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Amazing! This is about the dolphin kick performed on its side, rechristened “the fish kick.” I couldn’t fathom (ha) why the same kick rotated 90 degrees could b

Amazing! This is about the dolphin kick performed on its side, rechristened “the fish kick.” I couldn’t fathom (ha) why the same kick rotated 90 degrees could be faster but it turns out that the kicking motion is constrained by the motion of the water around it. In the dolphin kick, the water moves up and down and is limited by the water’s surface and pool’s bottom. The swimmer frees themself of these constraints by turning on their side.

bravesoul2 1y ago
Does that give advantage to those in the middle lanes?
- pfooti 1y ago
  They should just make the pool wider with a big unused area on either side.
- onlypassingthru 1y ago
  Any turbulence created by waves and vortices smashing into hard surfaces is going to slow the swimmer down. To paraphrase an old adage, smooth is fast.
  - mojomark 1y ago
    I'm inclined to concur with onlypassingthrough. If the resulting wake is similar to fish locomotion (e.g. thunniform or similar) vortices will shed off in a Karmen Vortex Street that spreads laterally with distance behind the swimmer (potentially into other lanes, and propulsive efficiency of propulsors are generally less efficient in turbulant vice laminar open-water flow... but not always, it can depend on the 'structure' [how chaotic] the flow is). The magnitude of the energy in that turbulent wake will depend on how efficiently the oscillating fin interacts with water over time to produce forward thrust. The cool thing about oscillating foils as opposed to rotating thrusters, is that when the fin 'swoops' once it creates Vortex 'A' spinning clockwise, and when it 'swoops' back the result would be a Vortex 'B' spinning counterclockwise, and the two vortices will partially cancel out. That cancellation serves to recover energy from Vortex 'A' and the energy is transferred back into forward thrust. In other words, fish tails create trails of contrarotating vortices and continually push off of them. It's like walking up a springy staircase, where each step you make, a little energy is recovered to bounce you up to the next step. In theory, if you had a swimmer in front of you, generating a Karmen Vortex Street and not effectively canceling out those vortices, but instead just shedding vortices, you can use the energy from the swimmer in front of you to 'spring' yourself forward - barely using any energy yourself. Those complex hyrdodynamic relationships could be why some swimmers/flyers tend to fly in specific formations with other animals in their school/flock. Bottom line, I would bet that any residual vortices that spread into adjacent swimming lanes will tend to interact chaotically and result in unstructured turbulance, which should yield less optimal swimming conditions for swimmers in those lanes.
    - onlypassingthru 1y ago
      >you can use the energy from the swimmer in front of you to 'spring' yourself forward This bears out in the real world. Much like a peloton in cycling, swimming directly behind another swimmer can be far more energy efficient than swimming by yourself and feel like you are getting pulled along for the ride.
      - nradov 1y ago
        Even swimming slightly offset another swimmer saves significant energy. It also reduces the chance of getting kicked in the face. We do this when possible during triathlon open water swims.
    - pdonis 1y ago
      > you can use the energy from the swimmer in front of you to 'spring' yourself forward When I swam competitively in the early 1980s, we did this during workouts; we'd all swim in a line with very close spacing, and switch off who was in front after every lap (two lengths--this was in a 25 meter pool). Being in front you could feel the extra work you were doing.
- analog31 1y ago
  Indeed, and as a consequence there are rules for who gets which lane.
- foobarbecue 1y ago
  Middle lanes are faster, and for some reason swimmer with the fastest record gets the middle in most events, which always seemed weird to me -- it's a positive feedback system. Seems like you should give the advantage to the people who are behind, not ahead... but that's common in sports and in modern society for some reason.
  - Scarblac 1y ago
    It's strange to reward slower contestants in sports.
    - sim7c00 1y ago
      yeah, otherwise good ppl will do bad in qualifiers to get good position...
      - koolba 1y ago
        Reminds me of the final boss in Smash Bros. If you purposefully let him whip you at first, the adaptive play would nerf him enough to let you easily finish him.
    - pfortuny 1y ago
      IIRC Ecclestone suggested getting rid of qualifiers and just putting the F1 cars n the inverse order of their last race. This idea was in order to get more overtakes (the best parts of F1 races). I think it would be great.
      - bravesoul2 1y ago
        Makes sense. More interest in F1. More money for Bernie.
        philistine 1y ago
        1. Ecclestone has been out of the sport for nearly a decade. 2. A race weekend is a three-day affair, with tickets sold for each day. What do you do on Saturday if there are no qualifs?
- fracus 1y ago
  You can't reward failure in competition. You will get people purposely going slower to get the middle lanes. What they could swim in a pool in which they aren't using the outer lanes, so bigger pools, or less swimmers.
xarope 1y ago
the rescue/combat side stroke is very efficient too, and that's due to the very large kick you can use since you are sideways

bravesoul2 1y ago

Does that give advantage to those in the middle lanes?

