Running low on air and failed safety stop

[JahJahwarrior]

Did your decompression course cover the different theories for how to handle missed decompression stops? That's good stuff to keep around, but of course in the moment, you want to take the right steps, quickly, and that can be hard. Especially in this case when you aren't sure if you'll need to administer medical aid to the diver, or if they might have some issue that will cause the boat to need to leave. It's not a good situation at all, one you hope to never face.

Hold my tongue on the boat? That's a very reserved way to put it. Glad you both got home safe!

I don't like the idea of diving with two computers that have different algorithms. It encourages you to not follow the more conservative one.

What's nice about the Petrel is the changeable gradient factor while on deco, so you can see at what "acceptable level of risk" you can surface immediately. Not that you'd want to delay sharing air while you checked that, but if you check it periodically while on deco, you'd see that if you are willing to dive a more or less conservative gradient factor, you could surface several minutes earlier. Refusing to share air because you have 2 minutes left that would go away if you accepted a slightly higher risk of becoming bent is silly, but it's still good to know exactly what that increased risk is, because it can help determine if you decide to try in water recompression, surface oxygen, trip to a chamber, etc.

Of course, always call DAN if you aren't sure you made the right call.

 

[Akimbo]

IMHO you did the right thing, even if you both got bent. Decompression sickness is far more treatable than drowning. You don't want to ask yourself “Could I have saved that diver’s life” every day for the rest of your life. Sure he could have just surfaced and probably been fine, leaving you to finish your stop. But would he panic and drown in the process?

 

[dumpsterDiver]

I would like to think that I would take control of the diver when I handed him the octo... but you would sorta need 3 hands.. one to pass off the reg, one to hold the rope and one to hold the diver. If he bolted immediately before you could grab him, he is probably going to rip the hose off the first stage or rip the reg out of his mouth if you just hold tight at depth to the anchor line.

In theory, you could hold him and the rope and allow him to ascend at 1 ft per minute if he demanded it, but once he took the reg and took off and got the jump on you.. I think you have pretty much lost the battle and might as well ascend the 20 feet at some semblance of an appropriate rate.

I mean the guy could have been having a heart attack and you would be the hero saving him on the surface rather than the guy who has to replace his octo hose..

 

[Dr. Lecter]

yeah i agree, plus if he violates one and is still good on another, he can continue to dive for the day without having his only computer been violated

Petrel's don't lock out violations - not even sure they have a violation screen/alert/notice post-dive.

 

[C Dub]

Was the Petrel showing actual deco, or a safety stop?

The title of thread says safety stop. So of course you go up with the tool. Then you kick his ass on the boat.

Diving a local dive spot off NSW Australia. I run a petrel and an Oceanic Pro Plus. The Pro Plus has a more aggressive algorithm, so normally it shows no decompression time required when the Petrel is showing maybe 2 min at 6 metres. I had about 2 minutes left at 6 m when an inexperienced diver came shooting up the line and stopped in front of me showing the out of air signal. I handed over my occy and he then took off for the surface before I could do anything else. I had 2 choices, try and stay ay 6m to complete my deco obligation while he was clawing for the surface, or go with him. I decided to go with him given the circumstances (one pc showing no deco) and given he was clearly in panic. Once on the surfacing and ensuring he was stable and ok, I then went back down to complete my deco.

Although I did not get time to check his air pressure, clearly he had air at 6m as he was still breathing his regulator, and had sufficient air to get to the surface whether nearly out of air or not (at 6 ), however his panic was preventing him from realising that. Also he indicated out of air when clearly he was low. Anyway it all ended well for everyone.


What would you have done in the same circumstances.

 

[Ouvea]

Was the Petrel showing actual deco, or a safety stop?

Shearwater introduced a new interface/layout for its Petrel dive computer some months back. It has an Open Circuit Recreational mode that gives you a Safety Stop Feature. However, if you dive it in Open Circuit Tech mode, it does not give you a safety stop. I use mine in either Gauge or OC Tech. It will show you the deco obligation and your ceiling. If you ascend to shallower depth and clear your deco obligation then the warning will disappear.

In truth, there are two people that deserve questioning, the diver and the diver's buddy.

