Altitude diving and Rebreather

Mikel-Deko · 2nd July 2007, 13:26

Hi
A few days ago it was a thread about that.(i can't found it).
I'm going to go to dive into a cave in 950 mtrs altitude.
I'm going to dive it with a Classic Inspiration.
After the other days thread, i don't know how to do it

.
Please, any clear clue?
My English is not so good

Thanks
Mikel

**Dave1w** · 2nd July 2007, 14:08

Hi Mikel,
I think with regard to your sensors, you can find a chart that gives the pressure at that altitude, and then just set your calibration to 21% of that pressure.

I think it is better to actually measure the pressure when you are there, and act accordingly.

Then for deco, most computers would be able to figure it out if you set them to altitude. Something to beware of, not all the computers take into account whether or not you have acclimatised to the altitude.

Tables made by software can also do it.

Best to add some safety fudge into whatever deco you plan.

I am sure someone will come along soon with better details

Dave

***caveseeker7*** · 2nd July 2007, 14:19

This is probably the thread you were looking for:
altitude diving

Mikel-Deko · 2nd July 2007, 14:32

Quote: (Originally Posted by Dave1w)

Hi Mikel,
I think with regard to your sensors, you can find a chart that gives the pressure at that altitude, and then just set your calibration to 21% of that pressure.

I think it is better to actually measure the pressure when you are there, and act accordingly.

Then for deco, most computers would be able to figure it out if you set them to altitude. Something to beware of, not all the computers take into account whether or not you have acclimatised to the altitude.

Tables made by software can also do it.

Best to add some safety fudge into whatever deco you plan.

I am sure someone will come along soon with better details

Dave

Sorry, but do you mean that i 've to know the mb in this altitude (pj: 1030mb) and in the moment that i'm calibrating the Rebreather thell him that there are 1030mb and keep on calibrating?
I've a VR3 that i think that it takes the altitude automaticly.
Thanks for your help
Mikel

Mikel-Deko · 2nd July 2007, 14:45

I've take this from the other thread.
""""An important point is to understand the relationship between linear depth (as measured with a tape measure), depth as measured by a surface calibrated depth gauge (like a VR3), and a non-calibrated depth guage (that just uses pressure).

So if the ambient pressure is 0.8Bar, at 2m underwater your standard depth gauge reads 0m.

If you are looking at a set of deco tables, what does "depth" mean ?

Similarly if you add a Rebreather into the mix, how is that calibrated ? With my YBOD I can enter 800mb when I calibrate so it is reading correct. On the surface it would read 0.17 ! On pure oxygen at 3m (linear) underwater the ppO2 is 1.1

You should be very clear on how all this effects your equipment and deco tables before attempting any significant dive at a significant altitude.

Guy""""

I don't undestand very well this.
OK, i take with me a baromether, in the calibrating procces i put 900mb or what the baromether says, and them the calibration is correct.
What my hansets will show then????(in pure oxigen)
Thanks

Another question:
I've a VR3. Is it going to give me the correct deepth for my deco obligations?
Thanks again

Mikel

**Dave1w** · 2nd July 2007, 14:53

Quote: (Originally Posted by Mikel-Deko)

Sorry, but do you mean that i 've to know the mb in this altitude (pj: 1030mb) and in the moment that i'm calibrating the Rebreather thell him that there are 1030mb and keep on calibrating?
I've a VR3 that i think that it takes the altitude automaticly.
Thanks for your help
Mikel

Hi Mikel,

To be honest, I have only thought of this with regard to the Sport Kiss, where I would find out for example, that I had 900 mb ambient pressure, so I would then fiddle my little screwdriver until my display gave me 21% of 900 mb. Therefore 0.189 ppo2. Does that make sense.

I don't know how this works on an inspiration etc. Sorry

The whole altitude and depth thing is another interesting thing. I need to get my head round it as I will be diving a lake at 1650m extensively in August. I intend to take a tape measure anyway, just to see.

