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Soft vs. Hard Monofilament for Leaders

by Philip Monahan

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Question: In hopes of catching more mature trout this season, I propose to tie my own custom leaders using George Harvey’s leader design formula(e). My issue, however, is locating and identifying soft and hard monofilament sources, and do some manufacturers identify their products as soft or hard by labeling?

Bob G., Thornbury, Ontario

RIO Powerflex Leader MaterialAnswer: For those who aren’t familiar with George Harvey leaders, they were created by the Pennsylvania fly-fishing icon to throw slack — in the form of S curves — into the leader at the end of the presentation cast. This slack counteracts the effects of the current on the leader and thus reduces drag, allowing a dry fly to float naturally for a longer time. Harvey’s original design combines a stiff butt section with a long, supple tippet.

It took about two minutes’ research to see why Bob’s having such a problem; the first dozen or so Harvey-leader recipes I found used the terms “hard” and “soft” mono without any discussion of actual brands — as if everyone knows which are hard and which are soft. A typical recipe looks like this:

Section Mono Diameter
Mono Style
Length of Section

The word “hard” is a bit misleading here because, when it comes to Harvey-style leaders, you’re more concerned about a material’s stiffness, which helps to transfer the energy from the fly line to the tippet and make the entire leader turn over. That said, there are several products that use the word “hard” in their name: Mason Hard Mono, RIO Saltwater IGFA Hard Mono, and Climax Hard Mono.

If you find that these products are too stiff for a light trout leader, there are also several medium-hard or medium-stiff materials, including RIOMax® Plus and Umpqua Tough Nylon. However, based on an informal poll, most fly fishermen who use Harvey-style leaders simply use Maxima Chameleon or some kind of conventional line for the butt section.

Soft (or supple) monofilament would be any of a number of tippet materials on the market. Look for the term “supple” or limp” in a product’s description.

But here’s the dirty little secret about the monofilament world: there is great disagreement among manufacturers, marketers, and consumers about what constitutes “stiff” or “supple” nylon. Some would argue that the products that claim to be stiff are really just thicker than their counterparts. Harry Murray — owner of Murray’s Fly Shop in Edinburg, Virginia — told me that he’d lobbied hard, to no avail, to get monofilament manufacturers to publish details of their products’ suppleness. When it comes to delicate presentations,” Murray said, “the strength of your leader materials is irrelevant. It’s the suppleness that’s important.” You may have to just try a few products to find the one that works best for you.

To further compound Bob’s decision-making process, George Harvey later revised his leader specifications and called for using the most supple monofilament for all sections of the leader. (For me info, see Joseph A. Kissane’s book Drag-Free Drift: Leader Design and Presentation Techniques for Fly Fishing.)

So maybe you don’t need the hard stuff at all!

Joseph Kissane Comments

I happened upon the discussion of leaders in Midcurrent and was flattered to find references to Drag-Free Drift. As Phil mentions, getting accurate diameters of leader materials, as well as meaningful information on stiffness is a problem. I, too have tried in vain to get specifications of leader materials out of manufacturers, and thus far, about the only thing to come of it is to at least give them the incentive to put expiration dates on nylon, as it degrades in time. That was a no-brainer — expiration means more sales. Diameters on the spools are becoming more accurate now, as technology allows greater quality control, and people’s response to what had been a marketing tool as much as a technical detail has increased scrutiny.

When I began my investigations into leaders that led me to write the book, the industry was very inconsistent in terms of its accuracy in labeling materials. The main motivator at the time was to promote the strength of the materials, and the primary means of increasing strength was to increase diameter. So some of them might sell 4X (0.007 inch dia) tippet as 6X (0.005 inch dia.) etc, and even then, the quality control was such that the diameter measured by a caliper or micrometer would show variations beyond that range in some manufacturers. Technology and awareness improved in the 90s, though, and they are better about it — because they know we’re watching them, and the real experts are now seeing the need for QC — Jim Vincent at Rio being a major force in this respect, along with the people at Gamma who make Frog Hair, and the guys at Umpqua.

I’ve come almost full circle on leaders, as I have less free time to fish now than I used to, and I use commercial tapered leaders as the center portion, clip off the typically over thick butt section, splice it to a permanent butt section at the end of my fly line, and doctor the tippet with additional soft (Climax or Frog Hair, depending on what’s in my vest), and go with that. I’ve also come full circle on the manner of connecting the butt of the leader to the line. I used to like loops, partially because they are easy and quick, but I now see too much hinging occurring (probably because I’ve become a lazier caster) and have gone back to a rigid connection between the butt and the line for better control. I use a nail knot for the larger lines and sometimes use a super glue or Zap-a-Gap connection for the butt section of smaller lines to reduce bulk. It’s all another aspect of the sport that we geeks can play with and take ownership of. How many ballplayers can make their own bats?

I had the pleasure of talking with George Harvey by phone a few times in the months before my book came out, even though his hearing was not very good at that time. We agreed that there ought to be simpler ways for people to figure out how to make leaders with the materials on the market. He was strongly opinionated, and even though legally blind, he somehow could still tie a blood knot and make leaders. I think he color coded his line spools so he didn’t have to use 5.00 dentist’s glasses to figure out which spool was which, and we both had come up with the idea of writing the dates of purchase on the spools, along with labeling the diameters as we measured them, rather than accepting the manufacturer’s data. But we talked about qualitative ways to figure out which tippet materials were softer. I proposed the idea to him that you could take loops of various materials made by pinching an inch of each material between your thumb and index finger or in your hemostats, hold them vertically, and see how each responded to the same weight — say a pencil, bearing down on them. The greater the deformation, the softer the material. You could, if you trust your sense of touch, even use your finger and push down to compare the materials’ reaction. It’s simple enough to do, and it will give you some rough idea of relative flexibility.

On the other hand, Harvey was adamant about the over use of fine leaders, saying he seldom used anything finer than 4X as tippet — but true 4X, not just labeled 4X. As an engineer, I said that he obviously was applying the knowledge that a longer length of a stiffer or thicker material will deform as much as a shorter length of a finer material, to which he responded: “I don’t want to reduce this sport to an equation, son, I just want people to be smart about it.” He admonished me that he had taught little old ladies how to tie leaders and they could out fish any celebrity fly fisherman from Hollywood or anywhere else. But when I explained that you can actually prove it mathematically — that you can substitute longer segments of thicker material for shorter segments of thinner ones and achieve the same effect, he agreed that this is what he did. In actuality, in engineering terms, the diameter is the single most important parameter in calculating stiffness of a flexible material.

It’s a fascinating subject, and one that I have been very interested in with for a long while – what else but some pathological obsession would lead anyone to write at length about it? And like anything in fly-fishing, there is plenty of room for debate.

Upon consideration, having only toyed with the idea of weight forward leaders, I think they might be of use in situations where you need to use a short line, but need to get the fly out from your location more efficiently. If you power the cast as you would with something like 30+ feet of line out, the dynamics of a weight forward leader may be the advantage you’re looking for. I still do, and recommend trial and error as the major way of learning about some things, but the important thing in the learning is not just to learn the results, but the reasons for the results. That way you can limit the number of trials, and increase the successes, instead of errors.

— Joseph Kissane

MidCurrent Fly Fishing
Phil Monahan is a former Alaskan guide and was the long-time editor of American Angler magazine. He's now a columnist for MidCurrent and writes and edits the fly-fishing blog at You can email your fly fishing questions to us at
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