Prebreathing Survey

[doctormike]

Absolutely not. Surface time is not prebreathe time. There was a rescue a few years ago at our local quarry- guy passed out in waist deep water in front of his teenage daughter. O2 feed on the Meg was off. If you are buoyant on the surface on the ocean and drop the loop, you are at risk for the dead bug syndrome (flooding and sinking).

But you bring up an important point that a buddy of mine mentioned. Boat divers in dry suits have different tolerances than cave divers on shady picnic tables. Different cultures!

 

[RainPilot]

Gotcha! "Requires" by software, by manufacturer standards, or by your training?

Yes.

 

[stuartv]

Of course you should vote, you are a very thoughtful diver!

So what do you do, what is "spec" for you?

When my rMS was working, I pre-breathed until the controller showed at 45 minutes. Experience so far is that that takes maybe 1 minute or a bit more.

During my training class, one of my rMS sensors seems to have crapped out. So, for the rest of training and until I fix it, I do 5 minutes - which really means start breathing and look at the time on the controller. Keep breathing until the time is +5. Since it doesn't show seconds, technically that means I could only be pre-breathing for 4 minutes and 1 second, I suppose.

My best "poll option" would be "wearing unit, 5 minutes or until system says it's ready".

ps. And, thank you!

 

[fsardone]

I did vote less than 5 before donning ... but:
I pre breathe like that until my temp stick shows an active scrubber section and that takes at least 2-3 minutes. In this time I see that the solenoid is firing and all is well with the unit.
But then I am back on the look after I don the unit (which might take a few minutes or an hour or so later) and before splashing (or walking in ...).

This ensures me I have a scrubber, the oxygen is on, I am ready to fix any issue and I am not going to pass out with the unit on my back. Then when is on me I am rechecking for all to have stayed fine as it was.

Cheers

 

[OceanEyes]

I did not respond to your poll @doctormike for two reasons.

The first is petty: I’ve quoted and/or replied to your posts and supplied you with specific, accurate information on several occasions. You have yet to show the common SB courtesy of taking the time to “like” anything that I’ve written, though I took the time to address your statements directly, with insight, and with all good intentions. Dr., you’re degrading my post-to-like ratio, and messin’ with my gravitas.. Congratulations. You've inspired my first ever usage of an emoji on these forums. (At least to be best of my recollection).

The second, and eminently more viable reason for my abstention is that my pre-breath procedure varies as circumstances dictate. A few examples:

1. Build and check the unit at home. Drive to the dock. Board a small boat and head out in sporty seas. Arrive at the dive site. Check all fittings, don CCR, perform 5 minute pre-breath, splash.
2. Build and check the unit at home. Drive to the dock. Board a moderately sized boat on a calm day. Check all fittings and perform 5 minute pre-breath en route to the dive site. Don CCR, check pO2, splash.
3. Working from a live-aboard; Build and check the unit. Perform pre-breath at my leisure. Don unit, check pO2, splash.

I suggest that you consider adding another option to the choices offered in the poll.

 

[happy-diver]

I built my Breathing Underwater Machine last year and haven't used it much.
It's manual, and been messing with a 32% dil with the O2 leaky valve off.
Read about that method somewhere and thought it was a good idea.
Currently I'm diving it clipped to a full oc setup in an extended
testing learning phase I suppose where I jump in negative
on oc and then breathe the B.U.M. when I level off.

How I am currently using my bum is relative only to
Queensland summer ocean boat diving circumstances
and my comfort

I'm utilising it at the moment as a fun sporting device

Had it with me yesterday, too hot, mental capacity diminished, left it on the boat.
Just wanted to jump in cool off doze off and float off, for around about an hour ish

It's just that I don't want to be on the loop when I've just suffered a 90min boat ride
in heat, diving in hot water before I've settled down, cooled off, stabilised breathing.

No prebreathe just fill up the sack with 32 look at the numbers buoyancy adjust and go

 

[doctormike]

I did not respond to your poll doctormike for two reasons.

The first is petty:

You are either joking or correct.

I’ve quoted and/or replied to your posts and supplied you with specific, accurate information on several occasions. You have yet to show the common SB courtesy of taking the time to “like” anything that I’ve written,

Well, I did say "Thanks!" when replying to your post in the eCCR thread. I think that's even better. Much more personal, amirite?

Dr., you’re degrading my post-to-like ratio, and messin’ with my gravitas..

Whoops! Never heard of that metric before, but sorry to degrade your ratio... What do you get if that ratio gets high enough? I will definitely remember to like your posts if I like one of them in the future.

The second, and eminently more viable reason for my abstention is that my pre-breath procedure varies as circumstances dictate. A few examples:

1. Build and check the unit at home. Drive to the dock. Board a small boat and head out in sporty seas. Arrive at the dive site. Check all fittings, don CCR, perform 5 minute pre-breath, splash.
2. Build and check the unit at home. Drive to the dock. Board a moderately sized boat on a calm day. Check all fittings and perform 5 minute pre-breath en route to the dive site. Don CCR, check pO2, splash.
3. Working from a live-aboard; Build and check the unit. Perform pre-breath at my leisure. Don unit, check pO2, splash.

I suggest that you consider adding another option to the choices offered in the poll.

OK, so you do a 5 minute prebreathe, unless you are on a liveaboard, in which case you perform a prebreathe of unspecified duration? And if the seas are calm, you prebreathe while driving?

 

[stuartv]

This is from 2015, but I just saw it for the first time and it seems germaine...

Should rebreather divers prebreathe test their rebreathers prior to a dive? - Shearwater Research

 

[rjack321]

But you bring up an important point that a buddy of mine mentioned. Boat divers in dry suits have different tolerances than cave divers on shady picnic tables. Different cultures!

Many units with offboard dil can't really be prebreathed out of the water. It is too heavy to put my cave bailouts/dil on and walk. I can put the loop in my mouth and jack up the O2 content in there. But I can't check the wing, dil MAV, ADV, and sometimes not even the drysuit until I'm geared up in the water.

 

[doctormike]

This is from 2015, but I just saw it for the first time and it seems germaine...

Should rebreather divers prebreathe test their rebreathers prior to a dive? - Shearwater Research

Yup, that's the link in my OP!