Fins and manoeuvrability

[danvolker]

How do you propose to get this elite group together to test fins? I would imagine they have already tested and found what works for them. There is the great possibility that none of them wish to play test dummy for no compensation. Also, with the parameters you set I think we may be straying away from recreational scuba and more to the "elite individually tailored" market. This sort of derails the experiment since I thought the end goal was to have the top fin manufacturers start producing better fins that encompass recent technological advances. I'm not sure if the general public is ready to buy a fin based on optimal kick shape, and the general public is where the biggest piece of the sales pie is for the manufacturers.

Each fin already has an OPTIMAL kick shape. Some fins are not terrible with a sub-optimal kick shape, and with some, they dont work well at all with poor kick shape.

If the terrible diver in the split fin video a few posts back, was to put on a pair of freediving fins, he probably would not even be able to move forward at all.
That is an exageration of the problem he would have with Cressi Frogs and many other of the better scuba fins.


Just a few of the issues relating to optimal flutter kick shapes for each fin...

• Some fins work better when you kick more from the hip, and less knee bending occurs...though this is really more about an ideal range of ankle articulation of the fin....the ideal angle the blade is at to the tibia
• Some fines gain best efficiency and best kick shape by all the kicking coming from the knee, not the hips. Force Fins actually work better from the knee than from the hip, but there is a kick shape they can do quite well, that is from the hip....several fins have multiple kick shapes that can work reasonably well.
• The articulation of the ankle can allow the blade to get it's ideal flex from the downward thrusts, and this angle "can" change when the power applied is increased or decreased.
• some fins are better with a slow cadence, some are better with fast cadence and snapping action
• some fins have different angles of articulation that can act almost like gears on a bicycle. Knowing how to alter this as needed can have a huge impact on how much you like the fins.
• Some fins can develop impressive push from the upstroke, particularly in dolphin kick, and the body assists with an oscillation of the spine and hips, and then the fin itself can be oscillated at a high frequency and low amplitude, for fast and efficient speed. Many fins have little or no propulsive ability on the upstroke, and the kick shape needs to concentrate on the down stroke, and then getting the fin back up with the minimum of effort.
• Even split fins have an ideal kick shape....or shapes.
• Some divers have serious limitations in their ability to swim with toes pointed in line with the tibia--they tend to try to swim flat footed---fin at more like a 90 degree angle like in walking. This is very bad, it is quite common, and often referred to as a bicycle kick. many instructors don't know how to fix this in a student, and either ignore the problem, or prescribe Splitfins

 

[gkrane]

I grew up as a competitive swimmer so I don't have any issues with kick form. However, to be fair the guy in that video looks like he is 2 days out of OW class and has never swam in his life. I would hope that after a few hours and minimum instruction he would make a dramatic improvement. I see the bicycle kick with most new diver who don't have swimming experience.

 

[dumpsterDiver]

I grew up as a competitive swimmer so I don't have any issues with kick form. However, to be fair the guy in that video looks like he is 2 days out of OW class and has never swam in his life. I would hope that after a few hours and minimum instruction he would make a dramatic improvement. I see the bicycle kick with most new diver who don't have swimming experience.

I think that most any swimmer can learn to use just about ANY fin, without too much trouble. I mean there are differences, but if you know how to swim and kick- doing a decent flutter kick is not that hard.

I personally don’t think we need “experts” to tell us which fins work better for us. With a little trial and error, I think any diver should be able to feel what is comfortable, seems natural and provides better efficiency, etc.

I think this video of my twins at 15 yrs old swimming around with long freedive fins provides as good of an argument as any that “it ain’t rocket science”. Incidentally, they are both using the CHEAPEST MAKO fins available. The ones for kids are about $50 yet they still work well.

My son also has a pair of carbon Fiber fins (spoiled kid), but for beating around the barnacles and rocks, a cheaper plastic freedive blade works very well for him – without too much of a compromise.

It should be emphasized that you don’t need to spend a ton of money OR be a diving god, to realize the benefits of better fins.

