NDL diving with onboard DIL-OUT? Smaller than 40/50's

[rjack321]

Doesn't the minimum vs. plenty BO characterization greatly depend on the specific dive? An assumed 40 L/min rate (throughout) and a safety stop and a minute to get sorted at depth seems pretty conservative. From 60 ft, that's 150 bar from a 3L. Treat that as your Rock Bottom pressure, stay within NDL, and enjoy the dive.

Obviously 1x3L won't work for all rec dives, but if you're targeting the extremely common, multi-level above 60 ft, what's wrong with a lightweight "reef rig"?

Or you could just bring an al30 or 40 and have something that passes the laugh test.

 

[flymolo]

If I was going 60-90 feet, NDL limits, I'd take a 2L. Chances are I could stay on the loop, and if I had to BO, the surface or a buddy is a small amount of BO gas away. Compared to single tank diving, you are less likely to have to swim to the surface. I see this as a slightly more robust equivalent to single cylinder diving.

Fails
O2 cylinder fail - SCR ( feather the bottls maybe) - Plenty of time to surface
Dil cylinder fail. - Stay on loop , thumb dive. hours of time, just cant go down.
Loop loss, unrecoverable flood - BO - BO to 10-13 CF of gas, that's not much but on a reef dive it is plenty to get to the surface.

If I were going deeper, I wood want the 3L

If I am goign to a care free type of dive, being light feels nice, I'll take the lightness and accept that I dive at alevel of safety similar to that of single tank diving which I think most would agree is acceptable.


A 3L is plenty to get to the surface on. This is a rec dive. What single failure leaves you with nothing to breathe to get to the surface? (rec, NDL...)

Crazy talk

 

[211ratsbud]

I would be specifically discussing or talking about manifolding 3 l, 30's, or some other appropriately sized bottle on the back mount unit. Oxygen goes where it should on any heavy configuration.

Nobody's trying to bring minimum, I even commented how the story I heard I believe that the minimum gas doesn't add up. I think you should reread my post, I'm inquiring about something I heard was changing want to know if anyone had already done it.

I currently dive with '50s back mount on my meg in a heavy configuration.

I have a couple setups of which I was considering making one a nice compact package for shore dives which rarely exceed 60 feet. Or occasional boat dives which may touch 100 but have a mooring line directly to the surface.

30s on the back seem just right for these dives to me. 3 l not being substantially less I thought might also work for these scenarios.

 

[mr_v]

If you want a compact config, just strap 2L bottles and bring an 40AL bottle. What's so complex about it? Is a 40AL bailout an issue?

I am all for experimentation, but the initial post sounds a lot like a solution looking for a problem.

 

[inquis]

Or you could just bring an al30 or 40 and have something that passes the laugh test.

So bring twice the conservative estimate?? If your BO deco plan calls for 25 cf of 50%, are you really bringing an 80 for that (since 2x25 doesn't fit in a 40)? If not, then please help me understand why one gets laughed at and the other does not.

 

[211ratsbud]

So bring twice the conservative estimate?? If your BO deco plan calls for 25 cf of 50%, are you really bringing an 80 for that (since 2x25 doesn't fit in a 40)? If not, then please help me understand why one gets laughed at and the other does not.

Unequivocally I believe the answer to that would be yes. This is my own observation of my opinon: I think that once you start considering decompression as planned then you have no harm no foul in rounding up gas quantity. So that seems to be ok in my eyes.

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For dives with no planned decompression, and in particular including a brand new rebreather diver an AL-40 seems appropriate.

MIN GAS quantity seems to be no different than a chest mount rebreather using a single AL40.

Is that a thing?

 

[Pavao]

When I was using my unit more frequently in recreational dives to get more hours on it, I did look for a way to make it simpler to dive, without compromises of course.
When I did go into rebreathers I was already pretty comfortable with tech diving, advanced trimix, full cave, advanced cave DPV…
So it wasn’t that I was burdened with carrying a stage for bailout, but not carrying one is even better, not just in the water, to/from car/boat, more crap to clean, anyway simpler, mainly the boat part.

So I just swapped the 3L which was there solely for the wing, for a LP40, basically I moved the bailout bottle to the place of the 3L and added and inflator hose to it, that’s it, that’s all I had to do.

But I did do slightly more, I swapped the O2 bottle to a LP40 also to be even and added an octo to the dilout bottle because I would be surrounded by OW divers, so yes, an actual yellow octo.

But my idea was to make it simpler, so, in this case I had to change nothing in my rig to go back and forth from this and the cave configuration with the 3L bottles, aside from 1 inflator hose, and I’d be carrying 65ft3 of bailout gas.

In the case of manifolding 3L, it seems to me it makes configuring the unit a lot more hassle than to just carry a 30/40 Al bailout slung as a stage, plus as Rjack asked, where does the O2 go?

 

[PfcAJ]

This is some dumb ****.

 

[Pavao]

This is some dumb ****.

And it can get dumber still.
In fact, I’m wondering now if the tech divers I see on rebreathers doing 180ft dives and all they’re carrying is 1 (one) AL40 bailout with 50% are the ones who started it by doing recreational dives with 3L dilouts only.
That’s a lot more dangerous to me.

 

[211ratsbud]

And it can get dumber still.
In fact, I’m wondering now if the tech divers I see on rebreathers doing 180ft dives and all they’re carrying is 1 (one) AL40 bailout with 50% are the ones who started it by doing recreational dives with 3L dilouts only.
That’s a lot more dangerous to me.

I've never seen nor heard anything like this ever. This happened or is this being facetious?