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Looking for advice on finding "best" freedive fin

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.
Trux has a good point contrasting efficiency and acceleration, they are different. Both are important, but different activities need a different mix of each. Doing dynamic or depth in tropical waters, efficiency is king, acceleration is not very important. For many kinds of spearfishing, especially shooting free shaft, acceleration is important, very important. You need to find the combination that is right for what you do.

I started diving with jet fins then used a very soft plastic fin for many years(cressi rondine garas). Loved the efficiency but was always very frustrated with the lack of acceleration compared to the jets. Empty kicks can make you crazy when trying to run down a fish. I switched to gara 2000s and got most of the acceleration back, much happier. Later I switched to Hybrids (hard), more efficient than the garas, even better acceleration, but a little too stiff for my skinny legs. Finally settled on Specialfin Kelpies (medium) as the best combination of the two.

Connor
 
I got to freedive again yesterday for 2 hours...

.....I tried concentrating on more knee bend as one poster on here had indicated, and I am finding that I can get much more out of these C4 fins with this.....

......In dolphin kick, which I use alot, they are easy to use to full potential, but on the standard flutter kick ( or whatever you want to call our normal freedive alternating leg kick) there is some significant technique difference from my B&W Special fins ( which I believe are much the same as the Kelpies..and mine are mediums).....

As I get more familiar with the C4's, I am beginning to think that the only way you could really use much more stiffness or size, would be for dolphin kick only...with the big kick and long glide. so maybe this fin really is perfect afterall

Fins are still a big part of diving for me, so I still have an interest in experimenting...
Thanks to everyone here for helping with suggestions.

Regards,
Dan V
 
danvolker said:
.....I tried concentrating on more knee bend as one poster on here had indicated
Click to expand...
Hm, I indeed mentioned knee bend, but you may have misinterpret it. Normally you try to limit it as much as you can for continuous swimming. Well, now, if you need to change the direction or accelerate abruptly, pushing off after bending the knees may be efficient, but normally you kick with pretty stiff knees to achieve optimal style. When bending knees, you actually propulse quite asymmetrically, hence spending more energy in one direction of the kick than in the other, and exposing you to a bigger drag in the opposite way. Continuous symmetric kick with pretty straight legs is considered to be optimal.
 

I am not making any huge bends in the knee...just a minor change from what I did with my B&W's.....It appears a very tiny bend can bring some energy back, that you would not get with the softer freediving fins.....it may be more of a feeling, than a bend you could really notice..anyway, I am working on optimizing the kick for these fins....Tommorow morning I will use them on a charter boat scuba dive trip in Boynton...and the scuba use is something I am particularly excited about....

p.s.

The language to discuss the fin use and technology is much more difficult, than the actual technique itself...trying to discuss this here is an easy place to get the wrong idea across.....please do not assume I am not familiar with how to kick a freedivng fin--in fact, I have used freediving fins to keep up with fellow WKPP divers on "Gavin scooters" on many dives, so efficient use is not my problem....I am trying to find a new "ultimate" performance fin, along with any special technique required.

Regards,
Dan
 
If you feel you need to bend the knees to get more efficient kick, then it may mean that the blades are too hard for you. In that case indeed the continuous symmetrical kick will produce too much waste energy by moving water mostly vertically, because the blade does not bend sufficiently to follow the ideal curve. Instead of cutting through the water with a smooth and steady symmetric sinusoid, it moves it up and down like a solid wooden board. In such case the only what remains is pushing off with the knee bends, but that's really far from the optimal mode.

EDIT: And yes, I believe you know how to use the fins. The problem is that we often do not realize our own mistakes. Most of us use style which is far from perect. It is always easier seing the mistakes at others. That's why I also suggested you post a video.
 
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Like I said, I will be scuba diving with the C4's Saturday, and this will give me a lot more time to figure out how to get the most out of them.

I would take your last comments to indicate you are saying I should try to keep my knees absoutely stiff--straight.
I have always thought a very slight bend , near the beginning of the down kick, would allow more speed and efficiency..would you care to elaborate on the zero bend issue ?

Thanks,
Dan
 
There are perhaps different schools, but usually it is indeed being taught to kick with stiff/straight knees. Well, there is always some small bending inevitable due to strong resistive forces, so you will probably see a slight knee bend even at those freedivers using this style, but it is not something being done intentionally.

So the kick should be continuous, steady, constant, smooth, and symmetrical. In the moment you start bending your knees, the kick gets asymmetrical, impulsive / unsteady. The stronger ending kicks with the knee and feet may feel good because you feel the force of propulsion in that moment, but because of the non-constant character of exercising the propulsive force, it is less economic. Also the stronger end kicks create more turbulences, and the bent knee also causes more axial drag. In this way only parts of the blade serve to the propulsion. In contrary, with the regular steady/continuous kick, the blade follows the sinusoid wave in practically constant speed, smoothly cutting through the water with nice laminar flow without excess turbulences, permanently/continuously propulsing with the entire blade length (similar to the propulsive movement of sea snakes), not just pushing off inpulsively like it is the case with the knee bend kick.
 
