At the risk of going down the optimal rod bend rat hole again I think it’s interesting to think about what is it that actually maximizes the distance of a cast.
Instructors may remember a written question that went something like, “all other things being equal, the deeper the bend in the rod the farther the cast. T/F”, The important thing with the question is not to over think it because all other things are equal - same rod, same casting stroke (don’t ask how you could make the same stroke with the same rod and achieved different loads, that isn’t the question), same line, carry, wind, etc. if you can think of anything other factor forget it because we at this moment in time space we only want to know which one of those two identical casts, except for magical difference in rod load, is going to go the farthest. I think it’s an obvious answer.
Now let’s build on that a bit. What are the critical things we want to develop to improve our distance casting? Again, instructors may remember a similar question about the main thing we want to do to increase distance. At one time the expected answer was to minimize loop size - smaller loop = less air resistance = line goes farther. I like to credit SL for putting that one to rest because, as it turned out nobody actually knew how to define the size of a loop. There are certain loop characteristics that will minimize air resistance but the distance between rod and fly legs at some arbitrary point is more about confusion than reality.
The standard answer now is line speed. If I get some amount of line in the air, the faster it goes the farther it’s going to go. In the past I remember a lot of discussion around conservation of momentum and conservation of energy but they both basically say the faster I get an object moving the farther it will travel before friction bleeds off all that energy or momentum and it comes to a rest. So yes - more speed = more distance.
Distance casters concentrate on carrying more line, reducing air drag and getting waves out of their line but when they do all that they are still at the mercy of line speed.
So turning this around - is there an optimal rod bend that is going to maximize line speed on any given cast or for any given caster?
No.
No, because we are confusing fly casting with catapults, bows and arrows and coffee cups on dashboards but this is fly casting. The bow and arrow concept has confused several generations of casters it seems. The idea that you can store energy in the rod and release it and that when you release it there will be an increase in line speed is a given. But you are ignoring the whole cast if you only look at the one brief period in time where the rod is unloading and hoping for some magic in that rod unload to make your cast go farther than the next guy’s. When you make a cast you apply an amount of force over some distance. You do work. Work is energy. The more work you do the more energy you’ve produced. Some of the energy will be lost getting from your body to the line. Is there any possible way that more than 100% of the energy you’ve produced ends up in the line? The laws of thermodynamics tell us absolutely not. There is no magic. You produce a certain amount of work, some of it is lost for various reasons and some of it is stored in the rod temporarily and released when the rod unloads. There is no possible way that when that rod unloads that it will release more than 100% of the energy stored in it during the cast.
Let’s look at the same cast with two different rod stiffnesses. By same cast I mean doing the same work in both cases. Let’s call that amount of energy E.
In cast one I use the stiff rod and at the point of rod unload E is distributed as energy in the line, call that amount of energy A, and energy stored in the rod (B). After the rod unloads the total energy we hope to have in the line is A+B which can never be more than E.
E=A+B=E minus some losses.
In the second cast I use a less stiff rod but still do the same work. This time my energy distribution is line energy = C and elastic potential energy in the rod which I’ll call D. Now when that elastic energy is released the total energy in the line is C+ D. But C + D = E.
E = A+B = E= C+D = E
There is no difference.
I think this puts two things to rest:
1. Rod stiffness is not a factor with respect to an optimal energy store and release. Leverage and moi are totally different matters but the amount of work I do as a caster is equal to how much force I apply to the rod handle multiplied by the distance I apply it. The handle is the same point for both rods.
2. How much the rod contributes to to the cast is 0%. Different rods will store and release different percentages of the total energy during the cast but the rod does not cast itself and the rod cannot somehow magnify the amount of energy you put in to the cast.
E is E.
PLEASE NOTE: In order to post on the Board you need to have registered. To register please email paul@sexyloops.com including your real name and username. Registration takes less than 24hrs, unless Paul is fishing deep in the jungle!
Rod bend vs rod unload
Moderator: Torsten
Rod bend vs rod unload
"There can be only one." - The Highlander. 
PS. I have a flying tank. Your argument is irrelevant.
PSS. How to generate a climbing loop through control of the casting stroke is left as a (considerable) exercise to the reader.
PS. I have a flying tank. Your argument is irrelevant.
PSS. How to generate a climbing loop through control of the casting stroke is left as a (considerable) exercise to the reader.
