Fin basics

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I am a finned swimming instructor.
In finned swimming competitions (and in underwater velocity competitions, which is finned swimming with a small scuba tank) the athlet must attain maximum speed for significantly long times, so they want not only an high speed, but also an high efficiency.
If you look at their fins, they are typically monofins, long and "properly" flexible, built in low-loss elastic materials such as carbon fiber.
Each human is different, hence there is not a fin which is ideal for all. Everyone needs to find (or, better, to build) fins perfectly suited to his legs.
The three main parametrs are length, stiffness and angle between the sole and the blade.
After months or years of training, these parameters change, allowing for longer, stiffer fins, and reducing the angle.
Top athlets often need a negative angle (the blade coming up instead of being angled down).
Of course using long fins of proper stiffness require an efficient kicking style, which synchronizes with the natural resonance frequency of the fin.
This is more easy to obtain using a dolphin kick, bringing the fins into resonance using a flutter kick is feasible, but more difficult to obtain.
In any case the knees must be kept almost perfectly straight, people who flex their knees loose thrust and efficiency.
When I was working as a dive master at Maldives I was not allowed to use a monofin. So I did employ freediving fins, having chosen them with proper length and stiffness for being used with my medium-grade drag setup (15 liter steel tank, horse-collar BCD and 3mm fabric-covered neoprene suit). This allowed me to being able to swim against the strong current in the Maldives' channels for short periods.
But my wife, who is also a finned swimming instructor and uses much less air than me, was instead using top-length and very stiff freediving fins, with a 10 liters tank, no BCD and no diving suit.
This allowed her to reach even higher speed and to sustain it for longer periods.
In fact it was her task to savage customers ripped away by the current...
All that said, if you plan to dive often in strong currents, you should take a number of actions:
1) minimize drag, leaving on boat all the equipment you do not need, wearing a very streamlined suit with smooth external skin (or no suit), using a very small rear BCD-wing (or no BCD) and streamlined harness and equipment.
2) experiment with a number of different fins, trying to find, for each of them, the proper kicking style and kicking pace.
3) hire a finning instructor (I do not know if finned swimming is a sport usually practiced in the diving clubs of your town) and get trained to proper finning methods, including dolphin style, which is the faster and more powerful.
4) for maximum performance evaluate the usage of a monofin. This takes away a lot of control, so it requires advanced body and arms handling. Usually you find that girls who have years of experience in synchronized swimming, or having worked as mermaids, can handle well to use a monofin during general-purpose scuba diving.
 
I am pleased to say the Quattros made a world of difference.

Double dip on the Spiegel. The afternoon trip. When I got on, there was a real question as to whether it would be a go or not. The morning was cancelled because the current was just screaming!

By the afternoon, it was like a swimming pool. Warm and still and easy. I did notice an enormous difference even under those pleasant circumstances. Frog-kick, flutter, modified flutter, it didn't matter. Just one or two kicks and it was off to the races! We'll see how they do tomorrow on ordinary drift dives in W. Palm.

One thing I did notice is they give me heavy feet! Staying in trim was a bit difficult until I was able to determine the balance point. At which point, it was very nice to be able to adjust nose up/down by merely moving my feet a bit.

Just a quick plug. I went with Horizon Divers and hired a private guide for this. They are a super group and my guide AJ not only knew the wreck well but was a good coach for me as well.

P.S. While we would all like to not swim into currents, it is unavoidable. Part of this sport and doing it safely is anticipating the adverse and being equipped to manage it.

Thank you all for the advice and the ideas.
 
I am pleased to say the Quattros made a world of difference.

I am glad to hear you were pleased with the Quattros. They are a great all around, general purpose, go to fin. It is a rare trip that I would be the only diver in Quattros, they are a popular fin for good reasons.

James
 
Just a final follw-up.

Saturday I dove off the Breakers with my OW instructor who had a new class of students. He asked me to film them for post-dive debriefing. As many of you know, the current off the Breakers is typically pretty light and it as again on Saturday. For the first part of the dive, he and the students went down into one of the current protected amphitheaters and I stayed a couple meters above to film from that perspective. Staying in a static position was beyond easy. A gentle flutter or frog-kick and I just stayed in position. Any more effort, and I would easily move position into the current.

I like these! Easy to generate power and easy to control it. Quite happy with my purchase.
 

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