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Extreme Dolfinism

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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neurodoc said:
How long is the pool that you are swimming in for the video? and, what was your time for 5k?
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Hi neurodoc,

I am really happy you responded. I was afraid no one will bother a bit on this topic

The pool is 50 meters long, I am swimming it on around one minute. A try to stick with a relaxed approach which is necessary for longer distances.

5 km time was 2 hours 28 minutes. But I spent at least those 28 minutes on fighting with the gear I was trying to pull behind me - an iPhone in a Tupperware dose for GPS tracking, a kids surf for a rescue scenario... Only after I have given up on all the gear I started swimming properly.

Endomondo | Community based on free GPS tracking of sports
 
Off topic, apologies - can you please kindly point me to navigation gear for surface swimmers? I dream of an iphone app with bluetooth earphones which would tell me "bear left".

What is the name of such app? Which bt earphones? Which iphone waterproof case?

Thanks.
 
One final entry, my 5 years old son swimming with X20. I put his Crocs shoes into my 45 size shoes. He only had 5 minutes training.




Ron - if you want to emphasize in your marketing communication how universal X20 is, lets agree that if a video of this kid swimming properly with X20 reaches 500 youtube views, you will provide me with a propotype of a kids edition of a hydrofoil / ronofin.


 
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Hi Mukiker,

Thanks for your contributions!

Ok here some suggestions.

Use a narrower blade, this will reduce the power needed much, whilst still using it with Ron's thorough research, experimentation, experience.

It's also likely you need to develop stronger muscles. Do strength exercises for belly, back quadriceps.

Also I suggest you push a small body board ahead on those long swims. On this you can put water, food, first aid etc. But more importantly rest both of your hands.

As for tracking your distance, there are HR monitors that are waterproof and have a gps tracking included.

Another option is to have your peddles floating a bit, keeping your arms up in the water.

A good friend of mine does not allow his young children to do monofinning, because their backs need to develop first.

When I swim with my hyperfin long distances I don't crawl, I alternate swimming on my belly, sides, back. About 800m across a lake and back. In my technique I'm not slapping the fin, instead I'm pushing focussing on having pure balanced movement.

Success!
 
Mukiker said:
...Ron says that there is a 25% drag penalization for hands not being stretched...
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That figure assumes swimming underwater. Surface swimming is a very different situation that includes wave drag which does not exist when underwater. I have not made any measurements at the surface.

I think Kars has some good advice for you. I concur with his statements with the possible exception of the comment on narrower fin blade. He could be right, but I also think the increased drag from surface swimming may favor the wider blade, as it will have more static thrust (assuming you have the strength to power it). I'd be inclined to bring the fin back to the short arm mount first and see if that does not work better for you. In general, high drag conditions favor larger fin blades on shorter arms. At least, that it how I see it.

If you want a narrower fin blade, it is relatively easy to cut the length down, but you should be pretty sure that is what you want to do. Once you cut it shorter, you can't go back to longer again without getting another foil.
 
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Ron, I've followed (and enjoyed) this thread since its inception. Here's a question: While I understand the advantages of using the cycling shoes, would it be possible to use a simple plate interface to attach footpockets to the fin? The reason I ask is that some of us have figured out a footpocket/fin bootie combination that works really well and it would be nice to apply that combination to the new fin. If the footpocket were not too elastic, introducing an additional variable, wouldn't that work? might also provide a way to give a user some familiarity if they do not like the cycling shoe idea.
Personally, I've raced and ridden road bicycles for the last 30 years, and two years of swimming has finally gotten my feet (and spine!) limbered up again as cycling shoes had made them quite stiff. I have even changed the shoes I wear to walk in to ones that allow more foot range of motion. So, the idea of switching to a new fin with cycling shoes is not as appealing to me as if the new fin had a footpocket option. I hope that makes sense-I've rambled somewhat!
 
I recommended a shorter foil from the general accepted: longer distance needs a softer fin. Since he tied to make it softer, and I notice his a bit jerky technique in the video, and dipping of the arms and snorkel I came to the idea a softer fin would benefit. I think the smaller foil makes it easier to have a proper and efficient technique within the swimmers capacity during the whole 5km swim.
 
