Gas Pressure Indication Redundancy

[Splitlip]

I probably stirred this up. I believe that nothing is an emergency until you no longer have a safe and reliable method of dealing with the problem.

This all assumes a recreational no-deco dive:

• A broken SPG or computer is not an emergency. The dive is over, and you do a normal ascent and surface with your buddy.
• OOA with your buddy close by is not an emergency. The dive is over, you do an air sharing ascent and surface with your buddy.
• OOA with your buddy not close by is not an emergency. The dive is over. You ascend to the surface, and attain positive buoyancy once there.

DiveDoug believes that the last option constitutes an emergency, while I do not. In fact, the last method was how many dives ended, only a few decades ago. I don't recommend running out of air as a good diving practice, but also don't beleive it rises to the level of "emergency"

It is certainly more risky than not running out of air, however given that divers pop up to the surface every day of the year with no damage, I don't believe it's a huge risk or that it constitutes an emergency.

flots.

I can certainly appreciate Steve's confusion. God knows I'm getting confused.

In the op, Jar is discussing the option of using an SPG to back up a wireless AI transmitter/computer so as not being required to cut the dive/dives short.

From there the early responses were in the event of failure, dive over. (well thats what Jar hopes to avoid)

Then we moved into with good gas planning, an spg is not needed.

Then the spg is unnecessary clutter.

Soon we had lively discussion if the diver relying on his plan without the spg should go OOG, that's not even an emergency as he has several options. One of which is a CESA. (what does the letter "E" stand for in CESA?

Now we are back to ending the dive in the event of a failure. See OP. Jar's suggestion was so as not to end the dive

I am confused.

 

[nimoh]

I will start out by apologizing, but I find myself getting confused over who is on what side of the fence and if they are arguing for.

By the above, I am interpreting your post to say that if your regulator fails and you cannot breathe, you have an emergency. Are you saying this to support a claim that is you run out of air in your tank and you cannot breathe, you do NOT have an emergency? Again I am confused by who is arguing to what point. If this is the case here, then it makes no sense. Out of air is out of air is out of air is out of air.

just intended merely as an example to argue that breathing compressed air is not an emergency situation, but both a failed regulator and an empty tank are emergency situations.

---------- Post added ----------

I can certainly appreciate Steve's confusion. God knows I'm getting confused.

In the op, Jar is discussing the option of using an SPG to back up a wireless AI transmitter/computer so as not being required to cut the dive/dives short.

From there the early responses were in the event of failure, dive over. (well thats what Jar hopes to avoid)

Then we moved into with good gas planning, an spg is not needed.

Then the spg is unnecessary clutter.

Soon we had lively discussion if the diver relying on his plan without the spg should go OOG, that's not even an emergency as he has several options. One of which is a CESA. (what does the letter "E" stand for in CESA?

Now we are back to ending the dive in the event of a failure. See OP. Jar's suggestion was so as not to end the dive

I am confused.

good summary...although I am confused too

 

[DevonDiver]

This all assumes a recreational no-deco dive:

• A broken SPG or computer is not an emergency. The dive is over, and you do a normal ascent and surface with your buddy. Agreed

• OOA with your buddy close by is not an emergency. The dive is over, you do an air sharing ascent and surface with your buddy. Near Miss, not emergency
• OOA with your buddy not close by is not an emergency. The dive is over. You ascend to the surface, and attain positive buoyancy once there. Emergency - being submerged without an air source is potentially fatal. This is especially dependent on depth, even within recreational ranges (<130ft)

DiveDoug believes that the last option constitutes an emergency, while I do not. In fact, the last method was how many dives ended, only a few decades ago. I don't recommend running out of air as a good diving practice, but also don't beleive it rises to the level of "emergency"

It is certainly more risky than not running out of air, however given that divers pop up to the surface every day of the year with no damage, I don't believe it's a huge risk or that it constitutes an emergency.
Some don't... that's enough to constitute an emergency in my mind.

Added my thoughts...

 

[diverdoug1]

given that divers pop up to the surface every day of the year with no damage, I don't believe it's a huge risk or that it constitutes an emergency.

flots.

Ya' know, I guess sometimes you just gotta' let natural selection take its course.

 

[flots am]

Ya' know, I guess sometimes you just gotta' let natural selection take its course.

As awful as it sounds, if someone manages to lose their buddy, run out of air and forget their training, eventually something bad will happen.

And just to bring this around back to the original topic, the people who run out of air are hardly ever the same people that a redundant SPG would have helped.

flots.

