Question: Freediving vs. SCUBA and diver drag

[REVAN]

I came across this short report on diver drag. The last page is the summary chart. At 1.5 ft/sec they show about 5 pounds drag for a single tank diver and about half that (2.6 pounds) for a diver without the scuba equipment (but everything else). So, strapping that single 80 cubic foot aluminum scuba tank on the back of a basic freediver is expected to double that diver's in-water drag.

This is interesting, because the tank is so much smaller than the diver. So, why does it double the drag? I think the answer lies in the interference effects between the diver and the scuba system.

If that scuba system could reconfigured to magically add no additional drag to the freediver, would the freediver become interested in using the scuba equipment?

I'd be interested to hear people's comments in the issue. Might you be interested in trying scuba equipment, if it allows you to swim as efficiently and as fast or faster than you do now? Are people who like to freedive interested in taking dive times from 2 to 3 minutes up to 40 minutes or an hour in duration as long as it doesn't slow you down in the water, or would it still be unappealing for other reasons?

 

[cdavis]

Interesting research. I'd have said the drag increase was more than double, but my experience includes a horse collar BC and some other stuff, not quite comparable.

Just me, but I don't think I would be much interested in scuba, even if the drag effects were similar. My main objection was the weight and hassle of scuba gear. Another issue, its not feasible to take scuba on my size boat for the length of trip I take.

There is another factor that might be affected if you could make the drag similar. Can't quantify it very well, but free diving is just more "free" It feels better, more like flying(my childhood dream). Maybe reducing the drag would make scuba "feel" the same.

 

[Kars]

Scuba and freediving are both very different experiences.
Expectations are also very different, and the people doing each are different.

To cut it short, being a freediver for about 10 years, I now practice scuba diving in a very different way. I breath much less; am more silent, swim much more efficient, and choose and arrange my setup with drag in mind. I wear long fins (Cressi Gara2000HF), use a 5mm nylon + open cell suit, carry no weights (my 15l tank was heavy enough), and wear a Sphera or Micromask. Thanks to this I'm faster and more air efficient then the others, using half of what they need. Also it made me realise that I only need a 10L or even an 8L tank to make no compression dives to 20-30m, which would again make my setup lighter and faster. Knowing freediving would influence my choice for equipment greatly! I would prefer to have low drag, but durable stabilising jacket, a low drag and resistance regulator, smoothskin sleeves, and pants, low drag computer, and tugged away console. All cool and fine, but...
The thing is that my buddy needs to be able to keep up with my speed and abilities. And you know that there are many overweight divers who love the carry properties of water, and avoid anything that might look like sport, because it makes them painfully aware of their physical short comings.
As a scuba diver I'm not aiming to make record distances. What I am looking for is nice animals, vista's enjoying the underwater environment and the fraternity of the diving scene.
Frankly I do not see much use in a mono for scuba; because the buddies cannot keep up, and it's unpracticality in manoeuvring in tight spaces on the bottom and surface. However Low Drag Gear (TM ) would be nice for scuba, especially in currents.
Navy Seals may find more use, infiltration and exfiltration (when speed and exhaustion is important) , if they also change their very draggy gear. I believe that the navy rather schedules a bit more time, then to teach the soldiers how to use the monofin, as swimming for some of them appears to be a challenge. (horrible scissor leg DNF's!)

For scubadiving I would love to have a silent, no bubble regulator, so I can enjoy the silence (cue Depeche Mode).

 

[prospector]

Freediving is living in a dream. Scuba is like driving a cement mixer to a construction site.

 

[REVAN]

Freediving is living in a dream. Scuba is like driving a cement mixer to a construction site.

If the scuba equipment could swim with that feeling of freedom, would that change the situation. Don't worry about how. This is more of a thought experiment at this stage. Assume that when you are swimming underway, that it will be hard to tell the difference between the freediving and scuba diving, except that you can magically breath when using the scuba equipment (therefore we can expect reduced dive-reflex/blood-shift).

 

[Lehmann108]

Many freedivers also scuba. It is a very, very different experience.

 

[Bill McIntyre]

People who choose free diving over SCUBA diving do it for all sorts of reasons, but I doubt that drag even enters their minds.

 

[Chipswim]

Interesting topic and comments.... Something between the two?

 

[Chipswim]

 

[REVAN]

Thanks for compiling the pictures Chipswim. Illustrations always spice things up.

 

[HydroApprentice]

Well, I think the question should be directed more towards SCUBA divers, and how much they'd like the idea of streamlined equipment. My guess is that it's a big step up for scubies, whereas it is a "not-so-big" step down for freedivers. My guess is that this tech would have a lot of potential in the SCUBA market

 

[baiyoke]

Well, I think the question should be directed more towards SCUBA divers, and how much they'd like the idea of streamlined equipment. My guess is that it's a big step up for scubies, whereas it is a "not-so-big" step down for freedivers. My guess is that this tech would have a lot of potential in the SCUBA market

My first and allmost immediate tought was along the lines of the above. It could be a big step up for SCUBAs, but it's not something that would extend what I do in freediving. I do something very different. Allthough I have great respect for SCUBA, it's just a different thing, just like table tennis and cricket are two different things despite similarities.

However: It is really difficult to relate to NOW, before the tech and practices are here. Like if someone came to me in the year 2000 asking "How about if we made a telephone, and you could use it instead of your computer, or even watch videos on it, and perhaps send money and buy stuff...?" I would have replied "What??! On a phone... No way!"

I think this could be really exciting for the SCUBA market, and they also spend a lot more than the more "cheap" freedivers... Going from cheap 50 $ bifins to a good 500-800 $ monofin is a big step. I think that many SCUBAs got basic gear for more than 3000 $ perhaps even much more...

