able to tell any difference? 2) What would we see under these same constraints if we developed and applied a completely objective way of test casting; i.e., using something analogous to a pitching machine?

This board really interfers with my job at times!!!

Bilgee

Formulas and patterns are fine and dandy in their place. But, the "Static Distribution Test"/method is 'where it's at' concerning guide placement. IMHO. If I'm not in a hurry I go by Tom,s article in the Library, above. If I'm in a hurry I place the butt guide, or, on a spinning rod I set up the guides from butt to choke guide according to the 'New guide Concept' then from the tip I place the guides at 4,5,6,7 in., etc. and tweak the positions of these guides till the line is in the best posiition relative to the blank, adding or removing a guide as necessary. All in all I believe that the Library, above contains all the information needed to place your guides on your rod in the most effective/efficient manner available at this time. Again, IMHO. All else is for the theorists(sp?). Some of you, LOL, would spend hours figuring to save five minutes at the bench. Ralph

If at first you don't succeed, go fishing, then try, try again.

RodMaker Magazine has done several articles over the past few years on how to determine the optimum size and placement for guides. Only two of perhaps a dozen are in the online library here. Of particular interest, have been at least two articles on determining proper ring size and frame height.

With something like the New Guide Concept - test casting has largely been eliminated. You would be hard pressed to tweak or tune the original set up to get anything better.

The information is available and with just a few rods under your belt, guide spacing becomes so much easier and quicker to do. Can you tell a difference between placement provided by mathematical formulas and that done by careful experienced manual means? By all means, yes you can. At least the rod can tell a difference and the item you're casting certainly can.

Nothing at all wrong with mathematical formulas for guide placement but I don't think I'll live long enough to see one that compares to any of the interactive methods.

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

GEOMETRIC-PROGRESSIVE Spacing-Distance Method Guide Layout: Used it or should I say, the more I learned the more I struggled with it.

STATIC GUIDE PLACEMETNT -N- Test casting: Easy, fast and the only way (at present) to go.

I, for example build a lot of 7' popping rods. Most all are spiral wrapped (bumper). Grab 8 guides + TT #16 to #7s. Set the TT and eye ball the remainder. Progressively load and Static Test for placement. Set the bumper guide. Make some test casts utilizing weights from the lower to the highest lure wt specs. Tweak and test cast (if necessary) again. Mark guide locations (just in case) and wrap away!

Regards......Doug@
TCRds

Cliff, thanks, your 'tome' got me thinking.

I basically agree with all of your conclusions, but there is two points I want to make and a couple of questions to ask:

(1) I've always been a little troubled with the static guide placement system because it depends on the AMOUNT (and direction) of deflection. A rod bends progressively, with the greatest bend first near the tip then, as the tip straightens out, farther back as the load is increased. This means that a small load will deflect the tip predominantly, while a larger load will affect the butt section more. If you place the guides on the rod to support the line under a small load you will need more guides near the tip, for example, because that's where the rod is bent the most. On the other hand, if you use a larger deflection you won't need as many guides near the tip because it's much straighter. Which is correct? I don't know.

(2) The placement of the guides on the rod affects two different tasks: casting the line and fighting the fish. There's no reason to think the number and placement of guides optimal for casting will be the same as for fighting. It's been my assumption that the most critical task of the guides is in distributing the load during fish fighting, to protect the rod, and that's good reason to place weight in the results of static load testing. I've also always assumed that the greatest risk to the rod is when the fish is near and the fisherman is likely to be high-sticking the rod, bending the tip more than he should. Thus I've always placed more emphasis on static load testing under a relatively small load, directed at somewhat less than 90 degrees to the rod.

And now the questions:

Has anyone ever done a rigorous study to determine if the number and placement of guides actually makes any SIGNIFICANT difference during casting? My gut feeling is it doesn't! I know Fuji had published on its web site a study purporting to demonstrate the superiority of their New Concept system over the old cone-of-flight system, but a quick and dirty analysis of the data (all 20 data points!) showed that the variation WITHIN casts using a particular system was larger than the variation BETWEEN the guide placement systems. In other words, yeah the average cast with their New Concept system was farther, but the difference was small and wasn't very statistically significant, given the normal variation between casts.

I know that when I'm building a rod I have very little confidence in the results of test-casting (which I always do, dutifully, for reasons that escape me!). Maybe I'm an especially crappy caster, but there are just way too many variables affecting the distance (wind, fatigue, guides slipping or rotating, incompetence . . .) to allow me to isolate the effect of guide placement. Unless I can actually see and hear the line slapping on the rod, which is caused by an improperly located butt guide, I just go with what looked right on the static placement test. Do others have this experience?

tom

Tom,

Related to your two questions, I say, "Right on!"

