FISHING REEL DRAG TRIBOLOGY

WHAT IS TRIBOLOGY AND HOW IF EFFECTS YOUR FISHING



             The study of fishing reel drags is an exercise in weird science, but is relevant however for every fisherman; be he fly, spin, spincast, or baitcast.  The average fisherman has evolved with a multitude of practical misconceptions, lost many a good fish, and purchased many fishing reels without adequate knowledge of how reel drags really work . . . or don’t work as is most often the case. 

            The science of Tribology might be defined in a number of ways, but it is a far reaching discipline involving surfaces, pressures, heat, and movement.  It is basically the interaction of contacting surfaces in motion; let’s just call it a study of friction in so far as it pertains to fishing reel drags.   Many of its principles were established as long as 500 years ago by very important scientists of their time; Leonardo Da Vinci, Isaac Newton, Coulomb, and French physicist Guillaume Amonton in 1699. 

            Some of the early work involved intuitive reasoning which has only recently been proven erroneous.  Even today we think the laws of friction should follow logic, but like I said, it is weird science. 

So we have had our little fishing corner of the universe perfuse with misconceptions that I am going to lay straight with good science, here and now

            For instance, how many of you think (and repeatedly hear) that more drag is a function of how large the surface of the drag washers?  Do you believe that the more you pay for a reel, the better the drag is likely to perform?  Here’s a good one; it takes more drag to stop a big fish than it does to stop a small fish.  These are just a few of the intuitive misconceptions under which we have operated when purchasing and fishing with our favorite reel. 

            Fishing reel drags are an example of what we call “ordinary” friction.  What I mean by ordinary is that they operate with common materials of common size and under common pressures, and produce common heat; nothing that takes space age materials or instruments to quantitate.  Certainly it is within our capabilities to learn how it actually works and apply it to our favorite pastime.  First let’s have a look at the basic function and components of a fishing reel drag system so we’re on the same page so to speak.

            Every fishing reel drag system is comprised of a few basic physical structures, all aimed at the idea of controlling a fish so that line is removed from the reel under controlled pressure.  This does several things.  First, it helps tire the fish so that it can be brought to hand more quickly.  It assures that the fish will not exhaust the reel of line on a very long run, and it protects the fishing line so that it won’t be broken.  This is intuitive and known by every serious fisherman. 

            The basic structures involved in this are the contact surfaces that spin against each other creating friction (drag washers), a spring to help apply the pressure evenly and uniformly (drag adjustment spring), and a screw or nut that applies the pressure to the drag adjustment spring (the drag knob or star wheel).  Typically the drag only functions in a fishing reel when the line is removed from the reel and is not in play when line is being brought onto the reel, but that mechanism is not a part of the drag itself. 

            A typical scenario is that you spool your reel, slightly tighten the drag knob or star wheel, and tug line from the reel by hand to see if the drag feels “about right”, to handle the fish you are after.  When you catch a fish, the fish runs line from the reel, one or several times, and if all goes well you will have adjusted your drag correctly and the fish will tire, your line will stay intact, and you will bring the fish to hand.  But in a fish fight, it doesn’t always go that way. 

            Sometimes you will be into a running fish and the drag will either seem too loose and the fish is in a run-away mode, or you may have tightened the drag too tightly and the line will break.  You may have to re-adjust on-the-fly to make sure it doesn’t.  You thought you had it right, so what happened?  Perhaps the fish broke free in the first half-second of the fight regardless of how well you adjusted the drag.

            The numbers of variables operating within the three basic elements of your drag might surprise you.  For instance, was your drag comprised of grease-impregnated felt, cork, grease-impregnated cork, carbon fiber, Teflon, cork composite, ceramic, or Rulon?  Were they frictionally compressed against aluminum, stainless steel, or some other exotic metal?  What were the compression characteristics of the spring?  Did it compress evenly throughout its compression range or did it become more difficult to compress with pressure?  What was the thread count of the compression screw or nut?  Was it 20 turns per inch, 28 or 32 turns per inch, or perhaps 40 turns per inch?  These all can have a profound effect on how the drag functions.  And all are fraught with misconceptions. 


