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Rod Design - Convex Tapers

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I’ve been looking at Vince Marinaro's ideas regarding convex tapers from his book, In the Ring of the Rise.  Most of the concepts are explained clearly in the book.  One idea that I would like to understand is the peak of the swell in each convex section.  VM explains that he liked three piece rods, he indicates this was more for ease of construction than for portability.  Each section had a unique swell to it, with the peak placed at a different location.  I understand his ideas on the location of the swell, but what isn’t clear is how the diameter of the peak of the swell is determined.  I know some of you who have been at cane for a while and live on the East Coast are familiar with his work and his ideas.  I would really like to understand VMs convex taper ideas further, and would appreciate your help.  (Kyle Druey)

I, too, have been interested in Marinaro's tapers and some time ago I asked some questions on the list and got the answers.  They are not informative since Marinaro was never specific about his work.  Nowadays the tapers are the property of the family and a museum in Pennsylvania.  I understand that they plan a book on him and that may contain the tapers. They do  not want to reveal them until the book is published Don Anderson (he's on the list) worked out a 9' rod that he brought to Corbett last spring.  It seemed heavy and somewhat awkward to me, but I am not a very good caster and it could be that I could not get out of it what the rod was capable of.

Perhaps he can tell you how he arrived at the figures you want. If you find out anything,  I'd appreciate your letting me know.  (Ed Hartzell)

I know there are a few folks on the list who have the answers but are have not yet responded, or can not for legitimate reasons - I understand.

From VMs work what is clear is that he wanted a fast tip, a medium to soft type of mid that would bend, and a stiff butt.  He somehow did this with a different convex taper formulation for each of the three sections of his rods.

Again, from his writings, he explains that the convex taper is formulated by leaving the ends of a straight taper fixed, but a swell is placed in between at a specified location.  What isn’t too clear is how the size of the swell is determined.  It seems like the swell would be larger than the diameter of the dimension on the large end, but I am just guessing here.  Another guess for what his rod might look like would be a fast action Dickerson type of tip and butt, with a Garrison mid placed in between.  Also look at the taper for the JJ rod listed in the Rodmakers taper archive, under the tapers for Chris Bogart.  One final guess would be the taper in Hexrod for the Payne 100 but with the last 30 inches stiffened up some.  I might just give it a try here on an experimental rod.

I supposed if no one has the answers right now we will just have to wait for the book.  (Kyle Druey)

I wish I could tell you exactly how Vince determined the nature (size and location) of his convex "swells," but without taper data from the existing rods, it's just not possible.

I would be happy to tell you the principles Vince taught to me, but as nobody has measured his rods (and, as he left behind no records or data), you would be left with the same trial-and-error process I had to go through.  Not that that's a bad thing for anybody to undertake, but it certainly isn't efficient, and my explanation still wouldn't answer the specific questions that you seem to be asking.

We will be taking all the measurements from Vince's rods in the near future, but the family has requested that the information be released only under the auspices of the Pennsylvania Fly Fishing Museum Association and the book which we are proposing.  We are a small, voluntary organization at present, with an extremely limited budget, so getting this work done is not easy.

Vince's surviving family, by the way, has sold the entire collection to the PFFMA and does not ask for further remuneration through possible book sales.  So, there is no profit-motive connected to the temporary dearth of information (not that anyone has ever implied this).  (Bill Harms)

I rather doubt that the "swell" was as as large as the large end of the section involved in Marinaro's rods.  My interpretation involves a  slowing down of the rate of taper at the beginning of the swell and then an increase after it reaches its maximum.  This would result in a swell like that on the tip of a Garrison rod which was put in to strengthen the tip so it would not throw humps.  I will have to look up the rods you mention to throw some light on why you think they may be like Marinaro's.  Exactly where to put it is another question.  I do not believe you can rely on the diagrams in Marinaro's book either for location or for diameters.  If I were doing it, I would look at the Garrison tip swell, use it as a percentage of the diameter at the largest point of the swell, then use that percentage on the mid and butt of your Marinaro experiment.

I am interested in the idea that he started from a straight taper and kept the dimensions the same at the ferrules.  I did not remember that from reading his explanation and will have to look it up also.

I would not go to extremes.  I have an idea that Don Anderson made too great a swell and that is what caused the rod to be unhandy in my opinion.  Maybe he will answer your questions also.  (Ed Hartzell)

The rod was an attempt to build the Marinaro taper from his book. The rod casts poorly although it will cast about 70 feet with a 6 wt. line. Feels limp though. It didn't meet the criteria of sub-4 ounces that I shot for as per Marinaro's description. Blank was nearly 4 ounces itself minus fittings. I assumed that the book showed the rate of change between stations. I was corrected by folks on the list. Like Ed says, Marinaro started from a straight line and graphed everything. The rod wasn't a complete failure however as it was used for moisture loss/gain experiments pre/post HT + I tried dying it with this and that. Not only didn't it cast well, after all the cosmetic stuff, it looked like hell as well. Mind you the bark handle looks OK and isn't as slippery as I would have thought.

