Deco with too less air, options from the book

[orange_diver]

I never noticed that but this is absolutely the funniest thing I have read today. No offense to JC but I guess this kind of supports my earlier post. I am still laughing out loud. "Hi, my name is dumpster diver and I admit I have a problem"........too funny.

i didn't catch it till i read his quote in your reply and laughed out loud myself.

it was a gift, truly.

 

[crpntr133]

not only is it simple, but we are on trimix for any dives that would present potential narcosis problems, which gives us very clear heads. RD shouldn't be done on deep air, where you are absolutely right, things could go sideways...

So RD is for mainly trimix and not air or nitrox?

 

[Rainer]

So RD is for mainly trimix and not air or nitrox?

GUE/UTD standard gases...

 

[Bismark]

i didn't catch it till i read his quote in your reply and laughed out loud myself.

it was a gift, truly.

Kind of like when the pitcher lobs a nice straight one right down the middle of the plate.......and it ends up in the next state........

That was really very funny. I hope JC has a good sense of humour.

 

[jtivat]

So when you decide to stay longer or go deeper does this simple math make sure you have enough deco gas also??

 

[Rainer]

So when you decide to stay longer or go deeper does this simple math make sure you have enough deco gas also??

Not directly, but we are also taught to do these calculations as well. Not brain science. This isn't anything specific to RD. I assume all tech divers are capable of calculating gas needs on the fly.

 

[jtivat]

Not directly, but we are also taught to do these calculations as well. Not brain science. This isn't anything specific to RD. I assume all tech divers are capable of calculating gas needs on the fly.

Ok so lets take a dive I do a lot. It is a wreck in Lake Michigan planned depth of 230 with a 20 minute BT. Mixes are 15/55 with 100% and 50% deco. My sac I use for planning is .6 BM and .5 deco. I am carrying 224 cf of BG, 40 cf of 50% and 32 cf of 100%. Now I am at the line but really want to go look at something new I noticed, this will push my BT too 30 min an extra 10 minutes. Do I have enough BG and deco gas to do it?

 

[Shearwater]

We should never underestimate our ability to do stupid things in high stress situations. Based on research by Dr John Leach, panic is most common in situations that are time limited like drowning and burning houses.

Even when we don't panic, as many as 75% will be stunned and bewildered. They will exhibit semi-automatic behavior and react without really thinking. The training agencies know this and that's why you repeat skills over and over. You want your reaction to be automatic.

On the other hand, RD sounds a lot like what John explained to me on a dive boat in the 90's. At that time I was a new trimix diver. He called it phone number deco. There was no such thing as a trimix dive computer, so if you went off your tables in an emergency you did phone number deco. You pick the digits in your phone number and arrange them in the way that seems to make the most sense and then you used that as a deco plan.

Of course this was just gallows humor about one of the nastiest and most dangerous things that could happen to a diver back then. But I think you will find that anyone with 500-1000 trimix dives could come up with a pretty good estimate.

I have to say that I still prefer two computers for me and two computers for my buddy. But I'm hardly neutral.

Bruce

 

[Chatterton]

Ranier,

I thought I was pretty clear, but apparently not? RD is not for me, and the misconceptions your mention below are way off target.

Regardless if your depth gauge is doing averaging as another poster mentioned, or not, you are still relying on a battery powered electronic device to give you information, and it can fail much like a dive computer.

Actually, I was a combat medic in Vietnam when I was 18 years old, and I have had to conduct both rescue and recovery of divers from deep water. In both cases, my ass was on the line, unlike your ER doctor who can finish his/her shift and go home in one piece and have a Merlot. There are probably a few other resume items I could mention here, but how much "practice" in emergencies do you think I really need? You don't know me, but I wonder how much "practice" do you have?

Divers get bent in all sorts of ways. Do you have some kind of scientific, balanced study fom a third party that you can refer me to, that indicates the safty record of RD vs dive computers or tables? Your "I know more divers" claim does not do it for me? I don't know you, or who you dive with? I don't know how many RD dives have been made, or how many dive computer/table dives have been made? Do you?

I think you could use all the RD information, and still run a computer or tables, but the point of RD is to keep it all in your head. I say it again, to me it seems gimmicky that you don't want to use a backup like a computer (or tables), actually why not insist on a computer or tables as a backup. Any diver doing deep technical dives has table and algorithm prefereces, and that was never the issue here. It is not about which profile is better.

You accuse me, of not wanting to learn? You think so? If I did not want to learn, I would be diving a steel 72 single with a J Valve and a hydrostatic test date of 1969, with a horsecollar BC? That instead of a half dozen different rebreathers? I must have some sort of desire to learn something? Maybe just not from you?

Perhaps, it is that you do not want to listen to me? RD is definitley not for everyone, and not for me for specific reasons I have that relate to the way I dive. I am not trying to convert you to computers or tables as I don't even know you, or the way you dive? Do as you please, because I really don't care.

Why are you intent on converting me to RD? Why do I have to see it your way, or I have "misconceptions", maybe if I disagree with you I could even mental illness? Sorry, but I am not drinking the kool aid, here. I want to dive the way that I think works for me for very specific reasons that address my goals and experience. End of story.

Have a special day.


JC

Again, I'm sorry to see that you won't state what you believe RD to be. Sort of odd.

To clear up some misconceptions:

I assume ALL of us are diving with some incentive. I don't think that's a difference.

We also aren't using a gauge to do the depth averaging. We do that ourselves (yes, using the gauge to tell us our current depth). The point is, we're keeping a running total, so if the gauge were to die, we could still plan and execute our deco, no electronics needed.

Your concern of a "full head" is reduced with practice. I assume ER docs don't forget all of med school when someone comes in after an accident. That same doctor probably didn't have that bandwidth in med school. Using RD successfully does take practice. Many divers are successfully using it. Personally, I know many more divers bent on computers than RD. I'm sure that's the case for you, too.

Also silly to suggest any of us can afford to get bent. Weird.

Your "gimmicky" comment suggests you don't understand RD. About what I imagined. If you care to actually learn, take a look at link I posted earlier. If not, that's cool. Like you, I really don't care what others do if it works for them. Always nice to educate yourself, however, about alternatives.

Thanks for posting!

 

[Blackwood]

Ratio Deco is a way to figure out deco obligation and profile.
A Personal Dive Computer is a way to figure out deco obligation and profile.
Desktop Software (such as Vplanner) is a way to figure out deco obligation and profile.
Printed Decompression Tables are a way to figure out deco obligation and profile.

None is better or worse than the other. Some are more flexible with respect to gases, and others are more flexible with respect to changes in profile.

Pick which one works for you, and let's go diving. Afterward, maybe we can all go do Disneyland to enjoy their roller-coaster rendition of a bobsled ride down the Chatterhorn.