DRAG WASHER SURFACE AREA

            It may surprise you to find out that within the framework of ordinary friction with common materials in your fishing reel;

The surface area of the drag washers has no relevance to the amount of drag your reel can produce.  The classic laws of friction state that the amount of friction is independent of the area of contact for a wide range of areas.

            That squarely places the most important function in your drag system to be the pressure applied with the drag adjustment spring and the drag knob or star wheel.   In other words, if you want more drag, apply more pressure; don’t get a reel with larger drag washers.   But you must be careful here.  The pressure must be applied with precision and uniformity or it will run away, go into “lock-down” we call it, and the drag forces will raise exponentially and uncontrollably. 

            Well, this is truly non-intuitive and confusing for a fisherman.  For the manufacturer it is especially confounding since the fisherman can usually examine the drag washers and admire their color and size (size isn’t important in this case), but it is usually not possible to see the drag spring or know its compression characteristics.  In fact, my experience, which is now considerable, has shown that most if not all manufacturers are also confused by this non-intuitive aspects of ordinary friction.  The work in our lab with DragensteinTM, the Drag Testing Beast, has confirmed this weird science. 


DRAG VS FISH SPEED

            Have you ever caught a bonefish?  They scream!  But the question here is, “How does the drag requirement change for catching a 5 pound bonefish as compared to catching a 35 pound redfish?  It might surprise you that it takes a better drag to stop the bonefish.  That’s because speed has a very non-intuitive effect on kinetic (moving) energy. 

            In other words, if a 5 pound bonefish is traveling twice as fast as another 5 pound bonefish, the faster moving fish has four times the kinetic energy of the slower fish.

A drag performs more work stopping a small fish going at a high rate of speed than a heavier fish moving more slowly.  It will take about the same amount of drag to stop a 5 pound bonefish moving at 10 feet per second, as to stop a 20 pound redfish moving at 5 feet per second.

Our work with DragensteinTM has demonstrated this to be true. 


DRAG ADJUSTMENT

            This may be one of the most problematic areas of working with your reel drag.  For most of us this has boiled down to adjusting the drag knob and pulling line from the reel by hand for the “right feel”.  Some may use a spring or strain gauge for some level of quantization, but most don’t since there is almost universally no indices on drag adjustment knobs to know “where you are” in the drags adjustment range when you get where you want to be with adjusting. 

            Before the work with DragensteinTM it was impossible to understand just what happened to drag pressures when line began to scream from the reel compared to the adjustment set by hand to “feel right”.  I’m sorry, but what we have learned in the DragensteinTM Project isn’t going to be of much use regardless of how enlightening it may be. 

            In reality, the pressure acting on your line from drag pressure when a fish is running has little or nothing to do with that crude setting you made by hand or with a strain gauge.  That is in part due to undefined characteristics of the drag components used by the manufacturer (or ignorance thereof as is most often the case).  It is also because the manufacturers have never tested their drag components with technical instruments like DragensteinTM so they can’t tell the consumer how the drag actually performs. 

The unfortunate truth is that very little good science has gone into reel drag design; it has come down primarily to what is the least expensive to make, what looks good, and what will sell.

            Make it sound good (we have bigger and better drag washers!) seems to have been the marketing ploy and the consumer will buy it because they can’t prove otherwise; very sad. 

            There is a general rule for drag adjustment that says you should only adjust your drag to about 25 or 30% of the breaking strength of the line.  That is presumably to account for changes in drag pressures when a fish is running.  We consistently found this to be a good standard during DragensteinTM tests.  That of course requires some level of quantization, perhaps with a strain or spring gauge when setting the drag adjustment by hand. 

            During our testing we found that adjusting the drag by hand, that is, pulling line from the reel by hand, will result in a setting that will only be about 30 to 50% of the running drag, sometimes more and sometimes less.  In most reels the drag pressures can quickly build to many times the hand setting.  That is not always the case however since heat will cause friction to decrease (just like fading brakes in your car).  Some reel drag will do a little of everything by decreasing at the start of the run and then exponentially increasing as the run progresses.  There’s nothing quite like having a heat tightened drag when you finally get a big fish to the boat . . . snap!


