We call dolphin nose to a very characteristic shape taken by the fly leg of the loop. Its origin seems obscure to me, but Grunde Lovoll (fly caster and Ph.D. in Physics) says that it is the result of a decrease in tension in the fly leg of the loop during unrolling.
A dolphin nose starts forming in the loop front…
…it gets bigger…
…and bigger
In my view one thing is for sure: the dolphin nose is not a shape that you see in the casts of beginners, quite the contrary, it is something reserved to those who can generate narrow, slow moving loops. I don’t see how a narrow loop with no more energy than that needed to completely unroll could be considered a fault, so, consequently, I don’t see the dolphin nose as the result of any casting error whatsoever.
Look how a very low line speed (not enough for a complete turn over of the leader) results in dolphin noses.
The shape of a dolphin nose being akin to that of a tailing loop may lead to confusion. There are fundamental differences, though:
- A dolphin nose appears after the loop has been formed.
- Consequently, a dolphin nose is not the result of an anomaly in the path of the rod tip during the casting stroke, as it is the case with tailing loops.
- The wave of a tailing loop is formed before the loop is born, so that wave is present before the casting stroke ends, and can be seen propagating along the fly leg during the whole flight of the line.
See below a clear example of the formation and propagation of a tailing loop.
And here a dolphin nose produced by an almost rigid “rod”. Since the rod doesn’t bend that shape can’t be result of an anomaly in the path of the rod tip.
onemorelastcast.net 
Nice 😉
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Thanks!
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So do you dispute this; the dolphin-shaped loop. (Figure 1.) It has a leading edge that protrudes on the rod-leg in the loop face. It comes from low acceleration during the loading phase, attempting too narrow a loop (another way to say too much SLP), and finally, poor rod-leg and fly-leg tension acting on the loop face. If I were coaching someone to cast Figure 1, I might say: ‘Throw as narrow and slow as possible.’
This is not a leading question
I have found that complete leader turnover sometimes fails in dolphins in practical ( stream fishing) situations and the the line often lands before the fly which is mainly a disadvantage.
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It does make sense. If I understand you correctly we are saying the same with different words: low line speed and narrow loop. Since a slow moving fly leg results in less tension than a faster moving one…
When casting with a very low speed the leader fails to turn over and the dolphin nose is always there:
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Nice one Aitor.
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Thanks mate!
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forgive me I got the wrong end of the stick, totally agree have a god time in the southern hemisphere
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Have you tried casting a dolphin nose with a silk line? Ie a very supple line? Are there any differences to a modern plastic line?
I don’t have a silk line to try but have always wondered how it might affect this if at all.
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No, I haven’t tried it but I will do. I had a very expensive Phoenix DT5 but I gave it away (I have never be very fond of silk lines), but I think that there is one level silk line left in my collection.
To be honest, I don’t think that supplenes can make a difference but it will be an interesting experiment. Thanks for your comment.
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My thinking on stiffness being a major factor changed when Lasse told me he could get DNS in a MPR. That said I do think that there might be a relationship with axial stiffness in some cases.
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Yes, it is easy to get them with the wool+macrame “line”. Slow speed and narrow loop are keys.
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What seems to be in favor of the lack of tension theory.
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The low tension theory works in normal casting cases, such as the end of a distance cast or the snaps. It’s the narrow loop that makes me think there’s a link to axial stiffness as well, some lines seem to be easier to produce them than others. My thought was that the core construction might make a difference.
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Well, Alejandro had a slomo video with an interesting DN formed in a bead chain.
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I had one in a leader, when it was falling at 90 degrees to the rod leg
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Thanks , always wanted to know why they form. All I could think of was that it looks like the fly leg is ‘catching up’ to the front of the loop which looks like it is being held back by something.
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I recommend the following book or even searching on the web. Fly Casting: Loop Dynamics by Soon Lee. He shows how to make many casts. The dolphin nose is actually a long distance cast, like a V shape. The differences are what happens to the rod tip after it straightens out. His book is awesome! It’s short and illustrated. It gives language to all parts of the cast. Enjoy!
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