-
Lasse Karlsson
- Posts: 5801
- Joined: Wed Jan 09, 2013 9:40 pm
- Location: There, and back again
- Contact:
Re: Rod bend vs rod unload
Your friendly neighbourhood flyslinger
Flycasting, so simple that instructors need to make it complicated since 1685
Got a Q++ at casting school, wearing shorts
Flycasting, so simple that instructors need to make it complicated since 1685
Got a Q++ at casting school, wearing shorts
-
Paul Arden
- Site Admin
- Posts: 19660
- Joined: Thu Jan 03, 2013 11:20 am
- Location: Belum Rainforest
- Contact:
Re: Rod bend vs rod unload
Hi Walter,
An excellent post.
But surely with a stiffer rod it allows one the option to apply more force within a given arc (let’s say 170 degrees!) and therefore the possibility to do more work through the time when the rod tip travels through SLP? Too stiff your SLP is too short or non existent. Too soft and you can’t apply as much force as you would otherwise. In this respect the rabbit hole of optimal bend is actually quite valid IMO.
The other side is I think counterflex opening the loop does play a part too. Arguably this is where stiffer (and rods with higher frequency) also assist because the loop is initially narrower and tightens faster. Why does this help? It keeps more line in the fly leg for the same carry.
I’m not convinced that line speed is such the determining factor that we often think. Many of our longest casts “float out”. I believe that it is line carry that is the dominating factor. Ie the amount of line shot is directly controlled by the amount of line we carry. The only significance I see where line speed plays a part is after loop straight when a little bit more line can be shot.
It’s the profile of the line itself that determines distance. Line profile, trajectory and a straight fly leg. The difference between soft but still castable rods and stiff but still castable rods is around maximum 2m on a 40m cast. Not very significant but also very significant. Far less significant than most people think but very important in competition!!
When I throw the HT6 with MED5 nowadays I feel that I have to back off on the force.
Cheers, Paul
An excellent post.
But surely with a stiffer rod it allows one the option to apply more force within a given arc (let’s say 170 degrees!) and therefore the possibility to do more work through the time when the rod tip travels through SLP? Too stiff your SLP is too short or non existent. Too soft and you can’t apply as much force as you would otherwise. In this respect the rabbit hole of optimal bend is actually quite valid IMO.
The other side is I think counterflex opening the loop does play a part too. Arguably this is where stiffer (and rods with higher frequency) also assist because the loop is initially narrower and tightens faster. Why does this help? It keeps more line in the fly leg for the same carry.
I’m not convinced that line speed is such the determining factor that we often think. Many of our longest casts “float out”. I believe that it is line carry that is the dominating factor. Ie the amount of line shot is directly controlled by the amount of line we carry. The only significance I see where line speed plays a part is after loop straight when a little bit more line can be shot.
It’s the profile of the line itself that determines distance. Line profile, trajectory and a straight fly leg. The difference between soft but still castable rods and stiff but still castable rods is around maximum 2m on a 40m cast. Not very significant but also very significant. Far less significant than most people think but very important in competition!!
When I throw the HT6 with MED5 nowadays I feel that I have to back off on the force.
Cheers, Paul
Re: Rod bend vs rod unload
Thanks Paul.
You raise a good point but I see that as the losses which occur in the overall system and the cast. Your longest cast test, Lasse and Graeme’s demos and the 8 rod, 8 cast test showed that there isn’t a lot of difference in the distance regardless of the rod. Usually around a meter or so. Less than 3% for all of you. When you are competing every inch counts so that meter or 3% is crucial but for the rest of us not so much.
I expect more losses with the softer rod - maybe a bit unscientific but more movement of the tip relative to the handle means more loss to internal friction due to more internal movement. I would wager that if you put both rods in a casting machine for an hour that the temperature of the softer rod would be higher because of that internal friction.
That’s only part of the answer. The other part is whether the caster can put more work into to stiff rod and my thoughts are that is no difference with respect to input. You are connected to to the handle and you can move both handles as quickly or forcefully as you like and how far you move it is limited by reach regardless of the rod. There will be a different output though. Kickback will be determined by a combination of stiffness, moi and input. The same for counterflex. Again those could be attributed to losses if you just decided to go all out in both cases or you could back off a bit to exchange energy for control.