I'm hoping that the museum mentioned earlier comes out with the "book" - that will be a must buy.   (Don Anderson)

When thinking about VM tapers let remember his goal was to make a 9' tip casting rod that was about 4 ounces If a taper proves to be a heavy one it probably need to go back to the drawing board.  I believe he had a 9' 5 wt and with all fittings including a spike in the reel seat it call came to 4 ounces.  Hmmm, that is quite an accomplishment.  (Adam Vigil)

I was very interested in finding out what VM had achieved because it sounds so good when you read of it but as I think you're implying it may not actually be that terrific if it's not to your style.

I know there are people who think they really need a para until they cast one and complain about it being slow and bending into the butt.

Remember this is the guy who sieged a trout for weeks and lost sleep on what pattern would finally fool him (the trout) and decided it was a house fly. 10 points for persistence and thirst for knowledge but beware the "perfect" VM rod you may discover it and be disappointed.

I can't help thinking "The Snow Fly" was written with VM and his tapers in mind. If it wasn't it could have been.  (Tony Young)

In The Planing Form issue I just received, Don Anderson did some work on Marinaro's concept of a 9' 5 wt rod weighing 4 oz. Well Don you came pretty close. I believe Marinaro did not put a finish on his rods. So before varnish your weight if close.

How does that rod cast?  (Adam Vigil)

The rod cast like crap @ first blush. Too wimpy. I tried it with a 5 wt. then switched to a 6. Things got better quick. It feels like it won't cast 20 feet till you get it working and 70+ feet casts are possible.

Now if I were to do it again, I'd try to make the slower sections even slower, the taper thinner and the components more to what Marinaro suggested or illustrated.

The rod was a series of experiments. First it was used for cane swelling after heat treatment using measurement, water absorption post heat treatment by weight,  a test bed for dying of the cane using waterproof markers, it was fitted with a cottonwood bark handle and reel seat insert and lastly and most importantly, it was used as an attempt to replicate Marinaro's tapers with not a lot to go on. Since then, I've been privileged to be provided by more information and will take another run @ the taper this winter.

And the question of varnish wasn't considered. Anyone know if Marinaro used varnish and if so what type or application technique?  (Don Anderson)

Don't quote me but I think I remember Bill Harms saying that Marinaro did not varnish his rods. I could be wrong. But I bet he would know if anyone did.  (Adam Vigil)

Yes, Vince did varnish his rods, although he insisted on only one coat (and just three thinned coats on the wraps) to save weight.  You would not be impressed with that part of his work, however, as he took no pains whatever to make his rods aesthetically appealing.  Curious duck that Vince was, it was almost a matter of principle that his rods should look a plain as possible.

On different occasions, teasing Vince about the horrid condition of his rods, Tom Maxwell and I each refinished one.  Upon returning the one I did, he just munched on his cigar and said "I guess it's OK if you like that sort of thing...."  (Bill Harms)

Thanks for the interest and help. Bill, one coat it will be. Maybe use rub on stuff.   (Don Anderson)

If you want to use the rub-on version, you can easily afford two or three coats, as this application doesn't build like a dip or brush would do -- and you do want adequate protection.  (Bill Harms)

You know, I think Tom Dorsey & Tom Maxwell made some rods that way (varnished wraps only) when they first started making rods through Vince Marinaro's influence.  (David Zincavage)

The memory of one of these is coming back to me.  Either just a tung-oil finish or one very thin coat of varnish, transparent wraps, skeletonized cork grip.  Very space age and strange looking, and I think the taper was from Marinaro.  (David Zincavage)

In a recent post, Jerry Foster commented on the nomenclature of "parabolic" and "convex" taper designs, saying; "It is interesting how we have switched from using the Para-semi-para nomenclature to now using convex. Indeed they are the same. Thank you Mr. Harms and Whittle."

In a state of total confusion, I sent Jerry an off-list email  -- asking for clarification and wondering what the two terms have to do with one another. I wondered, too, why Whittle and I are to be thanked for anything in this connection. This morning, Jerry gave me a phone call, and we had a lengthy conversation about his remark and its underpinnings. Jerry and I have never met, but we've been excellent telephone friends over the past three or four years,  always carrying on with a deep interest in one another, laughter and long, useful conversations. So, I've never had a "bone to pick" with Jerry in any sense, nor do I now. I was simply confused about his post to this list and Whittle's and my role in it.

