Minimum Experience for Rebreather Training

[KenGordon]

I agree with @KenGordon , it’s extra prep time, for every day diving.

I’d only do this if your plan is to do deeper dives, because that’s where the pros start beating the cons.

I.e, if I stayed at the 40m range and/or didn’t want to dive regularly deeper, I’d just stay on a OC twinset myself.

It is good for long dives too. Even in the 30-40m range a twinset can be the limiting factor, given you are prepared to do deco.

 

[LFMarm]

I agree with @KenGordon , it’s extra prep time, for every day diving.

I’d only do this if your plan is to do deeper dives, because that’s where the pros start beating the cons.

I.e, if I stayed at the 40m range and/or didn’t want to dive regularly deeper, I’d just stay on a OC twinset myself.

It greatly depends on bottom time. If you do wrecks or other dives that require a long time at 30m+, a rebreather is a significant advantage over a twinset. I am also using He for anything deeper than 30m so in my case it also makes it much cheaper to do these type of dives.

 

[lostsheep]

Yes, basic CCR class, which people may refer to as Mod 1, is air diluent only, no deco, 100ft depth limit. You need 50 hours to be able to go onto to Mod 2/Helitrox, deco, to 150ft.

So at the air dil no deco level, you’ve got a nitrox mixing machine on your back and NDL is longer, at least it seems to me, than on OC.

Not entirely, if you are AN/DP beforehand you can skip air dil and go straight to helitrox.

TDI CCR Helitrox Decompression Procedures - International Training - SDI | TDI | ERDI | PFI

www.tdisdi.com

FWIW, I highly recommend doing AN/DP first then going to Helitrox CCR. There’s plenty to see with AN/DP, you’ll need to be able to bail out to OC when it hits the fan, and you can skip air dil when you go CCR.

Personally, the primary reason I got my breather was for using helium.

 

[Marie13]

Not entirely, if you are AN/DP beforehand you can skip air dil and go straight to helitrox.

TDI CCR Helitrox Decompression Procedures - International Training - SDI | TDI | ERDI | PFI

www.tdisdi.com

FWIW, I highly recommend doing AN/DP first then going to Helitrox CCR. There’s plenty to see with AN/DP, you’ll need to be able to bail out to OC when it hits the fan, and you can skip air dil when you go CCR.

Personally, the primary reason I got my breather was for using helium.

OP was asking about the basic class.

Not all instructors will take you directly to Helitrox. Mine makes you do the basic air dil class even if you have OC Helitrox. You can get the Helitrox upgrade right away (like the next day or weekend), but it’s separate from air dil. She wants students to get the basics down first.

 

[lostsheep]

My basic CCR class was helitrox and as far as I know is colloquially called mod1; at least I sure hope so because when I completed the next class everyone called it mod2. The only other CCR I see is hypoxic Trimix which I thought was mod3? Maybe we should call helitrox mod 1.5

Marie is right about some instructors not being willing to skip air dil (which I find very odd). I’ve also encountered several charter operators who made me cite the standards.

As I think back, I literally don’t think I’ve ever used air as dil. Not that I wouldn’t use air, it’s just that at our typical dive sites we use helium. When I get to cave dive I want a higher po2 for my bailuent.

I stand by my answer to the OP’s question that “minimum experience before doing that training” should be AN/DP to helitrox mod1. I think this route ensures you have the necessary OC experience while value and usefulness are maximized.

 

[LFMarm]

My basic CCR class was helitrox and as far as I know is colloquially called mod1; at least I sure hope so because when I completed the next class everyone called it mod2. The only other CCR I see is hypoxic Trimix which I thought was mod3? Maybe we should call helitrox mod 1.5

Marie is right about some instructors not being willing to skip air dil (which I find very odd). I’ve also encountered several charter operators who made me cite the standards.

As I think back, I literally don’t think I’ve ever used air as dil. Not that I wouldn’t use air, it’s just that at our typical dive sites we use helium. When I get to cave dive I want a higher po2 for my bailuent.

I stand by my answer to the OP’s question that “minimum experience before doing that training” should be AN/DP to helitrox mod1. I think this route ensures you have the necessary OC experience while value and usefulness are maximized.

