[Paul Rankine]

Hiyah Magnus,
                   

TLT casting

OK, probably should be able to guess ,Duh ?

Yes, I remember reading the first para of the swing weight article and then went and got my "Fizics is Fun" book ,and then made myself a cup of tea and watched the football instead.
Heavy Going ......  Still I was older then and I,m that much younger now  ,   

I'll have another go ,particularly as you have that geeky calculator thingy and a rod database to look up and try to get my head around .

I'm convinced that a closed stance is more effective than an open stance for that type of easy straight line distance casting because if offers more freedom of movement - completely the reverse of what I was taught coming into casting.

Yes it was was,nt it . Vairy interesting..... You do realise of course that this is the latest in a long line of misdemeanours and downright heresy which the casting police can be only too aware of. Expect a knock at your door ...

 Yes, in the beginning , standard thinking had it that we used closed stance, book under elbow,  for short distance casts requiring pin point accuracy. Chalk stream style oft quoted for some strange reason. And ST said that longer distance casts were better made with open stances , particularly when hauls were involved. I am not sure how this came to be, possibly it was a teaching thing ,( getting the pupil to look at his backcast is quite difficult when he is closed stance , unless his name is Damian ).

Am I looking at the right clips ? In most of the clips I,ve seen no-one is standing with their two feet in line directly in front of them ,classical ST closed stance. I do agree however completely that for normal fishing distance casts it is perfectly possible to double haul perfectly well closed stance. Not too sure that it is the best  in the longer term for arm /shoulder joints though . Doesn't the open stance do exactly that. ie open out the body allowing greater rotation from the waist to come into play and saving shoulder joint rotation . Without being a doctor .....

So not too sure about the "freedom of movement " argument" but  I am probably brainwashed . Need to be convinced .
 
 
 Paul

[Irvine Ross]

BTW have you tried the article on Swingweight http://www.sexyloops.com/articles/swingweight.shtml - gives a brief introduction and access to the .pdf of the article and the rod database - now that really is geeky  (said the co-author)

Magnus

If I understand the paper correctly you make the assumption that the rod rotates around the butt as you measure the moment of inertia from the butt. However in practice the rod rotates around a point somewhere near the centre of the handle and the butt end of the rod and the reel seat act as a counterbalance. Would this not reduce the total MOI? Would it be more accurate to measure from the centre of the grip and to subtract the MOI of the butt section from the MOI of the rest of the rod to get a more representative figure?  ???

The comparison table is interesting but I am left wondering how big a difference in MOI there would have to be before I could detect it in the feel of the rod in my hand?

And anyway what about the weight of the line? How much does 30' of #5 line add to the MOI and would that mask small differences between different rods?

Sorry for all the questions

Irvine

[Magnus Angus]

Hi Irvine

You've spotted the central assumption. Actually the axis of rotation during a casting stroke is far more complex than you might think. It's unlikely to actually be anywhere along the length of the rod - the rod is at one the end of the arm which is flexing at the wrist, elbow and shoulder - so the actual axis of rotation during a stroke is probably below the end of the rod, depending on the style it may also be behind the rod... it can even move during a stroke. We also don't deal with the bend of the rod during a stroke.
We wanted a means of measuring rods of approximating the MOI so for that purpose placed the axis at the butt. Thing is, it makes it more intuitively obvious that if the mass anywhere along the rod in increased the MOI increases - so while fitting a heavier reel may place the centre of balance under the hand it actually makes it more difficult to rotate the rod - that's apply angular acceleration, speed-up and stopping force. (At this point I was about to suggest you think of a tightrope walker - holding a long heavy pole - they hold it at the middle and its the weight away from the middle that gives them stability - if this was Sexyloops that would lead to weeks of argument

You're right to question the caster's sensitivity. You might be surprised how sensitive we are when physically comparing quite similar rods, switching back and forth between rods, a decent caster can discern a difference of a few gm^2.

