Rebreather Hints/advice

[up 4 it]

The point of this thread is to try and make a comprehensive list of do's & don'ts and hopefully highlight pitfalls to be avoided when diving RB.

For those of you who obviously know everything, then hats off to you for being legends in your own minds, for those of us who don't know everything but aspire to be better, safer divers then hopefully it will be of benefit to us.

Thanks Mark, Alan, Padowan, just a shame things get spoilt by mental midgets who are intellectually challenged.

[Janos]

Originally Posted by up 4 it

The point of this thread is to try and make a comprehensive list of do's & don'ts and hopefully highlight pitfalls to be avoided when diving RB.

For those of you who obviously know everything, then hats off to you for being legends in your own minds, for those of us who don't know everything but aspire to be better, safer divers then hopefully it will be of benefit to us.

Thanks Mark, Alan, Padowan, just a shame things get spoilt by mental midgets who are intellectually challenged.

Steady on. Just because people disagree with you, there's no need to start calling people names.

I would DEMAND AN APOLOGY, but in the spirit of the thread I will add a couple of contributions:

5) Always wear a mask so that you can read your guages

6) Learn how to clear your mask in case a bit of water gets in while diving.

Janos

[aquaholic]

Originally Posted by Janos

Ah, well.. but thumb can be kept very busy at times ...

I'm with Alan, relaying experiences that others might find interesting & informative might be useful - warts and all.. so here goes for starters.. if things go wrong, in the end it all boils down to what the individual diver can cope with (whether based on experience or good training or just attitute, or all of the above.. ) and what level of stress they find accepatable. So, after reading the below... what would you have done - and why?

Recent event... first UK sea trip of the season.. Unit recently serviced, but used for a week in the Red Sea where various issues where addressed... buddy somewhat inexperienced, on OC, still getting the hang of diving in a drysuit - feels apprehensive, but happy to have a good go at this UK sea diving drysuited lark..

Situation: Pre-dive checks (KISS Classic RB) find O2 add valve sticking open on surface.. intermittantly... Sympthom: rapidly increasing ppO2 (obviously, but worth stating anyway). Decide to miss first dive and check out unit. Buddy joins another pair of divers and has a great dive.

A bit of extended fettling with thumbs and buttons seemed to stop the O2 add problem. Judgement call.. to dive or not to dive.. decide to attempt second dive as valve seems to behave ok now.

Jump in.. do dive.. Depth 30m, wreck dive, lovely viz...
After a while notice ppO2 raising again... bummer.
Response: Shut down O2, add DIL.. keep breathing.. open O2 again.. stable now.. carry on.
Training would suggest: bail out, abandon dive, get out..
But situation is 'managable', dive is planned as no stop, O2 flow rate is low, ppO2 increase is slow.. close down O2 tank valve a few notches then carry on by manually controlling O2 flow using, in my configuration, a flow stop on the O2 in line when required (placed there for exactly this purpose), valve at times reverts to normal operation, so keep watch on ppO2.

Dive proceeds.. buddy on 32% OC using air computer reaches deco (and doesn't tell me).. when next looking at my computer (set to 32%) I'm thinking buddy must have reached deco already... check situation, call dive... at start of ascent notice buddy is stuck in fishing line wrapped around fins and legs... check O2 - rising again.. bummer... close O2, address buddy's problem bit by bit, between checking O2 and controlling flow. Shout at buddy to stop f..king finning... trying to avoid getting wrapped in line myself, all the time keeping an eye on the ppO2 (am glad displays are on my arm where I can see them, not dangling somewhere else...). Eventually manage to free buddy and start ascent...

Buddy's computer now showing several minutes of air stops (though only 3 minutes on 32%), O2 valve still flowing freely, so keep controlling it on ascent when required till reach 6m and then just let it run and vent loop as needed.. Not happy, but situation was under control all the way if a bit stressy at times, but nothing I felt I couldn't cope with. Both buddy and I arrived safely back on the boat... and yes, I did carry on diving for the weekend, controlling the O2 flow manually as the need arose and felt happy that I could keep control of the situation, or bail out if need be.

Valve has now been checked out and the o-ring on the piston found to be worn, and the gasket around the orifice also a bit worn. So am sending off for a service kit...

Best

Anke
[donning flame proof suit and keeps typing]

[Odin]

and the girl done well!
I was on the trip and Anke made a good call.
I had a problem with my Dolphin that w/e.
Flow rate increased and so had to constantly blow out past mouth piece.
Book says bail-out.
I had gas to breath and was comfortable in controlling the buoyancy, so stayed on the loop for the deco and to surface.

As Anke says - it depends on what you feel comfortable with.

[MattD]

Originally Posted by aquaholic

Ah, well.. but thumb can be kept very busy at times ...

I'm with Alan, relaying experiences that others might find interesting & informative might be useful - warts and all.. so here goes for starters.. if things go wrong, in the end it all boils down to what the individual diver can cope with (whether based on experience or good training or just attitute, or all of the above.. ) and what level of stress they find accepatable. So, after reading the below... what would you have done - and why?

Recent event... first UK sea trip of the season.. Unit recently serviced, but used for a week in the Red Sea where various issues where addressed... buddy somewhat inexperienced, on OC, still getting the hang of diving in a drysuit - feels apprehensive, but happy to have a good go at this UK sea diving drysuited lark..

Situation: Pre-dive checks (KISS Classic RB) find O2 add valve sticking open on surface.. intermittantly... Sympthom: rapidly increasing ppO2 (obviously, but worth stating anyway). Decide to miss first dive and check out unit. Buddy joins another pair of divers and has a great dive.

