A word on Friction & Heat

[Tightlines667]

With all of the upgrading, hotrodding, and general high performance characteristics of the modern day fishing reel in mind...

I got to thinking a bit about a given reel's effective drag range, the friction forces which allow the drag components to function and the biproduct, our nemesis...heat.

In an admittedly oversimplified analysis (I'm no physicist). 

Velocity X Force = Friction

The total energy of the system is always conserved and the work the reel does (in response to the work put in by the fish & the fishermen), will produce heat.   Furthermore this heat will be primarily generated by the friction created in the drag system.  The symplified equation suggests that total friction is, in essence, linearly related to the force applied and the velocity at which the force is applied.  The amount of heat generated from this friction is primarily related to the time over which the friction force is acting.  The total volume, acting surface area, and material type of the surfaces that are actually generating the friction do not directly affect the amount of heat generated, but they do have an influence over heat retention/dissipation/distribution and through changes in the way different solids/fluids interact the actual working coefficient of friction and dynamic changes in kinetic vs. static friction (both at the macro and microscopic levels).  So there are lots of things that can and do affect the amount of friction and associated heat that a given drag system develops.

Despite all the factors that affect a reels drag efficiency, smoothness, and heat-related characteristics (when doing work), the basic linear relationship between force velocity and friction hold true. 

I started looking at this stuff and running some numbers to try to convince myself that higher drag settings generate more heat, and I actually found the opposite to be true.  Basically time is as important as pressure with regards to heat generation.  If higher effective drags reduce the time that the reel's drag is working as would be the case with most fish, then overall heat generated would be less.   

For example:

At 30lbs of effective drag, and a fish running line off of the reel at 30mph (44ft/s)
1,320ft•lbs of frictional force per second is being generated by the reel's drag system. 

Just as an oversimplified means of thinking about this number in terms of heat...
I did a conversion using the latent heat of stainless steel (which is roughly 155,104 ft•lbs/1deg F
It would take 117seconds of 30lbs of force at 30mph to generate 1 deg temp rise (keep in mind this would assume the average drag disc velocity is equal to the fish's velocity and that all friction is kinetic, and that all heat is generated in uniform stainless steel, so actual temp change in a working reel under these conditions would be greater. 

If we cut the drag force in half (15lbs effective), and the fish's speed doesn't change, the friction would be half so it would take 234 seconds to generate 1 deg of temp change in stainless steel. 

We can control the drag setting in the reel, if we double the setting, and are able to likewise cut the fish's run time by greater then 1/2 we are winning the battle on friction-generated heat.

Conversely, if drag pressure is cut in half, it might be resonable to expect that either the speed or tye time that the fish is actively pulling drag, or a combination of the two is doubled, the amount of heat the reel's drag system generates will be in direct proportion to this increase. 

Of course...
Depending on the given fish, and the given fisherman, one or the other may tire more quickly under heavier pressure. 

Basically what I seem to have gleaned from the over-symplified physics of friction is that:

If higher drag pressures lead to significantly lower fish run times and/or a decrease in the run speed then the reel will generate less heat overall.

If heat is the enemy, and you and your gear can stop the fish, don't be afraid to fish at a higher effective drag setting.

Keep in mind this doesn't account for the myriad of other factors at work. 

This still doesn't change the fact that I enjoy catching fish on light line, under ultra smooth, low drag settings the best

[MFB]

Interesting, the basic concept is sound. The quicker you get a fish to the boat the easier it is on your gear, seems logical. There are a few more variables in that equation though. My faculties are slightly impaired at the moment due to Appleton's rum, but here goes. Speed ft/sec or m/s is dependant on the diameter of your spool (including line) rpm x pi x diameter & not just the speed of the fish & as the line runs off the spool the diameter is effectively decreasing which means your linear speed increases assuming the fish maintains a constant speed. Thankfully I don't have these variables with conveyors.

Rgds

Mark       

[Reinaard van der Vossen]

Interesting but.....

If the summary of your thoughts is that double drag (30lbs) would generate less heat than 15 lbs than I think that is untrue if all the stated circumstances remain equal as you described.

You mention, as example, that speed and distance of the run are the same in both cases. If this would be true than you do not need high drag and taking it to extremes you could land any monster fish on 0.1 lb of drag.

