Doing Tech+Cave on a RB?

[trob09]

Thank you for the learning experience and comparisons to my known universe (e.g. cars, planes, etc.)

So I'm sitting here a GUE Tech1 diver. Normoxic trimix + 1 deco gas. Gauge + ratio deco planning on the fly. About as anti-potted-computer-monitored-injector as you can get.

I don't have a ton of dives this way but the thought process makes sense to me. My brain likes linear functions of time and depth with gas proportions remaining constant. I have no need or reason to return to using my old Vyper in computer mode. Or get a VR3 for that matter.

I also have very limited desire to get Tech2 to only then try an RB80. (I don't think there are any intro RB80 classes out there )

So which units are:
a) constant gas parameters (you're on 32% the whole dive, not you run a ppO2 of 1.2 the whole dive)
b) compatible with mental deco planning on the fly??

Not a problem. I spent many a year on OC and while not GUE trained, was a pretty heavy drinker of the Kool-aid. One day after lugging 3 sets of doubles and a dozen or so stage bottles on board for a few dives, I said - that's it. 6 months later I had my meg and was happy. I don't own a VR3 and until I got my meg, had never followed an in-water computer profile (I'm still kind of skittish about it - a couple of years later)

In my opinion, the RB80 and its clones are the best of the SCR breed. I do, however, feel compelled to quote my CCR cave instructor by saying that my bail-out off of CCR and onto SCR is the RB80's best-case scenario.

 

[rjack321]

So do you run the Meg in SCR mode or as a CCR?

If you have a Meg in SCR mode what's involved in bailing from that onto OC?

 

[trob09]

So do you run the Meg in SCR mode or as a CCR?

If you have a Meg in SCR mode what's involved in bailing from that onto OC?

I run it in CCR mode - what's the point of having a CCR & not using it as a CCR.

You can run it in SCR. That is taught as one of the bail-out methods and can extend gas in essentially the same way as the RB80, although there are some differences. It is a skill I practice.

Bailing to OC is a little different for me as I have an OC integrated DSV. a 90 degree turn of a lever closes the loop & puts me on OC that is plumbed to my bail-out tank. Nothing comes out of my mouth, I just switch to OC.

Before I had that, I would close the loop & remove the mouthpiece, pull the 2nd stage from my bail-out gas (doing all those DIRish gas validation protocols) put the 2nd stage in my mouth and breathe. From this point on I'm OC breathing off of stages.

 

[rjack321]

I run it in CCR mode - what's the point of having a CCR & not using it as a CCR.

In my case it would be to run a constant gas type, say 18/45. And then deco plan on the fly just like I would on OC. Relatively seamless transition between gear types.

I think I understand the switchblock...
What happens if you have a partial flood and caustic junk is in the loop?

 

[trob09]

In my case it would be to run a constant gas type, say 18/45. And then deco plan on the fly just like I would on OC. Relatively seamless transition between gear types.

If this is what you want to do, I would stick with SCR like the RB80. but in my opinion, you will have all of the drawback of both OC and CCR without the advantage of CCR.

I think I understand the switchblock...
What happens if you have a partial flood and caustic junk is in the loop?

Well, I have a cis canister in my meg so I am not so worried about caustic cocktail. before I got that, I would bail out to OC in the event of an unrecoverable loop flood.

 

[rjack321]

The biggest problem with the RB80 IMO is the prerequisites and the costs.

I have different profiles and objectives in mind vs. the WKPP's. So taking a boatload of time and energy to pass Tech2 before I can even try out the concept for my own purposes is not worth it.

Not that some other alternative couldn't/wouldn't work for me - that's why I'm here, and done a bunch of RBworld reading, and tried to ask people in the know about alternatives. But to seamlessly transition between OC and SCR planning seems to fit the way my brain works. Vs. having a CCR which would demand a completely new approach. And I wouldn't want to cross back and forth from that mode to OC - too much opportunity to screw something up.

 

[trob09]

There 's no reason you can't go back & forth between CCR and OC (Not that I do or would want to) but you know your comfort level better than anyone.

I think that GUE/WKPP are right in suggesting that the RB80 is mission-specific where OC won't do the trick. As I say I find it to have all the risks of both OC and RB with few of the benefits of CCR.

Other SCRs seem more geared towards the recreational diver and have limited capability for me.

Someone (Stefan I believe) suggested talking to Mel Clark. She teaches RB in Seattle and would be a great local resource for learning and discussing your wants/needs. I don't know Mel personally but I know one of her associates who is very knowledgeable.

T

 

[rjack321]

Other SCRs seem more geared towards the recreational diver and have limited capability for me.

I assume you're talking about a Dolphin?

I have yet to understand the all or nothing approach with some of these recreational units. I mean if my plan is for a 140 to 90 ft (120' ave) dive for 50 minutes I don't get why they need to impose structural limitations on that objective. Or 150ft for 25 mins for that matter.

As far as I can tell, an infinite collection of orifices (or an adjustable one with software to set it) would be a great idea. Anyone make an aftermarket mode that leaves it as an SCR but allows for He mixes and other add-ins?

 

[trob09]

I assume you're talking about a Dolphin?

Yep.

As far as I can tell, an infinite collection of orifices (or an adjustable one with software to set it) would be a great idea.

Sort of like a CCR....

 

[wedivebc]

I would like to jump in here and clarify a couple of things. The RB80 and the dolphin, while both SCRs are 2 different animals. The method they use to inject gas are entirely different and they are designed for opposite ends of the dive usage scale. The dolphin is a recreational breather that is well suited for long dives on tropical reefs by divers with slightly more training than a OC diver might have. The RB80 is designed for hugely long dives and is found in caves in both Europe and America going places where no diver has gone before. The benefits of the RB80 seem to be (and I am not certified to dive one) that they use gas efficiently, have huge scrubber duration and they give very definate feedback to the user in the event of a failure. The downside is they cost as much as a CCR, and don't offer the deco advantage a fixed setpoint can offer for many dive profiles.
It just seems to me when comparing semi closed RBs these 2 units should be considered independantly because they are nothing alike.