The more we talked, the more Jerry and I realized that his statement to the list resulted from several conversations, carried on elsewhere, and within other contexts -- conversations about stress-charts that reveal "parabolic" tapers, and conflating those data with mistaken notions of what a "convex" taper is presumed to be. As has been the case everywhere, the confusion about "parabolic action" now seems to have spread to the term "convex design." But the two terms are not the same (we have apples and oranges), and the two design principles do not produce rods with a similar feel.

I'm not sure what the public has been assuming about convex tapers, but somehow the current conversations seem to express a certain disappointment in not finding rods that reveal a totally fair curve from tip-top through butt. Indeed, stress analyses of several convex tapers, whether of two or three sections, reveal "dips" through each ferrule station. Thus, the apparent conclusions that "dip" means "hinge;" hinge means "parabolic;" and high stresses though a hinge mean there's no difference between the terms, parabolic and convex. But Jerry Foster and I now realize that this thinking has come from: 1) faulty assumptions about what "convex" means, and; 2) questionable interpretations of stress data.

1)  Those who first promoted and designed convex tapers (ie., George Parker Holden, Robert Crompton and Vince Marinaro) never meant the term, "convex," to apply to the entire, assembled rod. Instead, the objective was always to design convexity (a fair curve of one configuration or another) into each, respective section separately. Although certain areas in a section may appear to be nearly linear, no portion of the taper's trajectory (between ferrules) may show a dip or a hinge of any measure. Figuring the best way to manage convex, taper shapes for each section was the goal. Other assumptions about convexity (made by other people for other reasons) may have come into play since, but this was Marinaro's design-idea as Whittle and I meant to describe it in our book.

2)  When rods with a convex taper are assembled, the area through each ferrule station will reveal a "dip" -- as viewed across the rod's full-length, taper trajectory. But this is not to assume that stresses are necessarily higher in those ferruled areas; nor that the dips necessarily constitute "hinges;" nor that such dips imply parabolic action. Stress analysis, alone, is inadequate to evaluate ferrule areas since the calculations pertain only to the bamboo. It's because such calculations do not reflect the stiffening effect of a metal ferrule that one cannot assume anything one way or the other about the presence of a hinge. Indeed, one important consideration in designing the sections of a convex rod is to "build around" the stiffening effect of a ferrule  -- hence, the dip. (Some folks will insist that it's only the weight of a ferrule that matters, but that idea seems more anecdotal than compelling.)

Finally, Jerry and I have come to understand that the terms "parabolic" and "convex" are not synonymous, but neither are they exclusive of one another. Instead, we're talking about apples and oranges. Probably, the best way we could sort out the confusion would be to say that "parabolic action" is a FEEL (with some localized tapering considerations), while the "convex taper" is a section-by-section design METHOD. We shouldn't be confusing the feel of a rod with a design method, nor its action with a theoretical concept. In this, we might do well to realize that convex designs can be manipulated to yield rods of almost any desired action -- indeed, given certain "tweaks," even approximating the feel of a parabolic rod.

Anyhow, because Jerry referenced Whittle and me as helping with the current discussion, Jerry and I wanted to offer our best understanding of what that discussion implies.  (Bill Harms)

Now there's some meat to gnaw on for a Sunday afternoon!  (Mike Shay)

I keep reading this and I'm still no nearer to comprehension.

A convex taper is one with an ever decreasing rate of taper, reading from the tip.Most convexs are three pieces with three sections of convex taper, I haven't a clue why anyone might think that this is the right way to design a fishing rod taper. A parabolic taper is, it seems, anything anyone wants it to mean, including its normally accredited inventor.

If you want to design a rod to do what Ritz said he wanted it to do its quite easy and I've done it, but it bears no more than superficial resemblance,  in parts, to any known "Parabolic" design.

I say again, if you cannot justify every single five inch step of a taper design with a reason then its not a design, just a wild guess.  (Robin Haywood)

What is it Ritz was designing his rod to do?  (Jim Lowe)

R Kevorkian, of the list, was reminding me that there was quite a write-up in Schwiebert's "Trout" vol 2 about convex tapers and Mr. Ritz's design philosophies.

