Sloppy Rod

[Merlin]

Unfortunately after reading it I am still at a loss as to how you would look at a break from a breakage test like the one Echo does on their rods and be able to tell if it broke due to an ovalization failure or a compressive strain failure.

Gordy,

For slender cylinders like a fly rod shaft it is buckling first. In fact the strain limit which is calculated corresponds to buckling. At the end of the day the result is a break anyway, and for graphite rods it corresponds to a low level of ovalisation. For glass rods the ovalisation is slightly larger but the maximum buckling strain is also higher: there are little chances to break or to meet the critical ovalisation moment with those rods. Or with a car door maybe.

Only Paul answsered to the questions asked for in my former post, don't by shy , thanks. I don't think that well kept secrets are involved.

For Torsten: no, I do not use Abaqus, I had the opportunity to benefit from the experience of a world wide level research lab some years ago. They use Abaqus.

Merlin

[James9118]

Now I have some questions for competition casters: how do you know that you reach the maximum possible carry for a given rod? How does it feel? What feedback of the rod do you get? Finally how did you succeed in increasing your carry with a given rod (power application I guess)?

Merlin

Hi Daniel,

For me it all boils down to line speed, i.e. can I generate enough of it to keep the line in the air. There is a fight against sag that goes on and, as the line is extended, eventually sag and a build up of slack will win out, whether it wins at 50ft or 100ft depends on the skill of the caster. The actual failure of my carry takes maybe 3 individual casting strokes to fully seen; my first indication is often a poor turn-over on a forward false cast (the 'piling' of the BDB). The next back-cast therefore starts with a bit more slack in the system than normal, hence some of my initial movement is wasted just pulling this taught. This consequently lowers the line speed in the back cast resulting in much more sag. So ultimately the forward cast that fails start with a lot of sag, the trajectory of the fly-end of the line is downwards (as per BDB again), so on top of having to waste more effort pulling the line tight, a big tick is unavoidable and the forward cast fails completely.

Because it takes takes a number of casting strokes to complete the failure, it's easy for people to kid themselves about their carry ability. To me, extending to the point it fails and then measuring the line you're left holding is not a true reflection. I measure my own carry by what I'm able to aerialise for 10 or more casting strokes without it collapsing.

James

[gordonjudd]

Why is this becoming an interrogation?

Magnus,
I apologize if you feel that I was putting you on a hot seat. In checking back I see that I missed your response

As I recall they described a crush fracture, splits up two 'sides' then shards where the rod had splintered? The rod had flattened.

where you responded to my question about how you could tell what effect caused a rod to break so I am sorry to have asked about it again.

Rod flattening sounds like ovalization so it sounds like Merlin's summary that:

For slender cylinders like a fly rod shaft it is buckling first. In fact the strain limit which is calculated corresponds to buckling. At the end of the day the result is a break anyway, and for graphite rods it corresponds to a low level of ovalisation.

Is the take away from this.

I had thought that rods were designed with a layer of scrim that had a different orientation to the longitudinal fibers in the graphite material to increase its hoop strength so that ovalization would not cause the rod to fail.

It sounds like that is not the case. The hoop strength layer helps, but it does not prevent a cascade of failures that starts with a change in the shape of the rod from being nominally round to oval.

Live and learn.

Gordy

[Lasse Karlsson]

Cost benefit Gordy the more durable you make a rod, the heavier it gets, anglers want air, and the amount of people that can actually break a rod casting is few...

Cheers
Lasse

[John Waters]

Hi Daniel, missed your question, apologies.

For me casting is all about line speed and that is my indicator of performance. It does not matter if I am casting short line lengths to targets or casting a 5 weight MED and extending my carry length per cast for the Trout Distance, or using a fixed length head as is the case for the SHD, Trout Distance or either Salmon Fly Distance events. Whenever the speed is insufficient, loop profile suffers. On each cast, I look at the amount of sag in the line and whether the fly leg is directly above the rod leg. In the case of a poor cast, the rod feels like it straightens too quickly during the casting movement and tension on the tip is lost. So, for me the key is maintaining line tension on the rod throughout the cast. Power application must be smooth but the key is the range of, and timing of, the forearm movement and the backcast trajectory generated. When that is correct, rod bend and line speed just become outcomes, and thus, indicators of performance. From either a casting or a coaching viewpoint, statements like "increase your line speed" or "improve your tracking or loop profile" are useless unless supported by a movement change that will drive those outcomes.

