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Post by ScoobieDoo on Dec 20, 2003 17:50:14 GMT -8
Linda, About where on my back should my double hose reg be positioned? the center of the case at my lower neck, like C7/T1? Lower?
I am new to double hosers and just purchased 2 of them but have not gotten to dive them yet, being its a whopping 14 degrees with about 18" of snow here in New York state!
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Post by Linda on Dec 21, 2003 10:40:53 GMT -8
Hey, Mike! I could deal with a computer question a lot better... The only reference to your question that Dan could think of is in " DIVE " The Complete Book of Skin Diving, by Rick and Barbara Carrier, 1955. It simply states that "The harness... ...should be adjusted so that the regulator fits squarely between the shoulder blades and close to the back. It should fit comfortably and not wobble or float when submerged." If you'd like to read more, that particular paragraph begins at the very bottom of page 144 and continues onto page 145. There are also photos showing the regulator position: Figures 90-92. Oh, and if you want to jump in the water DESPITE the 14 degrees, I'm sure Frans (vintagediverMN) would go with you. ;D
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Post by Dennis on Dec 21, 2003 14:02:05 GMT -8
About where on my back should my double hose reg be positioned? Ahoy, Captain Scoobie. Look at the pictures in the chart "Single Vs Double Hose Regulators". The double hose regulator is worn really low, between the shoulders. They used short tanks back then. The base of an new aluminum 80 knocks you on the back of the knees when you wear the regulator that low.
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Post by ScoobieDoo on Dec 21, 2003 16:43:28 GMT -8
Ahoy, Captain Scoobie. Look at the pictures in the chart "Single Vs Double Hose Regulators". The double hose regulator is worn really low, between the shoulders. They used short tanks back then. The base of an new aluminum 80 knocks you on the back of the knees when you wear the regulator that low. I don't have THAT particular book, Capt. Barrunka!
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Post by Dennis on Dec 21, 2003 17:07:26 GMT -8
I don't have THAT particular book, Capt. Barrunka! Avast, Skipper Scoobie! You don't need a book. That chart is right here. Back up one thread and look at the listings under "Vintage Diver Instruction and Technique" for "Single Vs. Double Hose".
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Post by ScoobieDoo on Dec 21, 2003 17:42:11 GMT -8
Aye Captain!
I found it! Wow thats low! It's gonna look 'funny' having my AL80 hat low!
As long as it works!
I just got my 2nd USD backpack (aka in Mint Cond) in the mail this week for my wife! Combine that with that awsome mint USD 2-pc 7mm wetsuit that I got on eBay for $45 and another USD J-Valve this week also in EC - she'll be ready to go come Spring time!
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Post by John C Ratliff on Jan 19, 2004 20:12:24 GMT -8
The lower on the back, the better the double hose regulator will breath. The chart on the other thread shows what US Divers put together for their book, Let's Go Diving. The placement is dependent upon your harness system, the length of the hoses, and the size of the tanks. You will notice that the "ideal" position is as close to the center of the lungs as is possible, and any deviation is felt as increased suction effort for either single or two-hose regulators.
I have about 7 (plus some parts) two-hose regulators, and one is a DX Overpressure single stage regulator by USD (the predicessor to the Mistral). I put new hoses on it which were made for SCBAs (fire department self-contained breathing apparatus). These hoses are longer, and I've experimented with lowering the position of the regulator to the extreme. I found that the two-hose regulators breath best as low as you can get them. A reasonable complomise is to get them below the nap of the neck, and between the shoulder blades.
Backpacks will hold the regulator an inch or two off the back, and thereby increase breathing resistance by raising the position of the regulator. The old "military" harness for twin tanks is the ideal setup, as the regulators well nearly touch the diver's back. Cylinder size also affects the performance; the larger the cylinder, the higher the regulator, and the greater the water resistance for breathing with a two-hose regulator. I used to have a set of twin 40s from the US Air Force (twenty-man life raft CO2 cylinders converted for a 1/2 inch valve--they were our "jump tanks" for pararescue work). This set had the best characteristics of any I've owned. My best now is a set of twin 45's (1800 psi rated), which are standard cylinder size (same as the 72 cubic foot tank).
Enjoy,
SeaRat
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Post by caveman on Apr 8, 2004 15:25:42 GMT -8
Along these lines, is there a reason why some regulators have extremely long hoses and others have short ones? caveman
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Post by caveman on Apr 23, 2004 13:00:50 GMT -8
I do understand the reasoning behind getting the reg between th sholder blades and at the same pressure as the mouth peice, but why so long hoses on some regs? Is it just a matter of technique or is it a matter of personal prefference. caveman
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Post by SeaRat on May 15, 2004 17:40:25 GMT -8
The hose length was a manufacturer's decision. Some were too short (the original DX Overpressure Breathing regulator by USD, for instance). Some were quite long (Snark III hoses); this allowed them to be placed low on the back, but few divers did. The longer the hoses (with the exception of the DX, which had a venturi hose within the main intake hose) the worse the breathing characteristics. So it was a balance between performance of the regulator, positioning, and comfort. US Divers finally got it about right, but it took them awhile. Healthways did not; the Scuba Deluxe has hoses that are too short (the original Scuba regulator, with the Hope-Page mouthpiece, was about right). Dacor's hoses were also too short, in my opinion. A really nice combination was the Healthways Scuba Deluxe (with the venturi tube), and US Divers hose/mouthpiece system.
