Gents, I was wondering why if sinking S2S3 Scandi head A and B would have the same 'Active Line' load - but different total weight - they both load the rod differently when used in a Spey cast using water borne anchor?
I built two heads by using different sections of a AFS S2S3 Scandi Head (weight class #10/11 US, 640 grains, 39 feet), and using different lengths polyleaders to make them both 38' in total length. But version A loads less than version B (see below for details) even though they had equivalent Active Line weight (footnote 2). Infact, the difference is one rod weight class (B properly loads a #8 weight rod, A ditto for a #7 rod).
Referencing Figure 1, the 'Active' Line load is the line portion AC. The rest, the non-active line load, is proposed to not have a dominant effect on loading the rod (footnote 1)
Perhaps there are other dynamics in the non-active line (section CE) that come in play?
My initial thought is that the energy to move the Center of Gravity of the D loop in B is higher than A, as a result of head B being heavier than A (by a mere 47 grains). But then the D loop shape changes and morphs into the classic fwd cast loop, confounding things more.
I am interested to know more and appreciate your thoughtful responses.
Here are the details of the heads I created:
Head A: 510 gr total, 298 gr active line weight, 38 feet (footnote 3).
Head B: 558 gr total, 300 gr active line weight, 38 feet (footnote 4).
Footnotes:
1) Source: Henrik Mortensen's 'Fly Casting Scandinavian style'.
2) The assumption taken is weight of butt end half of head+ all sinking leaders (ie. 19' out of 38', tip end half).
3) AFS S2S3 Head A: 28' of # 10/11 S2S3 (434 gr), Fly end, plus 10' Sink 4 SA ST7 as polyleader (76 gr) .
4) AFS S2S3 Head B: 32' of #10/11 S2S3 (512 gr), Fly end, plus 6' Sink 4 SA ST7 as polyleader (46 gr).
B is heavier and it felt too heavy with one rod and lighter A felt too light with another rod.
edit: Sorry I already forgot what I already did read few hours ago
Perhaps this has something to do? When we do shooted OH cast and running line stops it forces remaining line energy to fly leg. With Spey cast when anchor stops energy goes to D-loop upper section and this bends rod slightly even before forward cast begins.
crunch wrote:With Spey cast when anchor stops energy goes to D-loop upper section and this bends rod slightly even before forward cast begins.
Sorry, that is not certain.
As for the active line problem, yes, it is certain that most of the load of the rod takes place for the mass of the upper leg of D loop, although depending the shape of the loop the tension is transmitted more or less from one to another leg.
Really, I don't see any problem. The heavy head load more the rod. The longitude of the upper leg changes throughout the cast, depends on the size of the loop. With heads of around 30' practically the whole head is part of the upper leg in RSP, in a standar switch or simple spey casting.
Alejandro wrote:The longitude of the upper leg changes throughout the cast, depends on the size of the loop. With heads of around 30' practically the whole head is part of the upper leg in RSP, in a standar switch or simple spey casting.
Alejandro
Hi Sushi,
that's a quite fair way of estimating the load when comparing two heads.
Alejandro perfectly answered your question I think.
I think having more mass on the fly-leg (anchor-leg) will provide a slight extra in tension for the D-loop as well (no pre-load for the rod).
Greets
Bernd
As for most of the head being in the upper leg of the D loop, I used an estimation that 50% of total length of this 38 foot head is in upper leg AC. The weights for both heads are identical (298 and 300 grains). So, it is hard for me to see the mere 2 grains will affect rod loading.
Even if I increase this 50% to about 75% for section AC, the weight difference between heads is 23 grains (Head A: 434, Head B: 457), not enough to explain the ONE (1) rod loading difference.
I read in Speypages about a virtual pulley in apex C for the Continuous Tension Loading (footnote 1). That when the D loop is in high tension, the connection between the Upper and Lower leg is such that pulley is constrained much like it there is a spring holding the pulley in the back cast direction. Not sure if this A-B mass difference adds to this spring.
I also thought maybe the weight of the Apex has something to do with it, but I suspect there is very little weight difference for such a small section.
That's why this makes me believe there are added dynamics in section CE much more than we normally think.
Hope this clears up things more, but making the rabbit hole look even deeper.
You are right Aitor when done right there is not any noticeable load. And if Spey back cast is faster obviously most of it is absorbed to the water if/when anchor slides.
When I built a mechanical Spey anchoring system which stopped anchor abruptly I noticed a jerk in rod until I got used to it because system had less drag.
