One dead, one missing (since found), 300 foot dive - Lake Michigan

[rjack321]

then how do we get out?

Sure they lock out. I meant that they are not breathing trimix for 20-30mins with a deco obligation.

Why are we mixing up submarine escapes with tech diving?

 

[cerich]

Sure they lock out. I meant that they are not breathing trimix for 20-30mins with a deco obligation.

And? I am addressing the assertion that cesa won't work ever from 300 plus.

Many problems occur at the very front end of a technical dive, and while far from the best solution (in fact last and least likely to end well), just saying "won't work" is neither factually 100% accurate nor should it not be in the toolbox.

 

[uwxplorer]

From my rEvo diving friends. How much lead does it require if you only have the drysuit? I. E. is the unit on its own negative or positive? The ones I have played with (mini Ti and standard SS) were all noticeably negative on their own.

You are asking two different questions, it seems.
On its own, a rEvo is heavier than pretty much all other units I have ever tried (but I suspect there are other heavy units out there), and since it is very slim and streamlined, it will sink without extra buoyancy source. However, a unit with weights and loop open at the surface, with BCD inflated, will stay there.
Once weighted properly for drysuit diving in cold water (as mentioned in other posts), there is no difference whatsoever with other units. Flood the unit, and you add a fixed volume of liquid, which I believe will be larger on many units, due to the unique rEvo backmounted counterlung design and hose configuration. It will be no harder (and possibly easier) to bring it back to the surface.
If they released the unit, weighted, from the victim with little BCD inflation, and it flooded, yes the unit will likely sink.

 

[cerich]

Why are we mixing up submarine escapes with tech diving?

Physics ..and survival

 

[rjack321]

Physics ..and survival

My comment about "you're definitely going to die" was about hypoxia and DCS from a *CESA* from a 300ft dive.

I don't see how a submariner locking out from a 1ata air atmosphere is remotely relevant, but troll away on the pendantics I'm done.

 

[doctormike]

My comment about "you're definitely going to die" was about hypoxia and DCS from a *CESA* from a 300ft dive.

I don't see how a submariner locking out from a 1ata air atmosphere is remotely relevant, but troll away on the pendantics I'm done.

I think that the issue here is that your phrase was well intentioned but somewhat hyperbolic. And that's fine, I agree with you, and it's a reasonable rhetorical technique. Assuming that you will definitely die from a CESA from 300 feet means that you don't have it as plan B, as you might on a shallow dive.

I'm assuming that you actually meant that since the chance of surviving a CESA from 300 feet is so small, that it shouldn't be considered as a reasonable option for a tech diver, but rather other systems should be in place to allow for a safe(r) ascent - e.g. bailout - in case of a catastrophic gear failure.

And of course, bent is better than dead, so if for some reason you were really faced with the choice of CESA from 300 feet or drowning - someone mugged you at depth and took your gear - I'm pretty sure that all of us would go for it.

 

[RainPilot]

You are asking two different questions, it seems.
On its own, a rEvo is heavier than pretty much all other units I have ever tried (but I suspect there are other heavy units out there), and since it is very slim and streamlined, it will sink without extra buoyancy source. However, a unit with weights and loop open at the surface, with BCD inflated, will stay there.
Once weighted properly for drysuit diving in cold water (as mentioned in other posts), there is no difference whatsoever with other units. Flood the unit, and you add a fixed volume of liquid, which I believe will be larger on many units, due to the unique rEvo backmounted counterlung design and hose configuration. It will be no harder (and possibly easier) to bring it back to the surface.
If they released the unit, weighted, from the victim with little BCD inflation, and it flooded, yes the unit will likely sink.

I'm sorry if my post wasn't clear. The question came up about rEvo vs other units in terms of "sinking when flooded" and I replied with my experience, limited as it is. To be clear, I really do like the rEvo, if they made one with a cell validation system like the Poseidon I would dive it in a heartbeat.

The unit itself, without any BCD inflation, is significantly heavier than my Poseidon in the water. In the case of the Poseidon counter lungs, the position of the shoulder t-pieces means that even if I hold the DSV open and above my head, there is a large trapped bubble in the counter lungs. From what I have seen of the rEvo, and indeed my Poseidon with back mounted counter lungs, is that the whole lung will flood in the same circumstance.

To reiterate, this is not a condemnation or criticism of either unit, but an attempt to explain why people say that the rEvo sinks when flooded.

 

[rjack321]

The unit itself, without any BCD inflation, is significantly heavier than my Poseidon in the water. In the case of the Poseidon counter lungs, the position of the shoulder t-pieces means that even if I hold the DSV open and above my head, there is a large trapped bubble in the counter lungs. From what I have seen of the rEvo, and indeed my Poseidon with back mounted counter lungs, is that the whole lung will flood in the same circumstance.

To reiterate, this is not a condemnation or criticism of either unit, but an attempt to explain why people say that the rEvo sinks when flooded.

On my Meg the way the Tpieces connect to the TOS lungs I can remove the mouthpiece and wave it around above my head and it won't flood.
If I did that on my Kiss sidewinder it would instantly 90-100% flood. I could remove the loop and keep it below my chin (when in trim) and only the mouthpiece would flood.

My understanding of the Revo is that due to where the loop hoses connect to the case and counterlungs is that its pretty similar to the Kiss (sidewinder and other kiss models) in this way. If a mouthpiece/loop gets higher than the case its going to flood.

Obviously if ~6L of air is replaced with water on any unit (counterlung plus other air spaces) the diver is going to be much more negative and sink.

 

[cerich]

My comment about "you're definitely going to die" was about hypoxia and DCS from a *CESA* from a 300ft dive.

I don't see how a submariner locking out from a 1ata air atmosphere is remotely relevant, but troll away on the pendantics I'm done.

Sorry if the discussion upset you. There is some good info and cross over there, connecting the dots is interesting for some, others prefer to take a position and defend at all costs

 

[HKGuns]

For the record, I never looked forward to ever having to use the escape trunk. Didn't sound like a solid escape plan to me at most operating depths.