Author Topic: Actual Low on air (Read 2027 times)

nanda666 · « **on:** February 22, 2008, 10:49:51 AM »

Just a simple question based on the earlier story on the 2 experienced divers getting into a Low On Air situation.

How much is it actually?

I've seen divers finish a dive with 120 bar, 100 bar, 50 bar, 30 bar and even 0 bar!!

the general rule is that low on air is 50 bar and we signal the DM.....at what depth?

What is a safe and reasonal amount of air to have when you start a standard 3 min safety stop at 5 m?
I, like most divers, want to get the most of my 200 bar...right?

Any ideas guys?

reen · « **Reply #1 on:** February 22, 2008, 11:11:54 AM »

What i know is by 50 bar you already must save it for the safety stop, compulsary if you are doing the deep dive.

So meaning at 28meter of depth, dont la jusst only want to signal air low to the DM..

add: at what specific depth ..i cant say...cause every person is different with their air consumption...best way is to tell either your DM or yr buddy of your balance bar before it reaches 50..remember diving is suppose to be safe and njoyable..

nanda666 · « **Reply #2 on:** February 22, 2008, 11:16:47 AM »

Quote from: reen on February 22, 2008, 11:11:54 AM

What i know is by 50 bar you already must save it for the safety stop, compulsary if you are doing the deep dive.

So meaning at 28meter of depth, dont la jusst only want to signal air low to the DM..

So how much should you have at 28m before you decide.... "that the last shot of that Mola-mola lah!!!" ????

John F SeaDemon · « **Reply #3 on:** February 22, 2008, 11:55:43 AM »

Taking an average surface air consumption of the recreational diver, at 28 meters, on 50 BAR you would have around 5 minutes before your air is completely depleted. Disclaimer: This figure does not apply to everyone as each individual's consumption rate differs.

The 50 BAR ruling is to give you enough buffer to surface safely after making an adequate safety stop to off-gas. 50 BAR is when you start ascending to the surface, with a safety stop in between. Yes, there are those who do finish off ALL air. What these people need to think about is in the event of an emergency: downcurrent that pulls you further down; or a Tiger Shark suddenly appears and is at a depth between you and your dive boat. That's when you are in real trouble.

Besides adhering to the 50 BAR ruling, you should also know your own rate of air consumption. It comes in handy when you are in trouble.

nanda666 · « **Reply #4 on:** February 22, 2008, 12:12:17 PM »

thanks, boss!!

and this is exactly what I mean. Consumption and sea conditions may differ considerably on a dive.

so it come down to experience and as the earlier story shows, can be wrong. Dead wrong!

We, "so called experienced", divers are sometimes soooo into our underwater photography that we tend to push that 50 bar limit....sometimes by just a little...everytime.....

Guilty as charged as I've done it too!!! (Telling myself that 30 bar is enough la....

)

I strongly feel that the message is not clearly sent across.

There are some things that is best not to @#$% with and depth, bottom time and air remaining are the most critical.

This is my opinion,

Depth: if the limit is 40m, than that's it.

LOA: if it's 50 bar, than that's it. (If your buddy runs out first, go up with him or her.....not say, " you go ahead...I've got a few more shots to take!!!

)

Bottom time: follow your tables and dive coms. (Not agak agak....)

For other stuff......have fun la....

but that's just my opinion..

reen · « **Reply #5 on:** February 22, 2008, 12:13:27 PM »

Quote from: nanda666 on February 22, 2008, 11:16:47 AM

So how much should you have at 28m before you decide.... "that the last shot of that Mola-mola lah!!!" ????

