???Future of Open Circuit Mixed Gas and Rebreather Diving???

[Dusty123]

It would be interesting if hydrox diving could revive deep oc diving in the future, or at least start there.

Playing with Fire: Hydrogen as a Diving Gas

 

[grantctobin]

It would be interesting if hydrox diving could revive deep oc diving in the future, or at least start there.

Playing with Fire: Hydrogen as a Diving Gas

Little late to the party:

Hydrogen, At Last?

In February, Dr. Richard Harris aka Dr. Harry and the Wet Mules conducted the world’s first hydrogen rebreather dive to a test depth of 230 m at Pearse Resurgence, New Zealand. The purpose of the 13.5 hour dive was to determine the practicality and efficacy of using hydrogen to improve safety...

gue.com

 

[rddvet]

It would be interesting if hydrox diving could revive deep oc diving in the future, or at least start there.

Playing with Fire: Hydrogen as a Diving Gas

How bout that liquid stuff from the Abyss movie

 

[Dusty123]

The rat in the movie was actually doing it that was real. Seems a person would need to be intubated to be able to clear the co2 or mechanical lung, dialysis type thing. Probably impractical….think how mad a boat captain will be when a dozen tech divers barf out gallons of perfluorocarbon all over the boat. Wish James Cameron would make a sequel to that movie.

 

[kimh]

Probably impractical….

Also, huge WOB/work of breathing issue – moving liquid through lungs that evolved to move gas.

 

[Germie]

I missed the solo part. But will look at it.

But 1 thing that is returning is deep air. Till 60-65m depth, you see returning air. It was never gone away in countries like France, but it is returning.
First oc divers go to 50m again, that goes well, then it will be 55, and then 60 and some go to 65. And if you don't dive deeper than 65m, you can do 80-85% of the dives all over the world.
That is why OC diving will never go away.

Most technical divers are ok with a 20-25 minute bottomtime at 60m. This is no problem on oc. Then they take air as bottomgas, and this kind of divers will never switch to ccr.

To switch to ccr, you can buy second hand units, but it can be as buying a second hand car. You can be lucky, or buy the problems from someone else. A unit will costs in Europe about 4000-4500 bucks for an Inspiration that still can be serviced by the factory (I don't talk about the classic). Sometimes you find revos for the same price.
Older megs that are not servicable are around 3000-3500.

Costs for mod1 is about 1000-1100 euro here. That is a unit specific course. The mod2 or 3 aren't, so only 1 time doing the course is enough. If you are oc full trimix, you can skip the mod2 course. But yes, you need to have done it oc, so with nowadays helium bills it is cheaper to do the extra ccr course.

Cavediving can be done oc and ccr. In Mexico there is plenty of oc diving, but in Florida, a ccr makes a lot of things easier. Also if you go to Bosnia for example where filling logisics can be a problem, ccr is the way to go.

Travelling around the world with a ccr is expensive, and sometimes more expensive than paying more for gases. For example, in Mexico in march this year, a can of 20kg sofnolime costed 270dollar. Also oxygen was expensive. Then a lot of oc diving can be done.
And as said if you go to shallower depths, air is growing interest again. Cheap, easier to get, no worries about a not working ccr, not the costs of extra luggage to fly your ccr in.

If the whole group is diving ccr, I see people taking their ccr. If only a part can dive ccr, a lot of ccr divers will go oc then because of the extra costs to fly a unit in. And then they stick with air technical diving.

I have the luxery of also having a sidemount ccr, which I bought to use as a bo ccr. But now I use it most times till dives up to 55-60m in caves. And deeper, most times diving with bo cylinders works well and is not limiting me. A bo ccr can be complicated, you must check during the dive 2 ccr's.
My sidemount ccr is very usefull for example in the jura region where caves are quite narrow, short, but no filling logistics available. Also sometimes long walking distances. So I can take cylinder by cylinder in a speleo backpack and also the ccr can carried in such a bag. For these dives, in most cases there is no need to use helium, but it are just the filling logistics that makes using a ccr easier.

But, the reason to start diving ccr 10 years ago was already the price of helium. I was not limited by the gas at depth. 17 minutes at 110m with a twin12 was doable. But the prices of gases was already then around 150-200 euro per dive. But always remember, even with ccr you need to have bo's, so staying longer at such depths is theoritically possible, but in case of ****, you need your bo's and that is most times the limiting factor. So for such dives, also with ccr, consider using safety divers.
And from diving a ccr to greater depths, I started using it in caves. Also if it was shallower.

 

[Cthippo]

Commitment

Diving a rebreather requires a lot of commitment in terms of money, training, practice and maintenance.

The obvious equipment cost is far far greater than open circuit. 10 or more times greater if you compare a single cylinder (new cost circa $1k for cylinder and regs) or a twinset at circa $1.5k. A rebreather plus bailout will be circa $10k or more. Basically the cost of a motorcycle compared with a pushbike (carbon fibre MAMILs didn’t need to spend that much!)

The training costs are for an intensive 5 days course for the "MOD1" initial training which is unit specific. If your existing skills are good and you’ve already got advanced nitrox training and experience, the course will be easier. Could not imagine a novice diver having an easy time on MOD1.

