Solid fins vs flexible fins and air usage

[dmaziuk]

You do of course realise that conservation of energy also means you can't put in less work, as in "smaller muscle groups", and get the same amount of propulsion out.

 

[tbone1004]

You do of course realise that conservation of energy also means you can't put in less work, as in "smaller muscle groups", and get the same amount of propulsion out.

correct, but there is a difference in the o2 consumption of the large muscle groups for the same amount of energy. More importantly, many people "over kick" their fins and the propulsion is directed in directions other than behind you so the frog kick is inherently more efficient as a larger amount of thrust is generated backwards, while also putting less metabolic load on the body by not using the larger muscle groups as much.

 

[kelemvor]

Conservation of Energy. You can't get more work (energy) out of something than you put in.

I think some people have the idea that once the fin is "pushed over" by the effort of the kick, it will "push back" and get you going further. But you can't get more work out of it than you put into it.

BTW, why are we trying to go further or faster? I forgot....I guess I was distracted by all the interesting things to look at....

- Bill

It sounded to me like he was concerned about air consumption. I didn't see him mention distance or speed.

 

[dmaziuk]

More importantly, many people "over kick" their fins and the propulsion is directed in directions other than behind

Yes, and even if they don't push much in other directions, it's likely still too much kick for the speed you're typically aiming for.

You can flutter-kick with just your feet, too, if you have ankles for it. I'd expect that to be more efficient than frog kick: same small muscles, less drag.

 

[tbone1004]

Yes, and even if they don't push much in other directions, it's likely still too much kick for the speed you're typically aiming for.

You can flutter-kick with just your feet, too, if you have ankles for it. I'd expect that to be more efficient than frog kick: same small muscles, less drag.

the shuffle kick is something we use in cave diving and wreck diving somewhat regularly but it isn't as effective as frog kicking because the thrust is still not going all behind you. Still have wasted water movement up and down

 

[dmaziuk]

As I said elsethread, during frog kick's recovery phase you have to push against the flow at least a little bit. You also have your ankles out of streamline: extra drag. Research is needed to see if a well-calibrated reference diver with perfect technique would lose more or less energy there compared to up/down push of the flutter,

 

[narke]

Should you change fins consider they may weigh differently too and change your buoyancy.
I see "softer" fins may be less efficient where there is current.

 

[REVAN]

When I started diving (10 years ago) I purchased solid (ie. no flexible rubber sections in it) fins. I was in the dive shop a few days ago and was looking at all of the modern fins with flexible rubber sections in the middle and all sorts of advertised advanced channels.

Is it worth upgrading? Do people see decreased air consumption by switching to more modern fins?

If you are considering upgrading to a fiberglass freediving fin (long blades), then yes. A freediving fin will produce thrust with a significant advantage in efficiency that is noticeable, particularly when using the flutter kick or dolphin kick.

If you are looking at scuba fins with channels, vents or other gimmicks, then the answer is usually no. Those things are marketing ploys that are designed to look cool but that usually degrade the fin's actual performance instead of improving it.

 

[narke]

f you are looking at scuba fins with channels, vents or other gimmicks

I try to swim backwards with fins with vents Tech Fin DiveSystem and that appears to work just fine and better than with cressi sub rondine which are however longer so I can't say if that works better because of the vents.

 

[TMHeimer]

I used a couple of different paddle fins at first and after 3-4 years switched to splits (I won them at a Treasure Hunt, and did find they helped with cramping). I have never noticed any real change in my consumption from day one after OW. If I kick faster or get more active, I use more air, regardless of fins. But, I have not experimented with any other fins, so this is only my experience.
Interesting side light--unlike many, I truly believe my consumption after 12 years is about the same as on my first dive. This could mean that I breathed correctly at the start and couldn't improve, or mean that I sucked then and still do.....