When we are doing deep dive we will do the deepest and then to the shallow rite?
so if you are taking a shoot for mola2 at 28m, i'll bet you still have around at least more than 130bar..isssh
dunno laa if u breathing like mad coww....noo offenseee neee~~
furthermore...can you stay >15mins at the same 28m of depth??
breathing rate is different to each divers..so you should at least have some idea at what rate your air consumption...
I dunno about you or the rest of the MUWians-->i never received any advise telling me..."ok reen at this depth ..or this depth...when you are about to reach 50 bar..u signal meee ok.."
i just get..."reen...when you are about to reach 50bar..signal ok"...
thusssss...my brain says...better be safe then sorry...no matter what depth...when i'm 100bar i better be
around the shallow depth.
i've heard story of a diver doing a 20m CESA...would you like to try that?? hehehehe..

seee...seeee the big sifuuu Seademon oso saysss..."individual's consumption rate differs"...

Andy · « **Reply #6 on:** February 22, 2008, 01:08:05 PM »

50 bar is the rule of thumb. IMO, here are some of the reasons:

1) Longer safety stop required - Although recreational divers should not even think about getting into decomp dives, it happens during one's dives for sure one time or another. You may need that extra air to get you that extra few minutes of safety stops.

2) Remember your buddy? - Bear in mind that there is also added responsibility that everyone has, a buddy. Although you may adhere to the 50 bar rule, your buddy may not. Or vice versa. It is nice to have some air left if one of the divers are in trouble.

3) Choppy sea - When diving with liveaboards, you may surface in really really choppy seas, with thunder storms maybe. While the dingy is busy picking up other divers, and even when you are at ther surface, it is difficult to breath with few meter high waves keep pounding on your face. In that instance, it will be nice to have some air left, and able to breath through your reg while you are waiting for your pick up.

Every diver should have a habbit of glancing over at the SPG every so often during the course of a dive, not waiting until the dive master or dive leader signal you to do so. Once getting use to it, there is no reason to surface with no air and giving an excuse of forgeting to check your air while diving. It is your life on the line (not to mention your buddy's too).

When you drive, you do check how much petrol you have right

? Same same here..

JD · « **Reply #7 on:** February 22, 2008, 03:15:22 PM »

Just want to add:

Another golden rule is Don't Panic! Keep a cool head and analize the options..but if your doing Technical dives your in deep s**t man

kimseng the maverick rogue · « **Reply #8 on:** February 22, 2008, 03:22:15 PM »

50 bar is good cause it's the 1/4 of the usual pressure of the tank. Just have to plan ahead.
If you want to get to precision. Don't read my next sentence...

i.e. if you suck

150 bar for 30 min then 50 bar should last you for another 10 min. but this is a very general idea...
this is the usual way i try to explain to my students. nothing too technical. even if i do there is no way to specifically determine exactly as there are too many variables involved

nanda666 · « **Reply #9 on:** February 22, 2008, 04:00:37 PM »

Quote from: kimseng on February 22, 2008, 03:22:15 PM

50 bar is good cause it's the 1/4 of the usual pressure of the tank. Just have to plan ahead.
If you want to get to precision. Don't read my next sentence...

i.e. if you suck 150 bar for 30 min then 50 bar should last you for another 10 min. but this is a very general idea...
this is the usual way i try to explain to my students. nothing too technical. even if i do there is no way to specifically determine exactly as there are too many variables involved

yup yup....that sounds about right....cool..

Snafu · « **Reply #10 on:** February 23, 2008, 04:51:10 AM »

Say 180bar is in my cylinder when i start the dive.

Rule of 3rd applies for me... 60 bar to location, 60 bar to return to boat & 60 bar in my cylinder when I am on the boat.

If u do wrong surface consumption rate calculation & not applying ur 1st stage IP & ur depth in ATA....U be in so much trouble

I supposed being Dive Pro we all need to know all this, as we need to be able to make the dive safer for our student

are we?

Sicko · « **Reply #11 on:** February 23, 2008, 10:06:36 AM »

Quote from: Syed K. A. on February 23, 2008, 04:51:10 AM

Say 180bar is in my cylinder when i start the dive.

Rule of 3rd applies for me... 60 bar to location, 60 bar to return to boat & 60 bar in my cylinder when I am on the boat.

If u do wrong surface consumption rate calculation & not applying ur 1st stage IP & ur depth in ATA....U be in so much trouble

I supposed being Dive Pro we all need to know all this, as we need to be able to make the dive safer for our student are we?