Overall tip path, maybe? Force is a vector quantity so straighter is better but from what I’ve seen of slow motion video in the past few years the tip path during the power application is never completely straight so it comes down to “how straight is straight”. Stiffness would be a factor there but I think it’s still part of that 3% margin. Waves from kickback and counterflex would bigger factors but that’s just opinion at this point.
So for you - more stiffness is good but I also think moi is equally or more important. For me - stiffness would be whatever feels good but that’s kind of like asking if I like a hard bed or a soft bed. It’s purely personal preference based on how much time I spend casting the rod and get used to its feel. In the longer term it’s not going to make an appreciable difference in how far I cast after I get over the psychological aspect of the change in feel. Moi is far more important to me because it affects my ability to spend a day on the water.
Kind of rambling here but does that answer at least part of the question?
Walter
You raise a good point but I see that as the losses which occur in the overall system and the cast. Your longest cast test, Lasse and Graeme’s demos and the 8 rod, 8 cast test showed that there isn’t a lot of difference in the distance regardless of the rod. Usually around a meter or so. Less than 3% for all of you. When you are competing every inch counts so that meter or 3% is crucial but for the rest of us not so much.
I expect more losses with the softer rod - maybe a bit unscientific but more movement of the tip relative to the handle means more loss to internal friction due to more internal movement. I would wager that if you put both rods in a casting machine for an hour that the temperature of the softer rod would be higher because of that internal friction.
That’s only part of the answer. The other part is whether the caster can put more work into to stiff rod and my thoughts are that is no difference with respect to input. You are connected to to the handle and you can move both handles as quickly or forcefully as you like and how far you move it is limited by reach regardless of the rod. There will be a different output though. Kickback will be determined by a combination of stiffness, moi and input. The same for counterflex. Again those could be attributed to losses if you just decided to go all out in both cases or you could back off a bit to exchange energy for control.
Overall tip path, maybe? Force is a vector quantity so straighter is better but from what I’ve seen of slow motion video in the past few years the tip path during the power application is never completely straight so it comes down to “how straight is straight”. Stiffness would be a factor there but I think it’s still part of that 3% margin. Waves from kickback and counterflex would bigger factors but that’s just opinion at this point.
So for you - more stiffness is good but I also think moi is equally or more important. For me - stiffness would be whatever feels good but that’s kind of like asking if I like a hard bed or a soft bed. It’s purely personal preference based on how much time I spend casting the rod and get used to its feel. In the longer term it’s not going to make an appreciable difference in how far I cast after I get over the psychological aspect of the change in feel. Moi is far more important to me because it affects my ability to spend a day on the water.
Kind of rambling here but does that answer at least part of the question?
Walter
"There can be only one." - The Highlander.
PS. I have a flying tank. Your argument is irrelevant.
PSS. How to generate a climbing loop through control of the casting stroke is left as a (considerable) exercise to the reader.
PS. I have a flying tank. Your argument is irrelevant.
PSS. How to generate a climbing loop through control of the casting stroke is left as a (considerable) exercise to the reader.
-
Paul Arden
- Site Admin
- Posts: 19660
- Joined: Thu Jan 03, 2013 11:20 am
- Location: Belum Rainforest
- Contact:
Re: Rod bend vs rod unload
Yes if does Walter but I’m specifically looking at tip path and torque. With the HT6 for example, if I apply the same force in the same way that I do with the HT10 for distance, then the result is a tailing loop. So I need to back off to control the tip path.
Conversely if I use a 14WT broomstick I can’t apply enough torque to get sufficient bend in the rod to get an SLP and the fly leg is domed.
If instead of looking at the rod we were to initially look at the amount of torque we want to apply then it’s the bend that determines tip path. I do think we need some of it to be straight! I have cast semi-rigid levers, Alejandro produced a rod for fun, that was a broomstick and very little fun it turned out. I definitely can’t throw that rod with a MED5 130’!!
So we can definitely be too stiff. Also I believe we can all agree that we can be too soft. That tells me there is an optimal stiffness somewhere in-between.
Cheers, Paul
Conversely if I use a 14WT broomstick I can’t apply enough torque to get sufficient bend in the rod to get an SLP and the fly leg is domed.
