Unusual occurance In Cozumel

[Scuba Duba Doo]

I felt it might havebeen rather risky, never seen it before, however it did run rather smoothly, it just felt that if this diver was that mich of an air hog, him breathing from anothers tank felt like you were borrowing from peter to pay paul.

Air sharing is adding quite a bit of additional risk and any time air sharing is required the dive should be aborted. What happens if you experience a free flow at depth? Your buddy may already be low on air (not OOA) and as you work through the problem it would be quite easy to bleed a tank dry on an AL80 while now sharing his air.

A better idea for the is to sling an additional AL80, and use it to breath off of that first, then switch to your back gas when down to 1000 PSI. This is not a technical dive but more planning gas requirements for the dive and a little more attention to your NDL limits since having additional gas will usually make NDL limits the limiting factor in the dive instead of gas requirements.

Plan your Dive and Dive your Plan

 

[redacted]

Air sharing is adding quite a bit of additional risk and any time air sharing is required the dive should be aborted. What happens if you experience a free flow at depth? Your buddy may already be low on air (not OOA) and as you work through the problem it would be quite easy to bleed a tank dry on an AL80 while now sharing his air.

A better idea for the is to sling an additional AL80, and use it to breath off of that first, then switch to your back gas when down to 1000 PSI. This is not a technical dive but more planning gas requirements for the dive and a little more attention to your NDL limits since having additional gas will usually make NDL limits the limiting factor in the dive instead of gas requirements.

Plan your Dive and Dive your Plan

I'm afraid I just don't get this idea that air sharing is "adding quite a bit of additional risk". Air sharing is a frequently practice drill for my buddy and I. And I don't see much difference in doing it for practice and doing it to balance gas supplies. Of course, it must be done before either diver has hit rock bottom so there is not question of having enough gas to safely complete the planned dive.

 

[Scuba Duba Doo]

I'm afraid I just don't get this idea that air sharing is "adding quite a bit of additional risk". Air sharing is a frequently practice drill for my buddy and I. And I don't see much difference in doing it for practice and doing it to balance gas supplies. Of course, it must be done before either diver has hit rock bottom so there is not question of having enough gas to safely complete the planned dive.

Well the way I see it air sharing for "extending bottom time" for the air hog has the following advantages/disavantages:

Advantages:

Extends bottom time for air hog. I can't see how much longer the BT really is, perhaps 5-10 minutes, 15 tops if it is a shallow dive since if he/she was that bad they would end up consuming your supply up.


Disadvantages:

Decreases your BT.

Uncomfortable to enjoy dive for both divers unless using 7' hose.

Air sharing as DM takes away from your concentration of leading/watching over the group leading to possibly not noticing a potential problem.

Air sharing for just for extending BT increases the time to deal with emergency situations with your and your buddy.




All I am saying is that there are better ways to make sure to deal with air management and sharing a 36" hose just to extend an extra 10-15 minutes that will be uncomfortable seems like a PITA as well as to "possibly" creating extra obstacles when an emergency situation arises. For me its just not worth it, I'd rather sling an AL80.

 

[RJP]

Disadvantages:

Decreases your BT.

In most cases, if one buddy goes LOA that effectively limits the other's BT anyway.

 

[Jim Baldwin]

Returned from trip to Cozumel, great diving and enjoyed ourselves but I was surprised to see one of the Overweight divers breathing off of the divemasters octo during one of the dives. The dive guest apparently breathed through his tank and then notified the divemaster of the near OOA situation but we/he continued the dive using the divemasters tank. Never seen that before, we had a medium sized group but i'm thinking the divemaster felt he could handle the situation at depth. We all ended the dive after I felt that we should have. We all surfaced as a group. The only thing I can think, and I wish I would have asked him, was he thinking he shouldn't seperate the group and ascend the diver with an OOA situation, he could have given anyone of us the dive flag and acended under it, dive depth about 50 ft, maybe he felt doing a safety stop and then decending back to the group would have been too much of a hassle....thanks

Your dive profile is not listed so I don't know how much experience you have have had.

This a common practice in Cozumel and I have done it myself. I dive with an operator that takes small groups and uses bigger tanks 95 and 120's, Living Underwater. The group descends togehter and comes up together under normal circumstances. We normally do hour plus dives.

The DM will tell the group when you reach 1200 psi, LP tanks, let me know. If a person is already down to 1200 say 30 minutes into the dive the DM will switch him to his octopus.