DRAG FRICTION MATERIALS

            This subject enters a nether region where more misunderstood opinions prevail than good science can verify.  Every one who has thought about drag washer material probably has their favorite for some reason or other.  None are based on actual science.  The reason I know I can say this authoritatively is because for the most part no drag washer science has existed before the DragensteinTM Project.  An entire article (or small book) might be written about this topic.  For the most part none of it would make a bit of difference except for a few very basic principles. 

One of those is that no drag washers, sealed or open, should be made from materials that are impregnated with grease.

            This type of drag is always subject to change based on ambient temperatures.  I don’t have to tell you the differences in temperatures between the deck of a flats skiff in the tropics and a tree limb rest on the bank of an Alaskan river.  These drags will never provide reproducible results.  As the ambient heat builds, the greases thin and the drag decreases.  As the ambient heat cools, the grease thickens and the drag pressure increases. 

            The only reproducible results will be obtained from combinations of materials that perform under dry conditions, are not compressible (or only barely so), will not disintegrate, and that can be periodically cleaned of debris and crud.  (crud is the material that forms on the surface of the drag washers from friction and heat.)

Beyond these criteria, it makes little difference what the drag washer materials may actually be . . . with one not-so-small exception.

           
HEAT

            One of the principle by-products of drag performance is the heat generated by the frictional surfaces.  Ok, you say that ain’t no big deal, after all, you are holding the reel in your hand and it doesn’t feel any different temperature-wise from hooking the fish to having brought it to hand.  While that may be true in a macroscopic sense, it is just the opposite at the microscopic level.  Heat is perhaps the single most important influence on how well your drag performs. 

More drag systems fail to perform because of problems with heat than any other problem.

            Two things happen when your drag starts to run and heat is generated.  First, frictional (drag washer) surfaces will lose friction (lower the coefficient of friction) as they get hotter.  And to offset that effect, heat causes all drag washer materials to “swell” (coefficient of thermal expansion).  That swelling in the components of your drag system means that you get the same effect as tightening the drag knob and compressing the drag adjustment spring; that is, drag pressure increases.  If you could balance the two exactly, you would lose friction with heat, but the heat would increase the pressure so you would get a compensating increase in friction.  Unfortunately this balance is very difficult to achieve in the real world, so what would actually happen in the worst case scenario is what is called a “thermal runaway”.  Eventually the drag system will fry itself and fail.  It’s not a pretty or sweet smelling event.  We have seen it happen very quickly in the DragensteinTM tests. 

            So how much heat am I talking about here?  I have seen what appeared to be normal drag system function generate heat in excess of 500 degrees Fahrenheit.  That is enough to melt most plastic components if that is what some of the components are comprised.  In one case during the DragensteinTM tests, the meltdown was only small in a component that came into contact with the drag washers, but it was enough to cause failure in the drag system. 


HEAT SINK

            Take heart there is a solution, though I have only seen it “incidentally” applied.  If the heat can be dissipated sufficiently, the drag will continue to perform in a steady manner.  I have only seen a very few reels do that.  When analyzed, they all did it for just one reason.  The drag system design had utilized an effective “heat sink”, that is, provided a place for the heat to be drawn away from the surfaces of the drag washers.  This single factor can do more to help a reel drag perform well than any other. 

            Most metal drag washers are made from either stainless steel or aluminum.  Presumably these metals are used to prevent rust and corrosion.  However, they are far from equal.  Aluminum has one of the highest coefficients of thermal expansion of all metals and also will absorb heat the fastest (thermal conductivity).  In the confines of a drag system, and sandwiched between other drag washers, its expansion will very quickly tighten a drag system and increase drag pressures; sometimes within moments.  Stainless steel and perhaps titanium, which is much more expensive, are better choices for drag washers, but they also will expand and increase drag pressures. 

In most spinning reels the best heat sink for drag washers is the body of the aluminum spool.  If it is heavy enough; that is, has enough aluminum, it can quickly absorb the drag system heat if the drag washers contact the spool body.  Plastic spools are a very poor choice for spinning reel spools.

