Diving to an underwater house/cabin....problems?

[yaffle]

Hi there,

Yesterday we had a discussion amongst some freedivers about diving in to an underwater house, and the problems that could occur from doing that.

In the Netherlands a dive club has, in a lake were we freedive a lot, just sunken an underwater housing. It is located at about 14 meters below the surface, and has the entrance in the bottom after which you can just breath in the house. They have installed a phone to the club house, video feed and fresh oxygen, so it's a pretty advanced and nice cabin.

We waved to the divers inside :wave:, and scared some of them , but did not enter since our mind screamed “warning,warning warning”, but after discussion on shore some of us thought it could be done next time.

The idea was that just entering with our compressed lungs at -14m and inhaling in the house, would cause our lungs to expand to normal size, and then when going up again, have the chance to rupture. But what if you go up very slowly and keep exhaling on the way?

Tips, thoughts and other insides welcome!

Greetings from Holland,
Yaffle

 

[alexrom1207]

I'm no expert, but I believe that breathing the air in the house at that depth would be the same as breathing from a scuba tank at that depth. Breathing out on the way up will prevent lung rupture, but you will still experience the same decompression needs to prevent the bends from setting in that any scuba guy would (I believe as a result of the oxygen in your bloodstream). For this reason I'd be a little leery. You should consult a decompression table, but I think that modern decompression tables require at least 1 decompression when coming up from 14m. Since I don't do scuba, I can't fill you in on the specifics, but I'm sure someone else can.

 

[Jorg]

In short: Don't breath in the underwater house, or you can have some serious trouble!

Besides rupture of the lungs, decompression is also a very big risk indeed.

If you want to go in, try scuba!

 

[rxcnc2]

Lung expansion: be careful. But if you start from the cabin with only 1/2
air or less, and additionally you exhale gently on the way up it
should be ok. Ascend slowly.

Decompression: it depends how long you spend there. I would say that
for a few minutes it's ok, if you plan to spend 1/2 hour or longer check
a DC table, or better yet ask what the divers do.

You have to talk to them anyway to see what they think of your "intrusion": in case of an accident they could become involuntarily involved.

Is it such a nice cabin inside that you absolutely have to go?

 

[osusim]

Even the uw house located on shallower water (about 10 meters) do not make stupid things. Any accident will create bad environment for freedivers in Maarseveen Lake.:naughty

 

[Erik]

It can be done, but be careful. DCS not likely, but the chance of rupture due to expanding air is really not worth the risk. You may intend to ascend with your lungs open, but what if you hiccup or swallow involuntarily? What if you panic? That 1 or 2 seconds with mouth closed could mean holes in your lungs.
As far as I can tell, wheelchairs are not fun.

 

[cdavis]

Looks a lot like the old hydro-lab that used to be off of Freeport, Bahamas. Spent some good times there. Damned uncomfortable place if you stay a few days.

In general, entering and breathing in such a habitat is not a great idea for a freediver. It can be done, but you need to be careful for at least three reasons. Of course, all divers must exhale high pressure gas on the way up. Also, if a freediver happened to have a mechanical(and completely unknown) constriction inside his lung tissue, it could cause some damage on the way up, if it did not "exhale" quickly enough. Finally, you have to treat such dives as scuba dives with LESS no-decompression time. Scuba tables assume a very slow rate of ascent. Freediver's fast ascent will create DCS problems where none would be present for a scuba diver with the same down time. I have no idea how much less no-decompression time a freediver would have. Caution says assume very short visits.

Connor

 

[ahofbauer]

Hi there!

Years ago, in one of the "Cenotes" of Yucatan in Mexico,
we filled the top of a small submerged cave with
air in such a way that we could later use it as a waypoint
station. The first air spillage was in fact rather an accident.
This place was some 12 meters below water level.

We had some minor decomp issues until we understood
that the time spent in this place had to be computed
as immersion time.

Nothing serious happened then, but it could have been
deadly.

It´s one of those things You only realize years later...