The DM will then continue the dive. When we get to the shallow portion of the dive or it's time to do a safety stop he will have the diver go back on his tank and we will do about a 10 to 15 minute safety stop depending on the profile. This was part of the dive plan and discussed prior to diving.

I dive a long hose and have donated my hose to a diver on just such a dive. I had sufficent gas reserves to accomodate this diver. The dive continued as normal and everyone surfaced together. I have been diving in Cozumel for a number of years and have seen this many times with different operators like Aldora, Liquid Blue, and Sand Dollar.

I have also seen in other groups, Dive Paradise and Sand Dollar, where the DM would send an individual or partners up when one got low. Sharing air does extend the diver's bottom time and enjoyment of the dive. When a person is OOA that is a different story and terminating the dive for that diver and/or his partner is the prudent thing to do.

Remember that you are always responsible for your own diving. The DM no matter where is a guide and is there to assit when he can but you are ultimately responsible for your own safety.

 

[Code Monkey]

I've seen that happen a lot, in lots of places. Particularly with large (not necessarily overweight, but large and athletic too), new divers. I've had DMs explain that they're trying to give a new diver a longer diving experience. Dunno but it seems dangerous to me...

 

[tjmills]

I'm afraid I just don't get this idea that air sharing is "adding quite a bit of additional risk". Air sharing is a frequently practice drill for my buddy and I. And I don't see much difference in doing it for practice and doing it to balance gas supplies. Of course, it must be done before either diver has hit rock bottom so there is not question of having enough gas to safely complete the planned dive.

I would agree with this. If nothing else it is good practice, especially for someone new that because you are sharing air there is no reason to panic. When you can do this and realize that there is no reason to stress out over it there is a good opportunity to realize it is not a reason to have a panic situation. Good lesson if you ask me.

The other thing is realize that a DM in Coz is diving all the time. They are at the bottom end of the air use scale and finishing dives with tanks over 50% full at times. It also stands to reason that when you are sharing air, you check you gauges a little more often.

Sharing air...not a big deal to me.

 

[Charlie99]

Dunno but it seems dangerous to me...

Why? What is dangerous about it? Maybe I'm missing something.

The key to safely extending the dive in this sort of situation is that the air share is done well before the air hog reaches the agreed upon ascent pressure.

In most of the cases discussed, the air sharing has been on drift dives. On a drift dive the gas plan is extremely simple ---- ascend when you reach ascent pressure. Don't violate that plan, and you have enough gas for both divers to safely ascend, even if there is a freeflow, blown o-ring or reg failure.

If the dive is an out-and-back shore dive, the complications caused by air sharing before the turnpoint could cause you to misjudge/miscalculate the adjusted turnpoint pressure, so air sharing in this sort of case should be used with caution. In particular, I won't do air share in this sort of case unless I'm willing to do a surface swim back to the boat or exit point.

==============================

NOT Air Sharing when it is appropriate adds danger.

I have seen this "air sharing is an emergency in and of itself" sort of attitude increase the risk in several instances. Specifically, I've seen low-on-air divers (i.e. a diver that has gone below the agreed upon ascent pressure) decline to air share, and instead continue to breathe down their tank until they empty it, and only then start air sharing. Or in some cases, they cut the safety stop short rather than air share. In both these sorts of cases, air sharing EARLY (at the latest when one hits the ascent pressure) would increase safety buy keeping adequate gas in both divers tanks. This air in then available in case of reg failure on the part of the diver with more air, and it also leaves some air in the tank of the LOA diver to assist in a surf exit, or to get back on a boat in heavy waves.

Charlie Allen

p.s. "airhog" in the above discussion isn't used as a pejorative term. It reads a lot clearer than "the diver with higher air consumption rate".

 

[Ayisha]

Just to clarify, out of the 2 air sharing cases that I mentioned, the first one was completely out of air and panicked initially, and the second had about 50 psi. These were not preventive air sharing done early on, but simply to extend the dive.

While I still had more air at the end of the most recent dive than what they determined the ascent point to be (700 psi), my computer showed my NDL to be in the yellow. It would have been safer to have ended the dive when the first person was out of/low on air.

 

[redacted]

While I still had more air at the end of the most recent dive than what they determined the ascent point to be (700 psi), my computer showed my NDL to be in the yellow. It would have been safer to have ended the dive when the first person was out of/low on air.

When you feel it is time to end your dive, you should do so. The DM is guiding a group but you still need to manage your own dive.