Diver Denny:
I have to respectfully disagree with you on this point. It wasn't luck at all but rather training and experience that got him through this. No one is arguing that some mistakes were made in the planning and execution, but once he found himself in a low-air situation he delt with it very competently. Most importantly, as it has been mentioned before, he did not panic.
Proper training and experience would have prevented this situation from arising in the first place.
Regardless, the problems continued throughout the dive. Once the OOA occurred
for the second time on the same dive, the diver abandoned his rescuer and did a free ascent to the surface. This left the diver solo on a decompression obligation. In addition, it is risky. Clearing a decompression obligation on a computer does not mean that your system is totally free of nitrogen. Ascending slowly is critical, particularly since the last 33 feet of a dive is the place where the most significant pressure change occurs.
Doing a blow and go from 20 feet on a deco dive is begging for a nice ride in an air ambulance.
So, respectfully, I don't quite see how training and experience played a significant role in this.
As for a lack of panic, based on the report, while the diver was not in a full blown panic, he was breathing at an accelerated rate and was putting other divers at risk. This is not a prime example of proper training.
Personally, I am not a proponent of solo diving but I've heard rational arguments for it.
I've heard arguments for many things with which I do not agree. Regardless, nothing I wrote above would prevent someone from solo diving. However, those who choose to solo dive should plan on being able to handle their mistakes and emergencies solo as well.
In the case of sharing air it does seem a bit of an imposition on the part of the solo diver.
It's more than an imposition. It's dangerous. It's relying upon other divers who have neither agreed to become responsible for the diver nor planned for it and expecting them to bail out your sorry butt. It puts the rescuer's entire team at a greater risk and decreases the pleasure of their dive.
If someone is planning to solo dive, then they need to be able to extricate themselves from a situation without running to another diver for help. Period. That means complete redundancy of all life support systems, strict adherance to proper dive planning and enough experience to either find the upline or know what to do if they can't. It doesn't mean attaching yourself to another team without their knowledge or permission, then expecting them to save you.
However, standard practice means coming out of the water with 500psi left in the tank.
Its not standard practice in my training.
Even if this was correct, and it is not, would you care to explain how you make this happen? In particular, how do you determine how much gas you will need in order to come up with 500 psi?
This also ignores the simple fact that I plan to donate gas to my buddies. We plan our dives so that we can share air and ascend safely. My reserves are intended to be used for emergencies that happen within my team. They are not intended to bail out other divers who can't, or won't, properly plan their dives.
Sparing a couple hundred pounds of air to help out a fellow diver is no big deal.
First, it sounds like this diver used far more than a couple of hundred pounds. Second, it is a big deal if the reason for the air share was the diver's inadequate equipment and planning.
So it's really only a problem if the donor screwed up his dive plan as well.
Which you won't know about until you go on their regulator. Of course, in this case, it doesn't sound like this was a problem because I never read anything about checking the donee's remaining gas during the air share.
I'm also curious about a comment you made earlier...
The certification I went through included decompression schedules for dives past the NDL. Of course this is in the context of a recreational dive within the 130' limit, we're not talking technical diving.
In other words, you've been trained to handle minimal decompression as part of an emergency. That doesn't mean that you should rely upon this training to deliberately exceed NDL's. Even if the training was adequate, safely executing planned decompression dives requires additional equipment. It also requires skills beyond looking at your computer and hoping that it has properly calculated your obligation.
Although it's our club's policy not to do deco dives, a prudent dive plan should include the deco schedule if there is a potential of breaching the NDL and make allowances for additional air requirements.
A prudent recreational dive plan is one that does not exceed NDL's. If the diver's situational awareness or other skills are such that they can't handle this, then the prudent dive plan involves an extended exploration of the kiddy pool at the local YMCA.
When it is practical to do so we have a hang tank near the safety stop for these situations. Between this and allowing for extra air on the ascent what other special equipment is required?
A safety tank on the line is utterly useless if you are not ascending on the line, if the regs are being used, if the tank or the reg fails or, since we are talking about divers who have incurred decompression obligations, if your ceiling is below the depth at which the tank is hanging.
Essentially, if you are going to be doing decompression dives, you need redundant systems that you carry with you, so that you can address failures, together with training to plan the dive safely and to adjust the plan if necessary.
