Is this IT?!

[SFLDiver3445]

I knew i'd get caught on that L!
I should've mentioned that i'm not a photographer either... which is a very valid reason to get a RB

Steve, since when do men need a legitimate reason to buy expensive toys!

 

[Diver Dennis]

I'm not a rebreather guy but I was on a deep dive trip with a rebreather instructor this weekend, two teams did two 120M dives on the Princess of the Orient just outside Manila Bay and I was taking photos. He used a different types of rebreather on each dive. He told me this was designed by Bill Stone who has a good reputation. His personal opinion is that diving a rebreather is more of a mindset thing and that perhaps designing a rebreather for "everyone" might not be the best idea. I think it will only do 40M max.

 

[SFLDiver3445]

I'm not a rebreather guy but I was on a deep dive trip with a rebreather instructor this weekend, two teams did two 120M dives on the Princess of the Orient just outside Manila Bay and I was taking photos. He used a different types of rebreather on each dive. He told me this was designed by Bill Stone who has a good reputation. His personal opinion is that diving a rebreather is more of a mindset thing and that perhaps designing a rebreather for "everyone" might not be the best idea. I think it will only do 40M max.

Hi Dennis,

I saw the pictures within the posting on RW, is this you guys?

Date with a princess - Rebreather World

Sounds like a great dive! Definitely on my todo list!!! I don't have access to You Tube at my office, but I'm looking forward to seeing the video this evening at home.

I agree that diving a rebreather is a mindset. Even though prior to making the switch to a closed-circuit rebreather, I dove deep oc trimix, which did require a fair amount of preparation, but using a rebreather has taken my pre-dive prep, and my general safety conscious mindset, to a whole new lever!

With regards to one rebreather fitting everyone's needs - Definitely not, as there will always be many different rebreather designs to suit each divers needs and preferences. However, as has been discussed within this thread, it will be interesting to see how the pending Mark VI will be accepted/applied by/to the recreational diving community.

 

[Gill Envy]

Yes, even though some of us appear to have diverging opinions about the degree of risk associated with eccr's, and about the future direction manufacturers will opt to take when designing future rebreathers, it has been a pleasure sharing viewpoints with such educated and respectful members of this forum!

And the really nice thing is that we can have this debate without detractions and personalities getting in the way. Thanks for that (to all). We both know that things can be a bit different in other places.

Yes it's been a pleasure!
:meeting:

 

[silent running]

Hello all, while I dive mostly in recreational limits and I welcome the addition of any CCR that makes diving easier and safer, there is one large problem with the Cis MK6. If I properly understand the posts from Richard Pyle on the MK6 RBW thread, the unit will not allow the diver to do a surface cal with O2 that is less than 99%. As anybody who dives in remote places knows, O2 purity is rarely higher than 97% due to the PSA method used to produce O2 in most small countries. This would be a deal breaker for me, or anybody who plans on trying to get most out of their recreational dive trips with CCR, which is whole reason went to CCR in the first place. Lucky for me, I have enough experience to know that this problem is a real one, but man would I be pissed if as a newbie, I went through the training and considerable expense of buying and training on the MK6 to find out that I was limited to diving only in places that have 99% pure O2, like large industrialized countries-not usually where the best recreational diving is. I hope they plan on informing prospective buyers of this huge limitation.

As for the remaining 2-4%, it is most likely argon, which depending on who you talk to is either more or less dangerous in recreational depths, due to the narcotic properties of argon, possibly enough to put you to sleep, as I was told somebody who's opinion I tend to respect. After diving my CCR for over 350 hrs in the remote parts of the Pacific with O2 ranging from 96-98%, including some deep tmix dives, I can say that I've never come to the verge of falling asleep, much less felt even mildly narced on my CCR. Well, with the exception of that 205ft dive on air dil at the Blue Hole in Belize many moons ago, won't do that ever again...

I still haven't got a straight answer from anybody as to why myself, nor any of my Pacific CCR dive buddies have ever had a narcosis issue with argon contamination in our units from using PSA generated O2. In my not so scientific opinion, I would think that since most of our loop gas at depth has come from our diluent supply filling up the loop during descent, which unless you are using heliox, is not blended with O2, the PPA in the loop at depth would be very, very, low. And, as we ascend and start to use more and more of our O2 supply, the FA would be rising, but some of the argon will also get vented out into the water as our CLs expand and we dump excess loop gas, not to mention that the narcotic properties of whatever argon is in the O2 supply will be lessened as we ascend. If this really is an issue, then the prudent and easy thing to do would be a few dil flushes on the way up, which some of us may do already for other reasons, like getting rid of the inert gas that we are off-gasing on the way up, or as a hedge against CO2 build up. I'm happy to have anybody tell me what I'm missing or have got wrong.

The obvious innovative feature of the MK6 is it's continuous automatic O2 sensor calibration, which is a very clever and impressive piece of engineering. But, it appears that the same sort of ease-of-use and safety-first priority which has put this system to use in the MK6, is also responsible for taking other decisions-like being capable to determine O2 purity on site and cal accordingly-out of our hands as well. Which again points out some of the problems and limitations of nanny-ism. I for one don't see how they can sell very many units without allowing for varying O2 purity and cal adjustment, and the travel that goes with it . Maybe it's a legal issue which has something to do with the fact that no specialized O2 handling or nitrox course is required, not something which necessarily bothers me, even though I think taking a basic nitrox course should be a prerequisite for CCR, if only to get a better handle on the idea of partial pressures.

