Inspiration Cave Dive

[rcojr]

I think you all are forgetting that this is a TV show. Ment to entertain the unknowing masses. The Discovery Channel used to have a show called Shipwrecks. In one episode the great John Stonehouse and his "team" were exploring the Emperor to try and determine why it sank. In one of the scenes Stonehouse makes a "grisly" discovery in the engine room.
It was a brand new flannel shirt layed out perfectly on the floor with a skull.
The bottom line is it is all BS put together to sell the show.
I have seen some of the same stuff put together by Wes Skiles. Supposedly 1000s of ft back in a cave but it sure looked like the entrance of Devils Ear to me.
Lighten up it's all just Hollywood.

[DRE]

I totally agree with you, but the problem is that it might give novice divers the impression that that is how proper cave diving is done or that they think that these guys are great divers and/or instructors because they're on TV.

PS: if anyone wants a great laugh out of a movie, watch Deep Blue Sea - at the end of the movie one of the actresses gives a frantic OOA signal to one of the stand by divers and it hasn't been cut ;D

[Chuck_Northrup]

Let's just pretend that the Inspiration is not a crutch for the weak, but rather an incredible tool which when controlled by a competent individual can enhance the diving experience.

For now we will ignore the benefit of silence (and the destruction saved on the cave system due to the lack of bubbles) and we will not argue the physiological pros and cons of constant PO2. Forget about the warm moist air, let's concentrate on gas consumption.

Given an SAC of .4 and an RMV of .8 for this cave system the OC diver is going to use roughly 110ft3 for the trip in and out (total 7000ft in 136 min) total gas carried must equal 165ft3. For each successive trip into the cave the cylinders must be either refilled or replaced.

Assuming our Inspiration diver is equal in every manner except chosen piece of kit, he could accomplish the same dive on 5ft3 of O2 and a (most likely) lesser amount of diluent. :o He carries enough gas on board to run 8-10 hours (regardless of depth). If he decided to stage an aluminum 80, and his buddy did the same, they would have more than enough gas in reserve. In the event they had a complete system failure, or both systems fail at the deepest point of penetration they would each have approximately 20ft3 of diluent to bail out to and 80ft3 of offboard, that is almost enough to do the entire dive on OC! :

In remote locations where filling is difficult or impossible the rebreather makes more sense. The difference is stark at 33ft but will be more apparent in deeper systems. At 130ft the OC boy would need over 400ft3 carried (270 used) and the RB diver would still use only 5ft3 each dil and O2. Staging 2 aluminum 80's would provide more redundancy than the OC diver would have.

I know a competent cave diver would never get lost, but if you did, or if a room collapsed on you, you would have +10 hours of gas time to find your way out! ;D Carrying less gas, and at the same time having more options for bail out and greater redundancy make the benefit of a CCR undeniable!

If you see a flaw in the logic please elucidate.

CN3

PS On the special I saw Chatterton was taking a cave class. When did he ever claim to be an authority on cave exploration? ???

[Omicron]

Cool info Chuck.

Now I just need to find a rebreather cheap ;D

Heh...yeah right. I need to plant more money trees.

[rcojr]

Any novice diver that would venture it to a cave based on a TV show is a candidate for a Darwin Award.
Thats twice DRE has agreed with me I don't think I can take it.

I totally agree with you, but the problem is that it might give novice divers the impression that that is how proper cave diving is done or that they think that these guys are great divers and/or instructors because they're on TV.

PS: if anyone wants a great laugh out of a movie, watch Deep Blue Sea - at the end of the movie one of the actresses gives a frantic OOA signal to one of the stand by divers and it hasn't been cut ;D

[DRE]