pfooti 1y ago
They should just make the pool wider with a big unused area on either side.
onlypassingthru 1y ago
Any turbulence created by waves and vortices smashing into hard surfaces is going to slow the swimmer down. To paraphrase an old adage, smooth is fast.
- mojomark 1y ago
  I'm inclined to concur with onlypassingthrough. If the resulting wake is similar to fish locomotion (e.g. thunniform or similar) vortices will shed off in a Karmen Vortex Street that spreads laterally with distance behind the swimmer (potentially into other lanes, and propulsive efficiency of propulsors are generally less efficient in turbulant vice laminar open-water flow... but not always, it can depend on the 'structure' [how chaotic] the flow is). The magnitude of the energy in that turbulent wake will depend on how efficiently the oscillating fin interacts with water over time to produce forward thrust. The cool thing about oscillating foils as opposed to rotating thrusters, is that when the fin 'swoops' once it creates Vortex 'A' spinning clockwise, and when it 'swoops' back the result would be a Vortex 'B' spinning counterclockwise, and the two vortices will partially cancel out. That cancellation serves to recover energy from Vortex 'A' and the energy is transferred back into forward thrust. In other words, fish tails create trails of contrarotating vortices and continually push off of them. It's like walking up a springy staircase, where each step you make, a little energy is recovered to bounce you up to the next step. In theory, if you had a swimmer in front of you, generating a Karmen Vortex Street and not effectively canceling out those vortices, but instead just shedding vortices, you can use the energy from the swimmer in front of you to 'spring' yourself forward - barely using any energy yourself. Those complex hyrdodynamic relationships could be why some swimmers/flyers tend to fly in specific formations with other animals in their school/flock. Bottom line, I would bet that any residual vortices that spread into adjacent swimming lanes will tend to interact chaotically and result in unstructured turbulance, which should yield less optimal swimming conditions for swimmers in those lanes.
  - onlypassingthru 1y ago
    >you can use the energy from the swimmer in front of you to 'spring' yourself forward This bears out in the real world. Much like a peloton in cycling, swimming directly behind another swimmer can be far more energy efficient than swimming by yourself and feel like you are getting pulled along for the ride.
    - nradov 1y ago
      Even swimming slightly offset another swimmer saves significant energy. It also reduces the chance of getting kicked in the face. We do this when possible during triathlon open water swims.
  - pdonis 1y ago
    > you can use the energy from the swimmer in front of you to 'spring' yourself forward When I swam competitively in the early 1980s, we did this during workouts; we'd all swim in a line with very close spacing, and switch off who was in front after every lap (two lengths--this was in a 25 meter pool). Being in front you could feel the extra work you were doing.
analog31 1y ago
Indeed, and as a consequence there are rules for who gets which lane.
foobarbecue 1y ago
Middle lanes are faster, and for some reason swimmer with the fastest record gets the middle in most events, which always seemed weird to me -- it's a positive feedback system. Seems like you should give the advantage to the people who are behind, not ahead... but that's common in sports and in modern society for some reason.
- Scarblac 1y ago
  It's strange to reward slower contestants in sports.
  - sim7c00 1y ago
    yeah, otherwise good ppl will do bad in qualifiers to get good position...
    - koolba 1y ago
      Reminds me of the final boss in Smash Bros. If you purposefully let him whip you at first, the adaptive play would nerf him enough to let you easily finish him.
  - pfortuny 1y ago
    IIRC Ecclestone suggested getting rid of qualifiers and just putting the F1 cars n the inverse order of their last race. This idea was in order to get more overtakes (the best parts of F1 races). I think it would be great.
    - bravesoul2 1y ago
      Makes sense. More interest in F1. More money for Bernie.
      - philistine 1y ago
        1. Ecclestone has been out of the sport for nearly a decade. 2. A race weekend is a three-day affair, with tickets sold for each day. What do you do on Saturday if there are no qualifs?
fracus 1y ago
You can't reward failure in competition. You will get people purposely going slower to get the middle lanes. What they could swim in a pool in which they aren't using the outer lanes, so bigger pools, or less swimmers.

xarope 1y ago

the rescue/combat side stroke is very efficient too, and that's due to the very large kick you can use since you are sideways