Safety stop deco bottle

[vladimir]

I'm not sure why you'd be surprised at arrogance from a physician . . .

 

[Web Monkey]

Ok just a quick question...

How many of you diving with a group or just buddied up leave a stage bottle at the recommended decompression safety stops during your dives for emergency? Do you feel a need for this or what circumstance would make you use, or not use one. I have been on a few deep dives with charters but have never seen these used.

Emergencies tend to occur at inconvenient times and places, most of which are not @15' under the boat.

If you need gas, bring it with you.


Terry

 

[Oxy]

I've never heard of this. Can you even suck air out of a second stage at depth if the first stage is on the surface? That doesn't seem possible; don't both stages have to be close to the same ambient pressure for the system to work?

Back to the original post - I've never used hang bottles, not at 130' at the Blue Hole, not at 90' at my NAUI AOW class deep dives - never.

isn't that a "hooka"?

 

[ucfdiver]

I plan my dives, hence I don't need a hang bottle. If you're cutting it close to the NDL, you really need to calculate exactly how much air a safety stop takes you.

 

[GLENFWB]

Mission accomplished! I followed the link, and I have been enjoying reading Bob's articles....thanks for posting the link.

It was actually intended to get the link into the thread so people would see it.

 

[IceBergSlim]

I'm not sure why you'd be surprised at arrogance from a physician . . .

I agree. It's a very funny idea...

Arrogance from a Physician?

Who could imagine that?


Lets all skip years of med school and decide a "Hang tank" is nothing more than a colorfull illustration of ways a dive operator can convince you to deny your own sense of self preservation.

Not that it matter much. Almost all divers dive NDL's and as long as they follow the 30 fpm rule they will deco without knowing it.

 

[Blackwood]

I had a snappy response to this, but I decided it sounded too mean.

No worries. I have thick skin.

My mistake. I thought the IP was an absolute pressure. In thinking about it, I see and understand my mistake. If that were the case, I'd have a hard time getting air out of it at/about/deeper than 300 feet.

Any good links on how surface supplied dives in the 2000 foot range work? For one, I must imagine their running high-pressure hoses.

No offense intended, but that seems like a rather arrogant attitude, especially coming from an ER doc!

Doctor jokes aside, it doesn't strike me as arrogant. Strikes me as confident. Big difference, however subtle it may be.

 

[Sinbad the Diver]

I look at a bottle hung as an extra safety measure in case some makes a mistake. Kinda like an inurance policy. I would think most people will have Dive Insurance but you don't plan to use it. If I were running a dive op to places where deep dives were possible I'd hang one just as an added safety measure. I can see the potential for people abusing it to extend their bottom time because they know it's there, but IMO...so what? I'll deal with that issue on the surface...with a living customer.

The operator sets rules like being back on deck in time X or with 500# of air. You violate those rules you sit is the implied or sometimes stated threat. They hang a bottle, they tell you if you use it that means you dove an unsafe profile and you sit...but if you make a mistake and dive that unsafe profile you get to sit...not take a ride in a helo.

Or you are diving a perfectly safe profile approaching NDL with plenty of air for a safety stop when something fails and your air is gone. Isn't having that option better than you and your buddy at risk of having to cut short your safety stop because you have to share air (NDL on a computer is an estimate, not exact and I sure want to make a full safety stop if I even get close). Maybe I should have a pony, but is not having a pony an ommision I should get bent for?

I agree with all the posts that say a diver should be responsible for themself and plan their dives appropriately, etc. But divers are humans, humans make mistakes, gear fails, gear failure and human error can get you killed when diving. Air is the most important thing we have when we dive (maybe second to our brain, but even stupid people with air can breathe) having an emergency source gives us one more chance to live.

 

[phunk]

Now that I think about it, as long as the second stage is only 15' deep, then you're only reducing the IP that the 2nd stage would normally have at that depth by about 7 PSI, so I guess it would work. But it sure seems strange to me to buy a 20' LP hose to rig up a system you have to suck on instead of just hanging a regular rig off the side of the boat.

Any comments from anybody who's actually used a rig like this?

If you had a rig for this, it would be easy enough to turn up the IP a couple PSI to compensate.

 

[muddiver]

Short answer: no.

Longer answer: nope.



The first stage doesn't care about the ambient pressure. It cares about the tank (internal) pressure.

Because you did not qualify your answer in relation to depth, I'm going to have to say "Sorry dude, you'r wrong"

Boat bottom scrubber use a second stage on a long hose all the time off of a first stage on a tank on the dock here in California. They are all over the place and doing just fine.