BE CAREFUL!!

 

[efattah]

I have done this many times. Breathing out of air pockets in wrecks between -8m and -24m. During the ascent, I would go very slowly (VERY slowly), feeling & concentrating on my lungs, exhaling slowly. Then you must exhale a bit faster as you approach the surface.

Also you need to use scuba DCS tables.

Also, after you do this, do not do any more freedives after, because that would be essentially 'freediving after scuba diving', which has increased DCS risk.

 

[wes]

In my youth about 25 years ago I built some structures in 25 feet of water with a Hookah type rig which was simply an air compressor and a hose, no regulator or mouth piece. I learned to breathe from the hose and safely did about 200 dives over the course of 2 years. Here are some safety precautions I took and things I learned.

1 - I got SCUBA certified before doing this. I strongly recommend that all divers, whether freediving or on SCUBA tanks get SCUBA certified if they enter the diving cabin.

2 - Practice free ascents alot while on SCUBA. They will be part of your open water certification and crucial to your safety and comfort freediving to this underwater cabin. You must learn to unconsciously and without effort passively exhale as you ascend. Note that if you do some freedives out of the cabin at depth and back into it you will be on compressed air so will have much more O2 available then at the surface, this should make your dives longer and more enjoyable. You may not always want to be breathing out, when diving down or sideways for example, its very very important to learn to breathe out when ascending. I learned after a while to constantly monitor my chest pressure and could easily let air out in a way that kept my lungs full without much thought.

3 - Figure out your Decompression tables. Remember it will be the depth of the hatch that is the depth you are at, not the top or bottom of the cabin or the bottom of the lake/ocean depth.

4 - If you decide to do some dives out from the bell and around and maybe to have some sound or music playing from the cabin that you can hear underwater. Once you practice you can easily swim to the source of sound underwater. When I would dive i would often be working or swiming around and loose track of my hose and I would listen for the bubbles and then swim right to the hose and breathe as the visibility was not always good on the bottom.

5 - Remember what you are doing is quite dangerous. Scuba diving is very dangerous and this in some ways combines the dangers of Scuba diving (deco sickness and air embolism) with the dangers of freediving (hypoxic BO). I did almost all my dives alone as I did not want to involve anyone else in the dangers of my activities and also i knew that if I did it very carefully I could compensate for most of the danger which I apparently did.

6. Have fun, it will be a blast.

Cheers Wes

 

[osusim]

I was there yesterday near by after "deep" training. The house located between 8 and 9 meters, platform at 10m. Nice to swim around and under but still see no reason to stay inside and take unnecessary risk.

 

[Mr. X]

Reminds me of the under water "tents" feature on several TV shows & in at least one movie in the 70's. I think it had a solid base with a hole for SCUBA divers to enter & exit. The "tent" was filled with air, so the divers could come off their tanks.

 

[yaffle]

Thanks all, for your reply's and insight. "Choose, and choose wisely" (can't remember the movie), and i choose thus to stay on the outside. Point taken. Eric's "Breathing out of air pockets in wrecks between -8m and -24m" exceptions transferred to my dreaming moments........
Be safe!

Yaffle

 

[LunkerBuster]

choose and choose wisely---third indiana jones movie, when choosing the chalice of the grail...the guy before him chose poorly

 

[sross]

Hi Yaffle,

I can understand where you're comimg from (better safe than sorry so-to-speak :crutch )

But if anyone else would like to think about doing it, or going in to another air pocket, perhaps the following would help. For example, going into the structure when it's only at 14 metres is quite doable, if you have to keep in mind certain things. I've gone in to air pockets without a tank in the past, and have used the following principles:

