Dolphin nose

[Paul Arden]

Hi gents, I think I'm right in saying that the dolphin nose occurring is due to line stiffness and loop diameter only. I'm playing around with a bead chain

Can someone please explain it in very simple words. Peter is asking how it works and he speaks Hunglish.

Thanks! Paul

[Walter]

Things bend.

They try to bend in a round shape until excess force is applied.

[Paul Arden]

[youtube]http://www.youtube.com/watch?v=a5QWBj0LoM4[/youtube]

[Walter]

Yep. Looks round to me.

This would be the result of excess force:

[Paul Arden]

So the dolphin nose occurs because the stiffness of the material requires a larger loop, and since the force is pulling from bottom the material bulges at the top? This means that the two determining factors as to whether or not a Dolphin Nose occurs is material stiffness and loop diameter, and nothing else. Speed doesn't seem to be a determining factor.

I'm not really sure that saying "things bend" fully explains it in English, let alone Hunglish

Cheers, Paul

[John Waters]

"Things bend.

They try to bend in a round shape until excess force is applied."

I don't understand that Walter.

If I include stiffness of (line) material as a causal factor I presume;

Force applied by the rod being equal, then high density sinking line will have a more pronounced dolphin nose than a floating line, or is it the other way around?
Does the force applied include the impact of air resistance on the thicker floating line?

My biomechanics study of casting shows that I threw a dolphin nose often when I was making major changes to my casting technique, however the dolphin nose shape rarely occurs now. If I assume that the force you referred to was the force applied by the rod, then I presume that I am now applying less force. The reason for me seeking clarification is because the objective of our casting study was to increase the acceleration through to line release and acceleration is a driver to force.

I will need to discuss this at depth with my coach because if force is the driver of dolphin nose loops, the force I am now applying must have reduced because my dolphin nose loops have diminished, albeit my acceleration and distances have increased . Of course these improvements come of a very low base and at my age, any base is fine by me, but this thread made me revisit my data and I have never been able to fully explain the casting technique drivers to dolphin nose loop shapes, why I threw them and why I do not throw them now.

Thanks,

John

[Paul Arden]

If I place the bead chain on the table and slowly - and I mean millimetre by millimetre - pull the bottom leg the dolphin nose appears. The dolphin nose does not appear however when the loop is wide or 7-shaped.

Cheers, Paul

[Bernd Ziesche]

Hi Paul,
I have played with the Dolphin nose a few weeks back. It seemed to me, that it does not come in per se when shaping extra tight loops. But combing extra tight loop shape in lowest possible line speed seemed to work best in order to create the Dolphin nose.
Seemed to me like tension is another key factor?

Can you shape a tight loop not having the nose?
Cheers
Bernd

[John Waters]

Hi Bernd,

RE speed: My dolphin nose shapes occurred when my line had a lot of speed. I had dolphin nose loops in a Scientific Angler T40 line cut to 38 grams and 15 .5 metres long, pulling 0.25 mm monofilament line as backing. Loops had a lot of speed as casts were between 55 metres and 65 metres depending on wind. The T40 is a high density fast sinking line.

RE tension: Very little tension with that gear.

RE speed and shape: My loops with that gear are now faster and very thin spear-point shape.

I am intrigued with this because I want to understand the body movement that creates the shape. At the end of the day, instruction needs to be sourced to a body movement because, other than gear, that is the only controllable factor in casting. In my casting the frequency of occurrence reduced when my acceleration increased and line tension over distance, increased.

John

[Walter]

Force applied by the rod being equal, then high density sinking line will have a more pronounced dolphin nose than a floating line, or is it the other way around?

It depends. Which one is stiffer? As far as I know density and stiffness are not related.

We've been through this with the whole rod bending thing. If we bend a non-tapered, elastic rod it will assume a naturally round shape at the bend until we apply too much force and then the rod will buckle and collapse. If we bend that rod by pushing the two ends together the rod will assume a tear drop shape assuming it doesn't buckle before getting all the way to the tear drop. We could also push inwards at different points along the rod. Let's say we push in at about the first quarter point and the third quarter point on the rod, ie. about midway between the middle and ends on both sides, and we push until the legs are parallel and we have a U shaped rod. Push a little harder and we will have the legs almost crossing, i.e that tear drop shape. Now get someone to push one end in the opposite direction until the legs become parallel. What does the shape look like at this point?

As long as we don't cause the rod to buckle or kink we can apply forces to different points on the rod to create all kinds of shapes.