Ron, and Kars-would changing the "angle of attack" of the fin have the same effect as a softer fin? So, allowing the X-20 blade to move farther before hitting the trim tab, would simulate a softer fin? Would that be similar to switching from a "conventional" monofin (no angle) to a "hyperfin" (maybe 22 degree angle)? I currently swim with a Waterways Nemo, #2 blade, and find that when I fatigue I start pulling the snorkel underwater when surface swimming. I had originally been thinking of switching to a hyperfin but if I understand the effect of the trim tabs, Ron's fin would do this too but in an adjustable manner-instead of having to have a sprint fin and a long-distance fin. Ron, am I correct on that? I do a lot of surface swimming as well as practicing underwater, and love it for exercise. And, I'd love to do both with the same fin, and be able to do sprints too!
 
Neurodoc,

It would be possible to do what you suggest with footpockets. This is basically what I did with the Shimano shoe, and it could be done again using another foot interface system. There just needs to be enough market influence to justify the costs of doing the work and carrying the product line. At present, I don't think there is enough market demand to support the development costs of another design, as I think the shoe works pretty well and will get the job done with better performance, comfort and style than a design based on bi-fin foot pockets. If you think I am mistaken on this and have ideas you want to develop, feel free to PM me and make your case. I could be persuaded to work with a partner who wants to expand the DOL-Fin product line.

Also, the different trim plates change the "angle-of-incidence" control for the fin (which may have been what you meant when you said "angle-of-attack"). Though not the same thing, AOI and AOA are related to each other. Firstly, the trim plate options are there to customize the fin to a swimmer's ankle flexibility. However, just as AOI is related to AOA, the trim plates secondary use is to match the fin's angle control to the swimmer's preference for stroke thrust and resistance. In this way, it has similar efficacy to selecting different blade stiffness in a traditional monofin.

Kars,

As I said, you may be correct about the narrower fin span in this case. I just would not go strait to that option as it is not so easy to go back. I'd dwell on some other options first and see how that goes before cutting the fin down. In any case, I'm glad that you are voicing your opinions. I think you have some good advice to offer.
 
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Reactions: Kars
Mukiker said:
5 km time was 2 hours 28 minutes.
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Just out of curiosity, do you know what time you need to cover that distance without fins? Just to see whether there is a problem with the use of the fin, or whether the time is proportionally corresponding to your no-fin swim.

Perhaps for the surface swim a modification of the connection of the hydrofoil blade to the shoes could be done to keep the blade much deeper under surface. It is clear that on the surface, there is enourmous loss, and on the video I have the feeling that you strugle quite a bit and propulse actually more with the hands than with the fin.
 
Seeing how fin pockets with interchangeable blades work - it is an interesting option. I've not seen the X20 - so I don't know how the shoe connection is set up, but I could picture some kind of interchangeable mounting plate since fin pockets essentially slide onto the blades.

I've been working quite a bit on surface technique with my hyperfin. Specifically 'slow-swimming' in a way that uses whatever waves might be around and minimal physical effort - so that when I arrive at my dive site I have minimal recovery time before being able to have and effective surface interval.
 
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Yes, I understand that the slow rythm may be on purpose, but I meant comparing no-fin and DOL-fin swims of about the same effort, of course. Just to see how it looks like with the efficiency, and whether there is some serious problem with the fin configuration or technique, or whether it is just a false impression from the video. I admit that it is not quite clear whether the pool is 25m or 50m. If it is a 50m pool, it is not that bad at all, finally, after the second look.
 
Now I have some thoughts about the videos.

Of course I may be completely wrong!

From surface swimming with my mono - I think it is a mistake to emphasize the upstroke over the down. With this technique you are missing out on gravity-assist - using body-position and weight to generate thrust. With the upstroke technique you must rely completely on your muscles - the movement also drives the rest of the body down - which you are countering with your arm stroke. I have practiced upstroke quite a bit in the pool - in order to make sure I am getting all I can from my fin. It is less efficient during submerged swimming, and much more so on the surface.

A better method would be a slower downstroke - emphasizing time-under-thrust over frequency and better employing the glide aspect of the foil while minimizing effort. I am able to get forward glide on the surface with my mono fin by using very slight tension in response to surface waves (works best going into or with the waves). For this it is helpful to think of the fin as a wing.