Problem is : PADI does not have rule of thirds in their syllabus.......It's extra information given by the instructor

JD · « **Reply #12 on:** February 23, 2008, 02:59:09 PM »

Quote from: Syed K. A. on February 23, 2008, 04:51:10 AM

Say 180bar is in my cylinder when i start the dive.

Rule of 3rd applies for me... 60 bar to location, 60 bar to return to boat & 60 bar in my cylinder when I am on the boat.

If u do wrong surface consumption rate calculation & not applying ur 1st stage IP & ur depth in ATA....U be in so much trouble

I supposed being Dive Pro we all need to know all this, as we need to be able to make the dive safer for our student are we?

Can you elaborate more on the Rule of 3rd bro....ada sikit kurang faham (can't savy fully)..do you mean after every dive one is meant to have 1/3 of air remaining in the cylinder?

Snafu · « **Reply #13 on:** February 23, 2008, 08:12:38 PM »

Quote from: JD on February 23, 2008, 02:59:09 PM

Can you elaborate more on the Rule of 3rd bro....ada sikit kurang faham (can't savy fully)..do you mean after every dive one is meant to have 1/3 of air remaining in the cylinder?

JD..Yes

Simple right.

HoleMaster · « **Reply #14 on:** February 23, 2008, 08:14:46 PM »

My rule of thumb usually is 50 bar. But then again it depends amongst others things air consumption rate, diving conditions (depth,currents,swell) diving experience and etc

nanda666 · « **Reply #15 on:** March 04, 2008, 12:40:33 PM »

Quote from: nanda666 on February 22, 2008, 10:49:51 AM

What is a safe and reasonal amount of air to have when you start a standard 3 min safety stop at 5 m?
I, like most divers, want to get the most of my 200 bar...right?

Any answers for the actual question? at 5m and starting safety stop......????

50 bar?
40 bar?
30 bar?
up to individual?
based on own consumption?
based on current?
back to square one i.e. experience?

The reason for the question itself was to overcome uncertainty and not justify it.

[/quote]

Mephisto the Heretic · « **Reply #16 on:** March 04, 2008, 01:41:18 PM »

in that the case we have to shift the paradigm and reconsider the question.

Initial question:

Constant: 200BAR
Variable: How much are you willing to push to have max dive time and a resonable margin for a safe finishing to a dive.

The question that should be ask is:

Constant: I want to be safe and alive at the end of the dive.
Variable: how should i conduct the entire dive to achive the above constant.

You do you own calculations.

nanda666 · « **Reply #17 on:** March 04, 2008, 01:51:49 PM »

lets "shift the paradigm" again and I'll rephrase the question:

If your son was 12 years old an asked you how much air EXACTLY he should have at 5m for his safety stop? (Key words are YOUR SON and EXACTLY)

My answer would be: 50 bar. (Otherwise I won't take you on another dive again!!

)

nanda666 · « **Reply #18 on:** March 04, 2008, 01:52:59 PM »

and of course I mean minimum la..

MACHA · « **Reply #19 on:** March 04, 2008, 02:07:14 PM »

Well, notes from Brickfields! My friends...normally when i lead a dive a few things i should be aware:

1) Divers air consumption rates.
Importance of check out dive especially those haven't been diving for a while,check their logbook latest dive etc.
2) Dive location / Tides & Current Condition.
Pick suitable dive sites prior current condition for all level divers to ensure safety / dive objective & fun.
3) Useful Briefing before dives..location,dive plan with map & route,buddy assign, hazards, recall signals, buddy seperation procedures.
On low on air scenarios...i always set a safety margin of 80 bar for shallow dives ( Max.18 meters ) & 100 bar for dives deeper than 25
meters. Seperate the low on airs

to another group, assist / led by other guides to shallower area & on the way doing their safety stop
The rest with sufficient air supply stick to plan....add this in dive briefs
By practicing these safety margin I can manage to plan a safe multilevel dive and try not to spoil the dive.

