Air consumption vs regulator ease of breathing

[Nemrod]

Nemrod, the point of my post above wasn’t about you, or convincing you about anything. I was pointing out your statement about J.Y. Cousteau, and why he went to a chest-mount system for his last dives. ‘Nothing to do with you….

A lot of people read things here, and the rest was to point out to them the correct way to wear a double hose regulator.

Saying that, I do enjoy my really easy breathing modern regulators, especially the A.I.R. I and the Pilot by Scubapro. ‘Don’t think that anyone has improved the breathing characteristics since the Pilot. Both of those are very nice in high currents too, as they are streamlined.

‘Sorry you thought I was talking more towards you than the rest of the readers here.

John (SeaRat)

PS, I’m now 77, going but 78 years old. I kinda envy you being on reefs in Cozemel too.

LOL . Yes, of course, I was gonna also say, ol'JC needs a new swimmin' suit as I think the Lycra in that one has gone a bit flat .

Thanks for the link, again, very good abstract, will take a while to digest.

 

[Gone for diving]

Dumb question I am sure someone has tried it. But has anyone made a sealed can on a double hose and ran a hose or pipe for water sensing at a lower point on your back? Seems that could solve a lot of DH positioning problems?

 

[CT-Rich]

Dumb question I am sure someone has tried it. But has anyone made a sealed can on a double hose and ran a hose or pipe for water sensing at a lower point on your back? Seems that could solve a lot of DH positioning problems?

I have a DH, but am not an expert on them. The position of the mouth piece relative to the regulator determines how easily the it breaths. That is why you wear it really low on your back when diving DH. The reason JYC had a chest mounted reg was to do what you are suggesting. Modern single hose regulators solve it by putting the second stage in your mouth.

 

[John C. Ratliff]

I have a DH, but am not an expert on them. The position of the mouth piece relative to the regulator determines how easily the it breaths. That is why you wear it really low on your back when diving DH. The reason JYC had a chest mounted reg was to do what you are suggesting. Modern single hose regulators solve it by putting the second stage in your mouth.

CT-Rich,

Actually, it is the position of the demand regulator compared to the center of the lungs, not the mouthpiece, that determines the ease of breathing for the double hose regulator. Here is a diagram which explains it from Bill Barada in a U.S. Divers Company book, “Let’s Go Diving.”*

Two- vs Single-hose reg001 by John Ratliff, on Flickr

What you are describing is the tendency of the regulator to free flow at the mouthpiece if the mouthpiece is above the demand regulator.

SeaRat

*Barada, Bill, Let’s Go Diving, Illustrated Diving Manual, U.S. Divers Company, 3323 West Warner Ave., Santa Ana, CA, November 1962, page 29.

 

[Tim K. SD]

I

I'm struggling to understand this sentence.

I'm with you, I had to read it and reread it and it still isn't clear. Sarcasm and semantics make poor bed partners

 

[CT-Rich]

There is no comparison between my SP regulators and the 60-70 year old DH single stage that I dive once or twice a year as a novelty. My G260 breaths so easily, I don't even bother with the venturi knob. I leave in pre-dive most of the time. The Venturi nozzle on the DH Mistral takes a sh*tty breathing reg and makes it less sh*tty. I don't trust it beyond a 25-30' (just wetsuit, weights, no BCD, no octo and J-valve reserve). In the 1950s-60s, I would have been super happy to be diving at all.

 

[scrane]

My DH Phoenix/ Aquamaster is a two stage regulator with a balanced first stage with the unbalanced second stage only having to contend with an adjustable IP around 135lb. This is a lot easier to control than a single stage like your Mistral that has to provide air directly from tank pressure. The modified second stage of my DH also provides variable venturi that can provide a lot of air without effort once flow is initiated. That's the good news.
That said, depending on your orientation in the water, at times you will either be force fed air or have to suck pretty hard.
I dive the DH quite often and make no allowance as far as air consumption goes compared to my easy breathing single hose rig. Also, I've had the DH down to 80' and beyond without problem. My DH provides for a nice modern Octo and a tank pressure gauge.
I believe SAC is heavily influenced by psychology.

 

[John C. Ratliff]

There is no comparison between my SP regulators and the 60-70 year old DH single stage that I dive once or twice a year as a novelty. My G260 breaths so easily, I don't even bother with the venturi knob. I leave in pre-dive most of the time. The Venturi nozzle on the DH Mistral takes a sh*tty breathing reg and makes it less sh*tty. I don't trust it beyond a 25-30' (just wetsuit, weights, no BCD, no octo and J-valve reserve). In the 1950s-60s, I would have been super happy to be diving at all.

I don’t quite agree with you about the Mistral being a bad regulator, rather it is a misunderstood regulator, and a Two-hose at that. The Venturi nozzle on the Mistral is extremely efficient and well-designed. This was shown in the 1950s or early 1960s in the U.S. Naval Experimental Diving Unit test, which by the way out-performed the DA Aquamaster regulator. Here is that test.

USD Mistral (new cover) by John Ratliff, on Flickr

This is why the Mistral was also approved for U.S. Navy use, along with the DA Aquamaster. Cousteau took the Mistral down to 300+ feet on the Brittanic wreck.

Screen Shot 2019-02-18 at 8.00.20 PM by John Ratliff, on Flickr


SeaRat

 

[Nemrod]

Working into a significant current in Cozumel just a few days ago I had to roll over nearly on my back and take a break. I was on my Kraken Series II with all the latest mods and tuned to DH perfection and correctly mounted and situated on me and the wing/BP. The currents were just weird this trip, running one way and then the other, a strong down current on one dive that sucked us down and often flowing at an angle to the reef/wall.

Any resistance to my demand quickly results in me developing an odd cough and nausea that only becomes more severe as a dive trip progresses. And I love my new G260s and Mark 17 Evo. Effortless air and I do not get next breath anxiety with them or my G250 sets. I am glad I had them along.

 

[CT-Rich]

It is a fun regulator to dive, but performance wise, it is out classed by my Scuba Pro. If this was fifty years ago, I can absolutely would dive the crap out of it. But is does have its down sides. It draws a lot harder on full tank. I have a steel 72 that goes with it, but I am not sure I would be comfortable using a 3000 psi tank with it. It wasn't made for those pressures. I love the incredible simplicity of a single stage reg. I can see why the military would like it. I am sure they are bullet proof reliable. I limit the dives with it not because I think it will fail, but because I dive it completely old school, no BCD, no bailout. no gauges (I did get a banjo fitting and a old SP SPG, circa 1960, but haven't used it yet).

I have an DA Aqua Master that I started working on, but haven't finished rebuilding.