Hog wrapping a bail out hose under a loop on a rebreather.

[ginti]

Back a few years ago it was just Jarrod and DRhea.

So the big advantage is reliability. The thing just WORKS. Every time. It’s ridiculously simple. No sensors. No solenoid. No MAV. Just two r190 injectors. There’s nothing to really monitor. If you can breathe and it burps some bubbles every now and again, it works. Reliability matters when you’ve put a tremendous amount of time into a dive with a ton of support poured into it.

Thanks, so I got it correctly. But shouldn't this be an advantage for sea diving too? Why would people prefer the JJ over the RB80 for sea exploration?

 

[rjack321]

GUE continues to teach RB80. There are more RB80 instructors now than there have ever been. One would choose it over CCR if they’re doing long range cave diving.

For accessible big cave. Although the sidemount version is competitive, just not really that much better compared to some SM CCR alternatives. There are other types of long range cave diving (outside of places like FL, MO and France), but there's no way to use an RB80. The cylinder requirements are insanity even with a dozen sherpas - when you need to haul them through many kilometers of forest and dry cave to get to the water.

 

[rjack321]

Thanks, so I got it correctly. But shouldn't this be an advantage for sea diving too? Why would people prefer the JJ over the RB80 for sea exploration?

Because you would generally need additional cylinders and gases to complete a dive on SCR vs carrying as few as one bailout gas on CCR.

 

[ginti]

Because you would generally need additional cylinders and gases to complete a dive on SCR vs carrying as few as one bailout gas on CCR.

But that is true also in caves, isn't it?

 

[rjack321]

But that is true also in caves, isn't it?

You can stage them at the beach, set them up in the cave ahead of time, drop them, and generally don't have to carry all of your cylinders all of the time.

The RB80 is part of a cave diving system that works exceptionally well - with big organized teams & support. The BOV, the long hose, the cylinder MOD markings, the gas switches, the injection method, the training and proceedures, it's all part of a system.

 

[ginti]

You can stage them at the beach, set them up in the cave ahead of time, drop them, and generally don't have to carry all of your cylinders all of the time.

Haven't thought about that, it makes sense

The RB80 is part of a cave diving system that works exceptionally well - with big organized teams & support. The BOV, the long hose, the cylinder MOD markings, the gas switches, the injection method, it's all part of a system.

Indeed all the people that told me "RB80 is the perfect machine for cave diving, the GUE JJ is the perfect one for sea exploration" are GUE instructors

Because you would generally need additional cylinders and gases to complete a dive on SCR vs carrying as few as one bailout gas on CCR.

However, as far as I understood, you have just one tank more than the JJ in the GUE configuration; the big difference is that, usually, you don't need to use the tanks because they are just bailouts. If I understood correctly, I still miss the advantages of the JJ over the RB80 - just one tank of difference vs better reliability doesn't seem worth it

 

[PfcAJ]

The bailout requirements are the same with ccr or scr. As far as extra gases needed, I disagree. For a 150’ dive I’d take the same backgas and deco gas as I would on open circuit, and that would be the same as a CCR diver as well. There’s not really much difference unless you start cutting corners somewhere and/or start talking about team bailout.

IMO, the biggest disadvantage to the RB80 in open water is the need to manually switch gas. Ccr guys push a button. Also, it uses more gas that a ccr.

Doing multiple dives off a set of backgas requires some careful management, transfilling, or resorting to using a bottom stage. Doable, but I wouldn’t call it ideal. With long cave diving, backgas isn’t touched anyways so it doesn’t matter. Top off the stages and you’re good to go.

Fwiw, I’ve used my RB80 on some pretty interesting and deep open water dives successfully.

 

[rjack321]

However, as far as I understood, you have just one tank more than the JJ in the GUE configuration; the big difference is that, usually, you don't need to use the tanks because they are just bailouts. If I understood correctly, I still miss the advantages of the JJ over the RB80 - just one tank of difference vs better reliability doesn't seem worth it

Not necessarily. On SCR the only way to increase or decrease your ppO2 is to change the fO2 of the injection gas. RB80 is more reliable in a sense, depending on the operator. CCR could be considered more reliable in another sense as it will try to maintain a breathable loop without human input.

So take a CCR, you can dive 10/70 diluent and the machine (via solenoid or the orifice & MAV) will inject oxygen to make up the difference so you have a breathable loop on the surface, no switching going down or up. You can dive that on a 60m dive if you wanted with 2 BO cylinders (untouched). As an eCCR, the JJ in good condition could do this "dive" without any human intervention. Not that you would dive without monitoring the loop, but it is designed to try to keep the loop at your specified ppO2.

If you want 10/70 gas on the bottom on an SCR you need to bring higher fO2 injection gases to start on, descend on, and switch on the way down, then again on the way up. This dive on SCR would take quite a few cylinders (probably O2, 50%, 21/35, 10/70) - you'd be (manually) switching to them both up and down. If you don't maintain a rigorous switch protocol you will die. This is how Jim Miller died.

 

[Wibble]

Does the RB80 optimise your PPO2 for a multi depth dive? What about decompression? Or do you just dive with a load of gases like OC and all your deco gasses.

Isn’t a CCR a lot easier and smaller, not to mention a damn sight more flexible and mixes gas to order?

And CCR is lot cheaper to run, especially trimix

 

[PfcAJ]

Does the RB80 optimise your PPO2 for a multi depth dive? What about decompression? Or do you just dive with a load of gases like OC and all your deco gasses.

Isn’t a CCR a lot easier and smaller, not to mention a damn sight more flexible and mixes gas to order?

And CCR is lot cheaper to run, especially trimix

No, whatever gas you have plugged in is what you’re breathing. Generally, caves tend to be fairly constant in depth. For deco, just plug in whatever gas you want. Just like OC.

Rb80 is a bit smaller due to not needing an oxygen cylinder. It’s often paired with real big tanks due to bailout requirements.

CCR uses less gas, for sure, but the amount of gas an RB80 uses on even a preposterously long cave dive is negligible in the grand scheme of things.