I hope this could help some of ya'll....safe diving!

nanda666 · « **Reply #20 on:** March 04, 2008, 02:16:07 PM »

Quote from: MACHA on March 04, 2008, 02:07:14 PM

On low on air scenarios...i always set a safety margin of 80 bar for shallow dives ( Max.18 meters ) & 100 bar for dives deeper than 25
meters. Seperate the low on airs to another group, assist / led by other guides to shallower area & on the way doing their safety stop
The rest with sufficient air supply stick to plan....add this in dive briefs
By practicing these safety margin I can manage to plan a safe multilevel dive and try not to spoil the dive.

Thank dude!! this is the kind of info i'm looking for.

By setting EXACT (as in your case 80 and 100 bar) numbers, I feel it is easier for new divers to learn their limits whereas the "many factors" method only seems to generate a new breed of diver who are learning from some "experts" and may endanger themselves and the people around them.

I'm very grateful to all of you who have made the effort to answer my questions and I think it clearly shows that most of MUW divers are a safe bunch.

Mephisto the Heretic · « **Reply #21 on:** March 04, 2008, 02:26:15 PM »

Key word is MY SON and EXACTLY.

''Son, always remember this and daddy will only tell you once. Always start your safety stop with at least 80BAR of air left in your tank.
Daddy think that this is a reasonable amount for you to do a complete safety stop and also as back up for any unforseen mishaps''

The above is being arbitary. For the ones i love, their safety is prominent and i prefer a higher safety margin and they would just have to be happy with 120BAR for diving.

But can i do the above with other divers (the ones i love and dont)?

nanda666 · « **Reply #22 on:** March 04, 2008, 02:56:40 PM »

as already said in the "conservative diving"thread, I'm gonna let the crazy guys do their own thing.

my concern is for the people I love and the people I will eventually train. The advice received here is great.

If you set 120bar for your son, good.....maybe as his consumption improves can lower to 100, right?

SAFETY FIRST is the best rule...hey, it is RECREATIONAL DIVING la....why risk it?

IkanBilis · « **Reply #23 on:** March 04, 2008, 03:12:52 PM »

All these information are good lah, thanks to all the sifus...

I do check my pressure gauge regularly, but sometimes the reading is just not right.

For example, lets look at this scenario, when cruising leisurely at 18m, I have 180 bars. 10 minutes later I checked, and I have 140 bars, meaning I consume 40 bars at leisure pace,at 18m for 10 minutes.

However, 5-7 minutes of leisure breathing later, my gauge is showing 100 bars left, meaning I consumed 40 bars within 6 minutes, while still at the same pace, same depth.

Even more alarming, 5 minutes later I'm already at 50 bars, time to slowly ascend...

Its very difficult to determine the average time and the average air that you consume over that period of time, even when the depth is constant. Maybe I am not experienced enough, but that's what generally happen, many times.

Is there something wrong with the gauge, or my breathing pattern? Maybe if i can look at my dive profile, it could show varying depth, but the difference would be too little to make an impact on the amount of air consumed. What is the cause of this scenario?

Any suggestions sifus?

kimseng the maverick rogue · « **Reply #24 on:** March 04, 2008, 06:01:03 PM »

wah liao............... u all really safe diver huh.... 100 bar and ascend? no way i'm gonna do that.
super kiasi

conclusion: don't dive with me. i'm not a safe diver....

ikanbilis,
try practising freediving, will help in ur consumption.

John F SeaDemon · « **Reply #25 on:** March 04, 2008, 06:34:32 PM »

In a normal condition, I will only ascend when I hit 50 BAR.

IkanBilis · « **Reply #26 on:** March 04, 2008, 09:56:10 PM »

Quote from: kimseng on March 04, 2008, 06:01:03 PM

wah liao............... u all really safe diver huh.... 100 bar and ascend? no way i'm gonna do that.
super kiasi
conclusion: don't dive with me. i'm not a safe diver....

ikanbilis,
try practising freediving, will help in ur consumption.