Jon Tarantino designed rods for Hardy, based on a stiff bottom third of the rod length. For me, that is a requirement for all my rods because if the butt is bendy, I cannot generate enough speed.

Hope that makes sense,

John

[Merlin]

Thanks a lot James and John

Yes, it makes sense John, so I focused on line speed. I had some tests with my 2D casting file. I can stretch both time and amplitudes of recorded inputs (and haul as well) and applied them to a medium rod (speed), and as I lengthen the carry what happens is a limit of acceleration applicable to that rod. Too much acceleration and the rod bends back to the point it looses response time. It is as if the rod was unable to unload because it spends time to bend back and forward (but too late). To improve the situation the acceleration has to be performed on a longer arc. I foresee to test it on a 170 input next time and see what happens, the situation is going to be difficult, whilst I tested 906 /908 /910 rods without any problem is such consitions. Maybe a 904 would be in trouble.

The torque history is interesting, there is a plateau as soon as the rod is sent back by acceleration until lauch time, which corresponds to the lack of rod response to the input. In fact the energy is released late and in the rod rather than in the line on due time. I have to make more tests to get a broader view.

Merlin

[Bianchetti Ivan]

Hi Ivan, your post is somewhat of a mystery to me

Daniel, good questions. Let me see if I can sum up my opinions. I would say that maximum carry is often dominated by flyline taper. However the rod also plays a part too of course and it’s actually a very rare 90’ line that can’t be carried to the backing knot on just about any 9’ rod. It mostly falls apart when the loop fails to straighten for whatever reason. It could tick the ground, tail, or simply just not fully straighten. Basically it’s that loss of control. If the line isn’t (reasonably) straight at the beginning of the next casting stroke, then it’s going to compound the loss of control.

The usual way to increase carry is with a faster later haul. It’s possible to sometimes even recover from loss of control with an excellent haul on the next cast. It’s definitely not about more force with the rod hand – there obviously is more force but it’s not the dominating factor. The tracking must be straight of course but I think that’s a given with regards this question. Long carry for me is about having a smooth, straight and usually “stopless” casting stroke with a blistering haul that controls the cast. If the tracking is straight then the most effective way to increase carry is to develop the haul.

Cheers, Paul

Hi Paul I deliberately put a poor post, when you are not sure it is better to use a few words, I was referring to the fact that a couple of times I have encountered this problem, and both times the rod was mounted with the loops in part to the backbone, the effect was that the tip was twisted, and it gave that feeling, I'm not sure if it was exactly like that, but by reassembling the loops the defect was almost gone, I don't insist because it could be one of those things that you put on your head but in the reality.......

[Paul Arden]

Ok thanks for the clarification Ivan. I now understand what you mean. It’s certainly possible. I would have to try that. Funny thing is I often (in fact always) cast with the rod rings aligned at different angles. Something to think about. I’ll have a play on the roof later. Thanks!
Paul

[gordonjudd]

Perhaps you could take a few pictures of the broken blank the next time you break one.

Thorsten,
If your rod broke at the handle do you think it was from a localized stress point caused by the discontinuity at the handle?

Comparing pictures of typical breaks from casting is a worthwhile project. I would suspect that none on the casting breaks will look like the "good" breaks that Tim Rajeff talks about in this YouTube video.

Those breaks that Tim calls "a complete de-lam failure over a large area" are the type of breaks he gets with the U-shaped bendforms produced in his breakage tests but I don't think you will see it when you break a rod while casting.

I did not see one example of that type of break in the Kirkman article either, so I would think the cause of typical break when fishing is different than the type of break you get when the rod is bent into a U shape and the max strain is spread over a large area in the butt section of the rod.

Gordy

[Paul Arden]

Absolutely, Gordy. I’ve never seen a break like that from casting. I’ve got a rod at home that I broke while casting. It was an old instructor rod and I was half expecting it to go, and so it did! When I’m in town this week I’ll dig it out for a photo.

The most common casting rod breakage is in the ferrule. Usually it’s because they work loose, unnoticed and start to crack. Even a cracked ferrule can give a year of distance casting. But eventually they go. That’s just the nature of what we do.

Usually when someone really hits a rod hard the break is in the butt. But those breaks are almost always clean. I’ll have a few photos in my phone. I’ll dig them out tomorrow.

Rod tips are different. Those ai believe are usually collisions or poor rod angles when snagged or even playing a fish. I have broken a few rods in the upper sections while casting but in most circumstances I suspect an earlier collision.

Cheers, Paul