"S" Drills

[PfcAJ]

That 'point' is at the halfway mark (time, distance, or gas). This almost certainly allows enough gas for everyone to exit comfortably (well, as comfortably as can be expected).

 

[SparticleBrane]

You are mis-reading. He means they do mod-S at the start of all subsequent dives.

Yes -- something tells me I could have worded that better.

We'll do a full s-drill before the first dive of the trip, and then modified s-drills before the start of all the subsequent dives. The full s-drill being there as practice, with the rest to show that we can fully deploy the long hose

Of course if someone has a special request to do a full s-drill before any dive we'll always do it; this is just our normal mode of operation.

 

[vioch]

In the S-drill as well as in the Out of Air Ascent, that are in the UTD Essentials video, divers show SPG after long hose full deployment....

 

[diverbob]

I also add the bubble check to the end of the S-Drill.

 

[Cave Bum]

What are 'S' Drills?

I've often heard folks at the Quarry and here on the Boards talking about doing 'S' Drills. I've assumed this is some type of shut down drill when diving doubles.

Hummmm, a lot of interesting answers here. For IANTD, NSS-CDS and NACD classes S-Drills, where the 'S' stands for safety, are done before the start of the dive, in open water just below the surface. The main part of them is the gas share demonstration where each diver un-stows their long hose and initiates a gas share with their buddy, then re-stows their hose. You also normally do a bubble check, which is where each diver does a 360 deg turn, in place, so their buddy can check for gas leaks, backup lights on or anything out of place.

The last part of this is usually surfacing and verbally confirming your gas matching -ie- 'I have 3500 psi in my double 104's. My thirds are 1100 psi. My turn pressure is 2400 psi."

Again, this is done before the start of the dive.

 

[b1gcountry]

Yes -- something tells me I could have worded that better.

We'll do a full s-drill before the first dive of the trip, and then modified s-drills before the start of all the subsequent dives. The full s-drill being there as practice, with the rest to show that we can fully deploy the long hose

Of course if someone has a special request to do a full s-drill before any dive we'll always do it; this is just our normal mode of operation.

Oh, my bad, that makes a lot more sense.

Tom

 

[DA Aquamaster]

That 'point' is at the halfway mark (time, distance, or gas). This almost certainly allows enough gas for everyone to exit comfortably (well, as comfortably as can be expected).

That's a risky assumption. If you are doing a long penetration to thirds in a no flow or even low flow cave (a risky practice already), and suffer the catastrophic loss of gas at the turn point, the odds are that it will take you longer to get out than it took you to get in.

First you have the potentially slower pace that results from the gas share itself. Plus when the loss of gas happens it may well silt out the cave through either percolation off the ceiling from the large volume of escaping gas, or from efforts to turn the team, sort out the air share and begin the exit. And if the cave itself is silty, the viz may be lower going out even without the emergency. Add a low flow going out and you may be in the silt you stirred up at the turn all the way out of the cave. Or maybe you just have some idiot somewhere in the system who sucked at using his scooter and blew out the whole cave. All of the above could slow you down. Plus the now OOG diver may be stressed and may have a higher SAC going out than coming in, especially if he thinks the gas issue is sketchy.

Which all means that relying on a single reserve third may not be enough - so you want to check the SPG periodically and also utilze a portion of both remaining reserve thirds to ensure that you do not end up with 2 OOG divers and a donor diver all trying to breathe off the two remaining regs, which will further slow down the exit.

 

[JeffG]

That's a risky assumption. If you are doing a long penetration to thirds in a no flow or even low flow cave (a risky practice already), and suffer the catastrophic loss of gas at the turn point, the odds are that it will take you longer to get out than it took you to get in.

There is a pesky thing called "Rock Bottom" or did you not see what forum you are in?

 

[PfcAJ]

That's a risky assumption. If you are doing a long penetration to thirds in a no flow or even low flow cave (a risky practice already), and suffer the catastrophic loss of gas at the turn point, the odds are that it will take you longer to get out than it took you to get in.

First you have the potentially slower pace that results from the gas share itself. Plus when the loss of gas happens it may well silt out the cave through either percolation off the ceiling from the large volume of escaping gas, or from efforts to turn the team, sort out the air share and begin the exit. And if the cave itself is silty, the viz may be lower going out even without the emergency. Add a low flow going out and you may be in the silt you stirred up at the turn all the way out of the cave. Or maybe you just have some idiot somewhere in the system who sucked at using his scooter and blew out the whole cave. All of the above could slow you down. Plus the now OOG diver may be stressed and may have a higher SAC going out than coming in, especially if he thinks the gas issue is sketchy.

Which all means that relying on a single reserve third may not be enough - so you want to check the SPG periodically and also utilze a portion of both remaining reserve thirds to ensure that you do not end up with 2 OOG divers and a donor diver all trying to breathe off the two remaining regs, which will further slow down the exit.

I'm agreeing with you. Let me break it down:

Dive A is out of gas at max pen (real bad day). Diver B donates. Diver A B and C start heading for the door. The team hits the halfway point to the door (determined by convenient arrows, time, pressure in the backgas that remains, etc) and now diver C shares gas with diver A.

By doing this at the half way point, we have enough gas to get diver A out (most likely. Things do happen, though) on diver C's backgas with a bit of padding. Diver B and C surface with 1/6th of his remaining gas (ish). By switching at the half way point (opposed to some arbitrary point) EVERYONE has enough to get out without that cluster **** 3 way gas share you were talking about, which would get someone killed.

 

[TSandM]

It's sort of good practice to hand off the OOG diver midway back. Or when you reach some gas milestone you have chosen. But you figure that out by watching your gauge. I still don't see what you really accomplish by pulling out your gauge and showing it around. UTD teaches it, GUE doesn't, and I don't think it really matters which way you do it as long as the team's happy. But I don't think it accomplishes anything.