The weight of the line is the weight of the line  so to speak. If I cast an S4 and an S3, same length 9ft and lineweight #5, with the same line why do the outfits feel different? Well one reason is the swingweights of those rods is different - 74.7 and 61.4 - those figures are specific to the rods measured but give a clear indication how Scott changed things and by what order of magnitude when they introduced the S4. The effect of that reduction in swingweight is that it is easier for me to accelerate and slow down the S4 - imho the effect is possibly more noticeable for short and medium casting distances - when I'm using smaller weaker muscles and trying to make small accurate rod movements. Try making a delicate mend using wrist alone - with a very heavy rod then a very light rod.

On the issue of the line, we work against both weight, meaning inertia, and drag or air friction - with a fixed length of line the inertia remains constant whatever the rate of acceleration the drag factor increases exponentially with velocity. The same is true of drag forces on the rod. So a fat rod feels different to a thin one. If you think we're not sensitive enough to feel that try casting two lines the same weight but different density - the only difference is the drag on the lines -  dunno about you but I certainly can feel the difference between a floating line and a sinker, even an intermediate sinker.

For that matter - try this  fit a bushy size 10 fly to the leader and cast - replace the fly with a bare hook. In calm conditions its quite possible to feel the difference - utterly impossible when windy.


Paul

TLT is an Italian school or style of casting - no reason you should have heard of it.

We need to get the next Outcast day and I can show you the difference in haul potential between open and closed stances.

[Paul Rankine]

Hiyah Magnus,
                     Yes, it will be far easier to do it than talk about it . 
Look forward to the next Outcasts day, and I have a new toy to play with ......... .

Why don't we have a wee guessing competition then . Guess the line weights/density - types  we are casting ? Could be interesting.

Thanks for asking that Irvine .

Cheers Magnus 

[Irvine Ross]

Magnus

Sorry I was confusing myself by bringing gravity into consideration. A counterbalance only evens out the effect of gravity, not inertia. A Rod and reel combination normally has a point of balance somewhere along the handle but that only makes it more comfortable to hold when the rod is horizontal and we are retrieving line.

 OK I can see that the MOI gives a useful comparative index. So long as no-one is using it to do anymore complex calculations on how much effort the caster is putting into the stroke it does not matter that you measure from the butt.

Just out of curiosity, have you any idea what the figure would be for the MOI of 30’ of #5 line hanging from the rod tip. I’m interested to see how small a proportion of the total MOI we can detect by feel. Reducing from 74.7 to 61.4 on the S3 to S4 is nearly an 18% reduction. I imagine that would be easily detectable. But with the line on is that 2% or 0.2%?

Curiosity hasn't quite killed me yet.

Cheers

Irvine

[Magnus Angus]

Hi Irvine

This is rough ok - 5 ft of #5 line weighs approx 1.61g. If I take the figures for a Z-Axis 9ft #5 4pce the Swingweight is 63.5 - then add 1.61g to the mass of the tip section and recalculate, we get a Swingweight of 72.4 (It's rough because that additional mass is assumed to be distributed along the tip section as the mass is distributed on the bare rod.)

There's a very simple practical way to explore what small additional masses do to rods and casting. Get some bluetak and a very accurate set of scales. Simply stick a 2g blob of blutack on the back of the tip ring of a rod and cast as normal - you can use line on the rod without problems. When I've tried it casting a short to medium length of line I can't confidently say if I can feel a 1g mass attached to the tip, I can certainly feel and see the results of a 3g mass on the tip - between those two? fuzzier!  IMHO you're at the threshold of what we can feel through the rod.
On the other side of the issue, when I cast and throw a loop the line goes on its merry way and the mass of the rod goes into counterflex - with 2g added to the tip top of a rod the additional counterflex is noticeable and any additional mass gets more obvious as it gets larger or the stop gets more abrupt.
(I've also used this technique to simulate a meaty brass ferrule half way down a rod - casting to a crisp stop the tip bucks and you can see two pulses going along the lower leg of the line.)

