What is "recreational" rebreather, and any recommendations?

[doctormike]

Check lists are good, but forgetting to turn on your gas is a minor mistake if your valves are on the bottom and can be reached easily. Things happen on boats, people get distracted. But if you understand the workings of your unit and body you will be watching your PO2 and your gauges during crucial phases like descent.

I agree with much of your post, but I respectfully and completely disagree with this. People have died because they didn't turn on their O2. Unlike OC, where it's immediately apparent that your gas is off and you can reach around and turn it on, the first sign of the gas being off on CCR might be loss of consciousness. It is definitely not a minor mistake. Yes, you should be watching your PO2, but as you say, "things happen".

PLEASE, use some kind of physical pre-splash checklist EVERY TIME.

 

[W W Meixner]

I am interested in a rebreather for my underwater photography. Not interested in extreme tech or cave diving, more interested in the "silent" aspect.

So,what is meant by a "recreational" rebreather? What brands/models does this mean? Why and how are they simpler to use than a "non-recreational" rebreather? I want something relatively simple, where if there is an issue it warns me, I have a bailout valve connected, and can end the dive safely, as opposed to trying to "fix" the issue at depth.

Any advice to get my research going would be appreciated!

Guy...

I know I'm way late to the picnic...

PM Abnfrog...and discuss the merits of SCR training/ownership...only 10 times the gas conservation of OC...as opposed to 40 times the gas conservation of CCR...but for 130 ft max recreational depth dives...SCR is less intricate...far less initial buy-in...simple to self service and maintain...Abn is probably the best in North America for SCR...he can answer all your questions...assist in your purchase decision...and provde excellent training...

Lots of push-back from the CCR tribe regarding SCR...works for me...may work just fine for you...

Best...

Good Luck...

Warren

 

[doctormike]

I was on a dive boat recently, and one of the divers was gearing up to go in. The captain asked him "what is your PO2"? He was a bit taken aback, but eventually told him it was 0.3. The captain told him that he had to get it up to 0.6 or so before splashing, and he pushed back, saying that the PO2 would go up on descent.

The captain told him the story of a crew member who did that same thing, got up from his seat in the back of the boat, walked towards the stern and passed out from hypoxia, fortunately before he made it to the dive platform. It doesn't take long to drop that PO2 if no O2 is being added to the loop. If you think otherwise, read the widow Bugge's powerful and brave writeup of what happened to her husband.

 

[silent running]

I agree with much of your post, but I respectfully and completely disagree with this. People have died because they didn't turn on their O2. Unlike OC, where it's immediately apparent that your gas is off and you can reach around and turn it on, the first sign of the gas being off on CCR might be loss of consciousness. It is definitely not a minor mistake. Yes, you should be watching your PO2, but as you say, "things happen".

PLEASE, use some kind of physical pre-splash checklist EVERY TIME.

Of course you are right and I’m certainly not endorsing a carefree approach to CCR diving. But to be clear, my comment is based on the fact that with my particular procedures, BOTH gasses are turned off after calibration to prevent accidental discharge of onboard gas, but the loop is also still full of O2. When I say I’ve splashed with my gas turned off, I meant both gases, which is different than just having your O2 off, which is of course very dangerous if your loop is not full of O2 after calibration, and you descend all the way to MOD and still don’t know the O2 valve is closed for 10+ minutes after descent. That could indeed result in accidental death.

The few times I have splashed without both gases on I got 5 feet underwater, realized I couldn’t get a breath off my ADV and had both onboard gas valves open in a second, no big deal. This is a very different kind of mistake from forgetting to turn on your O2, but not your diluent because in the rare scenario I am speaking of, there’s no way to descend without the jarring realization the dil is turned off, and I instinctively reach for both valves and start turning, get my breath then of course check the gages to make sure they are both now open. I have made this mistake only a few times in 1000+ hrs of RB diving. And yes a checklist, even if it only had one thing on it (!) TURN GAS ON, is certainly a good idea.

But further on the subject of safety, I was taught to verify my PO2 was rising during decent, also check gages, that computer is on and BO regs are still stowed where they’re supposed to be after splashing. I also look above me for bubbles and if I’m diving with someone else, we bubble check each other. Descent is the crucial time to make sure everything is working correctly, it’s the most apprehensive time for me. When I reach MOD, I’m definitely watching my PO2 and listening for that first solenoid firing to let me know all systems are go. It’s very hard for me to understand how anyone who is properly trained would not be checking all systems on descent and at MOD...

 

[silent running]

I was on a dive boat recently, and one of the divers was gearing up to go in. The captain asked him "what is your PO2"? He was a bit taken aback, but eventually told him it was 0.3. The captain told him that he had to get it up to 0.6 or so before splashing, and he pushed back, saying that the PO2 would go up on descent.

The captain told him the story of a crew member who did that same thing, got up from his seat in the back of the boat, walked towards the stern and passed out from hypoxia, fortunately before he made it to the dive platform. It doesn't take long to drop that PO2 if no O2 is being added to the loop. If you think otherwise, read the widow Bugge's powerful and brave writeup of what happened to her husband.

Thanks for the info, all good stuff to remember, but it does bring up the fact that different units have different predive procedures. And, different divers on the same unit may develop habits of their own which are better or worse. I typically check my sensors for 1.6 ish at the end of the dive at my safety stop/last deco stop, so my loop tends to have a high O2% still in it at the beginning of my second dive of the day. After my first dive, now knowing that my pneumatics and loop are tight, I give extra attention to sensor behavior, make sure my manual add button orings aren’t leaking and get into the rhythm of the solenoid firing as I kick along at depth...

 

[doctormike]

I give extra attention to sensor behavior, make sure my manual add button orings aren’t leaking and get into the rhythm of the solenoid firing as I kick along at depth...

Yeah, I can't hear my solenoid at all. Was going to suggest to Shearwater that they do a firmware option of a little light in the corner of the display for the controller / NERD when it fires.

 

[Sbiriguda]

PLEASE, use some kind of physical pre-splash checklist EVERY TIME.

Thanks for sharing this link

 

[doctormike]

Thanks for sharing this link

I'm also happy to mail anyone a couple of stickers, if you PM me your mailing address!

 

[silent running]

Guy...

I know I'm way late to the picnic...

PM Abnfrog...and discuss the merits of SCR training/ownership...only 10 times the gas conservation of OC...as opposed to 40 times the gas conservation of CCR...but for 130 ft max recreational depth dives...SCR is less intricate...far less initial buy-in...simple to self service and maintain...Abn is probably the best in North America for SCR...he can answer all your questions...assist in your purchase decision...and provde excellent training...

Lots of push-back from the CCR tribe regarding SCR...works for me...may work just fine for you...

Best...

Good Luck...

Warren

View attachment 526203

I started on SCR in nineteen hundred and ninety eight, and yes it’s a simple, reliable way to dive. Simple and reliable never go out of style..

 

[silent running]

Yeah, I can't hear my solenoid at all. Was going to suggest to Shearwater that they do a firmware option of a little light in the corner of the display for the controller / NERD when it fires.

Very good idea, all HUDs/displays should do something to indicate the solenoid is firing. I think some already do.

Yes, I believe you have mentioned before that you can’t hear your solenoid in other posts. And of course lots of people who dive CCR use hoods and dry suits, but being conscious of when it fires and how often ought to be part of everyone’s monitoring habits if it’s possible to hear it or see a visual cue...