And after that, I also say, "I've got to stop looking at the *^@$&^% rodbuilding board so I can get this *&%$#$ report done!"

Bilgee

The difference between a decent casting guide set up and one that is really optimum, is usually in the area of less than 10%. More often, we'd be talking about 3% to 5%. In one of the articles on guide placement that Rich Forhan did for RodMaker, he mentioned that in most cases, no one needed to cast at the extreme limit of their rod's ability anyway. This is certainly a valid point.

But then you come back to what a custom rod is all about. At some point, no single improvement makes all that much difference. But when you combine several key features or aspects, each perhaps contributing their own 3% to 5% in less weight, increase casting distance, better balance, greater comfort, etc., then you suddenly have a rod that is better by a considerable amount. Just one more aspect to think about.

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

Tom stated,

" I've always been a little troubled with the static guide placement system because it depends on the AMOUNT (and direction) of deflection. A rod bends progressively, with the greatest bend first near the tip then, as the tip straightens out, farther back as the load is increased. This means that a small load will deflect the tip predominantly, while a larger load will affect the butt section more. If you place the guides on the rod to support the line under a small load you will need more guides near the tip, for example, because that's where the rod is bent the most. On the other hand, if you use a larger deflection you won't need as many guides near the tip because it's much straighter. Which is correct? I don't know. "

This is a very true statement, but when you setup utilizing the Static Guide Placement, you set the guides in a progressive manner. Meaning, you load only the first 1/3 of the rod and set those guides required to evenly distribute that load, then increase the weight to flex the next 1/3 and setup those guides. Finally, completely loading the rod to set the remainder.

Once the rod is completely loaded, I don't spend time messing with the upper 2/3 of the rod, because as you stated above, that part has now pretty much flattened out. JM .02c


Regards......Doug@
TCRds

Dear Mr. Hall - Just a couple of questions from this wrapper/fisherman. I will let you decide just how many hours of math I successfully completed. Question one: Are you an English professor or numbers type academian. Now for the real crux of the matter. If you substitute u with 1/x in the integration by parts equation is it possible to prove that 1 is equal to 0? I am referring to the mathmetical law that states the integral within limits of 0 to infinity of uv equals -uv(integral vdu). You will not have to stay up all night to see that there may be strange outcomes when only mathematical expressions are delved into by the masses!!!!

My law of guide placement is put a lot of them em on in the right place but not too many!

Have a nice day!

Gon



Edited 1 time(s). Last edit at 10/20/2005 09:35PM by Bill Stevens.

Rich Forhan also wrote a great article on "Equal Distance Guide Spacing" and if you try it you'll find it works pretty darn well. Rich is a very practical guy and the equal distance system is a very practical guide placement system. Even if you only use it as a starting point it's quicker than the mathematical systems.

Thsi is a good conversation but I have to wonder if we're trying to fix something that's not broken to begin with. I began using the Forhan method for all my casting rods and find it quick and easy. The new guide concept system is where I go on all my spinning rods. It's also quick and easy. At this point it just seems like we have some very quick and easy ways to do guide placement. The ones having problems are in the vast minority and even then I think with just a little more reading or seeing it done they would catch on quickly.

The only stumbling block I see is that many beginning rod builders do not understand what you are trying to achieve with regard to guide spacing. Once you understand what it is you're after it becomes very easy to assemble the right sized guides in the right locations.

Bill Stevens – Did I try to say that "1 = 0"? –No. Or did I ever say, let's do calculus integrals to place our guides? –No. I don't see how that is the crux of the matter as you suggested. – Did I try to answer Justin Mitchell’s question*: “Is there a math formula to determine guide spacing on fly rods, casting rods? Are they different?”* –Yes, most certainly. That’s what I tried to do in this Post. [*Guide Spacing* by Justin Mitchell 10-18-05 [www.rodbuilding.org] ] .

I have learned in the last 15 months here at RBO by my carefully responding to over 500 Posts that the distance between language and math is much shorter than I have previously realized. Words or formulas which poorly represent their original image only add to the confusion, and I try to avoid either misrepresentation. (And I’ve been reminded countless times that a picture is worth a thousand words.)

I didn't stay up all night looking for STRANGE outcomes from ODD math expressions for the sake of amusing myself or you Readers. If I had wanted to do that, I may have picked a multi-order polynomial with some non-integer coefficients and exponents. But that would be next to impossible to discuss because I do not have enough of a DATABASE available to develop or force a good fit for such an equation. And it would be hard to interpret how those variables translate into real rod & reel parameters (or vice versus). I tried to collect data from other rod-builders in early August 2005, but that only netted several guide layouts – hardly the dozens needed to reach statistical significance.

