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Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

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Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#1  Postby aquaholic » Mon Dec 10, 2007 10:49 pm

Just to start a discussion - Why do you think it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single ta

Post Number:#2  Postby dp » Mon Dec 10, 2007 11:12 pm

erm.... running out of air?

:P
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single ta

Post Number:#3  Postby aquaholic » Mon Dec 10, 2007 11:28 pm

BuluDalam wrote:erm.... running out of air?

:P


True, that may be the ultimate result, but what are the sort of things that you have to consider that may cause it to happen?
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single ta

Post Number:#4  Postby ikan » Mon Dec 10, 2007 11:34 pm

Ur breathing patterns?? .....
if u are going to be dumb, u better be tough ....
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single ta

Post Number:#5  Postby dp » Tue Dec 11, 2007 12:09 am

aquaholic wrote:
BuluDalam wrote:erm.... running out of air?

:P


True, that may be the ultimate result, but what are the sort of things that you have to consider that may cause it to happen?



Hmmmm.. assuming that the diver stays within his/her NDL, the chances of getting hit by narcosis is higher. At which point, R Kelly's "I believe i can fly" will start playing in the divers head.

And we all know what can happen after that, esp at places like Sipadan.

:)
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#6  Postby John F SeaDemon » Tue Dec 11, 2007 12:14 am

Hello Bulu Dalam...are you talking about me? :D :D :D :D :D
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single ta

Post Number:#7  Postby dp » Tue Dec 11, 2007 12:42 am

SeaDemon wrote:Hello Bulu Dalam...are you talking about me? :D :D :D :D :D


u topside oso can narc...

:P :P :P :P :P :P :P :P :P :P :P :P :P :P :P
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single ta

Post Number:#8  Postby tulip » Tue Dec 11, 2007 12:50 am

BuluDalam wrote:
SeaDemon wrote:Hello Bulu Dalam...are you talking about me? :D :D :D :D :D


u topside oso can narc...

:P :P :P :P :P :P :P :P :P :P :P :P :P :P :P


:D :D :D :D :D :D
err... huh?
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#9  Postby Nazir Amin » Tue Dec 11, 2007 12:57 am

errmmm.. why do people need to be at 40m.. i dont think is worth to be that deep just to see nothing  ;) anyway i heard a term of TnG previously. anyone mind to share about the TnG thingy..  :)
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#10  Postby aquaholic » Tue Dec 11, 2007 1:11 am

4321, I think you meant people shouldn't go deep unnecessarily and especially when they did not plan for it. People dive deep for a reason (primarily to dive wrecks) and they plan ahead for it.

If you simply go deep during a recreational dive, I agree you will see nothing.
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single ta

Post Number:#11  Postby HoleMaster » Tue Dec 11, 2007 10:03 am

Based on PADI standards, u can still dive at 40m with a single tank ie still within the No Decompression Limits. Altho the RDP limits at 42m, it is only for emergency purposes. Max dive time at 40m is 8 min. However if u exceed those depths, it is Decompression Diving, of which u need the special training and equipments (twin tanks, stage bottles and etc). Diving exceeding 40m without proper training and equipments is dangerous because will result to:
-Impaired judgment due to nitrogen narcosis which is more serious at depth more than 40m
-Decompression sickness. To avoid u need to do deco stops. Nitrogen being inert gas are greatly absorbed into body tissues when breathed under high pressure. As such it must slowly released from body tissues by deco stops at various depths during the ascent to the surface. And to accelerate ur deco stops that's why u see tech divers carry stage bottles (higher O2 content) where they will use it at shallow depths to off gas their Nitrogen intake

My 2 sen worth opinion. Btw im not a tekkie. :glasses9:
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#12  Postby aquaholic » Tue Dec 11, 2007 11:33 am

I agree recreational divers are allowed to do no-deco dives to 40m. Someone might then ask if it is allowed, then why should it be dangerous? The intent of this thread is to clearly spell out the risks involved, hopefully in simple terms, so that it can be understood by all level of divers.

There are several reasons why deep no-deco single tank dives are frowned upon.
a) minimum allowable bottom time for no-deco dives means not much can be achieved during the dive (Holemaster, you correctly pointed out 8mins is allowed, but that includes 2mins of descent time to get there, so you only have 6mins left at the bottom)
b) because of item (a), there is an increase risk of divers losing track of time and the dive becoming a deco dive. You will have insufficient air if deco is required.
c) even if you managed to stick to the short no-deco times, you are at the edge of getting into deco. Hence you are susceptible to DCS – it is recommended that you do a 3 minute safety stop at 6m.
d) however, the most obvious major issue (which everyone correctly identified) is that a single tank has inadequate air when things go wrong.

