Addicted2H2O
Contributor
Not making light of what happened or what mistakes were made. Just saying it's done and over and can't be changed now. Learn from it, don't make the same mistakes next time, and move on down the road.
Basic rules broken become near miss
- Thread starter Yeason
- Start date
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I am not going to say surfacing with 20 bar is a good thing to do routinely, but 20 bar is roughly 300psi....that is plenty of usable air especially at 6 meters...the whole reason for the rule of thumb to surface with 50bar/500psi (and I know they don't compute as equal), is to have a reserve for that rare occasion when the s**t hits the fan....and when the s***t is hitting the fan all the air in the tank should be considered usable.
You have plenty to beat yourself up over, surfacing with 20bar because you were trying to keep a bad situation from getting worse is not one of them. Had your story ended with you stating that you did not know that you only had 20 bar left until you surfaced, well then you would probably be reading a different response, and my post would probably get deleted by the moderators.
Good job in staying alive...learn from the mistake, be humbled by it, and apply it to your diving. You may want to rethink who you dive with as for your group to grossly exceed the depth limit of the dive plan and to conduct a deco dive without planning the gas is just all shades of irresponsible...not the level of responsibility I expect of the kind of people with which I want to enter an environment hostile to my survival, but that is a decision you need to evaluate.
-Z
You have plenty to beat yourself up over, surfacing with 20bar because you were trying to keep a bad situation from getting worse is not one of them. Had your story ended with you stating that you did not know that you only had 20 bar left until you surfaced, well then you would probably be reading a different response, and my post would probably get deleted by the moderators.
Good job in staying alive...learn from the mistake, be humbled by it, and apply it to your diving. You may want to rethink who you dive with as for your group to grossly exceed the depth limit of the dive plan and to conduct a deco dive without planning the gas is just all shades of irresponsible...not the level of responsibility I expect of the kind of people with which I want to enter an environment hostile to my survival, but that is a decision you need to evaluate.
-Z
martincohn
Contributor
You lived and didn't get bent...congrats
You understand what was done wrong....good
This is a perfect example how what may seem like a few little things, can lead to task loading going to ****, and possibly turning into your last dive.
There is a lesson here for EVERY diver to lean from.
You understand what was done wrong....good
This is a perfect example how what may seem like a few little things, can lead to task loading going to ****, and possibly turning into your last dive.
There is a lesson here for EVERY diver to lean from.
johndiver999
Contributor
Lessons? Is it smart to dive to 160 feet and rack up 20 minutes of deco with a single tank and no bail out and no deco gas on a potentially challenging cold water dive?
When reaching the bottom and knowing that you powered down and were light, why not find some ballast like a rock or something and then carry that up? I would think that should be tactic that should have been thought about a bunch before the dive, in case a diver accidentally lost ballast during a deco dive.
How about, if you and your buddies are doing planned deco dives to well past the recreational depths with no redundancy in tanks and air supply, possibly the "team" should preserve a lot more air for sharing on the ascent???
Unless this was a repetitive dive, then I think it might be tough to have enough air in a single tank to get two divers safely to the surface after staying so long that they accumulate a 20 minute deco? So it sounds like (and I could be wrong) that the team planned to have no independent redundancy and also planned to dive in a manner such that they could not rescue a buddy if he simply got a freeflow for a few minutes toward the end of the dive.
I think the scenario described by the OP provides a lot of food for thought and the issues extend way past, making sure you have enough lead on your belt when you change exposure protection.
When reaching the bottom and knowing that you powered down and were light, why not find some ballast like a rock or something and then carry that up? I would think that should be tactic that should have been thought about a bunch before the dive, in case a diver accidentally lost ballast during a deco dive.
How about, if you and your buddies are doing planned deco dives to well past the recreational depths with no redundancy in tanks and air supply, possibly the "team" should preserve a lot more air for sharing on the ascent???
Unless this was a repetitive dive, then I think it might be tough to have enough air in a single tank to get two divers safely to the surface after staying so long that they accumulate a 20 minute deco? So it sounds like (and I could be wrong) that the team planned to have no independent redundancy and also planned to dive in a manner such that they could not rescue a buddy if he simply got a freeflow for a few minutes toward the end of the dive.
I think the scenario described by the OP provides a lot of food for thought and the issues extend way past, making sure you have enough lead on your belt when you change exposure protection.
There is an implied assumption here that the bottom was reached and even if it was reached there is an implied assumption that there was something available that could be used as additional ballast.
That may have been the case but it is not possible to tell from the account the OP shared.
Just sayin'
-Z
johndiver999
Contributor
From the OP's profile, I'm guessing this was a dive on the oil rigs. The bottom is quite a bit deeper than 53m
53m = 174ft
if it took 3 mins to get there, he/she had about 10mins of BT to accumulate ~17mins of deco on air. But the post isn't clear how long they stayed at depth.
I'm curious how the OP and anyone else would answer these questions.
1) do people really consider that an H valve qualifies as sufficient redundancy for technical diving? After all, if the burst disk fails (I've seen that happen on a cylinder just laying there), what are you going to do?
2) given Dr. Simon Mitchell's maximum gas density of 5.2 g / L (Alert Diver | Performance Under Pressure) which translates to a max depth of air to 100 feet / 30 meters, do people think it is a safe practice to exceed that with diving deep on air? If so, what are your thoughts on Dr. Mitchell's advice? Given his expertise in dive medicine, what is your reasoning for disregarding his recommendation? What do you know that he doesn't?
One thing that frightens me a bit about the OP's post is the exertion required to stay down, thus resulting in greater CO2, and thus more narcosis. I'm glad that this event didn't end badly, but I hope that people don't take this to justify normalization of deviance.
1) do people really consider that an H valve qualifies as sufficient redundancy for technical diving? After all, if the burst disk fails (I've seen that happen on a cylinder just laying there), what are you going to do?
2) given Dr. Simon Mitchell's maximum gas density of 5.2 g / L (Alert Diver | Performance Under Pressure) which translates to a max depth of air to 100 feet / 30 meters, do people think it is a safe practice to exceed that with diving deep on air? If so, what are your thoughts on Dr. Mitchell's advice? Given his expertise in dive medicine, what is your reasoning for disregarding his recommendation? What do you know that he doesn't?
One thing that frightens me a bit about the OP's post is the exertion required to stay down, thus resulting in greater CO2, and thus more narcosis. I'm glad that this event didn't end badly, but I hope that people don't take this to justify normalization of deviance.
Its impossible to tell if the OP's tank had a burst disk at all. For all we know the dive was in Europe (land of no burst disks). Catastrophic burst disks failures are so rare in the water that the H valve has been considered "ok" for a long time. I don't know of a single fatality attributed to total gas loss from a burst disk on an H valve. Admittedly they are not that common anymore, but at least to date, the absolute risk from this part is extremely low.
How exactly you plan an air deco dive on a 40m single tank dive is not my forte.
Stoo
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Meh, sounds like my typical Saturday. 
Ok, not really, but I think you have identified what went wrong, lived, and presumably learned.
And now you likely won't do it again.
Glad you didn't get bent though, so don't beat yourself up. There isn't one of us here with a bunch of dives that hasn't had one of these "character-building" dives.
Ok, not really, but I think you have identified what went wrong, lived, and presumably learned.
And now you likely won't do it again.
Glad you didn't get bent though, so don't beat yourself up. There isn't one of us here with a bunch of dives that hasn't had one of these "character-building" dives.
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