Agree. Here are the levels for TDI:

• Mod 1 is actually 3 levels – any of the three can be done as a first CCR certification based on your skill level, your OC certification and experience and judgment call from your CCR instructor:
  • Rec Air dil (air as diluent, max depth 30m),
  • Deco Air dil (air as diluent, max depth 40m),
  • Deco helitrox (trimix with FO2 at least 21% and FHe at most 35%, max depth 45m)
• Mod 2: is normoxic trimix (trimix with FO2 of 16% or higher, max depth 60 m), requires 50h on unit
• Mod 3: is hypoxic trimix (any trimix, max depth up to 100m), requires 100h on unit

If you can, I would go for Deco helitrox right away so that you can use proper gas for dives over 30m (required to start Mod 2) and practice decompression profiles that are necessary for Mod 2.

 

[broncobowsher]

My first rebreather cert was air dil 100'. That was fine, there was a lot of skills that need working on in that 100' range. Next up was Normoxic trimix to 200'. Even with that I still do some air dil dives. Did a recreational trip to North Carolina and the shop offered air and O2. That's what I dove. I have air dil on the rebreather at this moment, planning on a quick 60' dip in a local lake. Typically run a light mix for something like this (old fill topped off with air) but happen to have a hydro dome and they went ahead and gave me an air fill. I'm using it instead of just dumping it.

For a new diver looking for a rebreather experience, air dil is fine for a starting point. If you are already deep into Helium on open circuit, you will probably start with some Helium on a rebreather.

 

[Angelo Farina]

Hi folks, I'm very much a developing diver with roughly 100 dives. With upcoming schedule, I'll likely have about 200 by end of 2024. I've always been fascinated by rebreathers and would love to do some training down the road. I know everyone is different but what would say is the minimum experience before doing that training?

It is zero dives.
When I started my first OW course, in 1975, we were given a CC rebreather two months before we got the first air tank. At the time, you had to become proficient using the rebreather before being allowed to use air tanks...
Be aware that at the time here in Italy the OW course lasted 6 months, and involved training similar to what is now employed by Navy Seals...

 

[Wibble]

Agree. Here are the levels for TDI:

• Mod 1 is actually 3 levels – any of the three can be done as a first CCR certification based on your skill level, your OC certification and experience and judgment call from your CCR instructor:
  • Rec Air dil (air as diluent, max depth 30m),
  • Deco Air dil (air as diluent, max depth 40m),
  • Deco helitrox (trimix with FO2 at least 21% and FHe at most 35%, max depth 45m)
• Mod 2: is normoxic trimix (trimix with FO2 of 16% or higher, max depth 60 m), requires 50h on unit
• Mod 3: is hypoxic trimix (any trimix, max depth up to 100m), requires 100h on unit

If you can, I would go for Deco helitrox right away so that you can use proper gas for dives over 30m (required to start Mod 2) and practice decompression profiles that are necessary for Mod 2.

IANTD do a MOD2+ down to 70m/230ft with min FO2 of 14%.

From what I've heard and experienced, MOD1 45m (helitrox) is considerably harder to do than MOD1 to 30m. It's unlikely that someone with minimum diving experience and no prior open circuit ANDP experience would be able to complete the MOD1 helitrox.

In any case you MUST practice doing the shallower levels to cement your new CCR skills in place before venturing deeper.

 

[Angelo Farina]

Historically, the rebreather training course was considered to be at the pinnacle of technical training with extensive prerequisites and contained an almost overwhelming amount of information; much of it being of questionable value and some information being of questionable veracity.

"historicaly" we started using rebreathers way before air tanks were commercially available just after WW2.
A CC rebreather was the standard sport equipment, professionals were using surface-supplied air and an heavy bronze helmet...
Technical diving had yet to be invented.
The first course for sport diving was organised by the Touring Club in 1948, the instructor was Luigi Ferraro, and they used the Cressi ARO CC rebreathers:

Underwater Tourism | Luigi Ferraro

Rebreathers were considered easier than air tanks for decades, until around 1965.
And particularly suited to female divers, being lighter and less bulky than large twin sets which were used by coral hunters, and commercial divers.
See here one of the first students of Luigi Ferraro, named Celina Seghi, with the CRESSI CC rebreather in 1948:

Celina was a famous Olympic ski athlete: Celina Seghi - Wikipedia