Rod Loading - Spring v Lever

springer · Post by **springer** » Fri Jan 20, 2012 1:35 pm

Ive taken this quote of Paul's and started a new thread to save the other going way off topic.

"Numerous threads over the years. Ian Walker was the first to mention it. Torsten calculated spring energy as 15-20%, leverage 80-85%. Grunde measured it. Gordy graphed it. Leverage is the significant factor in casting, rod bend helps us apply this force in a straighter line"

Were these tests done with SH rods and OH casting?

The reason I ask is that if fly casting is all about such high percentages of leverage then why is it that heavier loads cast better with rods which bend deeper? Im thinking in particular about long bellied lines and skagit with a DH rod and spey cast.

Does that suggest that fast actioned rods deliver only the lower end of the spring percentage scale and through action ones the higher?

victor · Post by **victor** » Fri Jan 20, 2012 2:42 pm

With a single handed rod wrist strength must be part of the equasion. For instance when I cast the T38 events at BFCC meetings I could not bend the club rod so consequently the weight of the line was being levered by a near full length rod and my wrist was not strong enough to cope. When I aquired a rod that did bend I cast much further because the shorter cord length allowed me to have a faster stroke with much less strain on my wrist.

Reading back what I have just written also makes me wonder that if I can bend the rod then I have also created some useful PE so is the new PE giving me the extra distance or the faster stroke?

Mike

Malcolm · Post by **Malcolm** » Fri Jan 20, 2012 2:52 pm

Now I'm the first to admit that my technique may be at fault but I like to test things out. Perverse I know.

I took my 10ft 11-13weight rod (that's my lever) and my 10ft 4 weight rod (my spring).

I put a 5 weight line through each and marked the line at 40 ft and tried both overhead and switch casts.

In both overhead and especially switch casts the lighter rod (spring) cast much further. The switch cast was almost twice as far!

I'm intending to do the same thing by measuring the difference between the butt 45 inches and the tip 45 inches of a 3 weight rod this weekend with a wider audience.

I think switch/spey casting especially depends very much on the "spring" effect.

sms · Post by **sms** » Fri Jan 20, 2012 3:33 pm

The rod does not know if the line is in the water or in the air (spey vs overhead).
I think that it is mostly lever with DH rod spey too. That's because the PE is not that great that can be stored in a rod. I think I need to do some measurements with my expendable 14' rod.

Lasse Karlsson · Post by **Lasse Karlsson** » Fri Jan 20, 2012 3:58 pm

sms wrote:The rod does not know if the line is in the water or in the air (spey vs overhead).
I think that it is mostly lever with DH rod spey too.

I think so too

It's hard to discus this when it really comes down to the ability to accelerate the line in as straight a line as possible. The broomstick ends up going a much more curved path than the noodle, somewhere in between depending on the caster usually yields the best results.

Must go out with the 12 rod and redo this one to see if I get more distance :p

Pushing the border

Cheers
Lasse

James9118 · Post by **James9118** » Fri Jan 20, 2012 5:09 pm

With a single handed rod wrist strength must be part of the equasion. For instance when I cast the T38 events at BFCC meetings I could not bend the club rod so consequently the weight of the line was being levered by a near full length rod and my wrist was not strong enough to cope

Hi Mike,

I'm not sure I understand this. Surely you (being the strong, handsome guy you are) can generate a certain maximum force. It doesn't matter what type of rod you're holding, 5wt or T38, you will still max out at the same force. Yes, this force will generate different accelerations (and feel), but I don't see how you can say you weren't strong enough.

victor · Post by **victor** » Fri Jan 20, 2012 8:43 pm

Are you suggesting you can move a 9'6'' stiff rod with a T38 head hanging off the end as fast as a 9' five weight than bends to half its original length with the head of an MED out of the end James. I am not maxed out with the five, I am at my limit with the T38. In other words I can apply the appropriate force to the five, I can't to the T38, unless the rod is flexible.

Mike

Lasse Karlsson · Post by **Lasse Karlsson** » Fri Jan 20, 2012 9:07 pm

Hi Mike

I think there's more to it than just rod stiffnes here. HAve a look at the clip I posted, the two first ones are with the same rod, the line just differs heavily, I can rotate much fatser with the light line than with the heavy, and using a stiffer longer rod I can again rotate it faster (last example in the clip) Need to try it with a really stiff rod (not broomstick) to see if I slow down again?