 

[kelemvor]

In truth, there are two people that deserve questioning, the diver and the diver's buddy.

That's the missing part of this story. Where is distressed diver's buddy during all of this?

 

[demed]

Diving a local dive spot off NSW Australia. I run a petrel and an Oceanic Pro Plus. The Pro Plus has a more aggressive algorithm, so normally it shows no decompression time required when the Petrel is showing maybe 2 min at 6 metres. I had about 2 minutes left at 6 m when an inexperienced diver came shooting up the line and stopped in front of me showing the out of air signal. I handed over my occy and he then took off for the surface before I could do anything else. I had 2 choices, try and stay ay 6m to complete my deco obligation while he was clawing for the surface, or go with him. I decided to go with him given the circumstances (one pc showing no deco) and given he was clearly in panic. Once on the surfacing and ensuring he was stable and ok, I then went back down to complete my deco.

Although I did not get time to check his air pressure, clearly he had air at 6m as he was still breathing his regulator, and had sufficient air to get to the surface whether nearly out of air or not (at 6 ), however his panic was preventing him from realising that. Also he indicated out of air when clearly he was low. Anyway it all ended well for everyone.


What would you have done in the same circumstances.

The basic question is why are you running your petrel in a configuration so dissimilar from the other computer?
one of themany features of the Petrel is to change the conservatism to match your diving style and other dive computers (for example a rebreather) - if you trust the Oceanic, then you should match as closely as possible its profile on the Petrel, if you trust the Petrel in its current configuration, please ditch the Oceanic that only confuses you.

I use my Shearwater *always* matching the other computer I'm using (a Galileo or a Hollis or a Poseidon)

 

[Freewillow]

You did the right things and I do not see the problem with computors with different algorythms

 

[Peter69_56]

I'm of the opinion that one would dive two computers for the sake of redundancy. In a case where one computer failed the "score" would be the same regardless and contain less of an opportunity for confusion that would lead to task loading. I personally dive with multiple computers running the same gradient factor for the sake of simplicity. Why add a second set of numbers to track?

It seemed in this case that the second differing set of numbers led to the OP's confusion regarding his NDL status.

There was no confusion of my NDL I was simply using the conservative computer, in a crisis I am comfortable to use the more aggressive computer but prefer the least risk approach.

---------- Post added December 31st, 2014 at 08:04 PM ----------

yeah i agree, plus if he violates one and is still good on another, he can continue to dive for the day without having his only computer been violated

Thats where the petrel lets me off th hook ads it's the more conservative if I blow its deco requirements and not the pro plus I can accept the missed petrel setting and continue to use it whereas if I blow my pro plus I am screwed for the 24 hr period with it.

---------- Post added December 31st, 2014 at 08:15 PM ----------

Was the Petrel showing actual deco, or a safety stop?

The title of thread says safety stop. So of course you go up with the tool. Then you kick his ass on the boat.

I think it was 3 min @ 6 m and I was part way through maybe 2 min to go

---------- Post added December 31st, 2014 at 08:21 PM ----------

The basic question is why are you running your petrel in a configuration so dissimilar from the other computer?
one of themany features of the Petrel is to change the conservatism to match your diving style and other dive computers (for example a rebreather) - if you trust the Oceanic, then you should match as closely as possible its profile on the Petrel, if you trust the Petrel in its current configuration, please ditch the Oceanic that only confuses you.

I use my Shearwater *always* matching the other computer I'm using (a Galileo or a Hollis or a Poseidon)

Been trying to do that I normally use VBM and changed the setting to 0 but it appears that doesn't match so I need to play more to get the right setting

the reason I use pro plus is its part of my rec gear instead of a spg whereas on my tech gear I have spg and petrel x 2. I like the idea of backup thus carry the petrel but when it's in rec mode it's even more conservative.

---------- Post added December 31st, 2014 at 08:27 PM ----------

I don't know where his buddy was as he was not from our boat, but I do know when he went back to his the DM asked if he did a safety stop and he said yes. Clearly he didn't and was happy to bulls()$t about it. They asked me what happened and I told them so I think he got a grilling from them.