Once you’ve completed your MOD1, the hard work begins. You MUST practice as you need to have those skills drilled into your subconscious. Rebreathers are complex machines and require constant monitoring. Death awaits anyone who looses attention or focus.

You count rebreather dives by the hours spent on the unit and the number of ascents you do. Ascents are probably the most tricky phase of a rebreather dive as, unlike open circuit, there’s a lot happening with your buoyancy and reducing oxygen levels.

Buoyancy skills do eventually return. For some it only takes a few hours. Many people take a lot longer to be stable at shallow depths for a long time, a requirement for deeper diving due to the decompression obligations. Buoyancy is much easier at depth hence shallow practice is important— literally pool depths.

Be aware of the "50 hour" complacency incident awaiting most people. 50 hours, an arbitrary number, is when you start to get used to it and maybe start cutting corners or not thinking of the basics. My self-inflicted caustic cocktail bailout happened at 130 hours — just when I thought I had bucked the trend— a full bailout saved my life. Training and practice work.

Rebreathers seem to bide their time and will strike when you’re being complacent; take nothing for granted!

Maintenance is a vital aspect of rebreather diving. There’s any one of a thousand things can ruin your dive. Take care of your unit and equipment. Rebreathers need cleaning and periodic disinfecting.

Prior to any dive you must allocate time to build and set the unit up. You must be pedantic as you go through the process. Written checklists are really useful to instil discipline so you don’t skip steps. Just because someone on ScubaBoard only takes a few minutes to do this doesn’t mean you should follow their poor examples. Who is responsible for your kit? You, you and only you.


Rebreather diving is absolutely not for everyone. If you have commitment issues with any of the above, stick to Open Circuit diving. It’s far more simple and there’s much less to go wrong.

What would it take, technology wise, to bring CCRs into the realm of recreational diving? By that, I mean what would need to happen to have a unit you could just put on and not need to think about, aside from refilling consumables and cleaning it once in a while? Presumably a reliable system to monitor O2, PPO2, CO2, etc, and something to prevent "caustic cocktails". What else?

 

[Germie]

A ccr is a really **** thing when the oc divers of a group are already relaxing with a beer and you are still cleaning the unit and preparing it for the next day.
This can be a big disadvantage of ccr diving.

 

[AJ]

What would it take, technology wise, to bring CCRs into the realm of recreational diving? By that, I mean what would need to happen to have a unit you could just put on and not need to think about, aside from refilling consumables and cleaning it once in a while? Presumably a reliable system to monitor O2, PPO2, CO2, etc, and something to prevent "caustic cocktails". What else?

Sound like the self driving mode from Tesla. I don't rely on that either. Automated systems won't be fool proof for a long time to come because they can only react to what they know, they can't intepret unknown situations. The power of human intelligence is that they can interpret situations and act accordingly.

I would never let my CCR decide for me what's the best action, I do however take it's advice in my considerations.

 

[Wibble]

To switch to ccr, you can buy second hand units, but it can be as buying a second hand car. You can be lucky, or buy the problems from someone else.

Excellent quote! So true.

The biggest problem with a new CCR diver is you know nothing about CCR except from what you informally learn from others. Even choosing a first unit is challenging as you really aren't qualified to make decisions outside of the "standard" units, e.g. JJ, Inspiration, Revo, etc. If you've CCR diving friends and they're diving "standard" units, look at getting the same as them.

IMHO, your first unit definitely needs to be kept and dived for the first >100 hours and 2 years. You need to become proficient on that unit including working through all the problems. In other words commitment.

A unit will costs in Europe about 4000-4500 bucks for an Inspiration that still can be serviced by the factory (I don't talk about the classic). Sometimes you find revos for the same price.
Older megs that are not servicable are around 3000-3500.

A friend bought a cheapish AP Inspiration Vision (Classics should be avoided as they are no longer supported by AP). The number of problems he's had on that unit is amazing. He's pretty much had to replace most of it and the total cost spent is probably more than a new unit.

However, I bought a 2 year old Revo but it had only two dives (poor chap who bought it had an injury and had to give up diving). My unit has been fine -- one temperature sensor and now the Nerd has been sent back for a new sensor.

Costs for mod1 is about 1000-1100 euro here. That is a unit specific course. The mod2 or 3 aren't, so only 1 time doing the course is enough. If you are oc full trimix, you can skip the mod2 course. But yes, you need to have done it oc, so with nowadays helium bills it is cheaper to do the extra ccr course.

Good training is vital on CCR so that you get good habits. There's 1001 things that can go wrong with your CCR that will be dangerous or can stop your dive. You absolutely must spend time maintaining the unit and be very pedantic in your pre-dive preparations. Fix things as they happen and never skimp on replacements.

The MOD2 course is easier if you're experienced with OC trimix. However, there's a lot of very subtle things you learn on that course, especially dealing with problems such that you don't always have to bail out and end the dive. It's actually a hard course and you need to be proficient on your machine and can demonstrate all your MOD1 skills.