[video=youtube_share;ZqRVbaHs520]http://youtu.be/ZqRVbaHs520[/video]

 

[REVAN]

Fin evaluation is actually one of the hardest gear evaluations to do well. How you test will depend on what you want to evaluate, and the fin's efficiency is the hardest thing of all to get a good measure on. When two fins are fairly close in performance, the best way I know of to break the tie is to carry all the gear, but don't breath from the scuba. Instead do hypoxic interval dynamic training, like sets of 25m every 2.5 minutes until you can't complete a lap without a BO. Whichever fin get you more laps before that happens is the more efficient fin. It is hard work, and has to span multiple days because you need each test to be entered freshly charged, but it works and takes all the breathing variables out of the equation. A CCR rebreather can do this also, but it changes the hydrodynamics, so it's not as good a test unless you actually want to evaluate it with the rebreather configuration and tank pressure gauges are not all that accurate so it's going to be a long swim to get an accurate read.

 

[John C. Ratliff]

Fin evaluation is actually one of the hardest gear evaluations to do well. How you test will depend on what you want to evaluate, and the fin's efficiency is the hardest thing of all to get a good measure on. When two fins are fairly close in performance, the best way I know of to break the tie is to carry all the gear, but don't breath from the scuba. Instead do hypoxic interval dynamic training, like sets of 25m every 2.5 minutes until you can't complete a lap without a BO. Whichever fin get you more laps before that happens is the more efficient fin. It is hard work, and has to span multiple days because you need each test to be entered freshly charged, but it works and takes all the breathing variables out of the equation. A CCR rebreather can do this also, but it changes the hydrodynamics, so it's not as good a test unless you actually want to evaluate it with the rebreather configuration and tank pressure gauges are not all that accurate so it's going to be a long swim to get an accurate read.

This is a prescription for suffering shallow water blackout (SWB), and if done alone could be life-threatening. Quite simply, DON'T DO THIS!

Shallow Water Blackout Prevention

SeaRat

 

[Diving Dubai]

Perhaps I've missed this having skimmed through the thread.

But surely fins are more than anything the most subjective choice of all the equipment? What a new OW dive may think is a "good" fin, will be different from a tech diver humping twins and dec, will be different from wreck diver, from someone pootling around a reef or someone in fairly strong currents or needing long surface swims?

Also people are different, yes they may benefit from learning the correct kick but have different strengths of leg muscles.

If you make a simple graph with cheapest fins on the left and most expensive there will be a steep improvement at first before the graph levels out with smaller increments per $ and it may even dip

Look how many choices in Gold club there are, with different weights and shaft stiffness as well as length.

I have to respect Dan and his enthusiasm especially as a fellow Raptor owner (2014 Screw for me) but...

If I were to set up a simple Audio test with a CD player, amp and different speakers, 10 people would have 10 opinions. If I were to add different amps and different CD players, the permutations would increase logarithmically.

I could prove scientifically which set up has the best reproduction over the frequencies - but since you all have different hearing characteristics, that would be pointless too.

Just because I can prove which is best, doesn't mean its the best for you

 

[danvolker]

Perhaps I've missed this having skimmed through the thread.

But surely fins are more than anything the most subjective choice of all the equipment? What a new OW dive may think is a "good" fin, will be different from a tech diver humping twins and dec, will be different from wreck diver, from someone pootling around a reef or someone in fairly strong currents or needing long surface swims?

Also people are different, yes they may benefit from learning the correct kick but have different strengths of leg muscles.

If you make a simple graph with cheapest fins on the left and most expensive there will be a steep improvement at first before the graph levels out with smaller increments per $ and it may even dip

Look how many choices in Gold club there are, with different weights and shaft stiffness as well as length.

I have to respect Dan and his enthusiasm especially as a fellow Raptor owner (2014 Screw for me) but...

If I were to set up a simple Audio test with a CD player, amp and different speakers, 10 people would have 10 opinions. If I were to add different amps and different CD players, the permutations would increase logarithmically.

