I purchased a medium action fly as my first fly rod a couple of years ago when I started fly fishing, I didn't realize it was medium action till recently. A Greys Gs2 9' 5wt. Its got a lot of use and I haven't handled it with kid gloves. It feels very comfortable to cast. I can cast 35 to 45' without thinking about it, and if I concentrate and double haul I can add 20'.
I think I like the medium action. What would I gain switching or "upgrading" to a fast taper outfit.
I also have fast taper 9' 8wt outfit, but I don't think its a fair comparison as when talking actions.
You would gain the ability to extend your casting range especially in the wind and the ability to cast heavier rigs like double nymphs with large strike indicators more easily and farther. But this ability comes at a cost and I am not talking about the cost of a new rod.
There is NO FREE LUNCH. You would need to relearn or add the ability to match your casting stroke and stroke timing to the faster rod action. A faster rod bends less for the same line speed. As the rod bends, the rod tip gets closer to your casting hand (see illustration below). As you cast, the effective rod length shortens. One of the purposes of the stroke path is to move the rod in a convex path, to correct the concave path of the rod tip as the the rod shortens due to its flex. Depending on how far you are casting, you need to adjust both the stroke length of the rod and the convexity of the stroke path to compensate for the lesser rod shortening with the faster rod.
The fly line speed and loop shape is what determines the length of the fly cast. The fly line does not care if the rod stroke to produce that speed and loop is long or short. To produce the identical fly line speed with a faster action rod, the rod stroke length will shorten and the stroke speed will increase. It is obvious that to feel the rod bend, you will have to bend the rod. With a stiffer rod, you will need a faster rod stroke to bend the rod. Therefore, to cast the same distance with the faster rod, you will need a shorter rod stroke. So a faster and shorter rod stroke to make the same distance with a faster action fly rod.
The faster rod will also have a stiffer rod tip. This will mean it has less ability to protect the tippet from breaking. So if you are using light tippets, you should consider staying with the medium action rod. On the plus side, your reaction time to strike especially on those heavier nymphing rigs will improve. There will be less tip lag on a strike.
With all due respect, I must disagree with some of what has been posted by others. Higher line speed does not translate into tighter loops. They are relatively independent. Fly line speed is rod tip speed. Loop shape and size is determined by several things including the shape of the fly line path, the timing of the rod stoke, the wrist flick just before the rod stop, the relative position of the casted line when the opposite direction cast is made, etc. Note that the second image below from Jason Borger's casting book shows the control of the loop size by the size of the wrist flick (tipping the rod tip out of the way of the trailing fly line at the rod stop). Larger flick = larger loop.
The following set of images below from the FFF certified casting instructor study guide show 3 ways a wide loop can result = classic convex rod tip path, top of loop too high, and bottom of loop too low.
So lets get rid of the idea that a fast rod is a prerequisite for the tightest loops. If that were true, however did the fishers with slow rods in the bamboo era ever cast tight loops?
Also I disagree that faster rods are always more accurate. In fact, The winners in the accuracy section of the fly casting competitions did not use fast action or even medium fast action fly rods. The 2016 Women's Fly Accuracy World Champion is (Maxine McCormick), and the 2016 Men's Fly Accuracy World Champion is (Chris Korich). It is pretty well known that both of these champions used a medium action graphite rods to win their respective divisions.
As to the reference to “high-tech rods,” three years ago, Korich gave Maxine McCormick a 40-year-old fly rod, he said, worth about $50. She used the same rod Friday to win the gold.As to the reference to “high-tech rods,”
To cast accurately, the caster has to feel the rod bend. Rod “feel” is a combination of both fly rod action and fly rod mass distribution resulting in “swing weight or moment of inertia.” This rod feedback is what the caster uses to make accurate casts. Here is what accuracy champion Chris Korich writes about fly casting accuracy.
”At a 60 foot target distance, the heavier amount of line extended is going to help BEND a rod more deeply. Deeper bending, when not excessive, generally improves LINE FEEL and can easily help a caster execute his/her stroke and resulting cast more accurately.
At 30 feet, especially with modern light graphite and stiffer rod designs, minimal bending can easily rob a caster of adequate LINE FEEL. Hence, it's very easy to misdirect a short cast to a close target.
In essence, short strokes at close targets happen so quickly, the caster doesn't have the extra milliseconds and bio feedback to execute the stroke accurately. Combined with a lower mass of line extended and generally less line speed at 30 feet, it's also easy for air and wind conditions to negatively affect accuracy on the final delivery.
Hopefully now, the U.S. team's recent accuracy success using deeper bending and slightly heavier 1st gen graphite rods, makes a bit more sense.”
Sometimes you will see a post that says the fly rod action is the the taper of the fly rod = how it thickens from tip to butt. This is NOT always true. The taper we see is the EXTERNAL taper from tip to butt. HOWEVER, fly rods also have an INTERNAL taper that is determines by the rod mandrel. So the actual wall thickness of a fly rod and its shape is determined by the shape of the mandrel and the shape of the composite “flag” that is wrapped around it. Since the flag can be and is composed of material of different modulus formed into a sheet and cut into shape, the actual external rod taper we see and rod action we assume may differ from the true wall thickness and the actual rod action.
Phil Monahan speaks to the fact that rod stiffness can vary from tip to butt because of how the rod mandrel and flag are designed. Although he does not get into manufacturing, the methods above are what he is referring to when he writes. “trying to define action simply as the “stiffness” of a fly rod doesn’t take into account that the relative stiffness is not uniform throughout. A rod may have a tip that is stiffer than the butt-section, for instance, and the placement of stiffness along the blank can be one of the key determiners of rod action.”
Finally, rod action is only one of 3 main properties of a fly rod that get confused. In addition to fly rod action, there is fly rod power and rod line rating. I wrote a sticky post explaining these three properties here: https://www.theflyfishingforum.com/forums/fly-rods/222260-fly-rod-line-rating-power-action-explanation.html#post370934