Recreational divers, post your rig here, let's share good and bad ideas

[Blackcrusader]

Assuming that, plus a 5 minute safety stop @20 ft (very unlikely, since you don't have to do one if you're under the ndl and keeping a safe ascent rate): 5 min*0.5 cu ft/atm/min *~2 atm=5 cu ft.

Safety stops are optional not like an obligated deco stop. So safety stops can be skipped.

 

[Blackcrusader]

Even that is extremely rare, unless you run out of air from lack of awareness. A burst hose, free-flow, or any malfunction that drains a tank still gives you more than a single breath. In an emergency situation, you would likely have enough air to make a controlled ascent.

Or this ( can see the replies that will come in lol )

Emergency Breathing from Your BCD: Undercurrent 06/2011

 

[LI-er]

Hopefully you mean, "in each tank".

As @jborg pointed out, no I meant that the total of the gas in both tanks is equal or greater too (usually greater) then the minimum recommended reserve that recreational divers have in their tanks when they begin their acent.

I think one thing to take note of here is [in the event of a failure of a tank at the end of a dive] you would not have gas in your "stony" to perform a normal ascent should your primary system fail just before ascent.

Similarly, you'd be hard pressed to assist an OOG buddy...

That's true, in the highly unlikely event that one of my tanks failed at the end of the dive leaving me with no avalable air, I would have less than the minimum recommended amount of reserve in which case I'd make a controlled, rapid ascent to the surface, probably skipping all or most of the safety stop, using gas in the remaining tank which is always going to be at least 500 psi.

My gas plan is for when I am diving solo. If with my wife or one of a few trusted buddies I wouldn't be extending the dive because they'd be OOG long before I could use the extra gas in the stony bottle.

 

[kinoons]

Feck me. You do have an active imagination. You should write a novel. I never implied I would try to put on a torniquet during a dive. No where did I write or even insinuate that. . But at the surface? Yes. Thing is even on a boat dive an incident can happen out of sight of the boat such as when diving around a small island and the boat is on the other side and there is only a wall that cannot be climbed to get onto the island. I guess you are correct though about the shoe laces. Once when boarding a slight I forgot I had a very small 2 inch star screwdriver I used for screwing my camera to my platform. It was taken as a security issue. Very threatening device I was told. I asked what about the sports shoe laces. The security people told me they are not a security threat. So I showed them how to make a torniquet.... sorry wrong word... a garrote , and showed how easily I could kill someone by choking them to death.

Right they said give me that. I asked were they going to remove all the shoe laces from the passangers as well. This does not compute on their faces was priceless. OK you can have your lace back.

So how about using a weight belt as a torniqet? I have not seen one boat with a torniquet but you can read about many people being hit by propellors.

I carry an emergency satellite beacon as well. I never use it during a dive either? Actually never used it at all as have not yet been swept out to the sea and lost.

The width is only 1/2 of the equation. The other half is being able to apply enough pressure as well as maintain that pressure.

As you again demonstrate your lack of knowledge, as well as a failure to read the research I linked to, I’ll explain further.

In one of the linked studies the overwhelming majority of improvised tourniquets, even wide ones, failed without a windlass. The windlass is required to generate and maintain the needed pressure to occlude arterial flow. I don’t see any way a weight belt could be used with one, so it would likely fail according to the research.

I carry a PLB when I dive as I believe the risk of losing the boat or being swept away justifies one when compared to the weight and size of the PLB and container.

I don’t feel the risk of major laceration/bleeding when I dive recreationally is enough to justify a tourniquet be carried in the water. As I said that is something that can be left on the boat/shore and be used on the boat/shore. Perhaps in a perfectly calm day the surface may be still enough to possibly apply a tourniquet, but I’d argue any degree of swell would make this task very difficult, as would any thermal protection. So much so that returning to shore or the boat while holding direct pressure on the wound would likely be a much better use of a rescuers time than attempting the tourniquet on the surface.

If the boat is on the other side of the island? Sure you can try, I likely would try with whatever I had on hand too, but the cold reality is the injured diver is likely up **** creek. Sometimes you roll snakeyes in life and have to pay the piper.

One of the first things I was taught in EMT school and had reinforced in paramedic school is that sometimes a person will die from the injuries that happened prior to my getting there no matter how hard I try to prevent that outcome.

 

[LI-er]

Also @jborg I don't necessarily agree with that. As @MaxBottomtime is fond of pointing out, you can ascend on one breath of air from typical rec depths. Obviously the point of a pony is to avoid that, but even so, consider:

Assuming a SAC of 0.5 (about average, we'll get to stress in a moment), and a bottom depth of 100 feet (the deepest I would consider common for rec dives).
Pressure at the bottom: 4 atm (1atm/33ft*100 feet+1atm for surface pressure).
Pressure at surface: 1 atm.
Average pressure assuming a constant ascent rate of 30 feet/min: (4+1)/2=2.5 atm
Ascent time at 30 ft/min: 3 minutes, 20 seconds or 3.33333333 minutes.
Total gas consumed on ascent: 0.5 cu ft/atm/min*2.5 atm*3.33333333minutes=4.1625 cu ft.
Even assuming a double consumption rate for stress: 8.325 cu ft (which I find unlikely, since after the first minute or so you should've calmed down)
Assuming that, plus a 5 minute safety stop @20 ft (very unlikely, since you don't have to do one if you're under the ndl and keeping a safe ascent rate): 5 min*0.5 cu ft/atm/min *~2 atm=5 cu ft.