Irvine you need to realise that differences are magnified by rod length and speed. So, for example, most of us think we can feel a difference of one lineweight? Taking 30ft of fly line the step from one lineweight to the next, #5 to a #6 or #6 to #7, is 20 grains or 1.3g (in reality that may vary a bit but the difference is of that order). Personally, all else being equal about test lines, casting short I'd have a hard time telling a #5 from a #6 - as I lengthen the line and increase casting speeds the differences become much more apparent and the heavier line feels heavier

Hi Paul
Yep I'm up for a guessing game It makes more sense if the game is a comparison - cast the same rod with two lines and say which line is more dense.

Magnus

[Irvine Ross]

Magnus

Thank you for your patient and thorough explanations. I am surprised that we, or some of us at least, can detect such small changes in mass. I'm beginning to understand why the rod makers are investing so much in relatively small weight reductions  in their blanks.

Meantime my brain is oscillating faster than the tip of a Z-Axis after an abrupt stop. Maybe it's because it has a very low swingweight

Now I have a bit more theory in my head I'd like to get back to the practical. Maybe if Haddo freezes over and we can all walk on water, Mike will arrange another Outcast meeting. Meantime it would be good to go fishing.

Cheers

Irvine

[Stefan Siikavaara]

Hi guys!

I used to do this:

Cast: \\\\ / -->
Haul:   puuull!

Then I did this for years:

Cast: \\\\ / -->
Haul:     puull!

And this is how I try to haul nowadays:

Cast: \\\\ / -->
Haul:       pull!

Best regards
Stefan



 

 

[Paul Rankine]

Hi Stefan,
                 I know I,m probably going to regret this .   
Why ?


PS: For Unsexy Loopers could you please also just explain a wee bit about the notation.
       Cheers,

      Paul.      ..........

[Stefan Siikavaara]

Hi Paul!

The first question is easy, because it works better and gives me more line speed with less effort. I could elaborate on that if you want to. 

The notation. My dubious contribution to written casting explanation!!!    Magnus really is the man to explain it,   

-----------------

Let's say that this represents the entire rod movement during a cast. From start to end. Seen from the side.

\  /


Now let's take a closer look at that cast.

Every (good) cast has some translational movement. That is, the rod is being dragged without being turned over.

\\\ 

And every cast has a rotational part. The rod being turned over.

\/


So, here is a (good) cast with a late rotation.

\\\/


The rod is being dragged and then rotated. This is the dogs bollocks BTW. 


As for the haul you do not really need to go into detail, just try to haul late. Then learn how to haul even later. 

Mvh
Stefan

[Mike Barrio]

Hi Stefan

Re: "try to haul late" ....... Is that before, or during rotation? I would think it would be before

Best wishes
Mike

[Stefan Siikavaara]

Hi Mike!

That's just the thing! Try doing it during!  


This was starting to haul before the rotation:

Cast: \\\\ / -->
Haul:     puull!

And this is how I try to haul nowadays. This is during. Almost late in the late rotation.

Cast: \\\\ / -->
Haul:       pull!


The difference is radical on shorter casts with a short haul. You seen Paul Arden do smallish casts right? Listen to the sound of his loops...That extra speed does not primarily come from something he does with his rod hand...

Best Regards
Stefan

[Mike Barrio]

Aha .... I understand it now, your letter "p" in "pull" is located under the point of the cast ( in the line above ) where you would start your haul

I like that system of explaining things

My apologies ..... I'm a bit slow

Best wishes
Mike

[Peter McCallum]

Very clear but very simple Stefan thanks for that.

Peter

[Stefan Siikavaara]

Hi Mike and Peter!

Yeah, I think it is dead clear and simple. Magnum agrees to that too and loves the system. He thinks it is a sharp instrument.   

Best Regards
Stefan