Computer VS. Tables

[Storker]

I'm exploring pushing NDLs a little in exchange of doing mandatory stops - I'm not talking about tech diving

Yeah, right. "I won't put it all the way in, so you'll still be a virgin"

Mandatory deco stops takes you, by definition, from the rec diving realm to the tech diving realm.

• NAUI defines technical diving as "Any diving beyond the limits of the defined recreational diving limits which is currently set at the following - diving to 40 meters/130 feet, use of nitrox above 36%, multiple mix gas diving, penetration diving past the daylight zone and any form of decompression diving)."[citation needed]
• PADI defines technical diving as "diving other than conventional commercial or recreational diving that takes divers beyond recreational diving limits. It is further defined as an activity that includes one or more of the following: diving beyond 40 meters/130 feet, required stage decompression, diving in an overhead environment beyond 130 linear feet from the surface, accelerated stage decompression and/or the use of multiple gas mixtures in a single dive."[6]
• NOAA defines technical diving as "all diving methods that exceed the limits imposed on depth and/or immersion time for recreational scuba diving. Technical diving often involves the use of special gas mixtures (other than compressed air) for breathing. The type of gas mixture used is determined either by the maximum depth planned for the dive, or by the length of time that the diver intends to spend underwater. While the recommended maximum depth for conventional scuba diving is 130 ft, technical divers may work in the range of 170 ft to 350 ft, sometimes even deeper. Technical diving almost always requires one or more mandatory decompression 'stops' upon ascent, during which the diver may change breathing gas mixes at least once."[7] NOAA does not address issues relating to overhead environments in its definition.

Short version: When a direct ascent to the surface at any time of the dive isn't a safe option, you've ventured into tech. You may not be tech trained and/or equipped, but you're still, by definition, doing a tech dive.

 

[KenGordon]

Oh... Why so many assumptions? I am interested in learning and training. I don't know more than anyone else, that's why I'm here. If I knew better than anyone else, I'd just do it and wouldn't talk about it. I'd appreciate if you bothered me. You are giving valid points and I want to respond to those.
.

A useful rule in diving is "You don't know what you don't know."

Extrapolating from your current knowledge one step on might drop you in a hole. If you do a deco course with a decent instructor he will deliver a course which has been designed to cover what you need to know to dive to that level. It will leave out the stuff you definitely do not not need to know but should cover the "why so many assumptions?" question you raise.

Much of what you will be taught is non obvious, if it were obvious diving would not have changed over many years. The agencies try to learn from the mistakes people make.

After that go diving, find for yourself that in the sea, bouncing up and down, with cold fingers and knowing you have only JUST enough gas, your SMB line wrapped round you fins or whatever that your SAC will not be the same as bored for twenty minutes at 6m with nothing to do except count the minutes on a stop.

 

[mrdre]

Yeah, right. "I won't put it all the way in, so you'll still be a virgin"...

That works too

A useful rule in diving is "You don't know what you don't know."

Extrapolating from your current knowledge one step on might drop you in a hole. If you do a deco course with a decent instructor he will deliver a course which has been designed to cover what you need to know to dive to that level. It will leave out the stuff you definitely do not not need to know but should cover the "why so many assumptions?" question you raise.

Much of what you will be taught is non obvious, if it were obvious diving would not have changed over many years. The agencies try to learn from the mistakes people make. ....

Good points...

 

[rivers]

Oh... Why so many assumptions? I am interested in learning and training. I don't know more than anyone else, that's why I'm here. If I knew better than anyone else, I'd just do it and wouldn't talk about it. I'd appreciate if you bothered me. You are giving valid points and I want to respond to those.

You mentioned that I need 33 cft and so I'm trying to understand why. The deco stops require 14 cft. I reserved 17 cft for ascend. Plus I planned 17 cft reserve in my tank. Plus I have 19 cft pony. I want to learn where is a mistake in my estimate if I receive so much criticism.

I'm exploring pushing NDLs a little in exchange of doing mandatory stops - I'm not talking about tech diving, I'm not talking about hours of deco obligation. I'm talking about 5-10 minute decos just like in the example we talked about. I'm not looking to convince anybody. I'm not trying to prove anything. I'm just giving arguments and want to hear other arguments against. Maybe I'm doing something wrong. So I'll stop doing it. I want to know what are the risks, is taking those risks worth it, etc. If risks are too high - I won't do it, if low - meh. That's all.

When planning out gas reserves for ANY dive (not just dives with mandatory stops), you need to assume an elevated, stressed SAC rate for both divers. If sh*t hits the fan, the breathing rate of both divers will go up, so you need to reserve more gas. Also, it will take you about a minute to get yourselves sorted in an airshare situation on the bottom before you start your ascent. If you've got mandatory deco to do, that ascent needs to be controlled. You are not leaving yourself enough gas to get two divers to the surface, simple as.
I have no problem with divers doing a bit of deco in the recreational ranges, if they are equipped and trained for it. You are not. A single and a pony isn't appropriate for a dive requiring mandatory deco, even if only a 10 minutes. Get some training mate

 

[mrdre]

I'd like to sum up all the arguments. (and I apologize for hijacking the thread - I think we can go back to "tables vs dive computer" now).

As I understand, the strongest argument here is that the diver without enough training will not be able to handle a critical situation properly as trained and equipped diver would. The diver will be facing the choices: drowning or having DCS as he won't be able to do decos anymore.

I guess then few extra minutes underwater aren't worth the risks (those minutes could be gained with Nitrox anyway).

Boulderjohn, indeed my computer has the feature which tells me how long I'll be able to stay at certain depth in the next dive. I didn't realize that and it was the most annoying part for me - not knowing and not being able to plan the next dive more precisely.

I guess you guys are right. The risks are high enough and those extra minutes under water aren't worth it. It's good enough argument for me to stop doing it. Thanks for everybody who took time to reply.