To stop the fish you would require a certain power. This power can be on heavy drag with a short run or on light drag with a long run. If the power is equal the heat generated is the same. On heavy drag the generated heat is equal (approximately) but is generated in a shorter time frame

It is where the heat dissipation kick's in. Due to the limited heat dissipation of the metal drag disc the generated heat cannot dissipate quickly enough (if the reel is really challenged on a big fish). So a long run (for a longer time) on light drag is an advantage here as there is more time to dissipate the heat.

In real life it is slightly more compex as the heat generating curves are not linear (temperature dependant) and at a certain temperature the friction coefficients are changing (will get lower) etc.

If you would ever like more drag from a reel than this would be the area to look at. You can look at systems with much higher forces to see in which area's improvements can be made. More drag surfaces and more metal drag discs is one that is already used commonly. A next step could be ventilated drag discs in an open frame housing or a very thin drag disc (SS or titanium) explosion welded to a copper or silver drag dissipation plate.

It will all come at a cost though and I'm not strong enough to use the full drag capacity on my 50 or even 30 size reel (well, maybe for a short moment)       

[Ron Jones]

Asuming doubling the drag pressure reduced the fishes run by 50% then I agree with your theory. That is not my experience with large fish, however. If a fish is taking line it seems it takes line regardless of the drag you add on. The extra drag does seem to tire the fish subsequent to the initial run, or first few runs, but I am not certain it limits the length of the initial run. If the run is the same length and you increase drag then you are increasing heat.

Another thing to consider is the size of your heat sink. Any increase in mass helps with heat dissipation and limits the effects of heat absorption. So, adding material that readily absorbs and dissipates heat, such as thin stainless washers in a star drag reel, will reduce heat by increasing mass and dissipat heat faster via increased surface area.
Ron

[wallacewt]

so, large thin washers.

[Reinaard van der Vossen]

Wallace,

Slightly more complicated than that. In principle it could. Larger washers for more drag: yes. Thinner washers will have a quicker temperature rise. If one side is free to air than they can dissipate also relative quickly. If they cant dissipate the heat to air easily than a large mass can be advantageous.

To the ts: if you can significantly shorten the run ( far less than half) high drag would be advantageous.

[Ron Jones]

Larger washers for more drag: yes.

I'm not about to go down THAT road again!!

[Tightlines667]

I was thinking about the total heat production during the course of a fight on large Pelacics (like BFT, double marker YFT/BET and big Marlin), where the gear (and angler) are really pushed to the max.  If a heavier drag setting results in drastically reduced fight times (with decreased # of and time of runs), with respect to increased drag setting it may be advantageous to 'put the breaks' to the fish after the initial run.  As far as the many differences in design and function of big game fishing reels...heat generation, retention, and dissipation will vary dramatically with respect to time of runs, time between runs, and drag pressure applied with respect to a given reel's drag curve and overall effectiveness/efficiency.  The type if drag material, whether it is wet or dry, number, orientation/placement, thickness/mass of drag disc and associated washer(s), and anount of contact w/ other heat sinks, or airflow over system.  Larger diameter drag discs will have greater relative speeds during a run, but also are typically more effecient at producing drag, and are often more effective heat sinks (but because they usually involve more massive components with respect to drag surface area, they would likely have a tendency to retain heat longer esp. during prolonged fights.   Free floating type drag systems with duel carbon fiber pressure discs operating on a single relatively massive, free floated metal washer, are capsble of producing relatively high effective drag settings, but have the potential drawback of having fewer contact points for heat dissipation due to conduction, and convection (which is much less efficient) ends up playing a larger roll in cooling.  Conversely, a large diameter and massive pressure plate acting on a single stationary drag disc (I.e. mounted to the spool), like many Avets, will be slightly less efficient at producing high drag but typically has a much more massive heat sink (relatively speaking), resulting in the ability to stay cool longer, and disappear heat more quickly.  However, it seems reasonable to expect that at some given threshold if heat developed/time the larger mass will not be able to dump heat as fast as its being produced.  Smaller stacked washer drag systems have many design advantages, but heat production, and dissapation is not likely to be one of them.  Centralizing and compacting drag surface area, and heat production along with reduced mass of the overall system, make for relatively poor heat sinks, and quick heatinf, sliw cooling type properties.  Some reels (the Everol comes to mind) are have massive drag systems, with both freefloated and fixed drag components that allow for maximum heat dissapation through both initial heat sink, loss through conduction to other parts, and some convection (through an open design that allows some airflow), but the drag system is still centralized to one region of the reel.  Some Avets (and others) have seperated drag systems to different regions of the reel (I.e. duel discs on either side of spool).  This really optimizes the total heat sink available. 

