Pervasive Fallacy about Split Fins

[djanni]

I have actually been in pools where you could kick up a good amount of silt...

Ouch!!?! I'd avoid those pools like the plaque.

 

[Temple of Doom]

Yeah, it is called resistance. I am not sure if you have tried different fins to see for your self the difference, but try this at home. Take a piece of 8.5 X 11 paper in one hand and wave it back and forth in front of you. Now take a piece the size of your car and wave it back and forth. The air resistance from the surface area will increase the work load on your arm. This is the same for fins, wetsuit vs. dry suit and dive profile. The way the fin moves through the water contributes directly to the energy expended. You can move your arm in a waving motion a lot longer when your hand is empty then when you are holding something large and flat. My suggestion to you would be to get a pair of Turtle fins, Twin jets and something like a Kinesis. Try them out in a controlled environment and see for yourself how design impacts performance and diver fatigue. After you tackle that you can look at profile and exposure suit differences.
:monkeydan

I'm not sure what it is you're arguing, but the discussion you're entering about the scenario of swiming 65 feet as fast as you can sustain. The energy output of your body will be the same regardless of fin.

If you wave either piece of paper as hard as you can, it will be just that, as hard as you can. Whether you're trying to wave a playing card or a hang glider as hard as you can, that means you can't do any more. It's your body's max energy output.

Your body determines its max energy output, not your fins. Think about it! Likewise for your 'optimal' sustainable energy output.

It's crazy to think that putting a different piece of plastic on your feet can change the maximum amount of energy your body can generate. That would be remarkable! Theoretically if that were true you could fine tune the fin, so that eventually you could generate enough extra energy to heat your house.

While exerting your max energy output (or your optimal sustainable) the only difference on your speed is going to be the efficiency of the fin (all else being equal).

Craig

 

[dk2943]

The one thing I do notice in all of these split v. paddle threads is that, almost universally, anyone who started with paddles and then switched to splits would never go back to paddles.

 

[Diver Dennis]

Dennis, you can borrow mine.. I am going to get a pair before the Mega DOR. Will be bringing it down to have a go. I still love my quasi-paddles (Volo-Power) but I won't mind trying out a split.

BTW, I have used SP Jets, Mares Planar Avanti, Planar Avanti Quarttro.

Why thank you Tim...

 

[MauiScubaSteve]

At least one other diver has come to the same conclusion. Atomic Split Fins vs. ScubaPro Jetfins -- and the winner is AQUALUNG BLADES!

In a recent nav class we had split, paddle and blade fins. We timed and counted strokes for 100', averaging two runs with now interesting results. Overweight and oldest had the fastest pace with the least strokes (blades), decent shape resort instructor slightly slower with a couple extra strokes (paddles), decent shape mountian man then again slightly slower with many more strokes (really!), ave times 1:02, 1:03, 1:05.

I then timed and counted strokes for four minutes while students counted and compassed, 120deg turn, current adjusted stroke count, 120, secondary adjusted stroke count. The big guy slowed noticably toward the end but had better accuracy on distance, both slowed half way through first leg. For what it's worth, the admittedly soft guy went faster than I thought he should have, faster than his buddy or I wanted to go (remember your buddy).

16 minute exercise, ave depth ~24', air consumption 500psi, 640psi and 800(100cf), distance estimate 400', 440', 470'. In the students defence, this was their first attempts at measuring any activity underwater, much less trying to measure a difference. Considering all the variables, all I can conclude is that the split fin guy estimated distance least well!

Do you honestly believe that the energy output of your body is changing depending on the fin you're using? Are your legs able to metabolize sugars any more because you have a different piece of plastic/rubber on the end of your feet?

Of course not.

By bending the knee often, does that not result in more O2 debt for the muscles of the bicycle flutterers? I use that muscle much less (backfin/helicopter?). People who say their knees hurt more before splits might have been bicyclers all along. Different kicking styles use different muscle groups. Swing a ping pong paddle, then one of those beach ball paddles. Can you swing them with the same energy? Since they react differently in the air it is hard to compare.

When there are reasonable studies of real world dives documenting better air consumption due to split fins on a variety of profiles, then we can talk about which fins are most efficient (for people who dive like the testers).:shakehead

 

[Divesherpa]

:monkeydan:

:mfight:









:1poke:

:help_2:

I never got the smiley thing. Now I see where it's useful.

 

[Meister481]

The one thing I do notice in all of these split v. paddle threads is that, almost universally, anyone who started with paddles and then switched to splits would never go back to paddles.

I switch back and forth weekly. Took my ow class in blades, bought splits, bought turtles. I guess I'm the exception to the rule.

I think I'll dive my turtles at Gilboa this weekend, after I use my splits in class Thursday.

 

[CameronMartz]

If you don't think energy expediture is affected by fin type, try swimming without fins at all. Fins do indeed act to increase the thrust efficiency of kicking, and different fins affect thrust efficiency differently.

While you might be able to produce the same maximum energy expenditure regardless of fin type, what you get for it does indeed change. Thus, fins allow us to use less energy to accomplish the same thrust as our feet alone, create greater maximum thrust, and everything in between. The specific design of the fin will indeed affect thrust per calorie expended.

Likewise, some fin kicks utilize leg muscles more efficiently than others, and changing combinations of fin types and kick types take everything to a new level.

Cameron

 

[Matt_NJ]

:





:1poke:

:help_2:

I never got the smiley thing. Now I see where it's useful.

Haha. I like those icons!

You know - According to Einstines theory of relativity the ammount of energy an object has is based upon it's total mass. So technically if we used our fins for there peak energy output we should be able to convert themselves into pure energy launching ourselves across the entire ocean in seconds. I bet the paddles would have more mass though so they would probably be more efficient - maybe go from SanFranciso to Hawaii in .08 seconds as opposed to 1.23 seconds. I should change out my splits incase I can ever use my fins as a set of portable neuclear reactors so I have the optimal mass to energy conversion for super propulsion.

Seriously though - Why is this always an argument? Just dive the fin's that you like... Is there a reason for the eternal quest for the "BEST" fin, split vs. paddle? Is there ever a true universal best for all people?

 

[scubalifer]

I think the only way to empirically solve this question is on a machine that produces the exact same force and rate of stroke so that the result of the fin and not the fin wearer can be measured. That being said, I like each type for certain diving condition. Can you really own only one pair? That don't make no sense!