More than "Advanced", but not really "Technical"

[waterpirate]

Just a side note:
The navy tables are for the navy. Navy divers are young,fit, and at the top of physical conditioning. The really important point is that all navy diving is done with onboard chamber access. Soooo " bend you and mend you " is an acceptable level of risk. Not to mention that whole thing about you being govt. property.
Quoteing the navy tables only confuses those you are seeking to help further.
Eric

 

[tomfcrist]

Just a side note:
The navy tables are for the navy. Navy divers are young,fit, and at the top of physical conditioning. The really important point is that all navy diving is done with onboard chamber access. Soooo " bend you and mend you " is an acceptable level of risk. Not to mention that whole thing about you being govt. property.
Quoteing the navy tables only confuses those you are seeking to help further.
Eric

Eric,

The US navy tables have been used for MANY years by recreational divers, both for no deco and deco dives. There are definately better algorithms and tables out there for deco, but as far as no deco goes, they are pretty much identical to the PADI, NAUI, SSI etc tables. You are correct that the navy deco tables do accept a certain amount of DCI risk due to the onboard chamber aspect, but by adding a little bit of extra deco time or finishing out deco on O2 vice air(say the last 10 minutes) the DCI risk is almost 0. Vplanner and the like is a relatively new concept, and prior to technology taking over the industry the US Navy tables were essentialy the primary gouge for deco diving.

Tom

 

[uncfnp]

I was doing some research on an older topic in another forum today, and I came across a long post in a thread related to a scuba diving fatality. I thought part of it might be interesting to those who are reading this thread. I have blipped out the names. The one I identify as NAME2 was an open water scuba instructor. I added some explanations in italics and brackets.

A few weeks ago, NAME1 calls me from the hospital, telling me he got bent at the nest! [He is talking about the Eagles Nest dive site, a very challenging and deep site recommended for advanced cave divers only.] I promptly said WTF!!! He told me that HE READ THE INFORMATION ON LINE, and that since he didn't have a trimix cert, he and NAME2 dove air. They planned on decoing on 32% and "cleaning up" on 80% as he put it. He did not use a plan, and was diving off NAME2's VR3 (they were sharing). He also told me that NAME2 called the dive early because of a catastrophic gas failure, in which they were forced to isolate. Due to the loss of gas, they were not able to complete their deco plan.

I was at a loss for words. I pleaded with him to never ever do this again. That they got VERY lucky to make it out, and that they had no business being in there.

Not long after that, NAME1 contacted me about getting advanced Nitrox certified so that he could get his o2 filled. That seemed to be the inherent problem, shops refused to fill their tanks with Trimix or 100% o2 without certs. Knowing that he had only been diving a short while, I asked him why he wanted this class, specially without decompression procedures. He told me he wanted to dive the Nest and Wayne's world! [Wayne's World is another advanced site.] I just about jumped through the phone and told him to never ever go into that system, as he won't make it out. He repeatedly told me that NAME2 was confident as a CAVE DIVER and that he trusted NAME2 to get him out if a problem happened. [NAME2 was not cave certified--he just had introductory certification.] I asked him if he was Cave certified, and he told me he had finished Cavern and was working on Intro with Rich Courtney. I contacted Rich Tuesday night, and he told me that NAME1 never finished cavern due to a strained back. The last time I talked with NAME1, was about 1 week or so ago. He wanted me to take him through Cave 1. I asked him why he didn't continue with Rich, he told me that it was going too slow, and that he NEEDED to get certified. I refused. I told NAME1 that I did not believe he had the proper mindset or attitude to do these dives, with everything going on in his life right now. He told me that NAME2 needed a buddy, and he was going to dive with him. I pleaded with him to come dive a wreck with us, it was free, we have a boat, just show up and let's dive just to dive.

...that was the last time I heard my friend's voice...​

Both NAME1 and NAME2 died in Wayne's World that day. I wonder if during their last breaths they still thought doing the more advanced dives without proper training and certification was a good idea.

John, I've spend several hours pondering your post and trying to understand how you thought it relevant to this thread since most if not all of the participants have been for advanced training. My conclusion is that perhaps you are demonstrating an example of how the instructor may have changed the final outcome if perhaps, instead of just repeatedly telling him not to do those dives, he had truly listened to "his friend" and addressed the specific issues. Prehaps he could have then accepted him as a student and taught him "what he doesn't know." Even if ultimately he could not certify the divers, he may have been able to influence as friend's mindset and introduced more of the "risk mitigation" aspect of technical diving that DevonDiver spoke of in another thread.

 

[mmadiver]

Just a side note:
The navy tables are for the navy. Navy divers are young,fit, and at the top of physical conditioning. The really important point is that all navy diving is done with onboard chamber access. Soooo " bend you and mend you " is an acceptable level of risk. Not to mention that whole thing about you being govt. property.
Quoteing the navy tables only confuses those you are seeking to help further.
Eric

Not true, not all Navy diving is done with "onboard chamber access."