Chuck,

I did not want to imply that a RB is a crutch for the weak - I just wanted to point out that the dive Chatterton did is absolutely doable on OC and that a CCR adds a level of complexity far beyond OC. I totally agree with that CCR will give you much better gas usage than OC, but then again the unit - as you pointed out previously - is limited by the life of the absorbent, so in case of a collapse, while theoretically the diver has 8-10 hours of gas supply, the sofnolime would fail well before that, plus that in most cases shear exhaustion would take care of our unfortunate diver as well. So in reality the limitations of the unit are not dictated by the gas usage. In fact, for any serious dive, while the CCR does offer significant advantages in terms of gas consumption over OC, the overall dive time cannot be lengthened due to 1) absorbent life, 2) hypothermia in colder water, 3) overall fatigue. It all boils down to the question whether you can trust a machine playing with pure O2 UW for you or not, and there we are at opposite ends of the spectrum.
As far as deco is concerned (a whole other topic), I guess we are stuck in a similar position: while you argue that maintaining a constant PO2 reduces deco obligation (a theory which the Haldanian model strongly supports), I prefer a method in which N2 loading and O2 exposure during the dive is limited as much as possible, and where I let the gradient take care of the He, combined with toggling the PPO2. I believe that there is enough empirical evidence out there to support that the latter works fine (any deco program, with the exception of pure RBGM or VPM would add hours of deco to commonly performed dives). On short exposures (45 min or less) constant PO2 might give you 5-10 minutes less deco according to most models, but that can be overcome by being well perfused (ie working out on a regular basis and maintaining a low body fat percentage).
Like I said before, there's advantages and disadvantages to both ways of doing things - I just wanted to point out Chatterton's BS claims with regards to the use of RB's (but then I guess you don't really agree with his alpinist mentaliy anyways )

D




Let's just pretend that the Inspiration is not a crutch for the weak, but rather an incredible tool which when controlled by a competent individual can enhance the diving experience.

For now we will ignore the benefit of silence (and the destruction saved on the cave system due to the lack of bubbles) and we will not argue the physiological pros and cons of constant PO2. Forget about the warm moist air, let's concentrate on gas consumption.

Given an SAC of .4 and an RMV of .8 for this cave system the OC diver is going to use roughly 110ft3 for the trip in and out (total 7000ft in 136 min) total gas carried must equal 165ft3. For each successive trip into the cave the cylinders must be either refilled or replaced.

Assuming our Inspiration diver is equal in every manner except chosen piece of kit, he could accomplish the same dive on 5ft3 of O2 and a (most likely) lesser amount of diluent. :o He carries enough gas on board to run 8-10 hours (regardless of depth). If he decided to stage an aluminum 80, and his buddy did the same, they would have more than enough gas in reserve. In the event they had a complete system failure, or both systems fail at the deepest point of penetration they would each have approximately 20ft3 of diluent to bail out to and 80ft3 of offboard, that is almost enough to do the entire dive on OC! :

In remote locations where filling is difficult or impossible the rebreather makes more sense. The difference is stark at 33ft but will be more apparent in deeper systems. At 130ft the OC boy would need over 400ft3 carried (270 used) and the RB diver would still use only 5ft3 each dil and O2. Staging 2 aluminum 80's would provide more redundancy than the OC diver would have.

I know a competent cave diver would never get lost, but if you did, or if a room collapsed on you, you would have +10 hours of gas time to find your way out! ;D Carrying less gas, and at the same time having more options for bail out and greater redundancy make the benefit of a CCR undeniable!

If you see a flaw in the logic please elucidate.

CN3

PS On the special I saw Chatterton was taking a cave class. When did he ever claim to be an authority on cave exploration? ???

[/quote]

[igotoofar]

Dre, Now I don't dive an Inspiration, but I do know that the unit doesn't "play" with the O2.

[DRE]

No, it injects pure O2 into the breathing loop to maintain a constant PPO2 - sorry if my terminology wasn't correct 8)

[ghosch]

1) Rated absorbent life is 3 hours, in the case of an emergency and employing other bail out options could extend the life of the scrubber WELL beyond 3 hours.
2) True, but I'd rather be cold than dead.
3) If a person would just commit to running 10 miles three times a week instead of just 5 miles twice a week, he wouldn't be so worried about fatigue (j/k, but I had to say it!).

[igotoofar]

No, it injects pure O2 into the breathing loop to maintain a constant PPO2 - sorry if my terminology wasn't correct 8)

Dre, don't back away from you convictions. :o

I think everybody realizes that your terminology was exactly what you intended it to be. You have, if not stated, at least implied that one of your biggest complaints with the inspiration is the fact that the computer is mixing your gas. In your mind you see that as playing. You don't trust the computer to do this for you.

Don't "cave" 8) in to the pressure, stand up and yell at the top of you keyboard that you truly see this as playing.