 

[Thalassamania]

I have never had either a wireless or an air integrated fail me, and I've used both ... lots! I have had regular SPGs fail, but then I've many more hours withe them than any other. I guess I don't understand the problem though. When I had an SPG failure, I let my buddy know and we carried on the the dive with a plan that if I went OOA I'd share her supply and we'd surface. The same approach would work with a wireless or an air integrated. Why was the dive thumbed when there was plenty of good air in the cylinder, the only issue was how much? I guess the group had not give bingo air (aka rock bottom) much thought ... now that is a real issue.

 

[diverdoug1]

I have had wireless work only intermittently quite a bit. Always when there has been a source of external interference (DPV's or Strobes). I like having the wireless AI because it is easy to monitor while concentrating on taking pictures, but I like to have the SPG back-up.

 

[DevonDiver]

I have had wireless work only intermittently quite a bit. Always when there has been a source of external interference (DPV's or Strobes). I like having the wireless AI because it is easy to monitor while concentrating on taking pictures, but I like to have the SPG back-up.

Forgive me for sounding blunt - but you seem to recognize the major fault (strobes/DPV disrupt AI link). The obvious solution seems to be - don't use that model of AI computer, or use a regular SPG, on occasions when you'll be conducting strobe photography. That isn't an issue of unpredictable failure - it's a known (to you) issue. That means it can be avoided.

Of course an "intermittent failure" (I'm guessing means AI link is severed and then re-establishes shortly after) isn't that critical IMHO... if we're talking a couple of minutes. In such cases, I'd know my gas supply...I'd track the elapsed time without AI link...and I'd know where my gas level was. In expectation of AI link resuming, I'd only abort if I had some form of failure/gas loss, that meant I couldn't accurately estimate my gas supply for that short duration (i.e. there was some risk of running low-on-air).

Possibly a computer upgrade is in order - as more recently released AI computers are supposed to be less liable to that failure.

 

[Splitlip]

I have never had either a wireless or an air integrated fail me, and I've used both ... lots! I have had regular SPGs fail, but then I've many more hours withe them than any other. I guess I don't understand the problem though. When I had an SPG failure, I let my buddy know and we carried on the the dive with a plan that if I went OOA I'd share her supply and we'd surface. The same approach would work with a wireless or an air integrated. Why was the dive thumbed when there was plenty of good air in the cylinder, the only issue was how much? I guess the group had not give bingo air (aka rock bottom) much thought ... now that is a real issue.

Thal. You would seriously continue a dive without the ability to measure the volume of your gas?
What might happen if your buddy had some type of failure that required she share your gas? Would you have enough?
A lot of people adhere to the rule of thirds. Without an spg how would one know for sure if the turn pressure was reached. I've seen much discussion re not sharing a computer. I can't imagine sharing an spg.

 

[diverdoug1]

Forgive me for sounding blunt - but you seem to recognize the major fault (strobes/DPV disrupt AI link). The obvious solution seems to be - don't use that model of AI computer, or use a regular SPG, on occasions when you'll be conducting strobe photography. That isn't an issue of unpredictable failure - it's a known (to you) issue. That means it can be avoided.

Of course an "intermittent failure" (I'm guessing means AI link is severed and then re-establishes shortly after) isn't that critical IMHO... if we're talking a couple of minutes. In such cases, I'd know my gas supply...I'd track the elapsed time without AI link...and I'd know where my gas level was. In expectation of AI link resuming, I'd only abort if I had some form of failure/gas loss, that meant I couldn't accurately estimate my gas supply for that short duration (i.e. there was some risk of running low-on-air).

Possibly a computer upgrade is in order - as more recently released AI computers are supposed to be less liable to that failure.

It has happened with My suunto D9 trimix, My Gallileo Luna, and My Gallileo Sol (fairly recent models with the most recent firmware). Since it is a frequent failure point, I dive with a back-up SPG (I have 2 HP ports on my single tank set-up). When the wireless is working (which is at least 90% of the time) I mainly monitor that. When It is offline, I use the SPG (which is always on my console). When I am cave diving with a DPV, I never use a wirelss AI computer because of this well known failure point. When I am not diving an overhead I don't mind the dropped signals of the AI if I have the SPG, but in overhead environments I require more reliable redundancy. Then I use 3 Niteks, and dual SPG's on all my regs. When using my YBOD rebreather, I rig for triple redundancy. I use a Silent Submersion UV-N-37 DPV which has dual battery pack and a variable pitch prop, And I use triple DS 161 Substrobes on my camera rig,so I immagine that it must put out a good deal of RF interference with either my camera or my DPV. I wonder if there is some way ot shield the RF ouput from these devices. I have tried switching the side for the transmitter and which wrist I wear the AI computers to no avail. Oh well, just a minor annoyance.