Recent Opinions On Air Integrated Computers For Technical Diving

[Doby45]

I have not done any side-mount diving

That speaks volumes. Switching regs is not a hassle or a problem, nor do you automatically list to one side if you do not swap regs exactly within 500psi of equal tank pressure.

 

[Pavao]

Problem: switching second stages every 500-600 psig per side-mount tank. Each time the regulator must be switched, the diver is without a second stage in his/her mouth, must clear the alternate second stage, then again concentrate on the other factors of the dive. If a switch is not made, then the tanks' buoyancy characteristics deviate from each other, and trim is adversely affected.

Solution: use a second stage which accepts both tank's first stages, and drains each at the same rate simultaneously.

I experimented with this a few years back, mounting my two first stages on independent twin steel 52 cubic foot tanks from USD. Scubapro' A.I.R. I regulator, and their next two generations, allowed attaching a single second stage to two independent first stages, which gave redundancy and better performance at depth to the second stage. Note that I used a Dacor Olympic 400 or Voit MR-12 diaphragm first stage as one of the regulators, a Scubapro Mk V first stage, and was able to match the IP of both first stages.

SeaRat

WOW! Just when you thought you’ve seen everything

I’m sure someone has made a meme outta this already.

SeaRat, I’m curious to learn what advantages you found in this set up over manifolded doubles?


Edit: Aw, wish the pics would carry over in the quote

 

[John C. Ratliff]

WOW! Just when you thought you’ve seen everything

I’m sure someone has made a meme outta this already.

SeaRat, I’m curious to learn what advantages you found in this set up over manifolded doubles?


Edit: Aw, wish the pics would carry over in the quote

I didn't find any advantage, and have switched back to a manifold. I was just curious about whether I could make it work, as it is in the Scubapro materials on the A.I.R. I.

Sidemount seems very impractical to me, as I dive rivers solo, and need to walk down some rather steep paths and trails. Having tanks unsecured would inhibit my balance. I have trouble contemplating sidemount in high current too, as this technique seems hydrodynamically very unstreamlined.

SeaRat

 

[Pavao]

I didn't find any advantage, and have switched back to a manifold. I was just curious about whether I could make it work, as it is in the Scubapro materials on the A.I.R. I.

Sidemount seems very impractical to me, as I dive rivers solo, and need to walk down some rather steep paths and trails. Having tanks unsecured would inhibit my balance. I have trouble contemplating sidemount in high current too, as this technique seems hydrodynamically very unstreamlined.

SeaRat

I’m glad you went back to manifolded doubles man, that set up was just ridiculous, no offense.

Scubapro materials saying use a single second stage hooked up to 2 independently 1st stages? I’d like to see that. I know some models allows for either left or right feed, never seen anything about both being fed simultaneously, maybe you misinterpreted it?

I’m not sure why we are discussing sidemount, I’m not gonna go back to read, sorry if I forgot, but, sidemount is a fad man, and it seems to be a cult by many. My personal observation more and more people are getting fed up with the hassles of it and going back to back mount and using sidemount only when it’s needed, which by the way, 99% of the dives done on it, it isn’t needed, but that said, I’m not sure I agree with your assessment of it, pretty much every idea of it you got seems wrong.

 

[Mike1967]

sidemount is a fad

Your post was going great until this rubbish!
Unless you're trolling? If so, well done lol

 

[John C. Ratliff]

I’m glad you went back to manifolded doubles man, that set up was just ridiculous, no offense.

Scubapro materials saying use a single second stage hooked up to 2 independently 1st stages? I’d like to see that. I know some models allows for either left or right feed, never seen anything about both being fed simultaneously, maybe you misinterpreted it?

I’m not sure why we are discussing sidemount, I’m not gonna go back to read, sorry if I forgot, but, sidemount is a fad man, and it seems to be a cult by many. My personal observation more and more people are getting fed up with the hassles of it and going back to back mount and using sidemount only when it’s needed, which by the way, 99% of the dives done on it, it isn’t needed, but that said, I’m not sure I agree with your assessment of it, pretty much every idea of it you got seems wrong.

AIR I Performance001 by John Ratliff, on Flickr
Yes, this little pamphlet I received with my A.I.R. I when I bought it in the 1980s stated:

...The hose may be connected to either the right-hand or the left-hand port of the regulator. The unsued port must, of course, be capped with the provided plug. Commercial or advanced divers requiring improved flow perfrormance at depth can connect the A.I.R. I Second Stage to the first stage with two hoses, over over each shoulder. Maximum flow performance and safety can be achieved by attaching the A.I.R. I Second Stage to two independent first stages which, in turn, are mounted on separate high-pressure cylinders...