When using my arms with the fin I time the power phase of the armstroke with a full-body (very little knee) downstroke - which is more a straightening of the body using the frontal musculature. Amplitude is quite small but because I am at the surface gravity helps make a good glide ratio with not much effort. I leave the other arm extended forward for streamline and counterweight. Properly done the fin lifts the body - creating more thrust-as-glide because of weight.

Hope thats all comprehensible (not to mention if it actually works with the Dol-fin)
 
Reactions: Kars

I've been thinking more about your concept and questions.

Primary observations:

- You are offloading some of your propulsive effort to your arms. As such, you will have less localized fatigue. Understandably, this will have the potential to increase your endurance and range.

- Your techniques is very relaxed, which is also very good for endurance.

- Offloading the downstroke of the fin will reduce the surface interference because the stroke that starts at the surface is not producing much thrust. The return stroke that originates deeper underwater is now your primary power stroke. This same reason is why swimming on your back with a monofin is so effective. It inverts the power stroke which starts it deep under the water, achieving a similar effect, but with higher overall power and thrust.

It is all very interesting, and I have never seen anyone else use such a technique.

I mainly distance swim when I'm sea-hiking. It is different from what you are doing, in that I am primarily underwater. However, on several occasions, I have covered miles through the water in 20 meter hops underwater with about three to four surface breaths through the snorkel between dives. It is great hypercapnic training. :t

I suspect that as your core strength improves, you may want to increase the thrust from the down-stroke of your fin and pick up the pace of your swim. You will be less susceptible to ocean currents with a faster swimming pace.
 
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Interesting ideas, thanks for posting.

For long distance, using arms as well as legs makes huge sense. The trick is how to do it efficiently. As Ron indicated, being on the surface changes the drag effects considerably. I experimented with your pattern, multiple kicks between arm strokes, and it worked for me except I used a different kick and found three kicks worked better than 2. At the speed you quoted, it was so relaxed that swimming multiple kilometers should be no problem at all.

The type of kick you use makes a big difference. I used a straight leg kick, essentially no undulation, mostly ankle with a tiny bit of hip and knee action. For me, a mostly ankle action kick is faster(on the surface) than undulating and, at low speeds, much more relaxed. You might be different, but have someone video you using your undulating style and then using a straight legged ankle kick. I think you will see much less surface turbulence(that translates into drag) with the ankle kick. On the surface, with the upper part of the body partly out of the water, you lose half the channeling of water that makes undulation so efficient. Net result, ankle is easier(at least for me) Note: I make no modifications to my fin for these experiments.

On carrying stuff. A buggy board can be towed with little or no drag. Use a leash that is a cheap, nylon cord one, not a spring like good one. Attach it to your leg and forget about it once you start moving. Works great with bifins and, as long as the line passes above the x20, it should work just as well.

Connor
 
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Food for thought! I seem to stay most relaxed with my arms in classic mono fin position. I've been using my arms mainly just when my shoulders get a little tense. The stroke I've been using involves thrusting the lead arm straight through the water - rather than lifting it out - then pulling down as I extend the other arm. The accompanying fin stroke is more like lifting my rear out of the water - with mostly straight legs. As mentioned I'm using the darkfin gloves - which really add some oomph to the arm stroke. I'm sensing some points of divergence with the Dol-fin technique - it sounds like the Dol-fin requires a little more movement. I'd have to have one for quite awhile before I could really measure it against my mono fin.
 
I'm just guessing here Connor. A buggy board is really a boogie board full of lobsters. Right?
 

Firstly I am no expert, just a beginner, and don't do distance swimming.

I am only posting because I have been doing a very similar stroke to you for a while but for short fast swims using small swimming fins. Just in case it helps, couple of things I do differently:

1. I swim more 'underwater' between breathing

2. I breathe every 3 strokes

3. I try to keep the undulation going even when I breathe. I use the momentum of the 3rd stroke and the arm stroke to bring my head above water, so in the period I breathing my arm is recovering to the front.

Your style is interesting as it looks more of a cross between front crawl and butterfly - looks much more relaxed than mine though as you glide/float on the surface for longer and during the arm stroke it looks like you can relax the rest of your body... Will give it a go next time I am in the water..
 
Right. Should have mentioned, a bag really full of lobster adds considerable drag to a buggy board.

Connor
 
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