John
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Post by caveman on May 16, 2004 8:52:24 GMT -8
Thank you for your answer, it makes sense and I do appriciate it very much. caveman
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Buzz
Senior Diver
Posts: 64
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Post by Buzz on Apr 15, 2005 10:01:42 GMT -8
longer hoses so you can lower the reg and breath better is only beneficial when you are vertical.
Buzz
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Post by John C Ratliff on Apr 15, 2005 10:41:29 GMT -8
the reason that a double hose reg will breath better when worn lower on the back (only when the diver is vertical) is because the second stage is at a deeper depth than the mouthpiece. The second stage keeps the air pressure available to the mouthpiece at that higher pressure which results in easier breathing. when the diver is horizontal, this is no longer true. In this case the second stage is always at a shallower depth if the diver is facing down, but it will be deeper if the diver rolls over on his back. Even just these few inches of depth difference can make a difference in how well a reg breathes. bottom line is that longer hoses so you can lower the reg and breath better is only beneficial when you are vertical. Buzz Buzz, That really is not quite true. It is not the position of the regulator and the mouthpiece, but the position of the regulator to the center of the lungs. Even when a diver is horizontal, his back is rarely horizontal. Our back form an "S" curve, and if we lift our heads up to see, normally we are not completely horizontal when swimming horizontal. What we are trying to do with the double hose regulator is to position the regulator box as close to the center of the lungs as possible. Dropping the tanks allows the regulator to be positioned between the shoulder blades. Any higher, and the regulator will be off the surface of the back, and separated by several inches of water pressure from the back. This consequently increases the breathing resistance. If a diver is swimming slightly head-down, with the tanks completely horizontal, your case holds. But if the diver kneels, or even looks up, it does not. The best way to visualize this is to take any photo of a diver and mark an "X" in the center of his/her lungs. This is the "ideal" position for a regulator, which none fits. Draw a horizontal line (with respect to the earth, not the diver), and measure the number of inches over or under that line where the regulator box is located. That is the positive (if under) and negative (if over) inches of water pressure that the regulator positioning exerts on the effort of breathing. It is only relavant to the mouthpiece if the regulator is located there too (as with a "single hose" regulator). There is a diagram that also explains this located on this site. Take a look, then look at different diver's regulator positions. Two other comments: --The new Aqualung Mistral double hose regulator is revolutionary, in that the regulator position can be changed independent of the tank/valve positioning because of the hose to the second stage. This means that it could be chest-mounted, which would be a significant advantage. It also means that the tank position can be higher, to maintain contact with the valves, yet allow the regulator second stage to be positioned close to the ideal back position. --Longer hoses only work if the regulator's venturi system can handle them. The regulator I used, the DX Overpressure single stage regulator, has a venturi hose within the intake hose, and allows a longer hose to be used without loss of venturi effect. SeaRat
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Buzz
Senior Diver
Posts: 64
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Post by Buzz on Apr 15, 2005 12:05:36 GMT -8
Searat The point that I was trying to make was that the difference in height between the second stage and the mouthpiece is what is responsible for the air pressure that is available to the diver's mouth. My explanation was only considering the effects of the hardware position. The position of the diver's lungs with respect to the mouthpiece is what is responsible for how well the diver can take advantage of the pressure at the mouthpiece. Since the allover effect is a combination of the location of all the components, then we should all probably be wearing our rigs low on our chest Buzz
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YankDownUnder
Pro Diver
Broxton 'green label' Aqua Lung and 1954 USD Rene triple 44s.
Posts: 162
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Post by YankDownUnder on Apr 15, 2005 15:42:13 GMT -8
You would be surprised at some of the variations and how little some makers seemed to know. One advertisement, by La Spirotechnique, shows the regulator facing out!
In a story on how to make an 'aqua lung', a British article shows it on the chest, with a hp hose coming from the tank on the back. On Australia's east coast, in the late '50s, Siebe Gorman hookah units were used with tanks inverted on the back and the regulator on the chest, like the article depicted. My new Mistral will not allow this without substantial modification.
The first hoses used by Cousteau were American WWI surplus gas mask hoses. They were tan and cloth covered. (bakelite prototypes and some early C45 models) That was all that was avilable. Russian rebreather hoses are still that way and would make good restoration possible.
What makes the history of these products so interesting, is that the makers and the divers experimented with many ways, shapes, variations and sizes. Each evolved looking at the others. There was no right or wrong, but there is a best way, which each user decides for himself.
Mike Nelson's wet suits were painted by a dive shop to make them show up on camera. No one knew what color any of that equipment was, as the shows were in black and white. Some hoses were grey, others black. His gear changed as the show went on.
Yellow was known as 'come bite me yellow' in Australia, even though though there was nothing to show that sharks were interested in yellow. Most suits were black, which made us look like a seal, the white shark's main diet. We would have been safer with the yellow striped suits and yellow hoses, and perhaps more .......tasty.
The single stage Mistral was the cheaper of the two USD regulators sold here and was sold with yellow hoses. It was therefore thought of as a cheap rig, and snubbed. Black was considered more professional, back then and preferred. Long hoses or short, were not an option as the maker decided that. Long hoses did make the diver more vulnerable to snagging and water drag.
Try it all. Enjoy the differences. Uniformity is boring.
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