So, assuming you're absolutely slamming air out of stress, and you decide on doing a 5 minute safety stop, your air requirements are 13.325 cu ft (actually less since I rounded up from 1.6 atm in the safety stop). Let's call it an even 10 cu ft, since you presumably won't be that stressed. So, a thousand PSI on a 30 cu ft pony would be sufficient even in a fairly worse case. Don't blow through air like crazy and skip the stop and 5 cu ft (or 500 psi on a 30, 750 on a 19) would be enough

Now, I don't necessarily recommend running super close to the margins at 100 feet, but at say, 40? Then your 1000 psi reserve is several times more air than you actually need, even if you did a safety stop.

These intensive SAC calculations when applied to an emergency (or very fast controlled ascent) should be thrown out the window. Who CARES what a diver's SAC rate is when the diver is only going to take about half a dozen or so breaths when making a rapid controlled ascent from a max depth of maybe 130 feet (and it's not likely to be anywhere near that deep).

For example, I can swim a 40' pool and back on one breath, that's 80' while working hard, as compared to an ascent from the bottom (max depth 130') with ever expanding available compressed air in my lungs. Therefore it naturally follows that I can do it with a half a dozen or so breaths from my backup pony which will provide a lot more than that.

@MaxBottomtime isn't as wrong as you think he is. On one breath from the bottom a fair number of divers will make it to the surface on that one breath, and a pony bottle will provide a heck of a lot more breaths than just one.

 

[LI-er]

I'm just going by the posted numbers. He said he uses 500 psi in an AL80 to make his ascent. .

I can't find the post you're referring to but what I did say, or meant to say is that after switching from my main tank which has maybe 700 psi, I will breathe the stony bottle down to 500 psi switch back to the primary tank and start the ascent. Also note that at the point in the dive where i'm switching tanks around I'm at or in the vicinity of the exit point, not deep inside in a wreck.

Do you tell other recreational divers who are not solo qualified you dive with a stony bottle?

I dive solo, unless I'm with my wife or a few trusted buddies. I don't tell them anything other than "do you need me to do a gear check with you, let's try to keep in sight of one another, if we get separated enjoy your dive, see you back at the boat. Although with my wife I keep a close eye and check her gear carefully as she's not nearly as experienced as I am. I do not use the stony bottle to extend a dive when I've got a buddy, there's no point, they'd be OOA long before me.

 

[Blackcrusader]

One of the first things I was taught in EMT school and had reinforced in paramedic school is that sometimes a person will die from the injuries that happened prior to my getting there no matter how hard I try to prevent that outcome.

Death is a part of life. The final frontier.

 

[Centrals]

The width is only 1/2 of the equation. The other half is being able to apply enough pressure as well as maintain that pressure.

As you again demonstrate your lack of knowledge, as well as a failure to read the research I linked to, I’ll explain further.

"Lack of knowledge"!!!
What is the news?

 

[LI-er]

Obviously, what I carry depends on the dive.

You raise a good point. You say obviously what you bring depends on the dive, but at least in my case, it's not obvious because most of my gear is either attached, or conveniently tucked out of the way and it's either problematic to remove it or pointless, and you never know when you might (for example) need to shoot an smb from depth on any dive, or grab that foldable snorkel for a long swim back across a lake.

So I typically carry all my gear on every dive (unless I leave it behind such as on an overseas trip which includes puddle jumper flights, where bringing it just isn't worth the hassle) the exception being the stony bottle but even then, it's usually a good idea to bring it in case you want to use the air to extend the dive. I can't think of a single piece of gear I would leave behind even if the dive is easy and shallow, even if the odds of using a piece of gear is zero.

 

[Blackcrusader]

As @jborg pointed out, no I meant that the total of the gas in both tanks is equal or greater too (usually greater) then the minimum recommended reserve that recreational divers have in their tanks when they begin their acent.

So what is the minimum recommended reserve? Most guides will bring divers shallow to 10m or less when they get to 70 bar or 50 bar. In any case many divers need to ascend to avoid exceeding NDL before they have gas limitations unless they are shallow to begin with. On some longer dives I may stay at around 15m depth to extend the dive time. This dive was on 21% so went to a wreck ran down the NDL.. stopped at around 26m depth to get some nice photos of a seahorse pair then followed a grassy slope back to a reef wall and followed that at the sea bed. Of course if using 32% on shallow dives which I see some divers do they might end up low on gas if they stay around 20m depth for the whole dive then ascend to a safety stop with around 40 bar.