A bit of extended fettling with thumbs and buttons seemed to stop the O2 add problem. Judgement call.. to dive or not to dive.. decide to attempt second dive as valve seems to behave ok now.

Jump in.. do dive.. Depth 30m, wreck dive, lovely viz...
After a while notice ppO2 raising again... bummer.
Response: Shut down O2, add DIL.. keep breathing.. open O2 again.. stable now.. carry on.
Training would suggest: bail out, abandon dive, get out..
But situation is 'managable', dive is planned as no stop, O2 flow rate is low, ppO2 increase is slow.. close down O2 tank valve a few notches then carry on by manually controlling O2 flow using, in my configuration, a flow stop on the O2 in line when required (placed there for exactly this purpose), valve at times reverts to normal operation, so keep watch on ppO2.

Dive proceeds.. buddy on 32% OC using air computer reaches deco (and doesn't tell me).. when next looking at my computer (set to 32%) I'm thinking buddy must have reached deco already... check situation, call dive... at start of ascent notice buddy is stuck in fishing line wrapped around fins and legs... check O2 - rising again.. bummer... close O2, address buddy's problem bit by bit, between checking O2 and controlling flow. Shout at buddy to stop f..king finning... trying to avoid getting wrapped in line myself, all the time keeping an eye on the ppO2 (am glad displays are on my arm where I can see them, not dangling somewhere else...). Eventually manage to free buddy and start ascent...

Buddy's computer now showing several minutes of air stops (though only 3 minutes on 32%), O2 valve still flowing freely, so keep controlling it on ascent when required till reach 6m and then just let it run and vent loop as needed.. Not happy, but situation was under control all the way if a bit stressy at times, but nothing I felt I couldn't cope with. Both buddy and I arrived safely back on the boat... and yes, I did carry on diving for the weekend, controlling the O2 flow manually as the need arose and felt happy that I could keep control of the situation, or bail out if need be.

Valve has now been checked out and the o-ring on the piston found to be worn, and the gasket around the orifice also a bit worn. So am sending off for a service kit...

Best

Anke
[donning flame proof suit and keeps typing]

Thanks for sharing that! As a diver who is set to take CCR training in July, your post reminds me of exactly why I would abort an OC dive when somethings "Not quite right" In the old BSAC system we learned about the incident pit.

If one small thing is wrong, it makes fixing a second issue tough, which could lead us to more and more problems, with the sides of the pit getting deeper and deeper, and thus harder to get out of.

It seems to me, that on the ascent/decent I am going to be very focussed on my unit, and this will reduce my ability to look after my buddy. Indeed I just spoke to a mate Gareth who mentioned that on the ascent/decent he felt that it was like CCR solo diving as everyone was so focussed on their units. (We are talking about divers who are new to CCR here)

So the point is, your report has reminded me, that when I get a good deal of experience on my unit, I must try and remember the basics of the incident pit, and if I can't fix the problem, then it's time to ascend.

Please note, I am using your experience to aid ME, not trying to tell an experienced CCR diver what to do! I hope that's clear!

Thanks everyone for sharing.

I am about to take the course, and having these bit of info is great. You can never have too much information, and you can't learn to dive from the internet. That doesn't stop such threads being of interest to some of us.

[Phoenix]

Originally Posted by aquaholic

Jump in.. do dive.. Depth 30m, wreck dive, lovely viz...
After a while notice ppO2 raising again... bummer.
Response: Shut down O2, add DIL.. keep breathing.. open O2 again.. stable now.. carry on.
Training would suggest: bail out, abandon dive, get out..
But situation is 'managable', dive is planned as no stop, O2 flow rate is low, ppO2 increase is slow.. close down O2 tank valve a few notches then carry on by manually controlling O2 flow using, in my configuration, a flow stop on the O2 in line when required (placed there for exactly this purpose), valve at times reverts to normal operation, so keep watch on ppO2.

I haven't done training on the Kiss but I don't see why the suggestion would be to bail out, seems to me that you did exactly the right thing. The biggest issue to me seems to be your buddy, you seem to have managed the CCR issue well.

Ian

[Mark Chase]

A few points some of which are YBOD specific.


1: There is no such thing as a bimble CCR dive

2: 02 cells are far from perfect and can fail from new, never fully trust them

3: On a two day dive dive 1 and dive two are totally separate events and pre dive checks should be just as meticulous.

4: Assembly of the unit should follow a totally strict list of events and checks. If you mis cock up or feel unhappy about any stage of preparation my advice is take the whole thing apart and start again.

Assembly of the unit is best achieved by laying out all the components in task specific order prior to starting.

5: Sofnalime is damaged by frost and should be stored in an area comfortably above zero c and propped up on insulating wooden blocks.

6: Flapper valves are probably one of the least checked / inspected items on the CCR and yet one of the most likely to kill you.

7: Bailout gas is for people who need to stay alive. Alpinist is for people who don't care if they do or not.

8: Small bailout cylinders are carried by people who pretend they want to stay alive.

9: Bailing out to Air can and probably will kill you at depth

10: If you breathing a little hard and cant think of a reason why BAIL OUT IMMEDIATELY as in a few moments time you wont be able to.

11: BOV's and Full face masks are a major contribution to CCR safety

12: HUDS are critical safety equipment and should be fitted to EVERY ccr. Diving without one leaves you blind to whats going on for 75 - 80% of the dive or ruins the dive because all you see is 1.3 1.3 .13

13: Electronics and salt water are sworn enemies. Dead divers are collateral damage in their epic struggle


ATB

Mark Chase