What would be nice, would be for me to be able to trust that Mr Suunto, when his manual says I can use my computer at altitude, means that I can just jump in (figuratively) and read off whatever depth it is say, and do whatever deco or safety stops it suggests, and come out straight, with the little computer having done all the altitude / depth compensations stuff.

What I expect we will find is that whatever the computer says is different from the "tape measure".

So what does this mean? (please excuse the bottle of red wine)

I think what is displayed on my wrist is shallower than what I actually am at because of the lower starting point at the surface pressure, but whatever it is, it will have a bigger effect than what is displayed (on my wrist) (and maybe even a bigger effect than the real depth at normal sea level)because of the ratio of the pressure due to depth against the ambient surface pressure, which will be greater and therefore worse for us.

Sorry of this is not too clear (red wine!)

Cheers

Dave

ps the brackets are making it look like one of my XL spreadsheet marathon efforts!

Mikel-Deko · 2nd July 2007, 14:57

Quote: (Originally Posted by Dave1w)

To be honest, I have only thought of this with regard to the Sport Kiss, where I would find out for example that I had 900 mb pressure, so I woudl then fiddle my little screwdriver until my display gave me 21% of 900 mb. Therefore 0.189 ppo2. Does that make sense.

I don't know how this works on an inspiration etc. Sorry

Dave

Hi Dave,
Now it is a little bit clearer. Still have a lot to work to undestand everythink but i will do.
Thanks
Mikel

**Dave1w** · 2nd July 2007, 15:09

And to confuse us both more

At-Altitude Arithmetic

It starts talking about mercury etc, which reminds me of the time in hospital I used a thermometer to sir my coffee which then exploded the bulb. I didn't drink it, it that good?

Dave

Mikel-Deko · 2nd July 2007, 15:25

Quote: (Originally Posted by Dave1w)

And to confuse us both more

At-Altitude Arithmetic

It starts talking about mercury etc, which reminds me of the time in hospital I used a thermometer to sir my coffee which then exploded the bulb. I didn't drink it, it that good?

Dave

Oahhhhh
The history of Indiana Jones is really dangerous

The rest of the text... need to re-read it few times before to undestand anything.

Thanks
Mikel
PD: were are the cave divers to tell us in practice how do they do it

**Dave1w** · 2nd July 2007, 16:24

They're probably all out diving...

Another (maybe relevant) tale, the company I work for makes mining equipment. We have one group that does underground mining kit. This in itself is pretty cool, being down about 1000/1500m under ground. Then one of our product support reps came to them and asked what was the high altitude capability of their machines, which really confused them. (We have a large mine in indonesia that even the underground portion is at maybe 3000m altitude)

Dave

2nd July 2007, 13:26	#1 (permalink)
Mikel-Deko Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Other CCR Join Date: Jul 2005 Location: Basque Country -Sp- Posts: 422	Altitude diving and Rebreather Hi A few days ago it was a thread about that.(i can't found it). I'm going to go to dive into a cave in 950 mtrs altitude. I'm going to dive it with a Classic Inspiration. After the other days thread, i don't know how to do it . Please, any clear clue? My English is not so good Thanks Mikel __________________ Mikel-Deko Basque Country www.olatu.net "DIR is the nanny state for divers who cannot think on their own" Ron Micjan
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2nd July 2007, 14:08	#2 (permalink)
Dave1w Born Again Diver! Current Rebreather/s: Sport Kiss Dolphin Ray Home Build Other Rebreather/s: Classic Kiss Dolphin Ray Home Build Join Date: Jan 2005 Location: Singapore / UK Posts: 338	Re: Altitude diving and Rebreather Hi Mikel, I think with regard to your sensors, you can find a chart that gives the pressure at that altitude, and then just set your calibration to 21% of that pressure. I think it is better to actually measure the pressure when you are there, and act accordingly. Then for deco, most computers would be able to figure it out if you set them to altitude. Something to beware of, not all the computers take into account whether or not you have acclimatised to the altitude. Tables made by software can also do it. Best to add some safety fudge into whatever deco you plan. I am sure someone will come along soon with better details Dave
(Offline)

