Deco with too less air, options from the book

[RonFrank]

I don't want to get in the middle of this, but here is a thought.

Why NOT use every available technology to make a dive as safe and fault redundant as possible?

It seems odd to me that in scuba, which is a technology based past time, that some folks seem to believe that older technology is somehow the only option.

I use both an SPG, and a wireless dive computer. After 100 dives my wireless SPG has never had an issue, and it is MORE accurate vs. my SPG, but I choose to use both. IMO I am prudent in my decision making, but this is also MY opinion and my way of being safe.

OK, carry on...

 

[Rainer]

Uh, I clearly said dive how you want. I don't give a **** if you dive RD or not. Really.

 

[shoredivr]

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?

These are good questions. Something objective would be useful to all.

 

[orange_diver]

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?

i'm not certified for these depths, but i *believe* the DIR way would add a third deco bottle at 120 (40cf) which would greatly aid in managing rock bottom BG. also use a 40cf of 100%

in addition, you didn't mention if you are saving any gas for your buddy. we would calculate a sac rate of 1 cf/min (emergency stress) x two (for 2 divers) on the BG and that would be our rock bottom.

 

[Blackwood]

Why NOT use every available technology to make a dive as safe and fault redundant as possible?

Because you end up looking like this:

 

[jtivat]

i'm not certified for these depths, but i *believe* the DIR way would add a third deco bottle at 120 (40cf) which would greatly aid in managing rock bottom BG. also use a 40cf of 100%

in addition, you didn't mention if you are saving any gas for your buddy. we would calculate a sac rate of 1 cf/min (emergency stress) x two (for 2 divers) on the BG and that would be our rock bottom.

Ok the dive is real but I would not use the gases or the amounts I listed. The point was to see if this RD can tell me if have the gas to extend my BT or not. Some posters claimed that RD enabled them to extend a dive or depth if they wanted. What good is that if it cannot tell you if you have the gas to do it or not?

 

[shoredivr]

Still would like to know who/where that photo is from...

An example of RD in a non-stressful (albeit deep air) situation which illustrates that things can go wrong calculating in one's head on the fly, with good analysis afterwards.
http://www.scubaboard.com/forums/near-misses-lessons-learned/264517-type-i-bends-hit-chuuk.html

 

[Rainer]

Ok the dive is real but I would not use the gases or the amounts I listed. The point was to see if this RD can tell me if have the gas to extend my BT or not. Some posters claimed that RD enabled them to extend a dive or depth if they wanted. What good is that if it cannot tell you if you have the gas to do it or not?

What RD does is tell you how much deco you need to do and where. If you can calculate an average depth for your deco, and know the deco run time, you can calculate how many cf of gas you'll need for that extension. In any case, I wouldn't personally extend a dive past a time/depth I hadn't already been to on a previous planned trip. In which case, I'd already know first hand how much gas that dive requires. What RD would do for me on the future dives is let me determine the deco for that extended dive.

 

[jtivat]

in addition, you didn't mention if you are saving any gas for your buddy. we would calculate a sac rate of 1 cf/min (emergency stress) x two (for 2 divers) on the BG and that would be our rock bottom.

Well first if you are doing deep trimix dives and your sac goes to 1cf in a stressed situation you need to rethink doing these dives. Next you had better use 130's for deco gas.

 

[orange_diver]

Ok the dive is real but I would not use the gases or the amounts I listed. The point was to see if this RD can tell me if have the gas to extend my BT or not. Some posters claimed that RD enabled them to extend a dive or depth if they wanted. What good is that if it cannot tell you if you have the gas to do it or not?

why post like that with gases/amounts you would not use? makes no sense and it feels like a set up.

RD cannot tell you if you have enough gas. only proper gas management can tell you that which of course is also done. when u figure out your gas management, at that point you should know how much you have to safely extend your dive if u need to.

RD will help you do the deco once you have extended your BT by 10 mins if proper gas management allows you to do that.