Recreational Scuba Deco Diving

[Blackcrusader]

I don't change my PDC out of "tech" conservatism for NDL dives, so 3min deco stop is the same as 3min safety stop for me. Does that count as back gas deco? If my PDC does not call for deco, I don't need a safety stop.

I set my safety stop to 6m for 5 minutes. Extra time cannot be a bad thing and on most dives after the safety stop I am often at 5m for another 10 mins or so taking photos on the reef so I may do 15 mins at safety stop level. What I like with the Perdix is that is shows the plus number of minutes you do after safety stop is cleared.

 

[rx7diver]

I don't change my PDC out of "tech" conservatism for NDL dives, so 3min deco stop is the same as 3min safety stop for me. Does that count as back gas deco? If my PDC does not call for deco, I don't need a safety stop.

@vogt,

Some of the posts in this thread, including this one of yours, are having me wondering if I am thinking of things too narrowly. When I am speaking of a planned deco dive here, I am thinking of a dive that is planned ahead of time using published tables, or maybe using deco-planning software on a laptop/desktop, rather than a dive where someone simply "plans" to allow his/her PDC to go into deco.

When I "plan" a deco dive, I literally use a published table, and a pencil and a calculator and a yellow pad. As mentioned, I ceased doing deco dives quite a while ago. However, I still "plan" them, occasionally, when I get questions from students enrolled in the university scuba course here.

So, at this point, I don't have an answer to your question.

rx7diver

 

[Blackcrusader]

@vogt,

Some of the posts in this thread, including this one of yours, are having me wondering if I am thinking of things too narrowly. When I am speaking of a planned deco dive here, I am thinking of a dive that is planned ahead of time using published tables, or maybe using deco-planning software on a laptop/desktop, rather than a dive where someone simply "plans" to allow his/her PDC to go into deco.

When I "plan" a deco dive, I literally use a published table, and a pencil and a calculator and a yellow pad. As mentioned, I ceased doing deco dives quite a while ago. However, I still "plan" them, occasionally, when I get questions from students enrolled in the university scuba course here. So, at this point, I don't have an answer to your question.

rx7diver

I believe you need to allow for the fact that some divers will plan for the Deco added time after they start their dive or just add unplanned DECO to a recreational dive.

 

[rx7diver]

I believe you need to allow for the fact that some divers will plan for the Deco added time after they start their dive or just add unplanned DECO to a recreational dive.

You might be right, @BLACKCRUSADER. But, as mentioned, this is not what I had in mind when I wrote my op.

rx7diver

 

[Blackcrusader]

You might be right, @BLACKCRUSADER. But, as mentioned, this is not what I had in mind when I wrote my op. rx7diver

I see it this way. You are now like the parish Priest asking all the naughty people to come to confession. They are resistant to tell their naughty stories in public and even in the sanctity of a confessional who is to say no bugs are installed. Your good intentions are well founded. I like this thread spinoff you have done. Sometimes though people criticize those who do RSDD and really the question is have you done it, do you plan on doing it? Do you think it's acceptable for short added deco times at say 30m or less after all we are chatting about recreational dives where people use a single tank.

Should I do that 32% nitrox dive to 25m for 50 minutes bottom time? I've run the numbers for me using an AL 80 or AL 100. As I would be with a dive buddy my limiting factor is my buddy's tank size also being an AL80 and AL100 and air pressure ( 210 bar start ) so really how many liters of air and the SAC rates. I would use less than 1500 liters of air at best for the total dive time so lets add 1.5 to that say 2250 liters at worst, in theory. GF 45/95 for me as that is also important to know.

So I could plan for that 32% as I would need 36 mins to get to exceed NDL and of course at any point abandon the deco part or shorten the deco part of the dive if say conditions not good at that point, low air for myself or dive buddy, strong current to swim into or what not. Would I do it on the spur of the moment? No. Would I do it planned with my regular dive buddies, yes, an instabuddy on first dive, no. Regardless of their cert level.

 

[rjack321]

I see it this way. You are now like the parish Priest asking all the naughty people to come to confession. They are resistant to tell their naughty stories in public and even in the sanctity of a confessional who is to say no bugs are installed. Your good intentions are well founded. I like this thread spinoff you have done.

Or maybe we sin in more creative and devilish ways than racking up 10mins of deco on a single tank with no redundancy or deco gas.

 

[Celt]

Or maybe we sin in more creative and devilish ways than racking up 10mins of deco on a single tank with no redundancy or deco gas.

I think he wants to know how many have sucked the rust out of a tank with a minute or two of deco left, I wouldn’t hold my breath waiting for that answer.

 

[Degenerate]

At least IANDT advanced recreational Trimix/advanced nitrox/deco procedures gives 15 min staged decompression (50%), and considers itself a recreational education.

Actually the IANTD adv rec trimix doesn't have a time limit on how much deco you can do, the only limiting factor is that you can only have one deco bottle.
At least that is what we were told when we took the class back in May this year.

 

[Alekseolsen]

Actually the IANTD adv rec trimix doesn't have a time limit on how much deco you can do, the only limiting factor is that you can only have one deco bottle.
At least that is what we were told when we took the class back in May this year.

Hmm, that's funny. We've been told 15 min max, and given the 2015 edition of the IANDT "standards" which states 15 minutes.

Dod you get newer standards?

 

[Degenerate]

Hmm, that's funny. We've been told 15 min max, and given the 2015 edition of the IANDT "standards" which states 15 minutes.

Dod you get newer standards?

Actually now that you mention it, we did the ART+ class, with 51m max depth and 1 deco gas, no time limit.
So I'm guessing that would be the difference between the regular and the plus class.