Could this be used for mermaiding?

[spottedcatfish]

So I've been looking a finswimming, a sport you don't see much here in the U.S. There are three types of finswimming: Apnea (breath holding finswimming), surface, and immersion finswimming.

Immersion finswimming, basically involves a SCUBA tank, but instead of it being strapped onto your back, you hold it while swimming. I'm wondering if this could be done using a tail, as it would allow freedom of movement, and the ability to stay down longer. Is this more of a pool thing, or could it actually be used in open water?

Here's a video of the SCUBA tank in use with finswimming, and the swimmers swim very fast with it. Does anyone know anything about this piece of equipment?

http://www.youtube.com/watch?v=O_j0Lxa8_qk

[Winged Mermaid]

I don't know anything about it, but I must say.. WANT! *grabby hands*
May be jumping the gun, but I instantly thought that one could make a sleeve for the tank to make it a little more mermaid-y. Hope we can find some more info on this!

[MerAnthony]

I don't know if it can be used for mermaiding but with a tank it would seem a little bulky. Where would you put the tank? An how long can you stay underwater with the tank is another question? Now if maybe somebody designed a tank that could be hidden somewhere or to where it would not be noticed, That would be interesting to see.

[Joy&RaptorsUnrestrained!]

I don't know anything about it, but I must say.. WANT! *grabby hands*
May be jumping the gun, but I instantly thought that one could make a sleeve for the tank to make it a little more mermaid-y. Hope we can find some more info on this!

Oooh, Winged Mermaid, what if you designed the tank sleeve to look like a Mermaid Purse?

[Ashe]

Seems like a good idea, but I agree with MerAnthony. It would be a bit bulky and I know that I wouldn't enjoy it as much a breath holding. But if there was any way to disguise it a some sort of mermaid-like accessory...

[AniaR]

doesn't Hannah and Kariel both do something sorta like this? I've seen behind the scenes photos of them breathing from a mask before posing for a photo etc

[Morticia Mermaid]

Being a certified diver, I just wanted to let you know that to use any form of tanked air/breathing apparatus you need to be diving certified. I was looking into pony tanks myself, which are a LOT smaller and hold enough for about 9-15 breaths total. I was going to sell them with a "mermaid treasure satchel" as a disguise for the tank, but once I found that out, I'm only making them for people who can show me verification that they are in fact diver certified (I.e. send me a copy of their diver certification card)

[Capt Nemo]

I wouldn't want the liability that goes with selling "Life Support Equipment".

Yes, you need to be certified for ANY scuba use. (see Boyle's Law thread for the reason why)

Actually, finswimming with the cylinder out front acts like an aerospike and cuts drag quite a bit. But for open water, it could be a problem, as you will get jostled by waves and could have the cylinder slip from your hands. The cylinder will head for the bottom faster than you can swim, unless it's half or near empty, where an aluminium cylinder will go positively bouyant about 2 lbs.

For what we're doing, a 65 or 80 on a backpack is fine.

[MerAnthony]

As for hidding a tank that size that they use in that video is almost impossable. Now if there was some way to design a tank of some sort that can be hid under the tail between the legs or around the waist or something simaliar to that effect it could work.

[Capt Nemo]

Going with a Spare Air hidden in the tail would be a good idea for emergencies, such as getting your fin caught in a tree branch in open water, but for normal swimming, it's not worth it.

[Mermaid Melusinah]

I am also a certified diver. YES they can be used while mermaiding. However, you have to be certified in SCUBA in order to use them. There is not a dive shop that will likely sell or fill for you if you are not actually certified. if you arent certified, i highly recommend it. yes it can be costly, but its a certification for life and WELL WORTH the class costs!! Capt Nemo is also right as well ^_^ happy swimming!

[Winged Mermaid]

A tank small enough to hide would not be able to do much. It be one of the small ones mentioned above that only holds 10-15 surface breaths worth of air. Air tanks aren't meant to look pretty, they're meant to keep you alive! Can't really be too picky when it comes to being able to breathe underwater

[Mermaid Melanie]

If you really want to go down and get some awesome shots its a good idea to have a few safety divers- if you use a long hose configuration (which many tech divers use) you can simply work off of that. However you must be certified... well I wouldn't do this unless you are a competent diver. I plan on doing a shoot like this next month

[AptaMer]

Here's a video of the SCUBA tank in use with finswimming, and the swimmers swim very fast with it. Does anyone know anything about this piece of equipment?

Yes, I do. Finswimmers who compete in pools buy pony tanks, usually 6 cu ft (170 litres) models, and strip down a regulator so it will create as little drag as possible when you're swimming at high speed.

They're kind of pricey new. here's a listing http://www.leisurepro.com/1/2/2249-c...alve-6-cu.html

Pony tanks are very small bottles that extreme divers attach to their regular tank to provide a redundant air supply if they need to get themselves or a buddy to the surface in the event of an out-of-air or equipment failure situation. If you assume a swimmer tends to use about 1.7 litres of air per breath near the surface, you could expect to get maybe 100 breaths using a 6-footer. Of course finswimmers are working hard so they probably don't get that many, but they just need enough air to complete the race without surfacing.

In the case of open-water finswimming there are specially modified tanks sold that have a housing and stabilizing fin installed to reduce water drag and help you swim in a straight line. For orienteering you can also install a compass in the stabilizer.. here's an example of a really high end open water tank



You may notice that the guy is also wearing a special open water finswimming mask that minimizes drag when you're swimming at high speed.