Next topic: What can possibly go wrong during a deep dive using single tank?
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#13  Postby HoleMaster » Tue Dec 11, 2007 6:59 pm

I went too technical...btw what u mentioned aquaholic is very true ie from a different perspective
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single ta

Post Number:#14  Postby Nizaha » Tue Dec 11, 2007 8:50 pm

How about if the instructor conducting PADI Deep specialties at 40mtr with single tank with no deco obligations?
It's safe [-( [-(

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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#15  Postby aquaholic » Tue Dec 11, 2007 9:47 pm

I suppose instrutor-led PADI Deep specialities would mean that the divers have been briefed on the risks involved. Also during deep dive training, the instructor will be keeping his/her student very close in case something happens! :D :D :D
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#16  Postby aquaholic » Tue Dec 11, 2007 10:19 pm

HoleMaster wrote:I went too technical...


I thought you mentioned earlier you're not a tekkie  :D :D :D
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#17  Postby kimseng the maverick rogue » Wed Dec 12, 2007 10:56 am

BuluDalam wrote:
aquaholic wrote:
BuluDalam wrote:erm.... running out of air?

:P


True, that may be the ultimate result, but what are the sort of things that you have to consider that may cause it to happen?



Hmmmm.. assuming that the diver stays within his/her NDL, the chances of getting hit by narcosis is higher. At which point, R Kelly's "I believe i can fly" will start playing in the divers head.

And we all know what can happen after that, esp at places like Sipadan.

:)



only 1 more thing to add... sipadan down current or any down current at all!!!!! i usually end up doing deco right after...
know ur risks
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#18  Postby SuperKingKong® » Wed Dec 12, 2007 11:02 am

aquaholic wrote:4321, I think you meant people shouldn't go deep unnecessarily and especially when they did not plan for it. People dive deep for a reason (primarily to dive wrecks) and they plan ahead for it.

If you simply go deep during a recreational dive, I agree you will see nothing.


i don't think rec divers go down to that depth to see things.. rather it's a "macho" act to them... something like "see.. i've been down to 40m leh.. can u do it??"
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#19  Postby SuperKingKong® » Wed Dec 12, 2007 11:05 am

kimseng wrote:
BuluDalam wrote:
aquaholic wrote:
BuluDalam wrote:erm.... running out of air?

:P


True, that may be the ultimate result, but what are the sort of things that you have to consider that may cause it to happen?



Hmmmm.. assuming that the diver stays within his/her NDL, the chances of getting hit by narcosis is higher. At which point, R Kelly's "I believe i can fly" will start playing in the divers head.

And we all know what can happen after that, esp at places like Sipadan.

:)



only 1 more thing to add... sipadan down current or any down current at all!!!!! i usually end up doing deco right after...
know ur risks


hey kimseng,
can you please elaborate what do you do to deco with a single tank?
cheers...
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#20  Postby kimseng the maverick rogue » Wed Dec 12, 2007 11:23 am

KingKongKering® wrote:
hey kimseng,
can you please elaborate what do you do to deco with a single tank?


kkk,
serve the time my computer screaming me to do  :D (like going to jail)
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#21  Postby JD » Wed Dec 12, 2007 11:32 am

KingKongKering® wrote:
kimseng wrote:
BuluDalam wrote:
aquaholic wrote:
BuluDalam wrote:erm.... running out of air?

:P


True, that may be the ultimate result, but what are the sort of things that you have to consider that may cause it to happen?



Hmmmm.. assuming that the diver stays within his/her NDL, the chances of getting hit by narcosis is higher. At which point, R Kelly's "I believe i can fly" will start playing in the divers head.

And we all know what can happen after that, esp at places like Sipadan.

:)



only 1 more thing to add... sipadan down current or any down current at all!!!!! i usually end up doing deco right after...
know ur risks


hey kimseng,
can you please elaborate what do you do to deco with a single tank?


What actually is a down current and up current. What does it do to you underwater and how do you overcome it if you don't mind sharing?
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#22  Postby kimseng the maverick rogue » Wed Dec 12, 2007 11:44 am

JD wrote:
What actually is a down current and up current. What does it do to you underwater and how do you overcome it if you don't mind sharing?


JD,
current that flow vertically. usually lasts on short burts... but there are exceptions...
if it happens just try ur best on going the opposite direction...
upcurrent are more dangerous in my opinion - when i happens swim downwards and exhale more
downcurrent - swim upwards, mind ur speed after the current slowly dies off
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#23  Postby SuperKingKong® » Wed Dec 12, 2007 11:49 am

kimseng wrote:
KingKongKering® wrote:
hey kimseng,
can you please elaborate what do you do to deco with a single tank?


kkk,
serve the time my computer screaming me to do  :D (like going to jail)


ehehee... thanks for the info :)
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#24  Postby JD » Wed Dec 12, 2007 11:57 am

kimseng wrote:
JD wrote:
What actually is a down current and up current. What does it do to you underwater and how do you overcome it if you don't mind sharing?


