Redundancy Required for Decompression Diving?

[scubadada]

Redundancy is absolutely not required to deco dive redundancy is only needed when something goes wrong. If you chose to go into deco without redundancy you are potentially betting your life on the fact that you wont have an equipment failure and you are accepting of the consequences as remote or as dire as they may be. Which is something Im unwilling to do.

Similar to solo diving

 

[dumpsterDiver]

I just want to know if the Agencies state that it is required or not. I have my own opinion on the topic. Is redundant gas supply required or not?

 

[RandomGuy1]

I believe that standard for TDI AN/DP requires redundant first stages, but not necessarily redundant gas supplies for back gas. Note that is says: "Note: Independent and isolated back-mounted doubles, are allowed to be used." but doesn't say required.
https://www.tdisdi.com/wp-content/uploads/files/sandp/currentYear/TDI/part 2/pdf/individual/TDI Diver Standards_08_Decompression_Procedures_Diver.pdf

 

[Lorenzoid]

You can take GUE rec 3 which allows some deco.

I don't know anything about Rec 3, but if you're correct, then that is a good point. However, I would suspect that since GUE emphasizes "Minimum Gas" aka Rock Bottom, then they would account for deco gas in that calculation. So, you're not "relying on your buddy's gas" for redundancy/backup--you're relying on your gas for redundancy/backup, which your buddy happens to be carrying for you in case you need it.

 

[guruboy]

rec 3 requires doubles and a deco bottle.

 

[tbone1004]

You can take GUE rec 3 which allows some deco.

Do people every bring back-ups for their deco gas?

to answer this, as well as the original question is complicated

Part of this for me falls under the currently scary long thread about "lite" deco. Under certain circumstances, mainly planned decompression but only planned because of diving conservative dive plans, I have no issue with no redundancy for that dive so long as I'm diving within what some would say are the NDL's for that dive, and if I'm diving with a buddy. My buddy is that redundancy. Rock bottom planning for that dive would include sharing gas through the planned decompression obligation.
On the high end of things, that would be about 25cf reserved for decompression with a 1.5x safety factor with a planned 10 minute decompression obligation or about 15cf if you're feeling ballsy, this is not including the rest of the rock bottom calculation, so you're going to need a big cylinder to do a meaningful dive. I don't see this being a realistic scenario when diving on nitrox without HP130's or cave filled LP bottles bigger than 104's. On air it would obviously start earlier. Someone with deco software on their computer may be able to validate quicker than I can since I don't have it on this pc.

Your buddy is carrying your reserve gas in this case and for recreational diving, even that with limited backgas deco, I'm OK. Personal opinion, not agency opinion. I don't do it and don't recommend it, but I'm not going to tell someone they're stupid or unsafe if they do. Personally? I don't really dive single tanks hardly ever. Sidemount or doubles depending on the environment. If I'm diving singles, I'll limit it to 10 minutes of backgas deco on a fairly conservative GF, monitor the GF99. The odds of a reg failing when I've just started my deco, GF99 hasn't cleared yet, and no one is around to share gas with me are pretty small, so I'll risk it.

 

[Lorenzoid]

rec 3 requires doubles and a deco bottle.

Ah. Thanks for the clarification. Then I don't think that's what the original question is about. That indeed sounds like what most would call tech diving, with all the redundancy one would expect. Perhaps Rec 3 could be called "a tech course but with a waiver of the tech pass prerequisite, and a more limited curriculum" than Tech 1.

 

[tursiops]

I think DD is asking a disingenuous, trick question. He keeps using the word "required" and the answer is No, nothing special is required for technical *diving,* only for technical *training.* So, Yes, you need the redundancy during the training, and you'd be really stupid to ignore it all during the diving, but it is not *required* during the diving.

 

[guruboy]

Ah. Thanks for the clarification. Then I don't think that's what the original question is about. That indeed sounds like what most would call tech diving, with all the redundancy one would expect. Perhaps Rec 3 could be called "a tech course but with a waiver of the tech pass prerequisite, and a more limited curriculum" than Tech 1.

I think that's a pretty accurate description.

 

[RandomGuy1]

I think DD is asking a disingenuous, trick question. He keeps using the word "required" and the answer is No, nothing special is required for technical *diving,* only for technical *training.* So, Yes, you need the redundancy during the training, and you'd be really stupid to ignore it all during the diving, but it is not *required* during the diving.

I think you are right. The only thing that is truly required for decompression diving is enough air to excede NDL's. It isn't even really required to have enough air to complete your required decompression. As with everything in life , you can do whatever you want to, but you have to be prepared to accept the consequences of you actions.