Last night I tried to meet with my math expert / fishing buddy (Bill Pfeifer, MS) to further discuss how simple formulas like this geometric progression can be altered to better describe a casting or loading guide layout, but he was not available. … I’m not seeking Utopia here, just more insight.

ALL guide layout systems are inherently subjective to a significant degree, and so if that is the case, then math can have its place in the process, too. I am currently viewing guide placement as having a trumpet-flared shape toward the butt for casting considerations and viewing guide placement as being better accomplished by an equal intervals distribution toward the tip for loading considerations. New? Obviously not.

But the deeper appreciation of its benefits (and limits) is relatively new to me, and a part of why I am slightly fascinated with the math and physics in rod-building. There has to be in this formula for a geometric progression some variables which relate to the proportions seen in guide placement and to the parameters of rod loading. That’s what I’m after. I want a simple system, too. I’m just trying to use math to describe the system, in addition to the obviously much simpler method of verbal description and the relatively incognizant or mute “interactive” methods.

Sure, I can plot a semi-scale model of my rod project and grab a handful of guides and slide them around on the graph paper to get a good fit, and develop a first approximation for guide placement in a few minutes, too. And another rod-builder can tie a line from the reel to the rod tip, lay the rod on the bench-top, slide the guides around, and – Viola – get a good fit. And another uses the Intersect Method, and – Hocus Pocus – gets the ‘best’ fit. And so it goes. All within ~ 10 minutes. All within ~ 5% of each other. Which is what I was told was the range of engineering error for a given system. And is good enough for most rod-building purposes, since we are not dealing with the NASA Space Shuttle over here. … But in an attempt to answer an innocent Poster’s question, and invite discussion from other formula fanatics, and discover more about why formulas do and do not work, I opened this Post. … I hope you and the other Readers have enjoyed it.

Sincerely, Cliff Hall, Gainesville, FL-USA+++

P.S. – Since you asked, Bill Stevens: I have a B.S. degree in Chemistry, with 3 semesters of chemical engineering. So I know something about chemistry, physics and math. I am a 4th year student in a Doctor of Pharmacy program. So, I know something about drugs & medicine & the body & the mind. And I have 14 years of bench-top experience as a full-time Chemist, mostly in medical research laboratories here at the Univ. of Florida. LOTS of hands-on work, mostly routine, but plenty of problem-solving work, too. It provided me with lots of the time and free brain power to ponder the details of whatever else my mind was on, while the cerebellum ran the hands. So, whenever I encounter something I want to know more about, I seek the knowledge of those who are involved and see where it goes.

Thanks, Bill, for your input. And your excursion into the twilight zone of Calculus. By my 4th quarter of Calculus, I was barely hanging on, and was very glad that I did not have to take any more, or use it extensively in my later career. First and second order linear drug metabolism models were as far as I cared to go. And even in my 9 years of work for an endocrinologist on human lipoprotein metabolism, I was glad that all I had to do was generate the data points of radioactive labeling verses time. It took him and a graduate student about 3 hours to load the data and a super-computer in Washington, DC called SAAM about 24 hours to crunch the data that it took me 3 months on the bench-top to generate. The computer program was a 20-compartment kinetics model with over 50 rate constants, correlating hundreds of data points from several patients. …

So, "big deal!" – What did I learn from all that, that has anything to do with rod-building? (1) If you know enough math, you can describe almost anything (witness Game Theory for the recent Nobel prize). But, more importantly, it was one of the project leaders, who was an MD with a PhD in Chemical Engineering (which is perfectly suited for Kinetics & Metabolism) who said (2): that the MODEL of the SYSTEM and the VARIABLES in the mathematical model HAVE TO BE ANALOGS that closely correlate with and may be positively identified as real parameters in the natural system. Otherwise, there is no way to identify elements in the natural system which need adjusting. In that case, it was the human liver and body. …

In our case here at RBO, the natural elements would be the line guides and their placement, as related to line casting, and rod loading, for a given rod & reel.

I’m not trying to complicate anybody’s life here. Formulas are a CONVENIENCE, just as the other INITIAL guide placement methods are. I just know that I am far from alone in my preference for involving a formula for guide placement, and I had hoped to advance that subject in this Post. … Cliff Hall, Gainesville, FL+++

So I guess, no one would be willing to demo guide placement at the show. I know there are many articles. I have read them. They make sense to me, but I would still like to see the demo and the live version of guide theory and placement. I say DEMO.