I could prove scientifically which set up has the best reproduction over the frequencies - but since you all have different hearing characteristics, that would be pointless too.

Just because I can prove which is best, doesn't mean its the best for you

Now you've done it...

Get a true 24 bit 192 kHz miking of a classical Piano concerto....in a room with great acoustics... keep it carefully at 24/192 or above in all steps of the production to the final output of 24/192 ...Play it on a pair of Magnepans powered by a good Dac (like a Berkley as both DAC and preamp), and some good clean mono block amps....With perfect provenance( like this), the out put sounds exactly like the source--a person walking into your house, will really believe there is some awesome piano player playing a piano in your house....

Play it from a CD, and this is far less likely to be mistaken as real, even played on the Magnepans....the CD source at 16/44 has lost far too much in transients and sample depth to sound real.
Take most of the music sold on Pono today with the mistaken notion that it is Hi Defef 24/96 music, when in reality, it was just crappy 16/44 CD music up sampled to 24/96, and most of what was lost, can not be recovered...The few bands that DO record and produce at 24bit/192 ( or even at 88 or 96) , will sound much better than CD's of the same music...
It's all in the Provenance. Even analog tape masters, that were miked really well in great sound rooms, and had great care taken in production, will sound better due to their good provenance. They won't have the signal to noise ratio of the state of the art 24/192 recording possible today, but because they were recorded much better than is the norm today, they will still sound great....
In other words, in stereos today, there is way to much "Smoke and Mirrors" in selling hi def music. Much of the subjective nature is occurring because there are so many flaws in the path from the musicians playing the music, to what is left of the original when you hear it playing on a good stereo.

Back to fins, I'd compare them more to snow skis.....novices are not well suited to knowing a good ski from a bad ski.....but put the better skis on them, they can learn faster, and attain much higher skill levels than they could have if you put really sloppy novice skis on them, that did not help them realize any differences between Right and Wrong in their user inputs--in their attempts to turn or track.

And with snow skis, there are definitely skis much better for strong skiers, or heavy skiers, or light or weak skiers....just as with fins. There are skis that if turned aggressively, will actually throw your energy back, and literally throw you into your next turn....a racer or bump skier will love this, a skier that just wants to do easy arcing big s turns may not care for this.

Fins have even more need of the right mentor, helping the novice into the right fin, than Skis do with the right mentor being their to suggest the right skis for a novice, and the right drills to work on, and the right instruction so that they might learn how to use the skis optimally....and progress rapidly from skiing the novice slopes, to the blues and then blacks, and finally achieving the skills to ski whatever the skier wants to ski....Fins are just like this...But many divers are content to stay in the still water ( bunny slope challenge equivalent) because these places have all the beauty and wonders that these divers could ever dream of.....Unlike skiing, dive sites don't have to get more challenging to become more fun for most people.
For some divers though....they get to see things and to have better interactions with bigger marine life, in the far more challenging high current zones, which are much more like the double diamond runs....or the zones are penetration areas, like some of the most technical skiing through forests without trails.....places where raw skills become far more essential, and the rewards are great for those who love this type of skiing..or diving.

 

[Johanan]

Now you've done it...

I observe, sir, that you are an expert in more than one area. Actually, with my Mytek 192 DSD DAC and idividually built rest of the system, I like the sound of 24/96 records the most.

 

[dmaziuk]

If you make a simple graph with cheapest fins on the left and most expensive there will be a steep improvement at first before the graph levels out with smaller increments per $ and it may even dip

'Bang per buck' tends to be a log curve in many/most cases, not just fins. The part where you get double the bang for twice the buck is very short, ant the it tapers off towards horizontal. In theory anyway: in practice increased complexity tends to bend it back towards negative returns at some point.

If I were to set up a simple Audio test with a CD player, amp and different speakers...

Would Sir like pulled oxygen-free copper speaker wires with that? Running in the North-South direction?

 

[rx7diver]

Get a true 24 bit 192 kHz miking ...

Audio! Sheesh! Every hobby seems to have its over-the-top devotees: What's Best Forum (WBF Forum)!