If instead of looking at the rod we were to initially look at the amount of torque we want to apply then it’s the bend that determines tip path. I do think we need some of it to be straight! I have cast semi-rigid levers, Alejandro produced a rod for fun, that was a broomstick and very little fun it turned out. I definitely can’t throw that rod with a MED5 130’!!
So we can definitely be too stiff. Also I believe we can all agree that we can be too soft. That tells me there is an optimal stiffness somewhere in-between.
Cheers, Paul
-
gordonjudd
- Posts: 1860
- Joined: Sat Jan 19, 2013 11:36 pm
- Location: Southern California
Re: Rod bend vs rod unload
Paul,But surely with a stiffer rod it allows one the option to apply more force within a given arc (let’s say 170 degrees!) and therefore the possibility to do more work through the time when the rod tip travels through SLP?
Agreed. And that is where the timing of the angular acceleration profile also comes into play. As Walter notes the work done on the line that determines the line speeds depends on the integral of the force vs distance curve. Thus it is much better to delay the rotation as long as possible so that you have more tip travel distance available for applying the bigger force from a larger acceleration of the rod.
The same physics applies to the lag concept in a golf swing.
Gordy
Re: Rod bend vs rod unload
Hi Paul,
I misunderstood the torque bit. I was thinking a 9 foot rod is a 9 foot rod but you are right about mcl, or dynamic rod length. That will require a bit of math for an answer to satisfy both of us so let me think a bit. Also tip path does have to fit within some constraints as well. I was a bit too quick with that.
In the meantime the tailing loop thing is a real concern and part of the trading energy for control. The question is how much energy are you trading for control?
I have a wwii era fly rod made of metal. I put it at the extreme of high moi and low stiffness. A bitch to cast (excuse mild expletive), and you have to trade a lot of energy for control. I will never cast that rod 80 feet. Maybe you or Lasse or Graeme could break 100 feet with it but I would have to see it to believe it.
I also have the echo 5 weight distance rod. High stiffness and fairly high moi. Casts well but the moi gets to me quickly. I’ve also used an actual broomstick. I can cast it but not for long and I definitely won’t get my best distance but that has extremely high moi so most of my energy is going in to moving the rod and not into the line. I’ve played with other stuff ( I have to say SL encouraged me to do that) but not necessary to go in to detail.
The point is that, yes there are extremes. I fully agree with that. Too soft means trading energy for control and too stiff can also mean that too if you have to change your hand path to get some semblance of slp. Hadn’t thought of the too stiff bit before so some enlightenment.
I know you manufacture and sell rods so you want to find what’s going to sell best. I think the general trend in the industry is to push stiffness but it’s overrated imo, especially for most of us. You also tournament cast so you want to find what maximizes distance even if it’s only a few inches. Stiffness is definitely a factor for that but now we are talking the other extreme.
For most people any well manufactured rod is going to fit within those extremes and if they learn how to cast well then they don’t need to exchange much energy for control. Certainly much less than they are lead to believe. Even poorly manufactured ones perform well for a good caster which is why a lot of fly fishers are content with the big box store product and they just go fishing.
Moi. That needs to be the next marketing push. We all know it when we feel it.
I misunderstood the torque bit. I was thinking a 9 foot rod is a 9 foot rod but you are right about mcl, or dynamic rod length. That will require a bit of math for an answer to satisfy both of us so let me think a bit. Also tip path does have to fit within some constraints as well. I was a bit too quick with that.
In the meantime the tailing loop thing is a real concern and part of the trading energy for control. The question is how much energy are you trading for control?
I have a wwii era fly rod made of metal. I put it at the extreme of high moi and low stiffness. A bitch to cast (excuse mild expletive), and you have to trade a lot of energy for control. I will never cast that rod 80 feet. Maybe you or Lasse or Graeme could break 100 feet with it but I would have to see it to believe it.
I also have the echo 5 weight distance rod. High stiffness and fairly high moi. Casts well but the moi gets to me quickly. I’ve also used an actual broomstick. I can cast it but not for long and I definitely won’t get my best distance but that has extremely high moi so most of my energy is going in to moving the rod and not into the line. I’ve played with other stuff ( I have to say SL encouraged me to do that) but not necessary to go in to detail.
The point is that, yes there are extremes. I fully agree with that. Too soft means trading energy for control and too stiff can also mean that too if you have to change your hand path to get some semblance of slp. Hadn’t thought of the too stiff bit before so some enlightenment.