Sent from my iPad using Tapatalk

 

[tomfcrist]

John, I've spend several hours pondering your post and trying to understand how you thought it relevant to this thread since most if not all of the participants have been for advanced training. My conclusion is that perhaps you are demonstrating an example of how the instructor may have changed the final outcome if perhaps, instead of just repeatedly telling him not to do those dives, he had truly listened to "his friend" and addressed the specific issues. Prehaps he could have then accepted him as a student and taught him "what he doesn't know." Even if ultimately he could not certify the divers, he may have been able to influence as friend's mindset and introduced more of the "risk mitigation" aspect of technical diving that DevonDiver spoke of in another thread.

I can fully understand why this instructor did not accept this guy as a student. Diver 1 was the kind of guy that would go through the motions during a class, and immediately disregard the lessons learned after obtaining certification. Reckless people have no buisiness recieving Tech training of any kind, because they arent mentally capable of conducting those dives safely. I wouldnt want to teach him OW personally.

 

[DevonDiver]

The US navy tables have been used for MANY years by recreational divers, both for no deco and deco dives.

Which are we talking about? Those Navy tables used (or re-branded) by many agencies were (doppler) modified etc..

There are other prerogatives with the Navy tables... swift exit from the water being one of them, as a military-operational (not dive safety) concern.

They've been suggested as an example of 'valid' tables to suggest the acceptable parameters of 'recreational' sport diving. I'd suggest that they (unadulterated, and used as intended) are far from that... especially, as you say, because the inherent risk needs moderating by "adding a little deco".

 

[tomfcrist]

Which are we talking about? Those Navy tables used (or re-branded) by many agencies were (doppler) modified etc..

There are other prerogatives with the Navy tables... swift exit from the water being one of them, as a military-operational (not dive safety) concern.

They've been suggested as an example of 'valid' tables to suggest the acceptable parameters of 'recreational' sport diving. I'd suggest that they (unadulterated, and used as intended) are far from that... especially, as you say, because the inherent risk needs moderating by "adding a little deco".

Im talking about the US Navy tables, and that they are very close to the agency modified tables in relation to no deco diving. Like I said though, with Deco, I find them slightly outdated, however I dont need a doctorate to be able to logically modify them to be safe as a baseline.

 

[NAM001]

I have glanced over this thread and then looked back at the OP about why manditory doubles. Not saying it has not been responded to but just that i did not see it. I am not a TECH diver however i have a rec trimix cert. This is good for like 160 ft with multi depth deco with up to 100% o2 for deco gas. Part of the gas planning included the failure of the deco gas source. So when you look at diving doubles and you use say 70 of your 150 cubes at depth. You ascend to 70 adn go to 50% and then to 20 and go to 100% or some combination of gasses and surface with say 40-60 cubes left in your back gas. If you were doing a deco with 100% o2 only, and when you get to 20 ft and switch to deco, you could find you had a leak and have little or no deco gas available. So now you have to do your stop not only on back gas but instead of a say 15 min stop you now have perhaps 40 min to do at 20 ft. To do that you have to get the gas from somewhere. It is pretty safe to assume you dont have that much gas left in a single tank to deco on and surface. So in a way like the rule of thirds you have 1/3 out 1/3 back and 1/3 for backup deco if you need it. This does not even consider the need to privide for a buddy if needed.
Normally citing a single tank ususally conjures visions of a single 80 and not a steel 120 which is kinda close to twin 80's.

 

[Bob DBF]

Just a side note:
The navy tables are for the navy. Navy divers are young,fit, and at the top of physical conditioning. The really important point is that all navy diving is done with onboard chamber access. Soooo " bend you and mend you " is an acceptable level of risk. Not to mention that whole thing about you being govt. property.
Quoteing the navy tables only confuses those you are seeking to help further.
Eric

I served on four ships and each had divers, and none had a chamber. The divers were reasonably fit but none were SEALS and a few were young.

The Navy tables were made to be as safe as possible to provide a baseline to be pushed if necessary for "the needs of the Navy".
It was in the hands of the professionals how much the limits could be pushed and whether it was worth the price that might be paid.

I dove the old Navy tables till 1980 and then used the PADI tables, which were exactly the same as the old Navy tables, until I started diving with a computer in '04 or 5, which seems to be similar to the new PADI tables. Only during my earlier diving would I have been considered young and fit. I have had one incident in 50 years of diving and the issue was on me, not the tables.

I am only one data point, however the divers around me at the time seemed to do well using the tables that were available.

The phrase "Navy divers are young, fit, and at the top of physical conditioning." has been an admonishment used to keep exuberant divers from getting to fast and loose with the tables, kind of like "don't dive outside your training and experience" is now.



Bob
-------------------------------------
I may be old, but I'm not dead yet.

 

[mmadiver]

There are other prerogatives with the Navy tables... swift exit from the water being one of them, as a military-operational (not dive safety) concern.

Mind expanding on this? I'm a Navy Diver and have no idea what you're talking about...