OK, another almost unanswerable question :roll:
Basic question would be…Are there specific distances a given rod weight should be expected to cast?
Variables…let’s say 9’…average castor [or would intermediate be a better term]…
I guess another way to put it would be…How much farther can the same castor cast a 7wt vs say a 4wt?
Or will a rod one size larger cast say 10’ farther?
Googling didn’t help much but Al Campbell sort of alluded to the issue in this…
Depends on the caster. For me, No it doesn’t matter what rod weight. Length of rod and flex, yes that makes a difference.
Duckster,
Note this is all my opinion but there are differences inherent in how a rod will cast. I enjoy building my rods specific to fishing conditions. I find blank action, guide type, guide spacing, guide size, handle size, handle shape all play into how a rod will cast and fish. I use these factors to build maximum performance into my rods for specific fishing conditions.
With that said - what I said applies to about 5% of the true picture. The other 95% of the true picture concerns three factors - Practice, Practice and more Practice.
I’ll never forget how well those old glass rods improved in performance just sitting in the closet while I spent five years in tournament casting with higher quality rods. 
No doubt about it, my 9’ 9wt (fast action), will cast the farthest of my fly rods. Next it would be a toss up between my 8’ 8wt, the mid-action 8 1/2’ 7wt and the fast action 9’ 6wt. Even the mid-action 9’ 5wt will do a respectable distance, especially compared to the mid-action 8’ 5wt. So what an I saying … the higher the rod weight, plus the stiffer the action, the farther it will cast. That’s within the realm of my 8’ and 9’ rods … I don’t cast a longer rod that well (done tried it).
Dale
Everything being equal. I can cast a fast action rod about 20 yds further than a slow rod.
That could be partly that I don’t try to cast a slow rod very far. It just doesn’t feel like the right thing to do.
I agree Gramps and so do distance caster :lol:
Stiff rods at least 9’ from there I don’t feel that line or rod weight will make a difference.
Duck,
I have found that to get the very most distance and accuracey from any of my rods, is to have someone else toss’em! :roll:
…lee s.
this is a provocative question. I cast the farthest with my Sage SLT one weight and my Scott SAS 6 weight. SInce distance is not really a priority to catch fish I don’t thing about it much, but I like your question.
Going to bed pretty soon laughing :lol:
One thing no one has mentioned is the line being cast. I have been told that a rod generally is rated to handle 30 feet of the line it is rated for. So do a little math and reasoning.
I can cast my 3 wt with slow action with a 2 wt WFF line as far as I can my 9wt med action with a 9wt WFF line. I don’t own an 8wt line, but I bet I could toss that line farther on the 9 wt rod than the 9 wt line.
The faster action of a rod means it can handle more weight from the line during long casting without overloading. Generally that means you will beable to cast farther with a faster action rod than a slower action one, given all other variable are the same.
Now the higher weight of a rod will generally give you more strength, therefore more fishfighting capabilities. But not casting capabilities.
My questions to you are, How far do you need to cast to cover 90% of your fishing circumstances? Do you have enough room behind and around you to wave a stick and have a back cast? How far off the water do you fish (ie deep wading, float tubing, bank fishing, boat fishing)? What is the size and fight of the fish you will be fishing for?
The first question will give you you relative line weight. Within 40’ use a line the weight of the rod. Over that use a line made for distance or use a size or two smaller than recomended.
The second and third will give you your general rod length. If you are low, use a longer rod. If you don’t have much room, use a shorter rod. No room to backcast but pleanty around and above you use a longer rod to roll and punch cast. Try and find the happy medium there.
The Fourth will give you the weight rod. Small fish low weight. Increase accordingly. Remember, if you are catch and release fishing, land the fish as quickly as possible. Otherwise the fish will likely die anyway. That goes for tippet as well. Most fish are not leader shy, EVEN large trout and salmon. If you can hook fish but not land them, I’d rather be tying flies.
But for your direct questions, I would answer:
1.NO
2.All variables the same, Id say not much
3.Not likely
A question.
Do they deminish the size of the “running” portion of a WF line proportionately according to line weight for each size or do they run 3 or 4 sizes with the same running line size?
If you have to shoot the same size running line, would not the increased mass of a heavier “head” shoot (pull) more line?..unless you used the added mass to pull a bigger bug instead??? :roll:
…lee s.
Various companies use different diameter running lines per the head size. In other words, one WF8F line may have a bigger/smaller back part of the line than some other line makers line. Differing amounts of line rubbing on the guides, less or more weight/mass in the cast, differing wind characteristics just to mention a few things.
At some point in the front and back cast the average caster quits really stopping the rod and only ‘slings’ the now airilized line back and forth. The heavier the weight of the rod the sooner he quits stopping it. How much energy does a rod impart to a cast when it is stopped? Does the weight of the rod add more or less force to the forward cast when it is stopped. Since a slow rod bends easier, does it add more or less energy to a cast when/if it is actually stopped? Does the diameter of the rod (air resistance) make any real difference and or does the line? Since a sinking line is narrower than a floating line will it go farther? These are just a FEW of the starting questions. If you want to get into competition there are more advanced things to consider like the harmonic node vibrations of a rod length and material.
After watching Lefty Kreh cast the full 90 feet of line with only the top section of a 2 piece 9 ft rod in his hand, I’d have to say that the caster has more to do with it than the rod. He used to cast the full line with the top section of a 4 piece rod but said his shoulder hasn’t been what it used to be since he hit 70. My experience has been much the same as the others mentioned here with my 9 wt fast action rod casting the longest with the least amount of effort.
Jim Smith
Duck,
I am not aware of competition distance casters using 2 wt. bamboo rods. Likewise, not too many people fish a brooktrout stream with a 12 wt. There are reasons for this. Same as you won’t find too many .22’s on a 1000 yard range. This belongs to the .50 BMG’s. And it is more than just velocity.
Everyone will have an opinion on this one. And as Castwell alludes to, anything in between is very dependant on the skill of the caster and the nuances of his/her equipment. And I have never known Castwell to be wrong.
Ah ha, Grasshoppa, “He is never truly wrong who only asks questions, and is not so dumb as to ever give answers.” Observe him closely, for the most part, he says nothing!
We call them lurkers.
I interperted the question a little diffrently than most must have. We all know that there are variations in rods, casters, and lines. As I read it the question is, with the same brand rod and reel and line in different weights in the hands of the same caster how much difference in distance would one or two weight changes make? Can a person expect enough difference in distance to make it worth while to move from a 5wt to a 7wt in the same combo? I have a LST combo with GPX line in both a 3wt and a 5wt with the only difference being the 3wt is 8’3" and the 5wt is 9’. I seem to be able to cast the 5wt much farther that the 3wt but the 3 is much more fun if I don’t feel the need fot the extra distance.
You interpreted correctly. Bowmaker…
Unfortunately, your example compares two different length rods…so we’re still apples and oranges… 
I was [am] wondering if given everything the same if going say one wt up would be generally expected to yield “X” more feet?
Again I would answer not very much. And putting an X value on it wouldn’t really work. The answers would probable resemble some sort of inverse cosine curve when graphed out with your peak somewhere around the 9wt range. But between just one rod weight the gain would be very small. With the gain from the lowest to the highest somewhere around 15-20ft. Mind you these are only educated guesses but maybe we can get some people to actually test this at a show or fish-in in the near future.