Anatomy of a vertical jigging and/or SPJ rod

[JasonGotaProblem]

There's a great many times when I think something is far simpler than those who give things titles/categories and those who sell said things make them out to be. Now there's a great many times where I'm completely wrong in that simplification. And I'm assuming this is one of those times... But I'm not always wrong with those simplified analyses, which is why i ask questions.

In playing with a surprisingly expensive "SPJ" rod at the store I noticed it has a bend profile that's almost identical to that of a purportedly "fast taper 15-30#" graphite rod I have but almost never use, and the tip and but diameters are actually quite similar between the two, but i didnt have a caliper on my person to quantify that. And my understanding is that SPJ rods are often slower taper rods, but they give lure weight ratings not line ratings. So that brings up the question:
is there a meaningful structural difference between a slow taper "heavier" rod and a fast taper "lighter" rod?
And taking it a step further, is there a meaningful reason I shouldn't attempt to turn that unused rod into a vertical jigging setup? I know its my property so I can do whatever and none of you will come stop me, but is it a decent idea?

[jurelometer]

If you don't mind,  here is a primer in what makes one carbon fiber blank structurally different than another. 

When a blank designer is choosing the layup for a carbon fiber rod blank, any two (but not all three) of the following are available:  stiffness, (hoop) strength, light weight.

Stiffness comes from having more fibers oriented toward the length of the blank. This creates the potential for storing more energy in the tip when initiating the cast, and more lifting capacity in the butt.  Stiffness will generally increase frequency, which is how fast the tip oscillates when the load is released.

Hoop strength comes from having more fibers oriented toward encircling the blank.  This helps resist deformation of the cross section, allowing the blank to bend more  without breaking. Marketing babblespeak like "x-weave", "super-helix", etc., is simply referring to using the same woven cloth, but cut and wrapped with the fibers running diagonally to provide more hoop strength.

Lightweight is the result of using less cloth, which means less resin. Which means less weight. Building a blank that has both stiffness and hoop strength generally will require more total cloth, which results in a heavier blank.  No free lunch.

Depending on the performance goals, some sort of tradeoff is made between the three, and this tradeoff can be different in various parts of the blank.

At one extreme is a performance casting fly rod blank.  Very stiff, very light, very poor hoop strength.  A designer going whole hog on a new-style vertical jigging blank will go for hoop strength and lightweight, meaning not as stiff.

Most blanks are somewhere more in the middle ground between all three choices.  A technique becoming more popular is to use diagonal weave on the outermost layer, where it will do the most good. At least one of the big names actually spiral individual fibers for hoop strength, but it is not clear to me how much more beneficial this is.

[Update:    I left out one other key structural feature- diameter vs. wall thickness.  Given two otherwise identical blanks using the same amount and type of materials, the blank with a larger outer diameter, but thinner walls will be stiffer, but have less hoop strength than a thinner outer diameter blank with thick walls.   A performance fly rod will lean toward the large diameter/thin wall, but the hardccore newfangled jigging rod will tend toward the pencil thin blank with thicker walls.  Both will be light, but the stiffness vs hoop strength tradeoff are on opposite ends of the spectrum. Most other blanks shoot for a more happy medium.  The material scinece guys describe an optimal diameter to wall thickness ratio for elastic tubular structures for repeated flexing.]


In terms of what a vertical jig blank is supposed to do better:  First of all, it is lighter, which can come in handy when using some of the more vigorous jigging retrieves. The second thing that is that lack of stiffness allows the blank to load more fully on the upward jigging action while the jig goes from falling to moving upward, flicking the jig upward, theoretically resulting in more acceleration than would have been achieved by lifting a stiff rod at the same rate.    I use the term theoretically, because the blank action has to be compatible with jig action/resistance/weight, line diameter, depth and current.  With too much resistance, the blank stays bent when the jig stops moving upward, meaning wasted effort and less  travel.  If the resistance is too little, the blank does not load, and you don't get that acceleration.

A typical vertical jig blank description will specify the jig weight and line diameter(not breaking strength). Some will also specify the jigging sub-style.  This will give you a better chance of matching everything up. The rod companies suggest that you get a whole quiver of different rods.  They lurve vertical jigging

But as increasing fishing depth and current also increases the resistance from  friction along and across the line, the actual motion at the jig can decrease dramatically. Even though the rod is bending and unbending as you work up a sweat with your well choreographed jigging routine, the jig may be just twitching a little, and the handle turn is the only thing providing significant upward motion.  Not to mention the boat going up and down in the swells. So it is probably not worth getting all worked up about getting a perfectly matched outfit for each jig unless you are fishing shallower depths in calmer waters.

