Why use a double hose

[rhwestfall]

What willpower do you posses that helped you resist aquiring a Conshelf?

I have one or two (firsts), but haven't dove them.... Think I have a few seconds in some boxes somewhere too...

some day...

 

[lexvil]

I am curious as to which double hose regulators that you used that you found to be such a difference in performance.

Well I started diving in 1971 using a voit, I have used more various aqua masters up to and including the RAM, I’ve owned a Phoenix with HPR, and two Kraken’s, I’m curious what SH you’ve compared to what DH’s.

 

[James79]

Now I feel like one of us needs to give @rhwestfall a Conshelf!

edit: Disregard... he needs to try the ones he has, or give them to me! lol

 

[lexvil]

Now I feel like one of us needs to give @rhwestfall a Conshelf!

edit: Disregard... he needs to try the ones he has, or give them to me! lol

He may as well, since in this day and age there are few papers that need holding down

 

[stuartv]

yep

worn properly, tuned properly, and correct body position, it is an equal.

This seems to be usually included and often ignored in the fine print.

When worn properly and tuned properly, and the diver is inverted, head down to look under a shelf at the bottom of a reef without laying on or kicking other stuff, does the DH still breathe just as a well as a SH in that same scenario?

What about simply if the diver is perfectly horizontal (i.e. a line from shoulders through hips to knees is perfectly straight and perfectly parallel to ground level)?

 

[James79]

This seems to be usually included and often ignored in the fine print.

When worn properly and tuned properly, and the diver is inverted, head down to look under a shelf at the bottom of a reef without laying on or kicking other stuff, does the DH still breathe just as a well as a SH in that same scenario?

What about simply if the diver is perfectly horizontal (i.e. a line from shoulders through hips to knees is perfectly straight and perfectly parallel to ground level)?

I am new to diving DH, but last weekend I spent about five minutes inverted vertical (vertical line from toes to head, head down), because I could... it breathed wonderfully, and DRY.

Respectfully,
James

 

[rhwestfall]

On a head down plunge (or peeking under something), no, it will not breathe optimally. It will be drier than a SH though...

 

[GJC]

Well I started diving in 1971 using a voit, I have used more various aqua masters up to and including the RAM, I’ve owned a Phoenix with HPR, and two Kraken’s, I’m curious what SH you’ve compared to what DH’s.

Most or the Conshelf line, some Sherwood, Scubapro 109, 156, 250, AIR1, a few Hollis and SEAC.

I only have 1 DA Aquamaster with a Cyclone and new valves. I'm meticulous about rebuilding and servicing on all my regs and have done so with my DAAM.

I wish I could try all the double hoses you have.

I like the Kraken, but right now, I have too many vintage things on my list to spend my money on.

 

[lexvil]

Most or the Conshelf line, some Sherwood, Scubapro 109, 156, 250, AIR1, a few Hollis and SEAC.

I only have 1 DA Aquamaster with a Cyclone and new valves. I'm meticulous about rebuilding and servicing on all my regs and have done so with my DAAM.

I wish I could try all the double hoses you have.

I like the Kraken, but right now, I have too many vintage things on my list to spend my money on.

As soon as we can dive again, let me know and I’ll loan you some modern stuff to try

 

[John C. Ratliff]

Due to simple physics a DH regulator will not breathe like a SH. It's remote location and the resulting differential between where the breath is generated and where it is consumed will result in substantial variation in breathing effort dependent on the diver's attitude in the water. The DH diver's real skill lies in ignoring this fact.
Now, whether the perceived benefits of double hose diving override the inconvenience of its use is a decision everyone who tries a DH makes.
To those who say that breathing DH is as effortless as breathing a single hose I would recommend they invest in a better SH reg.

You are mistaking some things.

--First, the breaking effort on a very good double hose regulator and a single hose regulator are about the same. I have two of the best-breathing single hose regulators ever made, a Scubapro Pilot and a Scubapro A.I.R. I. They are exceptional breathers. I have a U.S. Divers Company Mistral, which at 500 psig will break at about the same effort. Two very different concepts in breathing, and time lines. I also have a Royal Aquamaster, which breaths about as good as any single hose regulator; breaking effort is about 1/2 inch.

--Work of breathing involves the entire breathing cycle, both inhalation and exhalation. With the modern double- or single-hose regulators, with Venturi action in the inhalation cycle, once cracking effort is overcome the breathing is almost effortless. My Pilot, if the Venturi is improperly set, will actually over-inflate the diver's lungs by itself. But now we need to talk about exhalation effort. The first, second and in many third generation single hose regulators did not meet the U.S. Navy Experimental Diving Unit's (EDU) requirements for exhalation effort. They needed to substancially increase the exhaust port diameter. The A.I.R. I and Pilot regulators have the best exhaust effort of any single hose regulator, is the entire diaphragm is the exhaust mushroom too. But this is on dry land, not in the water.

--In the water, the diver's position affects the breathing effort as the regulator's position in relationship to the center of the diver's lungs affects breathing effort, both with inhalation and exhalation. The EDU states that exhalation effort is as important, perhaps more so, than inhalation effort. Bill Barada, in his 1962 publication, Let's Go Diving, Illustrated Diving Manual, has a great diagram illustrating these advantages and disadvantages. Titled "Two-Hose Regulator Verses Single-Hose," this illustration shows that the single hose regulator, in a supine position, has and advantage for inhalation effort of several inches; but that also gives a disadvantage of several inches for exhalation effort. The same is true for the double-hose regulator, but reversed. The advantage is for the double hose regulator in exhalation effort, with inhalation effort greater in the supine position. If you really want to see this, use your very good, and expensive, single-hose regulator in a vertical position, look up, and inhale; you'll find a substantial effort to overcome the difference between the regulator's position over 12 inches above the center of the lungs. Do the same with a double hose regulator, and you'll note almost no difference.

I have been diving double hose regulators since I was a kid, starting with a Healthways Scuba regulator in 1959. I have a collection of both double-hose and single-hose regulators. Each as advantages and disadvantages. I usually choose double-hose regulators when I'm videoing, or when I'm observing small critters (hydra on a leaf, for instance, or small sculpin in the water, or one very small fish that's really easily spooked). When I'm working out in current, or trying out new underwater swimming techniques, I use my single-hose regulators. When I use a double-hose regulator, I usually used twin tank setups, as they place the regulator squarely between my shoulder blades. I also have most of my twins set up with a "military harness" which attaches to the bands, and not any backboard. This lets the regulator ride right at my wetsuit, and not several inches out from it; every inch counts from a WOB (work of breathing) standpoint.

I have three photos of my double-hose setups, one taken of me in 1975 in Clear lake with a single tank and my Trieste II regulator, and two taken off the following video of me diving a USD Mistral in the river, and unexpectantly finding a whole lot of lead on the bottom. They illustrate the relative positions of the double hose to the yellow mouthpiece where a single hose would be located. Sometimes they are equal distances from the center of the lungs, and sometimes one has an advantage over the other.

Here's the video I shot of that dive, titled "Getting The Lead Out."
As you watch this video, take a look at the relative positions of my yellow mouthpiece and the Mistral regulator on the tanks. One other thing; the Mistral's orifice is one of the best-designed for a Venturi effect of any double hose regulator, and once the breathing cycle is initiated, the air comes almost effortlessly.

SeaRat