One thing though. I don't get your first post Ron, can you be more explicit about this:

At 1.5 ft/sec they show about 5 pounds drag for a single tank diver and about half that (2.6 pounds) for a diver without the scuba equipment (but everything else). So, strapping that single 80 cubic foot aluminum scuba tank on the back of a basic freediver is expected to double that diver's in-water drag.

It is ONLY the tank, or tank plus everything else? Because this "strapping that single 80 cubic foot aluminum scuba tank on the back of a basic freediver" is not the case, since the BCD must add alot of drag also. Please specify

 

[cdavis]

The experimental data Revan is referencing only used a tank and regulator, did not include a a BC or other draggy gear.

 

[baiyoke]

The experimental data Revan is referencing only used a tank and regulator, did not include a a BC or other draggy gear.

Oh, sorry, didn't see the link refernce on my phone.

I don't know if I'm having an off day but that paper is one big mess to mee... What's figure 2? It seems like it was part of an unsuccesfull attempt, but there's no further mention. If 1 out of 2 attempts is messed up, surely more attempts would be a good idea + a detailed descriptionof the factors contributing. Why is the "trunks only" curve not increasing exponentially in that figure (2)? Why is there a configuration (trunk+mask+fins) that is not in the table (1)? There's mention of both frictional and Eddy drag, but nothing further explanation except from "Eddy resistance is much larger than the frictional component, suggesting that significant drag reduction is possible by streamlining the equipment". How did they conclude that? Why do a study without the BCD? Are these trustworthy data?

Apart from the above it's interesting of course. Speed is rather slow limited to app. .15-0.5 m/s. It would be interesting to see a DYN specifik study with freedivers... but that is not what this thread is about

 

[Chipswim]

This looks like fun to me. I think it is a good example for this topic.

There are a few youtube videos of this guy and a female swimmer in Morrison Cave.

His rig seems to be quite home made and functional. When you hear his voice on the video with the girl it is very distinctive. Some one here must know him?

I think the genius in his design is that he punches a hole in the water with the tank.... Then swims through that same hole!

Here is a photo of a girl with a clever tank cover to make it lower in drag than his. The video guy still goes OK especially considering his tank is blunt end first. He needs her tank cover:

 

[baiyoke]

SCUBA-CRUISING!!! That sure looks like fun. Almost a new kind of diving

But there are some safety concerns to consider...

 

[REVAN]

It's a government report, no doubt the people involved were going to get paid regardless of how well they did their job. Like @cdavis said, there is no mention of a BCD, and I concur that test #1 was nothing more than a failed attempt where they learned that body position is important to have right to get meaningful data. More tests are needed, and if I were to pursue anything along these lines, that is the first thing I'd do.

This is a bit of a conundrum. My first thought was to talk to scuba divers about this. But, upon seeing how I presently DOL-Fin scuba dive (which would be my jumping off point for any further developments), I was met with feverish resistance. You'd have thought I was preaching witchcraft to fire and brimstone evangelicals. It seems stupid, but the responses I got would indicate that most of the scuba divers are only interested in swimming backward and spinning in circles. Actually swimming forward is something they don't appear to care about improving.

I have come across very few scuba divers who care about drag and swimming performance, and so far, every single one that does care has been a freediver who also scuba dives. So, freediving appears to be the common thread to all interests in swimming performance while diving.

 

[REVAN]

This looks like fun to me. I think it is a good example for this topic.

There are a few youtube videos of this guy and a female swimmer in Morrison Cave.

His rig seems to be quite home made and functional. When you hear his voice on the video with the girl it is very distinctive. Some one here must know him?

I think the genius in his design is that he punches a hole in the water with the tank.... Then swims through that same hole!...

I think that is a DB member in the video you posted, I'm trying to remember his name, [ @rems doesn't connect to an account ]. He dives at Morrison Springs in W. Florida. His rig is designed after the underwater orienteering kits used in Russia and eastern european nations. This type of gear configuration has a big drag advantage by eliminating all the interference drag issues, but also has a big disadvantage that it occupies your arms making it not very appropriate for recreational scuba diving. I have always wondered if it would be possible to somehow back mount, or body mount a tank, but get rid of the interference issues that create all the extra drag.

 

[John B Griffith Jr]

Kars, I'm, appropriating your term, Low Drag Gear (TM ). So, I started as a snorkeler/freediver as a child in Hawaii; graduated to SCUBA at 12, and have dived every conceivable rig and contraption from US Navy MK5 to double steel 120's and my deco gas. Tried some side mount, Tech rigs, etc. I went back to Freediving (not exclusively) because I got tired of lugging a bunch of weight around..not the drag...but I do NOT miss the drag. In the DIR movement, the idea is to "streamline" and make gear as line-trap free as possible. Low Drag Gear (TM ) would fit nicely into this ideal. Most Technical Divers now seem to practice this approach to minimal, or streamlined gear configurations. What I see as the logical next-step is rebreathers...smaller, lighter and much less noise than SCUBA rigs...extended times and range. Otherwise, fins and a mask for me.

 

[cdavis]

How about mount the tank between the divers legs, like the scooter diving I've seen?

Fins for scuba diving is a subject that is trickier than it seems. When long fins first arrived in my area, we were doing a lot of scuba spearfishing that required covering a lot of ground. Long fins were a godsend, far far superior to jetfins(the next best). I figured long fins would sweep the scuba diving world. Nope. Boggles my mind, but you see lots of scuba literature that puts down long fins. As REVAN notes, most scuba divers just aren't interested much in propulsion and/or aren't in good enough shape to make use of more efficient technology.

That said, there are pockets of the market that do care, just like us with the original long fins. When we figured out how good they were, every serious spearo on the Florida West Coast switched to long fins, and it happened fast. You just got to find them.