JD,
current that flow vertically. usually lasts on short burts... but there are exceptions...
if it happens just try ur best on going the opposite direction...
upcurrent are more dangerous in my opinion - when i happens swim downwards and exhale more
downcurrent - swim upwards, mind ur speed after the current slowly dies off

Thanks for the info bro.Have not experience it before.Will keep in in mind.
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#25  Postby Adzri » Wed Dec 12, 2007 12:51 pm

KingKongKering® wrote:
aquaholic wrote:4321, I think you meant people shouldn't go deep unnecessarily and especially when they did not plan for it. People dive deep for a reason (primarily to dive wrecks) and they plan ahead for it.

If you simply go deep during a recreational dive, I agree you will see nothing.


i don't think rec divers go down to that depth to see things.. rather it's a "macho" act to them... something like "see.. i've been down to 40m leh.. can u do it??"



SKK rec divers went deep to look for those stuff divers (rec & techies) accidently dropped. i.e. camera, dive com, scooter, pointer, ROV, Sunblock, Okely and many more :D :D :D :D

No ... Im just joking!!!!!

It all about ego ... and the desire to chalenge yourself, experience the adrenalin being deep eventhough very risky. At one time im one of those divers you catergorised as MACHO diver. Went down beyond my level of certification, had some problem, luckily I was bailed by the DM and buddies. Regret doing it ever since and never after that practice this dangerous Diving attitude.

As what aquaholic said was very true...at deep, we are living a small amount of space to manage the problem if its happening (with a single tank). We are putting our buddies at risk as well and jeoperdizing thier diving holiday in general if something bad happened due to our personel ego.

But we are humans, the more people said we shouldnt to this and that, the more we want to do it. Some are lucky and some are not. Im the lucky one in this case because Im still alive. But for sure I will not do it again. If I think I want to go deep, I will take a proper course to prepare myself to cope with such environment. Thats why I have a huge respect to the techies, all they know is to keep on reminding themselves and others about safe diving. Or perhaps due to the fact that they are so coutious about being safe, and so obsessed towards it, diving in deep water is much safer than us the recreational diving.

So next time if you want to see hammerhead in Sipadan or want to explore Seven sea or POW, bring down compressor with you twin tank at least and offcourse take the course la.

For me I like the big fish, small fish, cute fish, ugly fish, nice fish and bad fish and all at 12 meters only  ;) ;) ;) ;)
Last edited by Anonymous on Wed Dec 12, 2007 2:03 pm, edited 1 time in total.
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Re: Why it is dangerous to do a deep no-deco dive (say to 40m) using a single tank?

Post Number:#26  Postby aquaholic » Wed Dec 12, 2007 1:24 pm

40m dives are supposed to be within recreational limit. Thus the rulebook implies it is safe to do single tank dives to 40m.....this is true most of the time. There is still a remote chance that a problem might occur during the deep dive. This thread is meant to educate divers on the risks involved for deep dives and get them thinking  :)

With the limited amount of air in a single tank, you have very little room for error. If a diver encounters a problem at 40m, any mitigating action on the diver's part must be correct first time and his/her reaction time must be fast. Small mistakes can lead to potentially life threatening situations.

What can possibly go wrong during deep 40m dives using a single tank? (single tank here means common S80 tank)
(To put this issue into context, you only have 6mins bottom time at 40m for no-deco dive)

a) Getting narked (slower response time / false sense of security / euphoria)
b) You or your buddy encountering a catastrophic free flow or tank valve failure at 40m (i.e. need to buddy breathe from a single tank)
c) You encountering a catastrophic free flow or tank valve failure at 40m and your buddy is nowhere in sight (no means to safeguard your remaining air supply or having a stage cylinder to fallback on)
d) Finding yourself having to do deco stops and soon realizing that you and your buddy have insufficient air to complete the stops (and having to make the ultimate diver's decision - that getting bent/paralysed is better than drowning)
e) Anything else that can result in you spending more time at the bottom than planned and having to do deco stops (e.g. downcurrent, getting snagged on something, and simple things like watching/photographing marine life)
f) Anything else that can result in you using more air than planned (e.g. finning against current, anxiety attacks from being narked, and simple things like watching/photographing marine life)

Deep dives requires planning and going through “what if” scenarios. Simply going deep on a whim may be safe 99% of the time....but there's still that 1% chance that you might unlucky!!!
Dive safe  ;)
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