Externet
Contributor
Close examining diving fins...
In the beginning, the flat fins were the norm... the basic, fishlike apppendices. Just like a fish, that is the shape to give us propulsion.
Then they made them longer, became somewhat more flexible because of their characteristics, as cannot be always as rigid if made longer. Claimed to be the ultimate technology. Wider posed a problem, prone to collide themselves, and were not 'developed'.
Later, in another marketing trend or real look to efficiency, came the 'turbos' with three ports to channel water though them...¿?
These ports are angled in such way that the most powerful of the two strokes, straightening the knee (the knee being folded going to straight position), allowed a certain amount of water to just bypass the fin to its other side, with my doubts that could improve propulsion efficiency.
The now split type of fins can be just a trend, a marketing maneuver to make us buy the newest 'designs' with no real improvement behind them.
To my opinion, the shape and architecture of a fin has to be proven, by submiting it to a -force-in - force-out analysis on a laboratory.
If I have missed published results of such analysis, fine; but have my doubts such analysis has been done.
The keyword is efficency. Cannot see any other related to fins.
For a given leg strenght, there has to be a given resistance from the fin to be moved. My backgorunds is electronics, and that is called impedance matching in that field.
Explain: A super large fin can impart a large propulsion if the muscle strenght matches and is capable of handling it.
For weak legs, a less resistive fin will produce the matching propulsion. Example: an adult can arm-throw a baseball the longest distance; but a tennis ball (lighter) or a basketball (heavier) won't make it that far. The one that gets the farthest is not the heaviest nor the lightest; it's the one that MATCHES the arm muscles capability.
Translate that to legs and fins. There has to be a fin that produces the most efficient propulsion, and it is NOT the harder to kick nor the easiest to kick. That is the question, WHICH one has been proven to produce more trust for an average adult?
For younger or weaker swimmers, a different shape -or lenght- matches their leg strenght. OK, that is why fin manufacturers have young and adult sizes. They are fine with that . But returning to shape and flexibility , WHICH is the optimal?
WHICH shape is the optimum? Flat, ported or split, flexible or rigid, or combination of them? To make matters worse, observing 'professionals and instructors' They usually do not keep straight knees to propel themselves with the theorical (or not) straight knee-leg scissor motion, and a fin design should take that into consideration -not everyone will kick properly-
What do you think? Is it marketing? Is there any science behind it?
Miguel
In the beginning, the flat fins were the norm... the basic, fishlike apppendices. Just like a fish, that is the shape to give us propulsion.
Then they made them longer, became somewhat more flexible because of their characteristics, as cannot be always as rigid if made longer. Claimed to be the ultimate technology. Wider posed a problem, prone to collide themselves, and were not 'developed'.
Later, in another marketing trend or real look to efficiency, came the 'turbos' with three ports to channel water though them...¿?
These ports are angled in such way that the most powerful of the two strokes, straightening the knee (the knee being folded going to straight position), allowed a certain amount of water to just bypass the fin to its other side, with my doubts that could improve propulsion efficiency.
The now split type of fins can be just a trend, a marketing maneuver to make us buy the newest 'designs' with no real improvement behind them.
To my opinion, the shape and architecture of a fin has to be proven, by submiting it to a -force-in - force-out analysis on a laboratory.
If I have missed published results of such analysis, fine; but have my doubts such analysis has been done.
The keyword is efficency. Cannot see any other related to fins.
For a given leg strenght, there has to be a given resistance from the fin to be moved. My backgorunds is electronics, and that is called impedance matching in that field.
Explain: A super large fin can impart a large propulsion if the muscle strenght matches and is capable of handling it.
For weak legs, a less resistive fin will produce the matching propulsion. Example: an adult can arm-throw a baseball the longest distance; but a tennis ball (lighter) or a basketball (heavier) won't make it that far. The one that gets the farthest is not the heaviest nor the lightest; it's the one that MATCHES the arm muscles capability.
Translate that to legs and fins. There has to be a fin that produces the most efficient propulsion, and it is NOT the harder to kick nor the easiest to kick. That is the question, WHICH one has been proven to produce more trust for an average adult?
For younger or weaker swimmers, a different shape -or lenght- matches their leg strenght. OK, that is why fin manufacturers have young and adult sizes. They are fine with that . But returning to shape and flexibility , WHICH is the optimal?
WHICH shape is the optimum? Flat, ported or split, flexible or rigid, or combination of them? To make matters worse, observing 'professionals and instructors' They usually do not keep straight knees to propel themselves with the theorical (or not) straight knee-leg scissor motion, and a fin design should take that into consideration -not everyone will kick properly-
What do you think? Is it marketing? Is there any science behind it?
Miguel