Extreme Dolfinism

[REVAN]

I enjoy visiting the monofin forum on Deeper Blue to see what new and interesting information I can learn, but for the past month we seem to be going through a bit of a dry spell. There just has not been enough fun stuff being posted to satisfy my cravings. Perhaps others have been feeling the same. Instead of sulking, I thought it’s time that I did something about it and open a new thread to discuss interesting monofin developments.

Monofins have been gaining popularity among freedivers, but I think they have shortcomings when applied to this sport and are not ideal devices to be used for freediving. Monofins originated with finswimming races, and as such were optimized for speed. To be fast, they had to be efficient, which is the one element that attracts freedivers. They have evolved slightly to make them more suited for freediving, incorporating a softer fin-blade and more angle between the blade and the foot, but I believe they still retain many aspects of their racing heritage that negatively impact their usefulness to freedivers. These aspects are acceptable or completely unimportant to racing, but can be a big deal to a freediver.

Among these are:

· The fin layout dictates a large torque integral about fin’s interface to the swimmer when the fin is stroked. Therefore, effective power transmission requires a tight fitting foot pocket and freedivers must try to strike a balance between comfort and efficiency. Evidence of freedivers trying to find the right compromise is all over this monofin forum.

· Streamlining for the swimmer’s foot, hyperfin-style, not only increases the length of the lever-arm which exacerbates the torque load problem, it loses the heal support to the foot for counteracting the torque, requiring the reaction forces to instead be carried through weaker bones of the foot. This is an uncomfortable price to pay for efficiency.

· Monofins don’t have much tolerance for accommodating environmental equipment. This is not an issue in a swimming pool where finswiming races are conducted, but freedivers sometimes swim where it is cold and a bare foot requirement is not acceptable.

· The fin blade oil-cans when it deflects. In addition to being noisy which scares off marine life and being distracting to the diver’s relaxation and enjoyment, the oil-caning is destructive to the fin itself and shortens its lifespan to an unacceptable duration for non-racing applications. (See Example - Breaking Monofin)

· Monofins are large, fragile and sometimes heavy. These features make them challenging to travel with. Unless you happen to have an awesome diving location near your home such that you have no desire to travel with your monofin, this can be a really big deal to a freediver.

I’m sure this list can be added to, but these are the big ones that I can think of. Please feel free to respond regarding other aspects of monofins that you find are issues to freediving.

I think we can to better, and I have a plan. Quite simply, I’m evolving a freediving monofin that does not have a heritage to finswimming monofins. As such, I think it has the potential to evade these issues and become “the right stuff” for freediving technology. This is an ongoing project and I think the best way to introduce it is over a period of time as it develops. The Lunocet model of development in total isolation did not have a positive outcome when the product finally made it to the hands of freedivers and I don’t want to repeat their mistake. Furthermore, I think the Lonocet may have made some people a little tech-shy regarding monofins, and the best way to overcome that is through lively interaction and discussion.

I’ll be posting new material to this thread periodically and responding to comments and questions so check back often if this topic is interesting to you. Being a project in development, your interaction can have a positive effect to the outcome and final product’s development.

Thanks in advance,
Ron

[Spear0Joe]

Trux and co will have a field day!

[REVAN]

The attached images show where I'm starting from. If you are unfamiliar with it, this is the DOL-Fin Classic. (For more info go to Smith Aerospace - Products.) It was designed primarily for scuba diving. However, it is not too shabby at recreational freediving either. The main issue with this fin regarding freediving is that this fin is a little like a tug boat. Being designed for scuba applications, it is geared toward producing high levels of thrust at low speeds for propelling a high-drag diver with scuba equipment through the water. Freedivers, on the other hand, have much lower drag and usually swim much faster than do scuba divers. So, the package needs to be reworked for the new loads and speeds of freediving.

The positive attributes to starting with the DOL-Fin architecture are:

· The fin layout minimizes the torque integral about fin’s interface to the swimmer for a given thrust production. Therefore, it will be much easier to strike a balance between comfort and efficiency, perhaps to the point of making no compromises at all.
· The bindings are designed to be used with a dive sock and are adjustable, so cold water environments are not issues.
· The fin itself is incredibly sturdy. There will be no issues with oil-canning of the fin blade or durability.
· It is light weight and travels relatively easy (using a snow-board bag as a dive gear bag).

So, how do we take this and evolve it into the ultimate freediving fin?
....

[monofin_diva]

this is waaaay beyond me, i just put on my monofin and off i go!

but i'm really intrigued by what you're doing.

be sure to keep us posted!

[monkeyhatfork]

I disagree that all current monofins oilcan, I thinks it results mainly if you have uneven pressure bettween your feet causing the blade to warp a bit during the bend, i,ve only experienced this on a few occasions when I was out of the water for a bit and my technique got rusty. I think you can not only focus on function, current monos have a special kind of grace and beauty especialy on film which which cannot be denied, no matter how efficient it may be if it looks like a dorky science experiment or you look awkward swimming with it, then it will be a hard sell. People who prefer warm water diving or pools i think much prefer going barefoot. Pool disiplines are an important part of this sport and this fin doesnt look to practical for the pool. Just a few thoughts hope not discouraging, having failed at a few attemps at making my own monos I have huge respect for anyone who tries to improve our underwater experience.