Realistically,  *any* flavor of vertical jigging is one of the least challenging fishing styles when it comes to blank design.  You can vertical jig with a more versatile standard conventional rod and do just fine.  Jig goes up, jig goes down.  But if you want to actually experience a new style bouncy vertical jigging rod, the difference is primarily in the blank, and they are typically very different beasts.

-J

[boon]

SPJ vs "mechanical" aka vertical jig is very very different.

The action of a proper SPJ rod should be nothing like a fast taper rod. Do you know what make/model it was? There are plenty of unscrupulous brands calling fairly generic rods SPJ or Jig to try to take advantage of the growing interest in both techniques, when the rods are in fact a long way off a "true" purist rod for either technique.

[JasonGotaProblem]

Thank you J for the detailed answer and boon for the answer from a different perspective. I do not remember the mfr of the one I felt, just that there was a lot of green on it.

So it's sounding like I could make a vertical jigging rod out of it but wouldn't be fair to call it a SPJ rod. That's fair. And I may just find a blank more appropriate for the task, and use this as a tarpon/cobia rig. at this point it seems im planning builds for 3 rods ahead of what I'm currently working on. I may have a problem.

[steelfish]

So it's sounding like I could make a vertical jigging rod out of it.

does your rod have an extreme bend as the vertical jigging rod have?

which can bend almost to form the "U" letter, maybe its will be just an upgraded all-purpose rod, but I say go for it.
if you check the next thread https://alantani.com/index.php?topic=32208.0
there is plenty of info about SPJ rods, if you check page #3 of that thread, I already did what you are planning to do, I took a cheapo graphite Bass rod with plenty of bend/flex (surely IM6) which had a pretty short reargrip, I upgraded all the running guides and also added few inches to the reargrip to put the reelseat to the same(average) distance as on the SPJ rods but I just called it a light vertical jigging rod (which is not). its pretty light and thin as some of the SPJ rods or some UL jigging rods, my plan is to use it the same way I use my trevala rod but with pretty light metal jigs if a decent size fish bit I might use the SPJ technique of point the tip of the rod to the fish and figh with the reel. maybe I like it who knows, for now I have an upgraded and 3x comfortable Bass rod that can be use it from the shore or shallow waters, it it can handle a LMB Bass then it can handle a rockfish

[JasonGotaProblem]

So I decided to be a bit more scientific, and it's irrelevant to name the spj rod mine seemed similar to, because I brought mine to the shop (left in car) so I could make a comparison minutes apart not hours apart. And yeah the similarities end at about 80° of bend when it becomes clear mine possibly can but shouldn't go past 90°, where the SPJ labeled rod feels like it can go another 100° bent.

So yeah foot in mouth, but that's nothing new. That's why i asked before I started cutting. Thanks all for the guidance.

[jurelometer]

I forgot about diameter to wall thickness ratio in my post on blank structure, and it bothered me enough that I HAD to update the post for posterity.  Can't help myself.

SPJ vs "mechanical" aka vertical jig is very very different.

The action of a proper SPJ rod should be nothing like a fast taper rod. Do you know what make/model it was? There are plenty of unscrupulous brands calling fairly generic rods SPJ or Jig to try to take advantage of the growing interest in both techniques, when the rods are in fact a long way off a "true" purist rod for either technique.

Good point about slow pitch vs other jigging methods - we keep lumping them together, but slow-pitch is on the more fussy end.   I think that the terminology sucks, because these are all vertical jigging methods (slow-pitch, high-pitch, long-pitch, full-twisting-double-gainer-pitch, bounce jigging, speed winding: You are working jigs vertically    But there are a million youtube videos on "slow-pitch vs. vertical jigging", so I am fighting an uphill battle.

I am sure that Boon already knows this, but sticking to slow pitch- the prototypical slow-pitch jig is designed to flutter more or less horizontally when free falling (this is where most of the bites happen), and to drop oriented vertically (and therefore dropping faster) with a bit of line tension.   The goal of slow pitch is to keep the jig in the zone fluttering down over and over, and to also take advantage of the sideways motion as the jig transitions from lifting to free fall while still in the zone. It is really just a useful refinement of good old classic bounce jigging. 

This is why slow pitch rod selection has to be so specifically tuned to the conditions to provide any incremental benefit. If the rod stays somewhat bent at the end of the lift/start of the drop, it will introduce line tension on the jig as it starts to drop, keeping the jig vertical longer and impeding both the sideways motion and fluttering freefall.  In which case, a broomstick would provide better jigging action .  As long as you can lift the jig and have it transition quickly to free fall, you are working it pretty well.   IMHO, too stiff is always better than too bendy when it comes to any style of jigging vertically.   

-J