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Post by tomcatpc on Feb 1, 2015 14:28:18 GMT -8
Another thing I think I noticed about diving with the Mistral compared to a modern single hose reg. with power inflated BCD. I could have sworn that when I switched the tank over to my modern reg/BC the air supply went down a lot faster? Does using the modern power inflated BC really burn up that much air?, or was I just noticing that wrong? Hope that made sense? Mark
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Post by SeaRat on Feb 1, 2015 16:47:50 GMT -8
Mark, yes depending upon your change of depth, it can affect the air supply if you use a power inflator. A couple of years ago, I dove my PJ tanks with a Broxton DA Aqualung from the 1950s. We didn't go too deep, but I was orally inflating my BC, and I seemed to have a bit more air. This is because I was using my exhaled breath for the BC, rather than tank air.
John
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Post by tomcatpc on Feb 1, 2015 20:28:22 GMT -8
And that brought up something else I wanted ask, but was scared I'd feel like a dorko. Orally inflating a Horse Collar BC underwater, never heard anyway talk about on here yet, but did not want to ask how difficult it was LOL. When I was using my modern reg-BCD setup, I did try and inflate the BC Orally and seemed to work alright.
I think that Vintage Double Hose has a new made Horse Collar BC, but looks somewhat vintage for about $50. Odds are I will end up snagging one sooner or later. Thanks Mark
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Post by SeaRat on Feb 1, 2015 23:43:39 GMT -8
Mark, When I talked about orally inflating my BC, I had forgotten that this may be a lost art. In the early days of diving, we did not dive with BCs. We dove with life vests. s3.photobucket.com/user/yaquinaguy/media/LimonsOsispreparesfordive1975_zps675b4b14.jpg.html?o=79An Oregon Department of Fish and Wildlife biologist Limons Osis equipped for clam bed research diving, 1975. We orally inflated our vests or used a CO2 cartridge to inflate it. Then we went to an actual BC, with an overpressure relief valve. Until we put these ORVs into the BC, we really could not use them for buoyancy compensation without the risk of bursting the vest on ascent. After a while, dive companies came out with vests which could be inflated underwater: I took this photo to illustrate that the cross-chest strap on the military harness had to be under the BC, and had to have the quick release routing on the double D-rings. A dive shop owner, Bill Herter of Deep Sea Bill's in Newport, Oregon. I took one of his inventions, a wet suit vest with oral inflation, to the Sixth International Conference on Underwater Education, IQ-6, and demonstrated it in a pool there. I think if you look at the photo, you will see representatives of some scuba manufacturers (Scubapro) watching me as I jump into the pool with the unit. In short, we used oral inflation for years before the "power inflators" were available. The cave divers started buoyancy compensation with wet suit dives in the 1960s and used chlorox bottles on a string under their arms; that's how primative it was early in diving. When Bill Herter decided to go with power inflators, he told me by saying, "John, I've become a 'push button diver.'" At that time, the only divers using power inflators were cave divers, wreck divers. Bill built these into his wet suits (he manufactured custom wet suits, and I bought two of his suits). Here is a photo of one of those suits when I was diving in the Alsea River, circa 1975 (Holy Cow, that was almost forty years ago!), in which the entire back of the suit was a BC (the white part was sandwiched 1/8" neoprene, sealed and with an oral/power inflator). John
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Post by diverdon on Feb 2, 2015 8:42:01 GMT -8
Hey John,
That wetsuit is wild. Any more pics/brochures? Glad to hear you got out diving. All my diving is limited to the pool with students. Maybe I'll bring my Mistral to the pool too.
Don
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Post by tomcatpc on Feb 2, 2015 10:42:51 GMT -8
The "BC" I'm looking at is basically a new made version of the May West my Dad was issued during the War as USN Aircrew. If that makes sense? Other than it is black than yellow. Mark
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Post by SeaRat on Feb 2, 2015 12:28:29 GMT -8
Don, Here's an interesting one, not a BC though. In the USAF, we wore "Underarm Life Preservers," or LPUs. Here is pararescueman Stephen Samo wearing the PJ tanks, a USD Calypso regulator, and the LPUs. These were bladders folded up into a bag under each arm, with an independent harness. Stephen Samo diving in Okinawa off the runway at Naha Air Base, Okinawa, 1968. John
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Post by nikeajax on Feb 2, 2015 12:46:19 GMT -8
So John, it looks like the tank valves are shrouded, no? Can you share that with the class please...
Jaybird
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Post by SeaRat on Feb 2, 2015 13:10:51 GMT -8
Jaybird, first here's more on the LPU concept, images from the net: This is what the bladder looks like. Each bladder has a 50 gm CO2 cartridge, and can be orally inflated too. This is out of a USAF survival manual, but being used by this Sea Survival publication. It shows how a person sits in the water with an inflated LPU system. John
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Post by SeaRat on Feb 2, 2015 13:24:42 GMT -8
So John, it looks like the tank valves are shrouded, no? Can you share that with the class please... Jaybird Jaybird, Yes, the tank's manifold for the PJ tanks are shrouded, or rather guarded by a manifold guard. This is a piece of sheet metal that is folded over so that there are no sharp edges, and extends over the entire manifold. But in fact, we used masking tape to complete the "shroud" so that we could use them for parascuba jumping. Here is a photo I took, again in 1968 off Okinawa, of a PJ making a parascuba jump (I had already jumped, and was in the pickup boat). Photo by John C. Ratliff, taken with a Nikonos II camera, 35mm lens. This, from one of our books, Pararescue--50 Years (1943-1993), will illustrate more than my words why we needed this guard. Pararescueman Nick Klimi shows a completely dressed PJ for a parascuba mission jump. Note that this was later, when we had an integrated harness design (incorporating the harness of the scuba with that of the parachute). In the earlier photo of Samo, he was using the military harness, and we simply used a regular parachute harness with an extended diagonal back strap to allow it to be mounted over the scuba tanks. Without the manifold guard, we could get parachute lines tangled in our doubles manifold when we exited the aircraft. Prop blast was a problem, especially the HC-130 Hercules aircraft, because of the turbojets. If we didn't exit perfectly, this blast would roll us or twist us mercilessly. With this guard on the scuba, at least we didn't have to contend with tangles we could not roll out of, and the risers or parachute line would not pull off the on-off valve or reserve lever when we jumped (that would not be fun!). We only had about a minute to undo whatever the prop blast had done, then steer toward the target and get ready to splash. John
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