[REVAN]

Originally Posted by monkeyhatfork

I disagree that all current monofins oilcan, I thinks it results mainly if you have uneven pressure bettween your feet causing the blade to warp a bit during the bend, i,ve only experienced this on a few occasions when I was out of the water for a bit and my technique got rusty. I think you can not only focus on function, current monos have a special kind of grace and beauty especialy on film which which cannot be denied, no matter how efficient it may be if it looks like a dorky science experiment or you look awkward swimming with it, then it will be a hard sell. People who prefer warm water diving or pools i think much prefer going barefoot. Pool disiplines are an important part of this sport and this fin doesnt look to practical for the pool. Just a few thoughts hope not discouraging, having failed at a few attemps at making my own monos I have huge respect for anyone who tries to improve our underwater experience.

Thanks for the comments. I like to hear what people are thinking. It is better than being ignored!

I can appreciate your skepticism of my dorky science project. Personally, I don’t believe that is a good description of what I’m doing, but then you don’t know where any of this is going yet, and I do. I agree with you that monofins have a grace and beauty about them, but that does not mean that something different will not also have grace and beauty. I believe that what works good, eventually looks good, even if you are not used to it at first. Experience and exposure are lethal to prejudices, and if it works well, you are likely to get plenty of both.

I think all the monofins currently available are oil-canning to some degree. However, the main issue isn’t whether or not they do it; it is the short lifespan the fins tend to have. The oil-canning may be contributing to the short lifespan, but it is not in itself a direct functional problem for the monofin (noise aside). DivingDane and mattbigblue have both opened forum threads regarding cracked monofin blades very recently, so it will be hard to argue that monofin durability is not an issue for freedivers.

I also have a comment regarding people preferring to go barefoot when diving in warm water. Here, the term “barefoot” is actually a misnomer and I should not have used that term to begin with. Unless you are diving no-fins (or possibly with an aqueon), you will not be “barefoot”. The question is what are you wearing on your feet, and why? Someone feel free to correct me if I’m wrong, but I think the reason people wear monofins without using dive socks is that it provides better power transmission to the fin than would be provided if they also had dive socks on. So, people’s preference is for efficient power transmission into forward thrust and it really has nothing to do with whether or not a dive sock is involved. The notion of “barefoot” being preferred assumes certain predisposed functional characteristics of the design of the monofin and foot pocket.

[wet]

I have wondered whether there might be a soft "fabric" fin, unbreakable, that worked more like a tensional sail of a clipper ship rather than a compressive blade of a windmill. It would require a different set of muscle movements, and might or might not be as effective in free diving as conventional monofins. Just a doodling thought.

[monkeyhatfork]

O.k. maybe dorky not the best choice of words, and not nessesarily aimed directly at your project, but a group of attemps i.e. lunacet, aqueon, etc. videos of these fins often look very awkward. I think people rather like the idea of taking on the appearance of an aquatic animal and you get that to a degree with current monos as opposed to looking like a human with high tech gear is what I mean by science project. As for blade durability I've never had an issue and all my fins are still going strong after much use, these are hand made though and occasionally someone will be unlucky and get a bad one, they are also usually shipped very long distances sometimes in less than ideal packaging so some come to you pre-abused. Yes the transmision of force is better without socks but I also think I have a better feel of how the blade is moving through the water. My biggest problem is footpocket sizing everyone has different feet even two people with a size 10 foot can fit in a pocket completely different, I have short, wide, high arch feet which mean most pockets sqeeze very tight at the entrance of the pocket and then are too loose toward the toes so an ajustable pocket without drag or loss of power transfer would be great. Have you used your fin in the pool, can you do kick turns of a wall with it? I have an MFA in printmaking so unfortunately I don't have any real sound technical advise to give you, but do consider aesthetics because it will matter to people, wheather they will admit it or not.

[monkeyhatfork]

Look at the surfing world, Laird Hamilton and his crew developed the foil board, he has all the credibility in the world, has proved it worked, and yet no one else will use it. Yet this same group starts stand-up paddling and everone and thier mom went out and got a stand up board. So there are many other forces at work other than just function you have to tap into if your goal is a successfull product. But by all means improve fuction, cause nobody want a pretty piece of junk either.

[REVAN]

Originally Posted by monkeyhatfork

Look at the surfing world, Laird Hamilton and his crew developed the foil board, he has all the credibility in the world, has proved it worked, and yet no one else will use it. Yet this same group starts stand-up paddling and everone and thier mom went out and got a stand up board.

That is a very interesting example. I’ll offer my opinions on why that is. If you have any more insights, I think we could all benefit from a thorough analysis.