            This points out that trying to make spinning reels especially light in weight may not be the best design. 

summary
           
            So what is a fisherman to do?  There are so many choices and most of them are bad.  So you say perhaps just spend more money and buy a more expensive reel?  That is not really the best decision since we were unable to distinguish any differences in drag systems of cheap or expensive reels; only the cost of the materials and manufacturing.  There are however, a couple of things I might tell you that can help.  Its OK to buy the best reel you can afford, but watch for a few features.

  • Don’t buy reels with plastic or spare plastic spools.  They will not absorb drag washer heat and will not give reproducible results.  A heavy reel will likely have more aluminum in the spool body than a light weight reel and can therefore pull heat from the drag washers. 

  • Don’t buy reels with grease-impregnated, compressible, or disintegrating drag washers.  That would include; felt, cork, composite cork, rubber, or Teflon.  Beyond that, it makes little difference what the drag washers are made from.  The metal contact washers should always be stainless steel or titanium, not aluminum. 

  • Thin drag washers are better than thick drag washers because they will expand less when they get hot. 

  • Don’t buy a reel with a sealed drag that cannot be opened.  It is very important to be able to access the washers, remove them, and wipe them free of debris and crud.  Crud is the material that forms on the surface of friction materials that have been hot.

  • The more turns the drag knob has while engaging the drag adjustment spring, the more forgiving and adjustable will be the drag.  Most spinning reels have less than 5 pounds of possible drag pressure, even in the 12 or 16 pound class.  It is desirable to have at least 5 or 6 full turns of the drag knob or star wheel from the beginning of drag pressure to full drag lock-down.  That would mean that the drag has a “drag adjustment index” of at least 1 or less. 

  • Check for spool stability; i.e., does the spool have a lot of wobble when the drag is not tightened.  Does the reel rely on drag tightening to obtain spool stability?  If that is the case, it may be that tightening the drag to achieve spool stability will require more drag than the standard rule of 25 to 30% of the line breaking strength.  That is only about 1.5 pounds of hand adjusted drag for 12 pound test line!

  • Find out if DragensteinTM knows anything about your reel drag.   





21 comments:

  1. This business of Amonton's 2nd Law has got me confused. I almost posted that I thought the claim about drag washer size was bunk due to the "disk brake" argument (larger diameter disks make for better brakes, due to the fulcrum effect - that should work for drag washers too), but if you've done the large vs small drag washer test, there must be another explanation why the larger drag isn't better. That must be be because the overall force is constant (only so much force can be applied by the star wheel on it's axle), so the force per sq in is less with a larger washer, and though some of that force is working at a greater distance from the axle, there is less force at the distances closer to the axle, than when using the small one. That is the small washer has a leverage disadvantage, but a force advantage. So though it's even less intuitive to consider Amonton's 2nd Law in the context of rotary motion, it must still hold, if that's what your tests show.

    So the solution is to copy the disk brake idea - make drag washers out of a large diameter ring of material - not a solid disk - so that the total force applied by the star wheel is being applied at greater distance from the axle. I haven't looked at many drag systems, but I think I saw this in a lever drag reel of mine.

    I would think a larger drag diameter, solid contact surface or not, would also help with heat dissipation - as it does in automotive designs - if the reel could be designed to take advantage of that.

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  2. As a BA fisherman (back to it after too many years to count!)
    I see a lot of your fixed spool reels are rear drag. Could you explain why you seem to prefer them?
    (I've got a rear drag spinning reel because that was the cheapest and wondered if it's better or worse)

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  3. Thanks for your comments. I don't know what a BA fisherman refers to? I have used a lot of rear adjustable drags, even for bonefish. They have worked fine and are easier to adjust on the fly. I do not necessarily prefer them however. Drag function is the most important regardless of how you adjust it. Perhaps one of the most important features if I had to pick just one is how well the drag compartment absorbs the heat from the drag. If the heat is dissipated it has a better chance of performing well. That requires aluminum to absorb heat, plastic will not do that.

