What should i do... if this happen to my buddy.

[ocrmaster]

Hypothetically

Given:
Both Divers using EANx 36% mix

Situation:
103 Bar or 1500 PSI
@ 30 Meters my buddy starts to free fall out of the blue.
He is sinking his regulator is still in his mouth but appears to be disoriented.

What should I do?

oh he just passed 38 Meters

 

[Kim]

Is this a hypothetical situation?

 

[Packhorse]

Depends.
Has he got life insurance with you as the main benifactor?
Considering he decender 8m in 8 seconds you would have to swim pretty fast to catch up. What depth would you get to him? what is your max depth on 36% mix?

 

[Tassie_Rohan]

The risk of taking an oxygen hit is a function of both oxygen partial pressure AND exposure time: so I'd drop the 8 metres, arrest his decent, and get back up above 30 metres asap.

I don't have the partial pressure tables on me but I'd take a very short exposure above 1.6 ppO to save the partner - just don't linger about down there.

Cheers,
Rohan.

 

[rockjock3]

Given:
Both Divers using EANx 36% mix

Situation:
103 Bar or 1500 PSI
@ 30 Meters my buddy starts to free fall out of the blue.
He is sinking his regulator is still in his mouth but appears to be disoriented.

What should I do?

oh he just passed 38 Meters

Hypothetically.

Considering I am already just beyond the 1.4ppO2 depth for .36% and that my buddy is already 15 feet further down, which would put me at approx 1.6ppO2 or just a little beyond then I am sorry, but there is not use of me becoming a second fatality. This dive seems to have been poorly planned from the get go due to the limits of the mix being pushed to the edge. You should never dive this close to the limitations of your situation (mix, training, conditions, etc) without being totally prepared to face the consequences. In this case I would have to sadly return to the boat and work on seeing what could be done to recover the body.

 

[rockjock3]

The risk of taking an oxygen hit is a function of both oxygen partial pressure AND exposure time: so I'd just drop the 8 metres, arrest his decent, and get back up above 30 metres asap.

I don't have the partial pressure tables on me but I'd take a short exposure above 1.6 ppO2 to save the partner - just dont linger about down there.

Cheers,
Rohan.

Most people will experience an O2 toxixity hit at 1.6 regardless of exposure time. Lower ppO2 are a combination of the pp02 and exposure time, but as your pp02 increases the required exposure time (not counting your cumalitive exposure time to present) greatly decreases.

I figure for somebody that has 1500psi left they have already been down for at least 20 minutes or about there. At this time any time spent near or beyond 1.6 can incapacitate you.

 

[ocrmaster]

36% oxygen and the maximum ppO2 is 1.4 bar, the MOD (m) is ((1.4 / 0.36) x 10) - 10 = 28.9 metres.

This dive seems to have been poorly planned from the get go due to the limits of the mix being pushed to the edge.

If in fact this was a well planned dive and this did happen. It is a What If situation.

Murphy's laws

If there is a possibility of several things going wrong, the one that will cause the most damage will be the one to go wrong.

 

[Packhorse]

The risk of taking an oxygen hit is a function of both oxygen partial pressure AND exposure time: so I'd drop the 8 metres, arrest his decent, and get back up above 30 metres asap.


Rohan.

He was 8m below you when you decide what to do. IF you can decend twice as fast as he does you will not catch him untill you are both at 46meters. By the time you factor in momentum you may even get deeper.

 

[rockjock3]

36% oxygen and the maximum ppO2 is 1.4 bar, the MOD (m) is ((1.4 / 0.36) x 10) - 10 = 28.9 metres.



If in fact this was a well planned dive and this did happen. It is a What If situation.

Murphy's laws

If there is a possibility of several things going wrong, the one that will cause the most damage will be the one to go wrong.

So where was it not a poorly planned dive to the edge of the limits? 1.6pp02 is contingency only and not the limit. The actual limit you should aim to not exceed is 1.4pp02. You make my case when I said it was at or just beyond 1.4pp02 for the mix. In fact 30m is just a bit past 28.9m you did with the calculation. As I was recalling from my head and not using my table and formulas I seem to have been dead on that 30m is just a bit past 28.9m and that would put you just a bit over 1.4pp02.

 

[Tassie_Rohan]

Most people will experience an O2 toxixity hit at 1.6 regardless of exposure time. Lower ppO2 are a combination of the pp02 and exposure time, but as your pp02 increases the required exposure time (not counting your cumalitive exposure time to present) greatly decreases.

I figure for somebody that has 1500psi left they have already been down for at least 20 minutes or about there. At this time any time spent near or beyond 1.6 can incapacitate you.

Yep its a tough call. Above 1.4 you're basically playing russian roulette. Chamber tests have shown that a person can pass out at 1.6 one day and on another day can been fine at much greater levels.

The only resource I have at the moment (US navy dive manual) sets a max depth for 36 at 100 feet (1.4 ppO) and indicates an exceptional maximum exposures of 30 minutes at 110 feet (?1.6 ppO)

If he was any deeper I’d wave him good bye and hope he left his car keys on the boat.

But 8 metres below – well feel free to flame away but I would still probably risk a quick trip down to inflate his BC if I could get him before he drops much further. Depends how fast hes sinking: theres no way I would take 36% below 40 metres: but why am I at 30 metres on 36% in the first place?

Cheers,
Rohan.