I have seen the foil-board in action (in videos only), and my first impression was “wow, that’s cool”. I looked into it further and found examples of the foil being attached to a windsurfer which also looked wicked cool. However, an interesting piece of evidence was observable in one of the windsurfing videos. Two boards surfing in the same wind with similar size sails (as well as can be determined from a video) and I could see the board without the foils going noticeably faster than the one with them. The foil system had more drag than the planning hull of the surfboard. Granted, it provides a smother ride than the planning hull, but it comes at the expense of exchanging a stable degree-of-freedom for a neutral degree-of-freedom that the rider needs to actively control. Given that surfers already ride on awesome shock absorbers (the surfer’s legs), the smooth ride is not really worth much. To sum up, the foil-board is both slower and harder to use. For recreation, that translates into less fun.

On the other hand, the stand-up paddleboard eliminates the most difficult part of surfing; the part where you need to transition from belly paddling to standing up. By starting from a standing position and using a paddle to get going, surfing became easier to learn and required less physical strength to catch a wave which made it more accessible to more people. In short, add a little complexity to the equipment-set in a way that makes it easier to use, and the recreational market grows. More people can get access to the fun of surfing a wave, and so they do.

Translating this example back to Extreme Dolphinism; my hope is that if I can build a high-performance fin system that is more comfortable, adaptable and easy to use than the currently available equipment, it will make freediving more accessible and enjoyable. Hopefully, this will grow the recreational freediving market, which is the foundation for all aspects of the sport.

[trux]

Ron,

I bet there are plenty of people who would love to try it, but I am afraid you won't find many freedivers who would purchase the fin before there are known personalities using it, and confirming it is really useful, efficient, and practical. One way would be sponsoring an excellent athlete who'd try setting a new record or a PB with it. If he/she really manages it, it will be an excellent argument for others to try it too. Another way to promote the product would be making tours at competitions, or sending a couple of samples to some national federations or bigger freediving clubs, so that people have the chance to test it without billing out $1200.

You can also consider promoting the fin more in Europe, and perhaps even more specifically in France, Italy, and Spain - that's currently a much bigger market for freediving products. For example in France alone there are more organized freedivers than in all AIDA worldwide. There is also a very popular freediving / spearfishing printed magazine, which brings every month reviews of equipment. JeanCharles Naes ("Avida Dollars" here on DB) makes most of the tests and writes the reviews, so consider contacting him and asking to test your fins too. You can't get any better promotion here than a test published in the magazine, and on his website. You can see some of his past tests on his own website too: PSMCAFE, toute l'info sur la Chasse sous marine, l'Apnée, Snorkeling & Photo subaquatique - Tests

And of course in the printed magazine Apnea too. Their website is here, but the reviews are not published online: APNEE, CHASSE SOUS MARINE, PLONGEE, SPORTS SUB AQUATIQUES

And, other European Med countries represent huge market too. I have hands on some more detailed statistics, so if you are interested, let me know.

[Fondueset]

With much trial and error - and practice - I've nearly overcome the fit/comfort problem with my hyperfins.

One thing I do not see in your design - and which the lunocet also lacked - is energy storage.

This really adds to the grace and feel of a monofin and is probably what I missed most in trying both the lunocet and the Dol-fin. (the very small energy storage in the lunocet - which comes from the silicone webbing - is barely noticeable.

Also - have the fin extend out lengthwise does intensive the leverage/core-strength issue - but also amplifies movement - improving streamlining by enabling smaller movements.

[titan]

I would prefer to see hyperfins or mustang shoes with another kind of blade probaly smaller blade with more width has anyone tried something like this ?!?!?!

[REVAN]

For dolphins, fish, birds and flying insects moving at their preferred cruising speed, the ratio of flapping frequency and amplitude to forward speed is constrained to a narrow but efficient range of values. This dimensionless ratio is called a Strouhal number, and evolution seems to favor efficient swimming motion with a Strouhal number in the range of 0.2–0.4. For cetations and fish this means that for every full cycle flap of a tail, the animal will move forward between 2.5 to 5 times the distance of the flap amplitude with the optimum distance being about 3.3 times the amplitude. (If you did not catch it, these values are just the inverse of the Strouhal numbers.)

After nearly 100 years of powered human flight, we have finally gotten smart enough in fluid mechanics to determine that this range of operation is in fact more efficient for the production of thrust, and if you look at finswimmers, you will see the ratio is usually right around 3. Also, a DOL-Fin scuba diver achieves about 3 times the fin amplitude per stroke. However, drop all of the drag producing scuba equipment and the fin produces enough thrust to propel the diver almost 5 times the fin amplitude per stroke. Though not bad, this is at the extreme edge of the preferred operating window. An ideal freediving monofin would be closer to the sweet-spot near 3. In my next segment, I’ll discuss how to get there (a point that Fondeuset already hit upon).

[Fondueset]

Nice reply Revan. You logic is like a glass of water