I know you manufacture and sell rods so you want to find what’s going to sell best. I think the general trend in the industry is to push stiffness but it’s overrated imo, especially for most of us. You also tournament cast so you want to find what maximizes distance even if it’s only a few inches. Stiffness is definitely a factor for that but now we are talking the other extreme.
For most people any well manufactured rod is going to fit within those extremes and if they learn how to cast well then they don’t need to exchange much energy for control. Certainly much less than they are lead to believe. Even poorly manufactured ones perform well for a good caster which is why a lot of fly fishers are content with the big box store product and they just go fishing.
Moi. That needs to be the next marketing push. We all know it when we feel it.
"There can be only one." - The Highlander.
PS. I have a flying tank. Your argument is irrelevant.
PSS. How to generate a climbing loop through control of the casting stroke is left as a (considerable) exercise to the reader.
PS. I have a flying tank. Your argument is irrelevant.
PSS. How to generate a climbing loop through control of the casting stroke is left as a (considerable) exercise to the reader.
Re: Rod bend vs rod unload
Hi Walter,
some nice thoughts, but your posting sounds a little bit convoluted to me.
What's the goal of this thread?
"At the risk of going down the optimal rod bend rat hole again I think it’s interesting to think about what is it that actually maximizes the distance of a cast."
Distance in general, or only related to the rod bend? (The topic title is "rod bend vs. rod unload").
Are we discussing fishing or tournament casting (different objectives IMHO)?
Should the rod bend be defined first?
Maybe we should first consider the fly line at launch time only. You have mentioned line speed and (kinetic?) energy. But that's too simplistic, one example is the range of a projectile:
https://en.wikipedia.org/wiki/Range_of_a_projectile
.. there the distance already depends on more variables like the initial height or the lauch angle.
For fly line it's even much more complex; the shape of the line related to the tip trajectory is for instance very relevant. You'll get a different result, if you're comparing a domed to a straight tip path during acceleration. Actually you don't just want to maximize the kinetic energy of the line but also the total momentum of all mass points. The shape of the fly line has an influence on the aerodynamic losses as well.
We can formulate (null-)hypotheses (I'd simplify that):
1. The fly rod has no influence on the cast.
This would mean, that we could cast without a rod (hand casting) and the outcome is the same. I think we don't need experiments for that, this hypothesis can't be right and is therefor falsified.
2. The properties of the fly rod have no influence on the cast.
I choose the mass as property and compare two rods, one weights 100 grams and another 100kg (perhaps made from tungsten) - I think without performing an experiment we know that most humans can't cast well with the second one. So this hypothesis was falsified as well.
Now we know that fly rod properties influence the cast; and need to refine them to further formulate hypotheses - I think you get the idea (e.g. try a hypothesis with the overall rod stiffness).
Greetings,
Torsten
some nice thoughts, but your posting sounds a little bit convoluted to me.
What's the goal of this thread?
"At the risk of going down the optimal rod bend rat hole again I think it’s interesting to think about what is it that actually maximizes the distance of a cast."
Distance in general, or only related to the rod bend? (The topic title is "rod bend vs. rod unload").
Are we discussing fishing or tournament casting (different objectives IMHO)?
Should the rod bend be defined first?
Maybe we should first consider the fly line at launch time only. You have mentioned line speed and (kinetic?) energy. But that's too simplistic, one example is the range of a projectile:
https://en.wikipedia.org/wiki/Range_of_a_projectile
.. there the distance already depends on more variables like the initial height or the lauch angle.
For fly line it's even much more complex; the shape of the line related to the tip trajectory is for instance very relevant. You'll get a different result, if you're comparing a domed to a straight tip path during acceleration. Actually you don't just want to maximize the kinetic energy of the line but also the total momentum of all mass points. The shape of the fly line has an influence on the aerodynamic losses as well.
To rest or to test?I think this puts two things to rest:
1. Rod stiffness is not a factor with respect to an optimal energy store and release. Leverage and moi are totally different matters but the amount of work I do as a caster is equal to how much force I apply to the rod handle multiplied by the distance I apply it. The handle is the same point for both rods.
2. How much the rod contributes to to the cast is 0%. Different rods will store and release different percentages of the total energy during the cast but the rod does not cast itself and the rod cannot somehow magnify the amount of energy you put in to the cast.
