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Post by surflung on Aug 1, 2014 11:51:52 GMT -8
- We make so much of the improvement in breathing ease by positioning our double hose cans against the middle top of our backs, I was surprised to see Cousteau's divers ignoring this when diving 380 feet down to the wreck of the Britannic. Triple tanks with a Royal Mistral mounted on the top of the far left tank. Watch the video...
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Post by nikeajax on Aug 1, 2014 13:15:17 GMT -8
Oh man, I love this show: yeah, at about 20-mins. in you can see what he's talking about... interesting!
Jaybird
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Post by SeaRat on Aug 1, 2014 13:25:27 GMT -8
I have seen this before (but will enjoy it again) and noted that the divers sometimes were diving with the triple tank units sideways, with the regulator down on that side. That would actually put the regulator very close to the center of the lungs. It is a different way of getting a good regulator position in relation to the lungs. (Note that they needed to extend the exhaust hose to do this too.)
The Mistral's venturi is such that once the flow is initiated, there is very little breathing resistance. So the problem of positioning would deal with breaking force to initiate the flow. This is especially true of deep dives, where the venturi is more effective due to air density.
John
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Post by SeaRat on Aug 1, 2014 20:35:15 GMT -8
I just finished watching the show again. I was impressed with how he humanized the show by having Shella McBeth Mitchel, a nurse who survived the sinking of the Britannic, come on board and take the final Diving Saucer dive onto the ship. This is how he differed from other adventurers--he told the story in human terms as well as historic terms. I really enjoyed seeing this show again.
Concerning the scuba, it appears that my original observation did not make much difference. I didn't see much modification of attitude to compensate for the position of the Mistral regulator. I did see that the configuration of the valve, with its "V" shape, probably put it a bit lower when horizontal, but only an inch or so. I also noticed that they had an on-off valve on the opposite cylinder, so they preserved their 1/3 reserve with a reserve cylinder, the same as their other 3-cylinder scuba configurations.
John
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Post by regulator68bj on Aug 2, 2014 4:55:32 GMT -8
The sets were via "Technisub" Italy branch of "US Divers /Spiro" good to see this again thanks surflung for posting.
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Post by surflung on Aug 4, 2014 11:43:48 GMT -8
The Mistral's venturi is such that once the flow is initiated, there is very little breathing resistance. So the problem of positioning would deal with breaking force to initiate the flow. This is especially true of deep dives, where the venturi is more effective due to air density. John - So the venturi flow gets better the deeper you go... That is a dynamic that I haven't heard before but makes sense of a few personal mysteries of mine. I have heard that Cousteau always preferred the single stage Royal Mistral and used it even for the deepest dives. I have also heard that those Mistrals were "modified for deep diving" with a larger orifice or something. So did they even need to be modified if the venturi was improved by the increased air density? |
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Post by SeaRat on Aug 4, 2014 13:14:45 GMT -8
Surflung, I doubt that they made any modifications to the La Spiro Mistral other than the obvious one of lengthening the exhaust hose. However, I have no actual knowledge of that, and maybe someone else can chime in on this (Ryan, are you out there?). Unlike some other regulators, which performed worse as they went deeper, the U.S. Divers Company performed better, due to the venturi unique to it. The Aquamaster performs worse at depth. Note that the old cover had better exhalation characteristics than the "new cover." This had to do with the duckbill valve that was being used at different times. Now, the duckbill is the same as the Aquamaster and Royal Aquamaster, so you can discount the exhalation differences.   Now compare that chart with this one, using the same criterion and test platform (Navy EDU) for the Royal Aquamaster:  John |
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Post by surflung on Aug 5, 2014 5:16:50 GMT -8
- That's pretty amazing... That the single stage would work better than the two stage. But those charts certainly say alot for why Cousteau preferred the single stage Royal Mistral.
- A friend was wondering if the TriMix they were breathing would have the same density enhancement on the venturi flow... Using less dense helium and less partial pressure in oxygen and nitrogen?
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Post by surflung on Aug 5, 2014 13:28:56 GMT -8
 - I got this photo from a retro diving site. Shows the reg position and ultra cool dive gear as it appeared on the surface. The looks on their faces must have something to do with being French? Maybe it's the crotch strap... The one on the right just un-hooked his crotch strap.  |
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Post by tomcatpc on Aug 5, 2014 17:30:54 GMT -8
Some of the technical aspects of this forum...just way over my head LOL!
Mark
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viaqua
Regular Diver
Old Diver
Posts: 13 
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Post by viaqua on Aug 14, 2014 17:17:19 GMT -8
What would a rig like that weigh?
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Post by nikeajax on Aug 14, 2014 17:22:37 GMT -8
 SNORT!  Jaybird |
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Post by diverdon on Aug 15, 2014 2:39:19 GMT -8
Snort? Or snap? Dang. Is that you JB? Does not look like fun  |
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Post by SeaRat on Aug 15, 2014 8:25:44 GMT -8
Jaybird, any symptoms? Apparently all of us will eventually have a ruptured disc or two.
I'm going to do an experiment next week using independent doubles and my Mistral with superflex hoses, to see how much that Cousteau regulator position hurt (or not).
John
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Post by nikeajax on Aug 15, 2014 8:59:57 GMT -8
Naaaaaw, I wish: mine is more like this:  Only I have two ruptured discs, super awesome, and totally rad dude... like cowabunga man! SIGH...Jaybird |
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