Something to be aware of. The (almost) stiff knee technique works very well, but requires a very soft fin. The reason is the longer lever arm, the entire leg length instead of knee to fin. For the same leg strength, you can't put as much immediate force on the fin and a stiff fin won't bend enough to give efficient propulsion. A soft fin in this application can be very efficient, but still will have poor acceleration relative to a stiffer fin used with more knee bend. Bend your knees and really slam a soft fin and you overload it and get zilch propulsion.

Connor
 
cdavis said:
Something to be aware of. The (almost) stiff knee technique works very well, but requires a very soft fin.
Click to expand...
Yes, that's exact. With a stiff fin and stiff knees, you will only waste the energy vertically, without achieving much propulsion force. And that's also what I am trying to tell since the beginning. Although stiff fins may be great for acceleration and maneuvering, and feel powerful, they are not great at all for economical steady underwater swim.
 
Good discussion. I don't think many divers really understand the relationship between fin stiffness, acceleration, efficiency and kick styles.

As an example, with my skinny physique, a much softer fin than my kelpie mediums would be optimal for efficiency(along with a straighter leg). I've tried much softer fins and found them fabulous for smooth easy cruising, the feeling of the fin continuing to push long after I quit exerting was really neat. Loved the very soft fin until I needed some acceleration, which I do frequently. Love quickly turned to hate. I've experimented with harder fins, too much acceleration not enough efficiency, and found a happy medium that works for me.

Connor
 
Did 2 scuba dives today, and some shallow 50 foot freedives after a surface interval....The C4 fins.....Now concentrating on zero knee bend, I found the C4's nice for scuba diving---cruising like this, an occaisionally alternative with some big dolphin kicks and very long glides....this is great for scuba, as the extra stiffness handles the added mass of the scuba gear....Also did some frog kicks, found it is possible, even with the rails, if you really turn your foot a lot at the beginning and end of each kick--and this can work well as half dolphin and half frog kick too. When I wanted to go fast--to go upcurrent and get to some lobster 40 feet upcurrent, they did an excellent job.

For freedivng, the straight leg issue worked well, and they were easy to do this with--though absolutely zero bend requires me to think about it a little....
All for now...
Regards,
Dan
 
BTW, be quite careful with the C4 rails - they are very fragile and tear off easily after just a few weeks of use. I am not sure if it happens more in water (when the fins cross each other while kicking) or during transport, but be aware of it, and try protecting them as much as you can (for example packing each fin into a separate neoprene pocket when transporting in a bag).
 
trux said:
BTW, be quite careful with the C4 rails - they are very fragile and tear off easily after just a few weeks of use.
Click to expand...

does anyone know where C4 rails can be purchased or does a new blade have to be purchased? Mine are destroyed or anything- but there is one i wouldn't mind replacing.
 
Whopperhead said:
does anyone know where C4 rails can be purchased or does a new blade have to be purchased? Mine are destroyed or anything- but there is one i wouldn't mind replacing.
Click to expand...

Mark Laboccetta is the C4 rep in the Usa. All I hear about his customer service is enthusiastic.
contacts in his website:
C4 Fins
 
osusim said:
Do not mix freediving and scubadiving. It's not healthy ...
Click to expand...

When I was doing a lot of my tech dives with WKPP buddies ( George Irvine, Bill Mee, etc) each of us were dopplered to determine our bubbling rates from extreme deco profiles..... I happen to be an extremely fast offgasser, and my profiles on the recreational dives I did the other day, left me quite clean prior to when I went freediving---and my freediving was not particularly extreme....and, if I ever did something stupid enough for me to feel a dcs hit, I have my own O2 in a 30 cu foot tank, and I would take it down immediately to 20 feet and all symptoms would certainly resolve..to date, this has NEVER happened to me, and I have been doing this a very long time now

As far as general advice, yes, you are dead on....if a person is already bubbling, the up and down of freediving will make the bubbles larger, and increase risk for DCS greatly.

Regards,
Dan
 
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i forgot my C4's this weekend and went back "plastic" with my fave Imersion Greens (amazing, cheap, flexy, abusable fin). I noticed how much more work I had to do in the same dives. I would say I would use about 1/3 more force for the given horizontal surface swims, and about 1/2 more for ascents and decents.

Having said that, my dive comfort level was probably better than the previous week on the C4's, but thats more about sleep, rest, breathup, head, etc. If only I knew better why I have "good" and "bad" apnea weekends..

Also (probably just me) the skinny falcons helped me to have a straighter leg, with wider fins I often knock them together. I have a bad style.

It was MUCH nice crawling between the rocks and weed with the 60e plastic fins than the C4's though...
 
danvolker said:
When I was doing a lot of my tech dives with WKPP buddies ( George Irvine, Bill Mee, etc)
Click to expand...
Then you need for freediving TWO tanks of oxygen (if I understand this religion RIGHT) :t
And you do not need any fins or fins technique, only a fast scooter.
Using C4 with scuba like a using of Ferrari for off-road safari.
 
osusim said:
Then you need for freediving TWO tanks of oxygen (if I understand this religion RIGHT) :t
And you do not need any fins or fins technique, only a fast scooter.
Using C4 with scuba like a using of Ferrari for off-road safari.
Click to expand...



Don't worry, I am not about to start pouring out Kool aid....

Regards,
Dan
 
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