We can formulate (null-)hypotheses (I'd simplify that):
1. The fly rod has no influence on the cast.
This would mean, that we could cast without a rod (hand casting) and the outcome is the same. I think we don't need experiments for that, this hypothesis can't be right and is therefor falsified.
2. The properties of the fly rod have no influence on the cast.
I choose the mass as property and compare two rods, one weights 100 grams and another 100kg (perhaps made from tungsten) - I think without performing an experiment we know that most humans can't cast well with the second one. So this hypothesis was falsified as well.
Now we know that fly rod properties influence the cast; and need to refine them to further formulate hypotheses - I think you get the idea (e.g. try a hypothesis with the overall rod stiffness).
Greetings,
Torsten
Re: Rod bend vs rod unload
Walter .. and about that:
https://www.sexyloops.com/index.php/ps/ ... stance-rod
or the older thread from Bernd:
http://www.sexyloops.co.uk/theboard/viewtopic.php?t=98
Sounds more like 10% for some of the board members, these results contradict with the 8 rods / 8 caster study, not very important for fishing but for tournament casting, at least if it's possible to reproduce the outcomes.
Greetings Torsten.
Check out the front page from JamesYou raise a good point but I see that as the losses which occur in the overall system and the cast. Your longest cast test, Lasse and Graeme’s demos and the 8 rod, 8 cast test showed that there isn’t a lot of difference in the distance regardless of the rod. Usually around a meter or so. Less than 3% for all of you. When you are competing every inch counts so that meter or 3% is crucial but for the rest of us not so much.
https://www.sexyloops.com/index.php/ps/ ... stance-rod
or the older thread from Bernd:
http://www.sexyloops.co.uk/theboard/viewtopic.php?t=98
Sounds more like 10% for some of the board members, these results contradict with the 8 rods / 8 caster study, not very important for fishing but for tournament casting, at least if it's possible to reproduce the outcomes.
Greetings Torsten.
-
Paul Arden
- Site Admin
- Posts: 19660
- Joined: Thu Jan 03, 2013 11:20 am
- Location: Belum Rainforest
- Contact:
Re: Rod bend vs rod unload
Hi Walter,
Too soft means trading energy for control (tip path) and too stiff means sacrificing arc to manage tip path. Most rods, ie just about everything we throw, sit somewhere in the middle. However there must be an “optimal” where we don’t sacrifice anything and instead just hit it to the best of our ability. As James pointed out in his FP this week we work out what that is by hitting it to the best of our ability and then measuring the results.
I agree that many manufacturers have gone down the stiff route, to the extent where line manufacturers are making lines heavier as a consequence (the only take I can have on this is that they have got it wrong). I haven’t done this and not everyone has. In fact I have to go to great lengths to everyone who buys a SL rod to explain the line mess, if they are unaware of it, and to buy either an AFFTA conforming line or else work according to the line weight it’s supposed to be and not what is printed on the box.
That however is not about ultimate distance but instead about comfortable controlled casting throughout all fishing distance ranges, utilising the rod’s variable bend! In other words about optimising the range of “gears” that a progressive rod action provides.
I personally don’t make rods for anyone but myself! I have thought about how to do this but haven’t explored it. Besides such rods are already out there.
Cheers, Paul
Too soft means trading energy for control (tip path) and too stiff means sacrificing arc to manage tip path. Most rods, ie just about everything we throw, sit somewhere in the middle. However there must be an “optimal” where we don’t sacrifice anything and instead just hit it to the best of our ability. As James pointed out in his FP this week we work out what that is by hitting it to the best of our ability and then measuring the results.
I agree that many manufacturers have gone down the stiff route, to the extent where line manufacturers are making lines heavier as a consequence (the only take I can have on this is that they have got it wrong). I haven’t done this and not everyone has. In fact I have to go to great lengths to everyone who buys a SL rod to explain the line mess, if they are unaware of it, and to buy either an AFFTA conforming line or else work according to the line weight it’s supposed to be and not what is printed on the box.
That however is not about ultimate distance but instead about comfortable controlled casting throughout all fishing distance ranges, utilising the rod’s variable bend! In other words about optimising the range of “gears” that a progressive rod action provides.
I personally don’t make rods for anyone but myself! I have thought about how to do this but haven’t explored it. Besides such rods are already out there.
Cheers, Paul