2nd July 2007, 14:19	#3 (permalink)
*caveseeker7* Who loves ya, baby Current Rebreather/s: Sport Kiss Other Rebreather/s: Prism Topaz Join Date: Jan 2005 Location: Too far from Neverland Posts: 5,435	Re: Altitude diving and Rebreather This is probably the thread you were looking for: altitude diving __________________ Cheers Stefan "Political Correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.'!"
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2nd July 2007, 14:32	#4 (permalink)
Mikel-Deko Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Other CCR Join Date: Jul 2005 Location: Basque Country -Sp- Posts: 422	Re: Altitude diving and Rebreather Quote: (Originally Posted by Dave1w) Hi Mikel, I think with regard to your sensors, you can find a chart that gives the pressure at that altitude, and then just set your calibration to 21% of that pressure. I think it is better to actually measure the pressure when you are there, and act accordingly. Then for deco, most computers would be able to figure it out if you set them to altitude. Something to beware of, not all the computers take into account whether or not you have acclimatised to the altitude. Tables made by software can also do it. Best to add some safety fudge into whatever deco you plan. I am sure someone will come along soon with better details Dave Sorry, but do you mean that i 've to know the mb in this altitude (pj: 1030mb) and in the moment that i'm calibrating the Rebreather thell him that there are 1030mb and keep on calibrating? I've a VR3 that i think that it takes the altitude automaticly. Thanks for your help Mikel __________________ Mikel-Deko Basque Country www.olatu.net "DIR is the nanny state for divers who cannot think on their own" Ron Micjan
(Offline)

2nd July 2007, 14:45	#5 (permalink)
Mikel-Deko Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Other CCR Join Date: Jul 2005 Location: Basque Country -Sp- Posts: 422	Re: Altitude diving and Rebreather I've take this from the other thread. """"An important point is to understand the relationship between linear depth (as measured with a tape measure), depth as measured by a surface calibrated depth gauge (like a VR3), and a non-calibrated depth guage (that just uses pressure). So if the ambient pressure is 0.8Bar, at 2m underwater your standard depth gauge reads 0m. If you are looking at a set of deco tables, what does "depth" mean ? Similarly if you add a Rebreather into the mix, how is that calibrated ? With my YBOD I can enter 800mb when I calibrate so it is reading correct. On the surface it would read 0.17 ! On pure oxygen at 3m (linear) underwater the ppO2 is 1.1 You should be very clear on how all this effects your equipment and deco tables before attempting any significant dive at a significant altitude. Guy"""" I don't undestand very well this. OK, i take with me a baromether, in the calibrating procces i put 900mb or what the baromether says, and them the calibration is correct. What my hansets will show then????(in pure oxigen) Thanks Another question: I've a VR3. Is it going to give me the correct deepth for my deco obligations? Thanks again Mikel __________________ Mikel-Deko Basque Country www.olatu.net "DIR is the nanny state for divers who cannot think on their own" Ron Micjan
(Offline)