[Kumori Kitsune]

great idea i was thinking that

[green52]

I think it'd be cool to have a small pony bottle. As long as we're all clear on their limited capacity, it might be neat to take one or two breaths underwater while otherwise free diving. Of course, it might not be worth the hassle in practice.

[AptaMer]

I think it'd be cool to have a small pony bottle. As long as we're all clear on their limited capacity, it might be neat to take one or two breaths underwater while otherwise free diving. Of course, it might not be worth the hassle in practice.

Freediving down to depth, then breathing in compressed air is very dangerous.

It should only be done by very experienced freedivers who know what they are doing, and have rehearsed how to manage the dive safely. Some trainers recommend never mixing compressed air with freediving.

[Seatan]

I don't know much about freediving, but wouldn't it have the same effect as with scuba, where you just need to exhale as you ascend and not out swim your bubbles? I mean, even though you are not supposed to you can descend without your regulator in, put it in down below, breathe in air, them ascend. You just need to make sure you exhale properly as you rise, like they teach in certification courses.

[AptaMer]

I don't know much about freediving, but wouldn't it have the same effect as with scuba, where you just need to exhale as you ascend and not out swim your bubbles?

That's a major issue. People have done this successfully, but there have been disasters too. Here are some of the issues.

1. Barotrauma
People have forgotten to change from breath holding to keeping a clear airway, and there have been some disastrous consequences, including arterial embolisms.

Nobody should do this without practicing beforehand, and developing the mindset to remain completely calm and consider every step of what they do.

There's more though.

2. Buoyancy Control
When you freedive down to any significant depth, your lungs shrink considerably. For example at 10 m/33 ft deep your lungs will be down to almost 1/2 the volume they had at the surface.

When you take a breath of compressed air your lungs refill to their original volume and you get a sudden shot of buoyancy that can shoot you up a few feet if you're not ready for it.

If you're not prepared, and maintain a clear airway when this buoyancy boost happens even a rise of as little as .6m/4 ft can cause a lung injury.

More science geekiness follows below.

I mean, even though you are not supposed to you can descend without your regulator in, put it in down below, breathe in air, them ascend. You just need to make sure you exhale properly as you rise, like they teach in certification courses.

3. Decompression Sickness
Many people are unaware that it is possible to get decompression sickness (the bends) from freediving. As you freedive, repeated dives start to accumulate nitrogen in your body. Repeated diving to significant depth will build up nitrogen in your body, and the so-called fast compartment may be a problem, but I'm not aware of research studies that have figured much out about nitrogen buildup during repeated freedives.

If you're going deep you need to wait at the surface before each dive down to let the nitrogen come back out. For example, some freedivers use a rule of thumb of keeping deep dives to less than three minutes underwater and then breathing on the surface for at least 10 minutes before going back down again. Some people use 5 minute rest intervals, or others. It does seem that 5 minutes is the time constant of the so-called fast compartment, but there will be slow exchange between that compartment and tissues that take up nitrogen more slowly. I personally think 5 minutes is too short, and 10 minutes is better. If you are the kind of freediver who can stay down for more than 3 minutes (I'm not ) then you should stay on the surface even longer between dives.

Going down with Scuba gear and putting in a regulator once you're down, without having dived beforehand is not the same as freediving down and up repeatedly, then using a small tank. This is also different from going down using the tank the first time, then freediving afterwards once your spare air or pony tank is used up.

Remember how the lungs expand when you breathe compressed air? What also happens is that gas exchange starts happening faster, and nitrogen accumulation starts happening faster. This throws your schedule for degassing from your freediving out of whack, and remember that you've already accumulate some low level of nitrogen in your body from your previous freedives.

Now, think about rising at 10 m/ min or 30 ft/min as many people recommend for scuba diving ( http://www.diversalertnetwork.org/de...?a=news&id=514 )

If you've gone down to 10 metres, it would take you 1 minute to get to the surface. From 20 metres or 66 feet, it would take you 2 minutes. Unless you're the type of freediver who can take that kind of time to go to the surface, and are able to maintain a calm frame of mind, this has the potential to lead to a fast, panic-style ascent, and this is where the unknown tissue nitrogen load may, and in fact has, led to bubbling and DCS. Again, they key is to be experienced, to know what you're doing, to be confident, and to maintain a very conservative dive time and decompression schedule.

Note that all of this is relevant for people going deep. You're not going to have any worries about decompression if you're just diving down a short distance, say like the mermaids at WeekiWatchee Springs who go under the surface, maybe at most down to 15 feet, and breathe compressed air from a hose.

4. Shallow Water Blackout
This is a huge unknown, but when you increase your lungs' volume and exchange capacity by breathing compressed air at depth, you must reduce the time you stay at the bottom greatly from what you're used to. The reason is, as you go into oxygen deficit, you will transfer oxygen to your bloodstream faster, and carbon dioxide, the gas that warns you, may not accumulate in the lungs as fast. This is actually a big unknown.

What is certain, though, is that as you rise and exhale your excess air to avoid embolism, the partial pressure of oxygen goes down fast. At a minimum this reduces the rate of transfer of oxygen to your bloodstream, and this can even lead to the situation where oxygen starts moving in the wrong direction. There hasn't been enough people doing this for a lot of evidence to be gathered, but my opinion is that you should be much more conservative on your time limits if you want to avoid SWB or sambas.



I hope this gas been helpful. I'm not saying you shouldn't do it. Just be aware of the possible pitfalls, and go way more conservative about breathhold time and decompression than you would if you were either scuba diving only, or only freediving.

[SweeteSiren]

Thanks for using your science geekiness to keep us all safe. You rock!