Triton rebreather or Hollis Prism2. Getting into CCR diving with a recreational diver background.

[broncobowsher]

You will be using your eCCR as a mCCR during training.

What he described is basically how all rebreathers work for reference, difference is you hear a click from the solenoid vs a constant hiss from a leaky valve.

mCCR's are computer agnostic so you order them with whatever you want to monitor, Divesoft, Shearwater, etc. quantity of them is a heated debate but the KISS units only come standard with a single computer, it is highly recommended you get a HUD which is standard on pretty much every other unit.

Disclaimer, my primary ccr only has a single computer on it but it is at least a Freedom so it gives me haptic feedback. This falls firmly within "do as I say, not as I do" and is very much not recommended.

Correctly diving my rEvo, the only time you should hear the solenoid fire is in the pre-dive checks, and maybe when you change the set point from 0.19 to 0.70 as you are putting it on. Hearing it during the dive is a reminder that you were not checking PPO2 and keeping it in check. But it will step in if needed. That is referred to as a hybrid rebreather. It is manual, but the electronics will press the button for you and add the O2 if you are not paying attention.

As for as computers go. You will almost always find 2 independent forms of PPO2 monitoring. Typically one wrist mount and one heads up. The basic heads up with blinky colored lights. Just lets you know that the O2 levels are still good. Nerd is a full computer in your eye. Then add a full computer on the wrist, typically the controller for the rebreather electronics. Since it is doing real time PPO2 monitoring, you get real time NDL/Deco numbers. Running a wired NERD gets you that info redundantly as well.

 

[JMBL]

I have been diving mCCR KISS rebreathers since 2007 and well over 1,000 dives on these units.

There is not much effort required to maintain the PPO2 during a dive on mCCR units. There is one button that typically hangs from your BC chest d-ring called the MAV (manual O2 addition valve). The constant flow O2 orifice is constantly leaking O2 into your loop as long as there is gas in the O2 tank. As long as your maintain the same depth and mild workload your PPO2 will maitain itself at a good constant. On assent or high workload it will drop. To increase the PPO2 you press the MAV button based on your Shearwater computer's PPO2 display. If the PP02 gets too high, you just exhale some loop gas from your nose and make a strong inhale to pull in diluent via the ADV (add diluent valve) in the head.

If this sound complicated at all, then that is what the training is for. Once trained and you have a few hours on the unit it is much like driving a car on the highway. Most drivers will not have their eyes glued to the speedometer constantly adjusting the speed. You become peripherally aware of PPO2 display and make the adjustments without much thinking, just reflex.

I am a photographer and don't have any problems keeping my PPO2 stable and safe. Options like a HUD or Haptic alerts can add safety with additional notifications.

I'll second that. Training will make you able to manage PpO2. On the Triton, you've got Monox (for Oxygen Monitor) + HUD (red : not enough ; yellow : too much ; blinking between the two : you're within an acceptable range) and your computer to control PpO2. During training, you will be taught when hand how to add or flush 02, not that complicated. Btw, you'll be taught that on any rebreather, either MCCR or ECCR, or HCCR for that matter.

With my Triton, I also use a non wired Petrel (which I already had) in case the one connected to the rebreather goes amok. Then I'll check PpO2 on the monox and deco on that second Petrel.

 

[davehicks]

[[/ISPOILER]

this is really useful information. How many computers do you use? Like a wrist computer plus a shearwater nerd? Do rebreather comes with its own computer?

I use a wired Shearwater Petrel that passively monitors the PPO2. I don't use a HUD or Nerd. I did upgrade to a Petrel3 recently that supports strong haptic feedback for PPo2 events, deco stops, etc.

I wear a secondary computer as well, but that does not monitor the PPO2. It's mostly for extra info I don't have on the primary like a Compass display or if I need to bail out because the primary computer dies. (which it never has in 15 years)

 

[Superlyte27]

You are getting out 30-50 minutes faster or them getting out faster?

CCR gets out faster on everything except absolute square profiles.

 

[BoltSnap]

CCR gets out faster on everything except absolute square profiles.

Do you mean that CCr has shorter NDL?

 

[Superlyte27]

Do you mean that CCr has shorter NDL?

No

 

[BoltSnap]

No

Your statement:

CCR gets out faster

Implies that it has shorter NDL.

 

[runsongas]

faster deco, not less NDL. but OP isn't looking to do deco, so benefits may be negligible depending on depth profile.

 

[Superlyte27]

Your statement:


Implies that it has shorter NDL.

Sigh….
Open your mind. Geesh.

You just did a 6 hour cave dive at 100’. The guy on CCR gets out 30 minutes faster because his deco is shorter because he’s diving the perfect mix for all depths of his dive, where his buddy is only diving the perfect mix while he’s at MOD for his 32%.

This isn’t hard to understand . Sorry I didn’t dumb it down for you sooner. I guess.

 

[Wibble]

Hi divers

My local dive shop has two rebreather available which are prism 2 and triton from M3S. My primary reason to get into CCR is because I want to increase my bottom time at the recreational depth limit without have to keep coming to the surface and change tanks. I also like the bubble free diving and helps with my photography due to the lack of bubbles.

I am not trying to get into technical diving, but just purely want to enjoy the CCR’s benefit at a recreational level.

Apologies for saying this, but this thinking is wrong in so many ways.

1. Rebreathers are technical diving. You may be diving within NDLs, but you are mixing gasses, having to deal with bailout, must use a lot of new skills, have very different planning and preparation needs...
2. You want to dive at the limits of NDLs, for example at 40m/132ft. A rebreather will give you the additional gas time, but you still have to carry sufficient bailout with you -- aka PONY. For this you need to do A LOT OF TRAINING, PRACTICE, PREPARATION AND DIVING otherwise IT WILL KILL YOU.
3. Rebreathers are very expensive. $10k for starters. Need at least one challenging course then YOU MUST dive with other rebreather divers for practice. Lots of practice.
4. Rebreathers need a lot of maintenance and preparation for every dive. OC: check gas, jump in. A rebreather requires hours of preparation which you MUST be pedantic and follow checklists. If you don't do this, it will happily kill you.
5. Rebreathers need high pressure oxygen which isn't commonly available from recreational dive shops.
6. Rebreathers, by their very nature, will encourage you to break the NDLs as there's basically no gas limits. A 40m/132ft dive is 8 minutes using the PADI (air) RDP. Most rebreather divers on here would dive that for an hour or more, with a full runtime of a couple of hours or more. This means that recreational dive boats will give you a hard time when you demand way more dive time than the 40 minutes of all the single tank NDL divers.
7. Rebreathers don't mix with open circuit divers. Sure, you can, but you're on your own as an OC diver hasn't a clue about your unit.
8. You NEVER buy a rebreather based upon the stock levels of a local dive shop. There's so much more to rebreathers than that.
9. Photography. You'll have to stop doing that for a long time whilst you practice your new skills on the rebreather. You CANNOT be distracted from running the rebreather otherwise you will get into trouble. You'll probably need a whole season to learn and practice on the rebreather before you go back to photography.
10. Rebreathers for this dive profile -- NDLs -- will be more expensive to run per dive than an open circuit equivalent. HP oxygen top-up; scrubber replacement; cells; cleaning; other maintenance.

Just dive on a twinset/doubles. Small cost (backplate + wing + twinset + 2 regs) costing under $1k if you buy wisely. This gives you loads of gas, there's very few new skills to learn (literally planning and shutdowns). You could even learn sidemount which would give you all the additional gas and redundancy you want.

Sorry to say this, but a rebreather really isn't for you for the reasons given in your original post.