2nd July 2007, 14:53	#6 (permalink)
Dave1w Born Again Diver! Current Rebreather/s: Sport Kiss Dolphin Ray Home Build Other Rebreather/s: Classic Kiss Dolphin Ray Home Build Join Date: Jan 2005 Location: Singapore / UK Posts: 338	Re: Altitude diving and Rebreather Quote: (Originally Posted by Mikel-Deko) Sorry, but do you mean that i 've to know the mb in this altitude (pj: 1030mb) and in the moment that i'm calibrating the Rebreather thell him that there are 1030mb and keep on calibrating? I've a VR3 that i think that it takes the altitude automaticly. Thanks for your help Mikel Hi Mikel, To be honest, I have only thought of this with regard to the Sport Kiss, where I would find out for example, that I had 900 mb ambient pressure, so I would then fiddle my little screwdriver until my display gave me 21% of 900 mb. Therefore 0.189 ppo2. Does that make sense. I don't know how this works on an inspiration etc. Sorry The whole altitude and depth thing is another interesting thing. I need to get my head round it as I will be diving a lake at 1650m extensively in August. I intend to take a tape measure anyway, just to see. What would be nice, would be for me to be able to trust that Mr Suunto, when his manual says I can use my computer at altitude, means that I can just jump in (figuratively) and read off whatever depth it is say, and do whatever deco or safety stops it suggests, and come out straight, with the little computer having done all the altitude / depth compensations stuff. What I expect we will find is that whatever the computer says is different from the "tape measure". So what does this mean? (please excuse the bottle of red wine) I think what is displayed on my wrist is shallower than what I actually am at because of the lower starting point at the surface pressure, but whatever it is, it will have a bigger effect than what is displayed (on my wrist) (and maybe even a bigger effect than the real depth at normal sea level)because of the ratio of the pressure due to depth against the ambient surface pressure, which will be greater and therefore worse for us. Sorry of this is not too clear (red wine!) Cheers Dave ps the brackets are making it look like one of my XL spreadsheet marathon efforts! Last edited by Dave1w : 2nd July 2007 at 15:04. Reason: Added more rambling
(Offline)

2nd July 2007, 14:57	#7 (permalink)
Mikel-Deko Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Other CCR Join Date: Jul 2005 Location: Basque Country -Sp- Posts: 422	Re: Altitude diving and Rebreather Quote: (Originally Posted by Dave1w) To be honest, I have only thought of this with regard to the Sport Kiss, where I would find out for example that I had 900 mb pressure, so I woudl then fiddle my little screwdriver until my display gave me 21% of 900 mb. Therefore 0.189 ppo2. Does that make sense. I don't know how this works on an inspiration etc. Sorry Dave Hi Dave, Now it is a little bit clearer. Still have a lot to work to undestand everythink but i will do. Thanks Mikel __________________ Mikel-Deko Basque Country www.olatu.net "DIR is the nanny state for divers who cannot think on their own" Ron Micjan
(Offline)

2nd July 2007, 15:09	#8 (permalink)
Dave1w Born Again Diver! Current Rebreather/s: Sport Kiss Dolphin Ray Home Build Other Rebreather/s: Classic Kiss Dolphin Ray Home Build Join Date: Jan 2005 Location: Singapore / UK Posts: 338	Re: Altitude diving and Rebreather And to confuse us both more At-Altitude Arithmetic It starts talking about mercury etc, which reminds me of the time in hospital I used a thermometer to sir my coffee which then exploded the bulb. I didn't drink it, it that good? Dave
(Offline)

2nd July 2007, 15:25	#9 (permalink)
Mikel-Deko Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Other CCR Join Date: Jul 2005 Location: Basque Country -Sp- Posts: 422	Re: Altitude diving and Rebreather Quote: (Originally Posted by Dave1w) And to confuse us both more At-Altitude Arithmetic It starts talking about mercury etc, which reminds me of the time in hospital I used a thermometer to sir my coffee which then exploded the bulb. I didn't drink it, it that good? Dave Oahhhhh The history of Indiana Jones is really dangerous The rest of the text... need to re-read it few times before to undestand anything. Thanks Mikel PD: were are the cave divers to tell us in practice how do they do it __________________ Mikel-Deko Basque Country www.olatu.net "DIR is the nanny state for divers who cannot think on their own" Ron Micjan
(Offline)

2nd July 2007, 16:24	#10 (permalink)
Dave1w Born Again Diver! Current Rebreather/s: Sport Kiss Dolphin Ray Home Build Other Rebreather/s: Classic Kiss Dolphin Ray Home Build Join Date: Jan 2005 Location: Singapore / UK Posts: 338	Re: Altitude diving and Rebreather They're probably all out diving... Another (maybe relevant) tale, the company I work for makes mining equipment. We have one group that does underground mining kit. This in itself is pretty cool, being down about 1000/1500m under ground. Then one of our product support reps came to them and asked what was the high altitude capability of their machines, which really confused them. (We have a large mine in indonesia that even the underground portion is at maybe 3000m altitude) Dave
(Offline)

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