1. Decompression stops are not possible for freedivers, so once you know the depth of the air-water interface of the air pocket, you should find the no-decompression time limit for that depth, and stay well within it
2. For example, for safety's sake let's assume the access port of the habitat is at 15 metres - then the no-decompression time limit is 100 minutes *** if you have not done any repetitive diving *** (nota bene)
3. Repetitive dive exposure makes things incredibly complicated (see, for example: http://www.ndc.noaa.gov/pdfs/NoDecoAirTable.pdf ) It would probably be wise to make a dive to the air pocket your first dive of the day
4. I would stay no more than half of the standard dive table limits (more on that below) so make sure you have a watch with you with a reliable timer or elapsed time function, and get out by the time you've decided on
5. When you ascend, you've got to be very careful to override that training we've all had pounded in to us to not exhale while ascending- from 14 metres there's no question you would get a pulmonary embolism if you held your breath all the way up. You have to keep an open airway and exhale the surplus air as you come up.
6. You can't waste time going to the surface, head straight for the top at a safe ascent rate and don't spend time doing anything else outside the habitat before you go up. The reason is that exhaling can still cause a SWB. As you go up exhaling, the oxygen partial pressure is going down in your lungs, and you don't want to be too long in a situation where the oxygen is going out of your bloodstream into your lungs , instead of the other way 'round :mute .
7. Ascent rate- this is the bugbear of a freediver being at depth for any length of time. The BASC for example, recommends a 15 metre/minute ascent rate, so from a habitat entrance at 15 metres, you should plan on spending 1 minute getting to the top. I don't know if you've tried ascending at that rate (or even worse, the 9 m/min rate that is recommended in the USA) but to a freediver it seems excruciatingly slow, and you might find it hard to keep yourself to that particular ascent speed. Realistically, it would be best to have a computer that can show you your ascent rate. This is also the reason I mentioned staying well below the standard no-decompression limits, it gives you a margin of safety if you come up faster than the speeds recommended for the tables.
8. A final note: are you sure you know what's in the "air" pocket? These guidelines only apply if you've got a gas mix that is real air. If it's used air, contaminated air or some weird mix for some reason, the standard table can't be relied on. You should not spend any length of time in a pocket you don't know the composition of.

Remembering the challenges that exhaling on ascent can cause, it's obvious that the deeper the air pocket, the more limited your ability to stay any length of time in the pocket. You are particularly limited by safe ascent rates once you have been pressurized for any length of time.

I think I personally would limit myself to no more than 20 minutes at 20 metres. Each person would have to evaluate what their limitsought to be, based on their abilities and experience, - and have a watch/depth guage, or better, a dive computer, and follow your plan exactly.

 

[osusim]

It would probably be wise to make a dive to the air pocket your first dive of the day

It must be other way around.
Meanwhile some pipe underwater work was done at last Thursday to provide air and electricity to the underwater house.

 

[mccordia]

I heard 2 freedivers played around and inside the divingbell/house past week.
They didnt breathe inside the house, just continued their breathold while briefly peaking inside the cabin and scaring the scuba peeps...

 

[sross]

It would probably be wise to make a dive to the air pocket your first dive of the day

It must be other way around.

Hi Osusim,

The reason for going early to an air pocket/pressure situation is that if you've been doing repetetive diving, you've built up nitrogen in your circulation, and the no-decompression limits become more difficult to calculate.

The 100 minutes at 15 meters no decompression limit I mentioned is for a diver who starts the dive with no residual nitrogen. If you've been diving repetetively, building up residual nitrogen, then you can't stay down as long without decompression. If you've been doing relatively simple scuba dives, the calculations are doable manually, as you can see in the NOAA tables: http://www.ndc.noaa.gov/pdfs/NoDecoAirTable.pdf .

However, if you've built up a complicated repetetive dive profile freediving, calculating residual nitrogen is complicated- in fact, the only way I think it could be done would be with a computer.

 

[osusim]

sross,
diving to air pocket or underwater house is similar to scuba diving. So, you need to follow decompression procedure like safety stops. Any freediving activity after that will crash N2 bubbles in diver's body and much more increase risk of DCS. That's why we always follow the rule: freedive first, scuba dive later

P.S. There are no DNL scuba dives, practically all dives are decompression :t