Rebreathers

[Shotmaster]

Plenty of rebreathers have CE certifications. And the Navy Mk28 is basically a tall Meg with an aluminum head.

Plenty of backstory on the APOC. Suffice it to say, it's the last thing you want to use to make an argument about safe rebreathers.

The Navy uses equipment and does other things that meet their mission. They also have on-board hyperbaric chambers, support diver, full medical staff and a Master Diver running the dive. I won't have that support package backing me up so I want a rig that is safer. I know a lot about the MK16, and newer rebreathers in use, and the guys who use them. I have been looking for some time. The Navy is rumored to be testing the Poseidon with a new sensor. I'm waiting to see what happens with the test.

 

[JohnnyC]

The Navy uses equipment and does other things that meet their mission. They also have on-board hyperbaric chambers, support diver, full medical staff and a Master Diver running the dive. I won't have that support package backing me up so I want a rig that is safer. I know a lot about the MK16, and newer rebreathers in use, and the guys who use them. I have been looking for some time. The Navy is rumored to be testing the Poseidon with a new sensor. I'm waiting to see what happens with the test.

The military is quite risk averse compared to the civilian sport world (in generally all aspects, hell the MC-4 is a 370sqft canopy!!! Even fully loaded, that's big...). Your example of chambers, medical staff, etc. perfectly illustrates that. If they were patently unsafe, they wouldn't use them in the first place, no matter the amount of support. In the civilian world, people are doing much more extreme dives without any of that support, and it's not the gear that causes problems.

Rebreather problems occur when people are not diligent in their maintenance, preparation, and operation. No amount of technology will ever weed that out. Hell, the military is a perfect example of "find a better idiot." A simple solid state O2 sensor is not going to save the life of a guy that doesn't stereo check his mushroom valves before a dive, or doesn't bailout when there's CO2 breakthrough, or doesn't analyze his gas in the first place.

You, personally, may be too risk averse to dive any of the rebreathers on the market, but that doesn't make them inherently unsafe. There's nothing wrong with being that way, but we accept risk in our lives everyday, and when properly addressed, the risk of diving a rebreather is lower than driving to the dive site.

Here's a fun little paper on the Meg configuration that won the Mk-28 Mod 0, and how its performance handily eclipses that of the Mk16.

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA549996&Location=U2&doc=GetTRDoc.pdf

 

[Shotmaster]

Thanks for the post johnnyC. It is a good read. The Megladon looks to be a large improvement over the 15% failure rate of the MK16. It is also good to have an independent test vs company sales info.

 

[Shotmaster]

The military is quite risk averse compared to the civilian sport world (in generally all aspects, hell the MC-4 is a 370sqft canopy!!! Even fully loaded, that's big...). Your example of chambers, medical staff, etc. perfectly illustrates that. If they were patently unsafe, they wouldn't use them in the first place.

The military conducts risk assessment and attempts to mitigate unecessary risks. There is a difference between taking risks and gambling. Civilians are free to gamble with their own safety, we call this "Darwin". In the military we are acutely aware of "Murphy". Whom still manages to introduce chaos in the best laid plans of men. The military uses processes and has some accountability for what is an allowed risk in peace time training. There are combat ratings for equipment loads and risk factors that take into account that war is hell. But it is foolish to take unnecessary risks with soldier safety for training. There are still risks.

War making is inherently unsafe. We do it with anyway, but with the the known risks and things are weighed on a scale of risk reward. At some point it starts looking like gambling. When the odds of success get small.

Also you mentioned the MC-4 as being large. It has a load rating of 360lbs. From experience, the guys I served with weighed in between 165-230lbs, we carried 100-120 lbs. rucksacks, 60-70 lbs of armor and kit, 10 lbs weapon, 5-6 lbs of helmet and night vision and sometimes a lot more. The heavier guys definitely exceeded the load rating. If you are a civilian, it looks like overkill, since sport jumpers are just wearing a jump suit and silk underwear!

I am taking a methodical approach and then make my risk assessment.

 

[JohnnyC]

You missed my point with the MC-4 comment. Even the heaviest jacked swole sick gains SEAL or PJ carrying everything he can possibly hang off his harness plus a set of PVS-31's just for fun, is still jumping a wing loading less than some, if not most, civilian skydivers are doing on a regular basis. It's not the weight rating, it's the wing loading ratio. This equates to rebreather divers running 8, 10 hour runtimes with depths at 100+ meters. Again, civilians are SAFELY, REPEATEDLY going far beyond what the military considers "safe" parameters for everything. But of course there will always be the outliers, the freak accident, the Brett Shadle or the Tom Pritchard, neither are immune.

You act like the military has a monopoly on risk mitigation, and it's just not true. The fact that there are rebreathers that CAN be dived to much greater extremes, without the need for all of those dive support assets you mentioned, and do on a regular basis, is a perfect example of the civilian world seeing a way to mitigate risk in the hardware, procedure, and implementation, doing it. In the end, going far beyond anything the military will ever do with the technology. There are some things the civilian world sucks at, or doesn't have the resources to easily do, things like easy IWR, so it gets fixed on the front end as much as possible. Hell, watch the video of Leon Scamahorn (the inventor of the Megalodon and former Special Forces) destroy his rebreather at 60m and finish the dive. That's about as worst case scenario as you can get.

At the end of the day, if you are unable to be the risk manager required to dive a rebreather, at a time when they're as safe as they've ever been, with best practices in place, and as bombproof hardware as you can get, then you shouldn't dive a rebreather. It's as simple as that. Doesn't make you any smarter or dumber than anybody else, doesn't mean you're better or worse than anybody else, all it does is mean that you don't have the mindset or ability to dive a rebreather. When it comes to today's rebreathers, it's 100% the indian not the arrow.

Found it:
I keep posting Meg stuff because it's the info that's out there, but JJ's, Revo's, Hammerheads, etc. are all capable of similar, and no matter what, bailout os always an option.

 

[doctormike]

Thanks for the post, Johnny.

I'm spending a lot of time thinking about all of this right now, having just finished Mod 1 on the JJ this weekend on a rental, and deciding about pulling the trigger on ordering one. I REALLY liked the unit, I liked the build, simplicity and quality. It's still hard to make that leap, but I'm pretty sure I'm going to do it soon!

I'm very compulsive about my gear and protocols, It's just that a lot of this talk gets into my head. Tom Pritchard was a good friend of mine.

 

[oya]

It's still hard to make that leap, but I'm pretty sure I'm going to do it soon!
.

Pull the trigger, Rothschild!!

 

[doctormike]

Pull the trigger, Rothschild!!

Hah! I'll be happy? You sure..??

 

[oya]

Hah! I'll be happy? You sure..??

I can say, uncategorically, that you will always be absolutely, 100% happy with your rebreather, never questioning the sanity of the purchase even for a moment.

And if I'm wrong... I promise never to give you crappy advice again.

(Seriously, though... that thing is pretty awesome. It's almost as nice as a Meg.)

 

[doctormike]

And if I'm wrong... I promise never to give you crappy advice again.

(Seriously, though... that thing is pretty awesome. It's almost as nice as a Meg.)

I love crappy advice!

The Meg is the one that I haven't tried but was considering. I really like the back mounted counter lungs on the JJ, though (I understand that you can modify the meg for that). In any case, didn't mean to derail the thread.