UTD Decompression profile study results published

[Rainer]

For our "tech" dives, our team would set a MOD (usually pegged to our backgas), a max amount of deco we were willing to do (that still allowed for one failure), and calculate min gas from MOD. We'd then go diving. If the site allowed for 170' but the cool stuff was at 120', we'd adjust on the fly. If the original research had estimated the wreck at 140', but it was at 160', we'd adjust on the fly (again, always keeping to MOD, total deco, and min gas). If you're trained this way, it's really not that hard. No one is suggesting you go do it if it's beyond your experience or training, but it's hardly rocket science.

 

[rivers]

I understand all that. But, if your plan is "anywhere from 30 to 45 minutes", wouldn't you actually do a plan for 45 minutes to verify that you have all the gas you need to accommodate that option? I would. In which case, you're exactly where I started - plan for a max depth and max time and then, if you only stay down for 30 minutes, no big deal. You have not exceeded the depth or time you planned for.

It's all part of proper dive planning. I know how much gas I need to get myself and another diver to the next available gas source, whether that's switch depth or surface, and complete any necessary stops. As long as I, nor any other team member violates min gas, then I don't see a problem with extending the dive a few minutes or changing your max depth. That's where ratio deco, as GUE teach it, shines. If you want to keep your deco the same, but end up deeper than planned, you know how long you can spend at depth. Works the same in reverse. It's a tool.

 

[Tassi Devil Diver]

Most of my dives are mutli level, very few are square profile I will know an approximate maximum depth and will plan my bottom gas/dil accordingly and, me and my buddy plan the maximum deco we want to do, 30, 60, 90 120 minutes based on the conditions and may alter this at the last minute if things are better or worse than expected and carry the gas needed for that deco or bailout. I find this provides enough flexibility using computers if we find we are diving shallower than expected. No need for RD for flexible dive planning.

 

[elmo]

All I can conclude is that I don't have the experience to feel comfortable doing what he talked about, nor do I have the experience to judge whether it's perfectly fine or normalization of deviance. I ask questions to try and gain understanding and, hopefully, one day have enough experience of my own to judge for myself.

That's a good approach. Don't let anyone convince you to do more aggressive diving (including changing your plan during the dive) than you are trained for and are comfortable with.
On the other hand, GUE and I believe UTD, teach methods to make reasonable adjustments (within limits) during the dive, some of which have been alluded to in this thread. It is not frowned upon to consider a plan flexible. In this case it is not normalization of deviance because you know you are diving within the scope of your training, ability, and resources. You do not "wing it" and hope you will get away with it.

 

[CptTightPants21]

I understand all that. But, if your plan is "anywhere from 30 to 45 minutes", wouldn't you actually do a plan for 45 minutes to verify that you have all the gas you need to accommodate that option? I would. In which case, you're exactly where I started - plan for a max depth and max time and then, if you only stay down for 30 minutes, no big deal. You have not exceeded the depth or time you planned for.

Yes, although that is not what you said. You said that if you plan for 45 min at 120' you would be irresponsible to dive at 90' for 60 min (violating your planned dive time). 90' for 60 uses the same amount of gas with shorter deco time.

 

[Michael Guerrero]

Sometimes I just watch what my Petrel says my first stop depth and duration is. When I'm getting close to my planned deco, which I have on my tables, I start getting ready to ascend. Outside of that, I don't really worry too much about 5 min here or 10 min there. These are of course not extreme depths, where five minutes makes a huge difference. Sub 200ft, I'd most likely just stick to the plan or something very close. I always have ample gas reserves (back and deco) so I don't sweat it.

 

[Michael Guerrero]

It seems to me that failing to dive your plan is no more or less forgivable when you do it on purpose than if you do it by accident.

I've never asked forgiveness from anyone for the way I dive

 

[Jack Hammer]

Being able to adjust the plan on the fly can be very useful. We had a plan to penetrate the engine room on a dive. When we got there we found the other group had decided to get in first and completely silted out that area. We saw the dirt coming out and adjusted our plan for a deeper section inside another part of the wreck and adjusted our bottom time accordingly.

 

[Remy B.]

If the only tool you have is a hammer, everything looks like a nail.

We changed the plan and we were able to do it easily because we had the tools to do so.

It's only "wrong" if you don't have the ability to do it. We did. Never exceeded min gas, never exceeded max allowable deco, never outran our reserve deco gas. Everyone was on the same page.

If you're on a recreational wall dive planned to 100' but you encounter something cool at 80' do you skip it because you said you wanted to go to 100'? Do you truncate your bottom time because you planned for 100'? Of, of course not. This is no different.

If you're so boxed in that you can't make adjustments do you really have a good hold on the dive and your resources and what they can do?

That is what I'm referring too, if you have a Tec DC, and you know the depth and you know your current dive time at "spot #1" and you know you have 25min more to go to complete your initial planned dive time ( gas quantity ) and it takes 10min to get to "Spot #2" then you know that you have will stay 15min in spot #2 before you start the ascent, why shall you need RD for that ???

I'm very new to diving and I don't understand a lot of things, but I don't see substitute to the DC ot BT or a reason of using RD, meaning that your DC and your buddy's DC or BT need to all fail before you really need to use RD, it seems you need to calculate mentally a lot less by knowing distance and depth of spot #2 having a DC or BT, than adding to that RD.

 

[Remy B.]

Being able to adjust the plan on the fly can be very useful. We had a plan to penetrate the engine room on a dive. When we got there we found the other group had decided to get in first and completely silted out that area. We saw the dirt coming out and adjusted our plan for a deeper section inside another part of the wreck and adjusted our bottom time accordingly.

Maybe I'm wrong but I believe you DC does the same, no need for RD, but what you are doing is even more ill, you are going from shallower to deeper, at least I understand AJ from deeper to shallower because you just get bonus gas.