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Post by tomcatpc on Sept 22, 2019 6:45:57 GMT -8
Off topic...I see a 1970's-1980's era US Divers "Blow-Mould" backpack being used with a double hose reg. I've always been told these were not the best to use with double hose regs, and to try and use something to get the reg closer to the back of the Diver for better performance. Is there really that much of a difference? I have dove a double hose reg with the thicker backpack and I honestly did not know the difference... My only set of doubles has a thicker ScubaPro backpack and I want to dive them with a double hose next Summer. I know that placement of a double hose has a lot to do with performance, but with the thicker pack is it really that big of a deal? In the future I am going to see about getting a reproduction harness and band set up for my doubles, but until them...see how this works. Mark
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Post by nikeajax on Sept 22, 2019 6:59:28 GMT -8
John, when I've thought about this before, I was going to use some brass, then solder a tube into it: they do have non-toxic solders now You could also make a plastic rivet to hold it in place then mushroom the end by using something hot to melt it. JB
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Post by nikeajax on Sept 22, 2019 7:07:40 GMT -8
...Is there really that much of a difference? I have dove a double hose reg with the thicker backpack and I honestly did not know the difference... My only set of doubles has a thicker ScubaPro backpack and I want to dive them with a double hose next Summer. I know that placement of a double hose has a lot to do with performance, but with the thicker pack is it really that big of a deal? Mark Mark, it's always been my understanding that you want to just get the regulator lower on your back: seeing as the positioning of the tank is going to be dynamic due to natural movement it seems like a moot-point JB
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Post by scubalawyer on Sept 22, 2019 9:08:26 GMT -8
Off topic...I see a 1970's-1980's era US Divers "Blow-Mould" backpack being used with a double hose reg. I've always been told these were not the best to use with double hose regs, and to try and use something to get the reg closer to the back of the Diver for better performance. Is there really that much of a difference? IMHO yes.
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Post by SeaRat on Sept 22, 2019 16:39:12 GMT -8
Off topic...I see a 1970's-1980's era US Divers "Blow-Mould" backpack being used with a double hose reg. I've always been told these were not the best to use with double hose regs, and to try and use something to get the reg closer to the back of the Diver for better performance. Is there really that much of a difference? I have dove a double hose reg with the thicker backpack and I honestly did not know the difference... My only set of doubles has a thicker ScubaPro backpack and I want to dive them with a double hose next Summer. I know that placement of a double hose has a lot to do with performance, but with the thicker pack is it really that big of a deal? In the future I am going to see about getting a reproduction harness and band set up for my doubles, but until them...see how this works. Mark Mark, Here's my current twin steel 52s. IMG_1254 by John Ratliff, on Flickr Note the USD backpack on this set. The backpack does set the twins slightly back away from the back. They also make it more difficult to lower the regulator on the back. Here is my set of twin AL 45s, a new set for me. It was originally set up for a back plate, but I simply used the bands to make a military harness system with it. IMG_0013 by John Ratliff, on Flickr Becasue this set is narrower, the regulator sits close to my back, and a great setup for breathing, but it does dig into my back slightly with a wetsuit on (more without the wetsuit). Now, does this make a great different? Not so much anymore. The difference is not in the overall respiratory work, but in the cracking effort. With the better double hose regulators with a good Venturi (Mistral, Healthwasy Gold Label, Aquamaster, RAM, Kraken, etc.), the Venturi takes all the effort out of the breathing. With older regulators, including the Healthways Scuba and Scuba Deluxe, the DA Aqualung, Dacor R-2, and even R-3 (now), the breathing effort will be increased by that distance due to the diver having to continually "pull" inhalations out of the regulator without the benifit of a Venturi flow. Marion Yaquina Bay Dive UW-1 by John Ratliff, on Flickr Here you can see how the military harness gets the regulator (in this case Marion Fisk's Aquamaster) close to the back and down between the shoulder blades. 'Hope this makes some sense to you. John
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Post by tomcatpc on Sept 22, 2019 16:44:27 GMT -8
I will dive my Mistral with my double 72's on the ScubaPro pack next Summer. I do plan on finding a Military Harness for the doubles in the future, but in the interim...I will dive them how they are now. I totally understand what you said and my Mistral is an easy breather to start with... Actually I never thought my Healthways SCUBA was all that bad, but I can tell night and day difference between the SCUBA and the Mistral, so what you said makes a lot of sense. Mark
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Post by SeaRat on Sept 22, 2019 16:56:30 GMT -8
Bill Barada, in his original book, Let's Go Diving, had an illustration which showed the difference between the placement of the demand valves very well. Two- vs Single-hose reg001 by John Ratliff, on Flickr* John Photos003 by John Ratliff, on Flickr Here you can see my Mistral regulator, in 1970 in Alexander Springs State Park (and yes, I did at one time have hair on top), in nearly the ideal position. These are the small twin 42 pararescue jump tanks (this time from the 55th Aerospace Rescue and Recovery Squadron's Pararescue Section. Now, the hose-within-a-hose concept gave these regulators a Ventuir flow, and was one of the first to do so. Divers in those days did not like the "gush" of air, thinking it caused them to use air too quickly. We now know that the Venturi flow actually conserves air by making the work of breathing less. John Barada, Bill, Let's Go Diving, A Condensed Diving Instruction Manual, Published by U.S. Divers Company, 3323 West Warner Ave., Santa Ana, Calif., Catalog No. 7804-00, U.S.A., 1962, page 29.
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Post by SeaRat on Sept 23, 2019 9:06:15 GMT -8
John, when I've thought about this before, I was going to use some brass, then solder a tube into it: they do have non-toxic solders now You could also make a plastic rivet to hold it in place then mushroom the end by using something hot to melt it. JB I read this, but wanted to answer Mark first. Yes, I could do this, but I am not yet very comfortable with soldiering stuff, and the vynal tubing was handy. I'm going to continue with the vynal tubing for now, but thanks for this suggestion. John
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