I simply decided for my dive on September 14, 2013 to try it out and see how it felt in the water. What I found was that the A.I.R. I did perform extremely well, but it always had. It was hard to discern any difference in 25 feet of water, even in a heavy current. So I went back to my manifolded doubles. I'm a 73 year-old diver, and will not be diving these extreme depths to ever need that again. But it was an interesting experiment.

Now, let's think about what Scubapro was stating. If you have two hoses, you have twice the volume of air at pressure inside these hoses. You therefore have a much larger (2x) reservoir of IP (intermediate pressure) air. At a given breathing rate, at a given depth, the IP will lower at 1/2 the rate during the breathing cycle. This is especially true at greater depths, say over 100 feet of seawater. Here, the pressure is at 3+ atmospheres, and the air is 3x the density. Therefore, in order to "feed" that denser air to the diver, the regulator has to flow more air, unless there is a larger reservoir. With a larger reservoir, the flow will still occur the same way, but will not require as much work from the first stage.

Now if you provide two independent first stages, the flow rate from HP air to IP air is doubled (assuming like first stages). The area and first stage "reservoir" of air is also doubled with two first stages (inside the first stages). This means that there will be less "work" done by each first stage to keep up with the demand.

This is especially true in extremely deep diving. At 284 feet, 890 meters, depth, there is 8x the density of air than at the surface (9 atm absolute). At this extreme depth, the single second stage fed by duel hoses attached to independent first stages becomes a substantial advantage in passing air to the diver. The IP at this depth is effectively 257 psig (140 + 117 (ambient pressure)), but that requires a lot of air. Increase the volume of the reservoir of IP air (like increasing the volume of a drinking water reservoir) will give you less IP decrease at a given demand level.

Now, let's get back to the use of WAI computers. I think they are great, as they decrease the "stuff" a diver tries to move through the water. Every piece of equipment in the water produces some drag (as does the side-mount system, due to non-streamlined alignment with the diver's body), and anything to decrease this drag is of benefit to the diver.

SeaRat

PS, I decided to upload those photos so you can see them again, and perhaps download them.

 

[Mike1967]

Every piece of equipment in the water produces some drag (as does the side-mount system, due to non-streamlined alignment with the diver's body), and anything to decrease this drag is of benefit to the diver.

Are you trying to say BM is more streamlined than SM now?

 

[John C. Ratliff]

Are you trying to say BM is more streamlined than SM now?

Not necessarily. It rather depends upon how the two different systems are harnessed to the diver's body, restrict or allow different types of swimming (flutter kick, frog kick, dolphin kick). I wear my doubles quite low compared to other divers. I also have rounded shoulders, and if the tanks sit low they are partially shielded by my shoulders. I have been talking with one of you offline, and he was saying that SM cylinders are at least partially shielded by the shoulders, being under the armpits. I'm open to that, but this is lost once the diver moves his arms in front of his body, in what would be a very streamlined position. I also have two sets of small doubles, and the profile with them is therefore more streamlined.

Here is an example of perhaps the best human underwater streamlining available, competitive immersion finswimmimg:

Now, a question about WAI; does the position of the transmitter below the body affect the wireless transmission?

SeaRat

 

[eelnoraa]

... If a switch is not made, then the tanks' buoyancy characteristics deviate from each other, and trim is adversely affected.

Are you serious?? Have you dive additional bottle to your BM tank? I have seen too many divers with 1 AL80 and 1 AL40 on my left side only and won't have trim problem, my self included. I often dive one AL80 side mount and without trim issue either.

...
Solution: use a second stage which accepts both tank's first stages, and drains each at the same rate simultaneously.

I am with tbone here. It is impossible to match the IP of two first stage perfectly across the entire tank pressure. If any side has IP creek, you will drain mostly from one side. What you are suggesting is exactly what UTD side mount manifold setup. In the case of UTD, they even recomment shut of one side when breath from the other side

 

[Mike1967]

Now, a question about WAI; does the position of the transmitter below the body affect the wireless transmission?

No. I've never had any signal issues with either configuration but if anything, the TX would be closer to your computer in SM.