Maybe there can be no CCR free lunch for the masses, I hope I'm wrong and they fix this problem with the MK6... -Andy

 

[Diver Dennis]

Wow, Roger was quick with that one! Yes, that's us on that dive. We had a great time, I'll have to have a read of that thread. I posted a couple of photos here under the Philippine Paradise Divers forum.

Now Roger has me wanting a rebreather!

Hi Dennis,

I saw the pictures within the posting on RW, is this you guys?

Date with a princess - Rebreather World

Sounds like a great dive! Definitely on my todo list!!! I don't have access to You Tube at my office, but I'm looking forward to seeing the video this evening at home.

I agree that diving a rebreather is a mindset. Even though prior to making the switch to a closed-circuit rebreather, I dove deep oc trimix, which did require a fair amount of preparation, but using a rebreather has taken my pre-dive prep, and my general safety conscious mindset, to a whole new lever!

With regards to one rebreather fitting everyone's needs - Definitely not, as there will always be many different rebreather designs to suit each divers needs and preferences. However, as has been discussed within this thread, it will be interesting to see how the pending Mark VI will be accepted/applied by/to the recreational diving community.

 

[djcheburashka]

It strikes me that there's a much bigger problem with the MK6, as thrashed out on the RBW forums: It has no manual inject.

That means that if the electronics fail, the diver has no choice but to bail out to the diluent.

It also means, because of the small size of dil tanks, that you really can't do a deco dive with the unit, because then you'd have no route to safety if the electronics fail unless you brought a bailout tank.

If you brought a bailout OC tank, then you've lost the benefit of the small, easy to use, convenient MK6.

And if you can't do a deco dive with a rebreather, then what's the point?

 

[silent running]

It strikes me that there's a much bigger problem with the MK6, as thrashed out on the RBW forums: It has no manual inject.

That means that if the electronics fail, the diver has no choice but to bail out to the diluent.

It also means, because of the small size of dil tanks, that you really can't do a deco dive with the unit, because then you'd have no route to safety if the electronics fail unless you brought a bailout tank.

If you brought a bailout OC tank, then you've lost the benefit of the small, easy to use, convenient MK6.

And if you can't do a deco dive with a rebreather, then what's the point?

Yes djc, I agree lack of manual O2 inject is not a good thing, but it can be worked around-it would be very easy to add a button to the exhale lung. Not being able to dive with less than 99% O2 can't be worked around.

And remember, they don't want you to do any dceo diving on this unit, that's not what it's for. And almost all CCR training agencies require you to bring BO, no matter how shallow or brief the dive, so that's a no-no no matter how you slice it and I'd bet that the MK6 training will require it as well.

As for the point of CCR, for me it's making the most of my wildlife encounters first and foremost, followed by the benefits of having the optimal nitrox mix to make the most of multilevel dives, the deco advantage for deep, longer dives and the ability to have ultimate dive planning flexibility... -Andy

 

[silent running]

Perhaps there should be a key to unlock the automatic set point controller in mod2, like some computers use for trimix. I really don't want to sound like some kind of proselatizing ludite but manual injection forces a person to learn the subletes of po2 change with changes in metabolism, depth etc, like nothing else can. I think learning manually on an eCCR initially is a really good idea, maybe for the first 100 hours or so.

Hi Gil, FYI during the Prism course, you must learn to fly the unit with manual inject only for the first few days. The electronics don't get turned on until the last day, if you get that far.

And, while I agree that complacency is bad and that MCCR divers tend to have better unit awareness than those who dive with a unit that does everything for them, there is something in between. You know what I'm going to say, don't you? The Prism and MK 15, 15.5 all have SP only controllers and a passive 2dry which allows the user to fly manually. In fact, as I've mentioned above, those units emphasize the capability of unit to be flown without power as a safety feature which thereby familiarizes the diver with manual injection, including the mindset necessary to use it and rely only on yourself to maintain PO2.

There have been, very, very few fatalities on these types of system, especially considering the huge number of man hours from military training, research and operational use. It's certainly amounts to many more hrs of safe CCR diving than has currently been wracked up by all the recreational MCCR users out there to date.

Just because I have a solenoid, doesn't mean I'm lazy. My HUD tells me all the info I need-SP, power, sensor voted out-and I use the 2dry to cross check it and to check the sensors directly, with power off.

"Trust, but verify". Now why does that sound so appealing, and where did I hear it before?

 

[padiscubapro]

Not being able to dive with less than 99% O2 can't be worked around.

... -Andy

Forcing cal with 100% isn't necessarily a bad thing, and with a few home made add ons, it can be gotten around.. MY HH requires 100%, yet I have yet to have a problem calibrating in far away places... Last trip to truk I had 92%

and BTW a PERFECTLY functioning PSA system without an extra argon removal stage generates 95.4% o2. 4.5% argon, .1% trace gases