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    1. Great explanation. Your article had me digging out my old Dynamics textbook from RIT. My two take-away's were to make sure the drag washers and discs are clean and check the washer material. I use mid priced Shimano spinning reels exclusively for inshore saltwater. Have not had an issue yet except for a lost Tarpon recently in the 40-50 lb. range on 15# braid, due to a line to leader knot failure. My bonefish rigs are all 10# braid. (Sure wish there was a way to set the drags leaving the dock, other than "feel", though.) Thanks again,

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    2. Thanks for your comments. Unfortunately, reel manufacturers are not trying to get much smarter on how to make drags more precise and more predictable. Most are still stuck in the larger-is-better misconception of how friction works and have made no effort to make drags adjustable so you know exactly how much drag you have when adjusting. Best to you and your fishing. Thanks again. Skip

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    3. And that as they say...is NOT the end of my story, ha, ha. Thanks for costing me $80! (But a well spent $80 at that.) I'm building up a popping rod for reds and sea trout and have been in the market for a new 10# reel. I've been looking at Shimano Stradic (of which I already have two) and some cheaper models from Shimano. After reading your article, I went to Shimano's web site and looked at all of the schematics for their 3000 series spinning reels. Low and behold, the higher end (read priced) models have a different stack, most notably in the shape of the discs. (Not sure if there is a material change.) Anyway I noticed that the Saros has the same disc part numbers as the much more expensive Stradic and Sustain, the latter being around $330. The drag washers vary a bit in shape and number of locking tangs (not sure if that matters), but all in all they look pretty similar. So to sum it up, I found a great deal online for a Saros and jumped at it. As your article states, I may not see any difference in performance (the most critical piece that being my left thumb and forefinger on the knob with a fish on), but it feels like I got a bit of a deal. We'll see! Thanks again.

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    4. Great Lan - Let me hear how all of this works out. I like Shimano reels pretty well, in particular the Shimano Calcutta 50 I have has the best performing of all the drags I have tested in baitcasting reels. Spinning reels - eh, well most are not so good and almost all other baitcasting reel drags are junk.

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  5. So, as a thoughtful well written article should, it got me thinking. Did you look specifically at start up inertia? It would seem to me, intuitively, that the rod should take up the role of reducing that as much as possible because of its uniform spring characteristics of the upper third or so of the rod. This would be especially important for light tackle fishing with species like bonefish and permit on the flats. Rather than add grease to reduce the start up inertia, I would strive to make sure that the rod characteristics have the right action and power. For the last few rods that I have built up, I have chosen the blank and spaced the guides specific for the reel to be used. (That forever mates the rod to a certain reel for best performance.) Besides having the spool aligned with the stripping guide, I had not considered the role that the rod tip would play in the fish's first sprint as far as drag release goes. This is not so critical for heavier lines on smaller fish, but underscores the importance of the complete system (rod, reel, line, knots, etc) for optimum performance using light tackle gear on the flats.

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    1. We did analyze start-up on every reel tested and it varied widely with little to reveal its differences. The type of surface and the amount of drag pressure are all factors of course. Surprisingly, greasing had little to do with reducing start-up and of course is ill advised for any drag surface since it makes controlling the drag impossible as the reel runs and heat builds.

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  6. Skip..I would be interested to see data from runs using stock, greased felt drag washers as compared to aftermarket carbon fiber (no grease)washers. Do you do customer testing? (If I sent you the reel and washers.) This topic really has got me intrigued. I'm a Lab manager for a large automotive company and deal with things like this on a larger basis (engine characteristics). It would be cool to see plots of a vs. b and see how they follow the typical "static" vs "dynamic" friction curves.
    Let me know if you'd rather correspond by email...

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  7. Lan - Please send me your email address to spinfly1@hughes.net. Thanks

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  9. Thanks Rogerio - I understand the 100% setting. I have done that myself a time or two for the same reason, but not black grouper. Thanks for your comment.

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  10. When i have to catch Black Grouper near the botton i adjust my drag to near 100% of the breaking strength of the line, Otherwise it goes to the rock.
    Great explanation, I really enjoyed your article.

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  11. Just read your article. Good one. I liked it. Keep going. you are a best writer your site is very useful and informative thanks for sharing!
    My blog: best spinning reel under 50

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  12. This is very informative article about fishing. It is an important fact for choosing best fishing reel for beginning of the time. Thanks for sharing this post.

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