There are things we can do increase drag efficiency, and to try to minimize total heat production and improve  cooling through manipulation if the drag components, tuning of the drag curve for a given gear and fishing type, and replacement/upgrading materials as well as changing base coefficients of drag (smoother grained drag material, lubricated w/teflon grease, etc...).  In general, I think increasing total drag surface area, making that area more efficient (throughout the heat and drag range), increasing the mass of drag components (available for conductive heat loss), increasing air circulation around these components, and fishing the gear within its designed specs (ideally at settings of ~50% of max?) can help to improve the reel's performance.  As with everything in life..you can't get something for nothing..so finding the right balance should be the goal.


Regardless of the inherent differences in the reel's design (with respect to the drag components), we can, through our utilization of the drag settings throughout a fight manage total heat generated and attempt to control or negate the negative effects. 

[Makule]

In my experience, when a large fish is taking out line, I will crank down on the drag until the fish stops (or something breaks).  We do not have the luxury of letting fish run unlimited distances when fishing from shore in Hawaii, as there are too many rocks, reefs, drops, etc. that easily can cut off the line when fish run off too far.  I would not say I double the drag, as I have never done a before and after comparison.  I simply tighten the drag to what's needed to stop the fish.  In those instances when I was not aware of the strike (sleeping or away from the rod), reels have been stripped.  I have not experienced a stripped reel when I was able to tighten the drag, however.

Stainless steel is a very poor conductor of heat (perhaps the worst of the commonly used metals).  Aluminum and copper are among the best.  This is the reason, for cooking pots and pans, high quality products have copper clad bases with surrounding SS.  The thicker the SS, the longer it takes to heat up and the longer it stays hot. 

If the SS drag washer is thin, it will heat up faster (i.e., be a more efficient heat sink than a thicker one).  At the same time, if it cannot dissipate the heat somehow, it quickly loses it's effectiveness (because it cannot transfer the heat to anything else).  Air is not a good conductor of heat.  In fact, some of the older coolers used air between plastic coverings as the insulating materials (before insulating foam or fiberglass).  Air is only effective if it is moving and of lower temperature than what is being cooled (convection).  Once the air temperature is at homeostasis with the hot disk, there is very little (if any) cooling.  A much more effective means of cooling is conduction wherein, for example, the heated disk is in contact with a good thermal transfer material (e.g., copper) and that material is also either exposed to moving air or a much larger surface area of good heat transfer material.  It is likely that reels with aluminum frames and spools dissipate the heat generated from the drag at a much faster and efficient rate than those that have side plates made of plastic (perhaps a better insulator than conductor, but this is just my guess).  The heat generated from the brakes, gets transferred to the aluminum reel spool and then to the wet line (good conduction), and to the aluminum frame that is exposed to free flowing air (making it a very good heat sink also).

Certainly, there is no question that increasing the size of the heat sink can only help to keep temperatures lower.  Perhaps the issue of heat dissipation of the brakes has not been considered adequately.  On the other hand, Kovalovsky did, in his design, give a lot of thought and consideration into the affects of heat from brakes and how to properly handle that issue.  The literature suggests that he was the only manufacturer to use a drum brake type of system specifically to address that matter.

Asuming doubling the drag pressure reduced the fishes run by 50% then I agree with your theory. That is not my experience with large fish, however. If a fish is taking line it seems it takes line regardless of the drag you add on. The extra drag does seem to tire the fish subsequent to the initial run, or first few runs, but I am not certain it limits the length of the initial run. If the run is the same length and you increase drag then you are increasing heat.

Another thing to consider is the size of your heat sink. Any increase in mass helps with heat dissipation and limits the effects of heat absorption. So, adding material that readily absorbs and dissipates heat, such as thin stainless washers in a star drag reel, will reduce heat by increasing mass and dissipat heat faster via increased surface area.
Ron

[Reinaard van der Vossen]

Makule, very interesting. In general I would be in favor of disc type brakes but I can see the advantage of a drum type brake for a fishing reel.

With a smart design the drum could be the right side plate with lots of external alumium exposed to free air and thus lots of possibility to dissipate. The sideplate would have to be wider though. I doubt whether that would be acceptable in todays world of smaller reels

Tightlines, I tend to agree with you that it makes a lot of sense to increase drag if that could shorten the fight although it would have to be within limits. I do not think that in most reels the heat is the big issue but the right side plate bearing suffers from to much drag pressure. From a drag perspective itself you might be right when you can turn the fish much quicker