Mssrs Harms and Whittle,

I understand that your and Mr. Marinaro's definition of "convex" was specific to 2 and 3 piece rods and the convexity within each section. The term was never intended to apply to rods which have a convex shape over their entire length unless each section has that "convex". From rereading Split-- and after my discussion with Mr. Harms my understanding of the intention of the convex shape is to compensate for the stiffness of ferrules. So the mild decrease in slope around each ferrule station is to provide a neutral transition across the ferrule so the intent of the taper is realized, regardless of the type of taper. Again corrections will be gratefully accepted.  (Jerry Foster)

Here's a link that might help.  (David Bolin)

He said he was designing for" High Line, High Speed, in other words, distance.  Which would be entirely credible if he wasn't fishing the Risle, where distance is hardly necessary.  (Robin Haywood)

Earlier this year a thread developed on this list regarding the ‘CONVEX’ design/taper developed by Vince Marinaro for a 7’6” 5wt 2pc dry fly rod.  Taper data were graciously provided by Jim Sobota.  I built one of these rods (using Jim’s data but incorporating an integral bamboo ferrule instead on using the standard NS hardware) and have found that it functions wonderfully.  I fished it on Henry’s Fork in Idaho a couple of weeks ago and my guide asked if he could try it (he has 18 years of guide experience on Henry’s Fork and the previous week had guided two gentlemen who both fished bamboo, one of his first experiences with the stuff).  After a few casts his face brightened into a broad smile and he told me he wanted one.  In fact, he said he REALLY wanted one.  At the end of the day, while we were unloading the boat, he showed the rod to a small group of his guide buddies and told them how it cast “short range, long range, and everything in between, almost automatically”.   Last week I fished a lower portion of the West Fork of the Bitterroot River in Montana and caught a heavy-shouldered 22” brown trout that my guide estimated to weigh 5.5-6.5 pounds with the rod.  I use an SA WF-5-F SharkWave line with it and it all works beautifully.  I’m very happy with it.

So now I’d like to make a few more of these rods.  I’d like to make a 4wt version, another 5wt, and a 6wt version, all in a 3-piece configuration.   Can anyone on this list provide the tapers for these rods?  Has anyone else had any experience with Marinaro’s ‘Convex’ designs?  Will RodDNA reliably convert the 2pc taper to a 3pc configuration? 

Any data, comments, suggestions, or input would be greatly appreciated. (Bryan Coles)

All of the rods I have built have had some variation of convex tapers.  I now build mostly 8’6”, 4-piece rods with carbon-fiber sleeve-spigot ferrules and each rod section has a convex character.  Particularly effective, in my view, is that the tip section be convex.  For my rods, the convexity of the other three sections is less than for the tip. Most of my rods are approximately straight tapers starting about 10-12” back from the tip-top with the convexity superimposed on that taper.  A number of people like my rods and I attribute much of that to using convex tapers.

For a lot of good information about convex tapers plus tapers themselves, I recommend finding a copy of “Split and Glued by Vince Marinaro” written by Bill Harms and Tom Whittle.  My efforts with convex tapers were strongly influenced by Bill! (Tim Anderson)

Every tip third to half of every fly or casting rod should have a convex taper. But there can be no technical or any other justification for anything but a concave taper in all or most of the lower half to third of the rod. Just look at the stress curves if you don't believe me. (Robin Haywood)

My justification for not using a concave taper away from the tip is what the rods feel like when casting or fishing.  I am not going by only my evaluation, but also on the opinions of a number of fine casters at the Golden Gate Angling and Casting Club as well as others who like my rods. That doesn’t mean you would like them, of course.  One of the wonderful things about making cane rods is the freedom we have in making a rod we and others like.

I do agree that convexity in the taper of the tip is beneficial.

I don’t happen to use stress curves in designing my tapers, so have not looked at them for my rods.  Nothing wrong with stress curves, they are just not something I use. (Tim Anderson)

+1 to what Tim said here, from another convert to convex design. You really should read the book if you want to understand, but be aware that the earlier rods do not always adhere to the principles that Mr. Marinaro worked out over time. The thing to understand is the subtle dips and swells center around the ferrule positions. What he did is to make a long, slow dip going into the ferrule, and then a shorter swell coming out of the ferrule. What I believe he was doing was compensating for the stiffness of the ferrule with the long dip in front of it, and for the weight by the swell behind it. One implication of that is that you cannot add or subtract ferrules with any of the stress based programs, because they will put the dips and swells in the wrong places. Because Tim’s ferrules are extremely light and flexible, he does not need the compensation. If you are using metal ferrules, you should incorporate them. As Tim suggests, the tip seems to be the big difference maker. Having said that, you probably could take the tip design from your rod and run that through a stress program to get that far to begin with. but then you should graph out the rest of the taper, starting out with the base slope of the Marinaro designed sections you like, and adding the subtle swells, sticking close to what Marinaro did on the rod you like. That is how I would proceed, anyway. Avoid big changes in length until you get a feel for how length, ferrule weight and slope affect the action of the rod.  (Tom Smithwick)

To my previous post, I should add that if you are not changing rod length or number of ferrules, only line weight, a stress based program should actually get you very close. (Tom Smithwick)