Heheheh kimseng, after 30 years of freediving to max depth of 35 feet and cowboy-diving, then only I took OWD at the age of 43. The cigarettes did their job, now need compressed air to breathe for me to enjoy the underwater world.

But that's not the question, I want to know if anyone experienced inconsistencies with the gauge reading, the feeling that as your tank begins to empty, the air seems to flow faster..

dp · « **Reply #27 on:** March 05, 2008, 12:26:30 PM »

Quote from: IkanBilis on March 04, 2008, 09:56:10 PM

Quote from: kimseng on March 04, 2008, 06:01:03 PM
wah liao............... u all really safe diver huh.... 100 bar and ascend? no way i'm gonna do that.
super kiasi
conclusion: don't dive with me. i'm not a safe diver....

ikanbilis,
try practising freediving, will help in ur consumption.

Heheheh kimseng, after 30 years of freediving to max depth of 35 feet and cowboy-diving, then only I took OWD at the age of 43. The cigarettes did their job, now need compressed air to breathe for me to enjoy the underwater world.

But that's not the question, I want to know if anyone experienced inconsistencies with the gauge reading, the feeling that as your tank begins to empty, the air seems to flow faster..

bro,

does this happen all the time, or one particular time only?

and was the equipment rented, or owned?

IkanBilis · « **Reply #28 on:** March 05, 2008, 12:31:59 PM »

Quote from: deepblu on March 05, 2008, 12:26:30 PM

Quote from: IkanBilis on March 04, 2008, 09:56:10 PM
Quote from: kimseng on March 04, 2008, 06:01:03 PM
wah liao............... u all really safe diver huh.... 100 bar and ascend? no way i'm gonna do that.
super kiasi
conclusion: don't dive with me. i'm not a safe diver....

ikanbilis,
try practising freediving, will help in ur consumption.

Heheheh kimseng, after 30 years of freediving to max depth of 35 feet and cowboy-diving, then only I took OWD at the age of 43. The cigarettes did their job, now need compressed air to breathe for me to enjoy the underwater world.

But that's not the question, I want to know if anyone experienced inconsistencies with the gauge reading, the feeling that as your tank begins to empty, the air seems to flow faster..

bro,

does this happen all the time, or one particular time only?

and was the equipment rented, or owned?

Happens most of the time and rented and borrowed equipment. So much so that towards the end of the dive I start to be very conscious of my breathing pattern, trying to regulate it so that I can meet the planned bottom time.

dp · « **Reply #29 on:** March 05, 2008, 12:53:03 PM »

Quote from: IkanBilis on March 05, 2008, 12:31:59 PM

Quote from: deepblu on March 05, 2008, 12:26:30 PM
Quote from: IkanBilis on March 04, 2008, 09:56:10 PM
Quote from: kimseng on March 04, 2008, 06:01:03 PM
wah liao............... u all really safe diver huh.... 100 bar and ascend? no way i'm gonna do that.
super kiasi
conclusion: don't dive with me. i'm not a safe diver....

ikanbilis,
try practising freediving, will help in ur consumption.

Heheheh kimseng, after 30 years of freediving to max depth of 35 feet and cowboy-diving, then only I took OWD at the age of 43. The cigarettes did their job, now need compressed air to breathe for me to enjoy the underwater world.

But that's not the question, I want to know if anyone experienced inconsistencies with the gauge reading, the feeling that as your tank begins to empty, the air seems to flow faster..

bro,

does this happen all the time, or one particular time only?

and was the equipment rented, or owned?

Happens most of the time and rented and borrowed equipment. So much so that towards the end of the dive I start to be very conscious of my breathing pattern, trying to regulate it so that I can meet the planned bottom time.

Hmmmm. this is very peculiar indeed.

As for me, the air flows the same, be it when the tank is full or nearing empty, with the gauge indicating the correct amount of air left in my tank.

The only time the gauge moved and hard to breathe was when i did not turn the tank valve fully (it was only half) - the needle on the gauge was moving like the odometer of a car (circa 3500 RPM

).

Buddy slapped my forehead when i showed him and fully turned the valve after that.