Cheers
Lasse

Bernd · Post by **Bernd** » Fri Jan 20, 2012 9:38 pm

springer wrote:The reason I ask is that if fly casting is all about such high percentages of leverage then why is it that heavier loads cast better with rods which bend deeper? Im thinking in particular about long bellied lines and skagit with a DH rod and spey cast.

Does that suggest that fast actioned rods deliver only the lower end of the spring percentage scale and through action ones the higher?

Hi Alan,
I understand it this way:
The longer belly needs more line speed. More line speed is easier to gain on a longer tip path. Longer tip path = wider arc matches better with the more flexible rods.
The shorter heads need less line speed and this matches best with shorter tip pathes = smaller arc. So a stiffer rod will be fine here.
Some years ago I sticked up my rod into the ground. I then bended it via pulling the line. When I let the line go not much happened as long as I used a very very short line (less than 8 meters). I understood the stored energy to be too small to cast an average length of line.

Percentages are mainly depending on the amount of bend. Sure you can have much bend in a stiff rod and low bend in a more flexible rod...

Greets
Bernd

p.s. Lasse, am not sure if a good caster with some training wouldn't be able to accel the tip of a broomstick very close along a straight line. It's a question of rod hand path and size of arc being necessary.

Ben_D · Post by **Ben_D** » Fri Jan 20, 2012 9:46 pm

I have similar questions......

I've got an old Daiwa Osprey 9'6" #7-9 that I am using for practicing Speys with long belly lines. It is far easier to get distance and much less tiring using this rod than a modern fast actioned and far lighter 10' #8 rod. However, if I was looking for sharp crisp overhead loops I would not be using the Osprey.

Cheers

Ben

Bernd · Post by **Bernd** » Fri Jan 20, 2012 9:54 pm

Lasse Karlsson wrote:I can rotate much fatser with the light line than with the heavy, and using a stiffer longer rod I can again rotate it faster (last example in the clip) Cheers
Lasse

Hi Lasse,
nice video. I ran similar tests some time ago. Adding line weight always wins in distance.

Are you sure you can rotate the longer rod faster ?

For sure you'll gain more tip speed via the longer lever.
Greets
Bernd

Magnus · Post by **Magnus** » Sat Jan 21, 2012 1:37 am

It doesn't matter what type of rod you're holding, 5wt or T38, you will still max out at the same force.

I think this is getting into biomechanics but I suspect that's right - or right enough anyway.

Are you suggesting you can move a 9'6'' stiff rod with a T38 head hanging off the end as fast as a 9' five weight than bends to half its original length with the head of an MED out of the end James.

This is where it needs some work and I'm certainly not saying I can do it. By speed I guess you mean acceleration. Then we have the idea that F=ma.

So if we can generate the same maximum force to move those two outfits - the T38 weighs more (higher MOI), the line weighs more - so if you apply the same force the heavier outfit will move slower, will accelerate at a lower rate.

(Just to confuse the issue a little I've read things which imply we have physical 'speed limits' independent of strength. I have no idea if that applies when we cast.
The way I understand that it would mean, for example, if we think of outfits getting lighter and lighter I will reach a limit where I gain no rod speed, I can accelerate the rod no faster, even though the outfit may be lighter.
Thing is, if that is the case and I can move a heavier outfit just as quickly and I'm looking for distance I might be better going for a longer rod and/or a heavier line?)

Lasse Karlsson · Post by **Lasse Karlsson** » Sat Jan 21, 2012 6:55 am

Bernd wrote:p.s. Lasse, am not sure if a good caster with some training wouldn't be able to accel the tip of a broomstick very close along a straight line. It's a question of rod hand path and size of arc being necessary.

Hi Bernd

I do that for a living, still I can get the tip of a bendy rod up to higher speeds in a straight line.

Cheers
Lasse

Bernd · Post by **Bernd** » Sat Jan 21, 2012 8:11 am

Hi Lasse,
if you had max speed in mind, I agree.
If it's about tip path I can move both tips in a slightly convex path. I don't think we achieve a straight line really...
Thanks
Bernd

Lasse Karlsson · Post by **Lasse Karlsson** » Sat Jan 21, 2012 8:29 am

Bernd wrote:Hi Lasse,
if you had max speed in mind, I agree.
If it's about tip path I can move both tips in a slightly convex path. I don't think we achieve a straight line really...
Thanks
Bernd

Hi Bernd

I'm taking about accelerating it right

Cheers
Lasse

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