Question CCR for recreational depths

[OceanOpportunity]

Sorry, what’s the benefit of diving CCR on an ultra shallow dive?

Massive complexity, cost (oxygen, scrubber, capital outlay, training), etc. Compared with blowing air bubbles costing next to nothing.

huge benefits - warmer, longer durations than a single cylinder, no bubbles (for wildlife/stealth). In my case, doing working dives, I can stay at work without swapping cylinders and breaking stride in what Im doing.

theres no 'massive complexity' in an oxygen rebreather. Its really no more complicated than OC if trained to think about it in simple terms

 

[billgraham]

In shallow water, one can learn all the skills needed to manage a breathing loop, dial in buoyancy, and become better in tune with the rebreathing mindset.

This is a good observation, shallow water diving with some ups and downs is the hardest thing to do.

 

[Angelo Farina]

Sorry, what’s the benefit of diving CCR on an ultra shallow dive?

Massive complexity, cost (oxygen, scrubber, capital outlay, training), etc. Compared with blowing air bubbles costing next to nothing.

When ARO rebreathers were the most widely used scuba systens (in the fifties and early sixties, here in Italy) purchasing and using them was way cheaper than using compressed-air systems.

 

[Wibble]

Quiet.

Learning the system so you can easily transition to deeper later on (if that's your goal).

Of course CCR is quiet, bubble free and has a long duration especially for heavy breathers.

There are some esoteric uses where diving a CCR shallow is important: military, fauna videography, long cave penetrations, etc.

Outside of those minor use cases, CCR is of little real benefit on shallow dives. There is no magical missing CCR application that will bring the massed ranks of recreational divers to spaff thousand$$$$ on equipment and training.

CCR is very expensive — an order of magnitude more than OC for the box. Then there’s the commitment to fettle that box; cleaning, pedantic preparation, checking, etc. Hours must be committed to that. What about the training and many hours of practice with the many different failure modes…. We also know that a rebreather is definitely not for everyone, some have the completely wrong attitude to dive them.

The running costs are high too. High pressure oxygen, scrubber, consumables (cells), analysis equipment, multiple cylinders… Compare that with a single air tank for an ultra-shallow dive: SAC of 20, depth of 5m/18ft/1.5ATA = 30 litres/min. Even an ali80 has 2200 litres, so that's well over an hour, more with a lower SAC. If you want longer bottom time, take two ali80s.


Of course if the diver's experienced diving a rebreather; if they happen to have a rebreather with them; if they've all the kit and caboodle; then dive a rebreather. If not, just dive OC for that really simple experience.

 

[L13]

CCR is very expensive — an order of magnitude more than OC for the box.

There is nothing inherent about CCR that makes it significantly more expensive than OC. If all the components were produce in the volumes that OC is, it would be no more than 2x as expensive.

Then there’s the commitment to fettle that box; cleaning, pedantic preparation, checking, etc. Hours must be committed to that. What about the training and many hours of practice with the many different failure modes…. We also know that a rebreather is definitely not for everyone, some have the completely wrong attitude to dive them.

At least some of that can be mitigated by improved design, much of that is already happening as newer generations of CCR are coming out. Training and attitude would be a real issue.

The running costs are high too. High pressure oxygen, scrubber, consumables (cells), analysis equipment, multiple cylinders…

other than cells, consumables are less than OC fills per hour of dive time. If you dive it enough, this would be true even including cells. Solid state cells in OC volumes would be cheaper as well.

Compare that with a single air tank for an ultra-shallow dive: SAC of 20, depth of 5m/18ft/1.5ATA = 30 litres/min. Even an ali80 has 2200 litres, so that's well over an hour, more with a lower SAC. If you want longer bottom time, take two ali80s.

True.

Of course if the diver's experienced diving a rebreather; if they happen to have a rebreather with them; if they've all the kit and caboodle; then dive a rebreather. If not, just dive OC for that really simple experience.

This could be the case for all divers if CCR's were mass produced and their initial training was CCR.

Given all that, I think it will be a very long time till CCR equipment is produced in current OC volume so none of this will happen any time soon.

 

[MichaelMc]

CCR refill logistics is simpler (given an O2 capable shop)
Five hours of dive time is a lot of OC tanks; even shallow it's three tanks.
Vs. one or two small bottles. I'm still OC, but the logistics are an appealing aspect on top of the no bubbles and warmer.

 

[Marie13]

CCR refil logistics is simpler (given an O2 capable shop)
Five hours of dive time is a lot of OC tanks; even shallow it's three tanks.
Vs. one or two small bottles. I'm still OC, but the logistics are an appealing aspect on top of the no bubbles and warmer.

It sure is. I have 3 O2 bottles and I’ll be diving with a pair of LP50s this year for dil and BO. Much nicer than hauling around 4 LP85s for fills!

 

[Wibble]

Sofnolime in US ~ $200 per 20kg keg.
Average scrubber size 3kg, 20/3 ~= 6
$200/6 = $33 per Phil

Max time on scrubber... In the CE anyway ... 3h.
So $11/hour for lime.

Plus oxygen at about 1.2 litres/min = 50 litres/hour


(Obviously if it were a Revo it would be 5h per 1.4kg Sofnolime, so 14 fills = $14 for 5 hours... )

 

[broncobowsher]

Sometimes enjoyment costs money. Some of my more enjoyable vehicles I have owned over the years were not the most economical to operate. I still drove them, because I enjoyed them. Not because I was looking for the cheapest way to get someplace.

If your biggest argument against using a rebreather is cost, you are missing the point. Many of us just find them enjoyable to dive.

 

[Wibble]

Sometimes enjoyment costs money. Some of my more enjoyable vehicles I have owned over the years were not the most economical to operate. I still drove them, because I enjoyed them. Not because I was looking for the cheapest way to get someplace.

If your biggest argument against using a rebreather is cost, you are missing the point. Many of us just find them enjoyable to dive.

You're absolutely right, it is about the far superior CCR diving experience. Someone who already dives on a rebreather would have sunk capital costs and proficiency.

It's a very different proposition for an OC recreational diver to acquire the equipment and skills to dive CCR on shallow dives.

The benefits of CCR become compelling on deeper trimix dives, especially in cost terms.

Of course if the diver's experienced diving a rebreather; if they happen to have a rebreather with them; if they've all the kit and caboodle; then dive a rebreather. If not, just dive OC for that really simple experience.

Interesting diving this Saturday. 12 divers on a boat with 11 diving all sorts of rebreathers; only one diving with a twinset. The dive to a mere 28m/95ft.

Only five years ago that would have been a majority or most on open circuit.