Musings about a homebuild BOB & pendulum rebreathers

**Dave1w** · 7th September 2006, 05:28

Quote: (Originally Posted by O.C.Diver)

Hmmm, hostile environment where you have to be self sufficient and equipment failure equals death. Sounds comparable to me.

When you stop to think that the first moon walks were done with what is now 40+ year old technology, science, etc., whether it cost millions or "thousand millions", that it succeeded is pretty remarkable even with today's technology.

Ted

I thought it was all done in a studio in hollywood?

Dave

Mdemon · 7th September 2006, 07:30

Quote: (Originally Posted by Dave Sutton)

Sorry..... i Cave Divers obviously look at life differently than wreck divers like myself, but it's just that men walked on the *moon* with *one* rebreather loop... you would think two to be sufficient anyplace... ;-)

Does anyone but me remember that the original Navy Mark-15's were set up with two sets of hoses and DSV's, the second hose and DSV set was held with velcro loops on the back of the shell and the bailout mode was to have two divers on one loop? This is one of the reasons for the loop volume of the Mark-15 being what it is. I actually have one fully set up this way and can show photos if anyone wants...

Dave

Hi Dave, thank's for your input and I've enjoyed reading your site. I would like to see the Mk15 with 2 loops too. Did you try using this with another diver? If so, how was it? My second loop is very long and I've left the DSV free to rotate, wondering if it would be possible to bring a buddy home. I wouldn't like to try it much though...

Interesting point about the moon Rebreather, but MarcT does make a valid point - there were a few dollars more spent on those than your average recreational RB! I agree with Jason that by the time you add OC bailout you feel like you might as well dive OC. However, I thought the better solution was the second independant loop and like Marc, I'm surprised at how easy it is to use in the water.

And also like Marc, a third Rebreather, passoff-able, is an interesting idea to me. I like his phrase "securing the deco stops". Unlike him, my thoughts were more for a staged 3rd RB, more for other divers than myself, but it would be a nice security blanket.

Marc T · 7th September 2006, 09:57

Quote: (Originally Posted by paulraymaekers)

you can also use a 'non-pendulum'-hose (like drager ray), and simply connect both endings at top of the scrubber: this way you don't inhale the exhaled gas from exhale-hose and your scrubber is used pendulum

paul

But your inhale hose receive your exhale gaz and so become a dead space no?

***Beanie*** · 7th September 2006, 10:35

Quote: (Originally Posted by Marc T)

But your inhale hose receive your exhale gaz and so become a dead space no?

worse you could in theory completly bypass the scrubber

jaap · 7th September 2006, 10:45

Quote: (Originally Posted by Marc T)

But your inhale hose receive your exhale gaz and so become a dead space no?

No, not if the system is well designed. Have a look here:
Italian 02 Rebreather C-96

Far down on the page there are some detailed pics of how the hoses connect to the scrubber.

Marc T · 7th September 2006, 11:24

Quote: (Originally Posted by jaap)

No, not if the system is well designed. Have a look here:
Italian 02 Rebreather C-96

Far down on the page there are some detailed pics of how the hoses connect to the scrubber.

Thats not a pendulum Rebreather

Woz · 7th September 2006, 11:49

Silly question: why not have the exhale hose running concentrically down the inside of the inhale hose. Then it will look like a pendulum Rebreather but is actually a loop. In fact you could do this for any RB. You do it concentrically because the larger dia hose doesn't have to be that much bigger than the smaller hose as the CSA increases as a squared relationship.

jaap · 7th September 2006, 11:50

Quote: (Originally Posted by Marc T)

Thats not a pendulum Rebreather

Its a semipendulum. Two hoses but the gas goes via the scrubber both ways, on inhale and exhale. Look closely on the pictures of how the inhale/exhale-hoses feed to the scrubber.

***Beanie*** · 7th September 2006, 11:51

Quote: (Originally Posted by Woz)

Silly question: why not have the exhale hose running concentrically down the inside of the inhale hose. Then it will look like a pendulum Rebreather but is actually a loop. In fact you could do this for any RB. You do it concentrically because the larger dia hose doesn't have to be that much bigger than the smaller hose as the CSA increases as a squared relationship.

Becasue manufacturing and repair cost would be silly that and you'd never know if the innerhose had failed.

Janos · 7th September 2006, 11:51

Quote: (Originally Posted by Woz)

Silly question: why not have the exhale hose running concentrically down the inside of the inhale hose. Then it will look like a pendulum Rebreather but is actually a loop. In fact you could do this for any RB. You do it concentrically because the larger dia hose doesn't have to be that much bigger than the smaller hose as the CSA increases as a squared relationship.

Nice idea, but if the inner hose leaks (perhaps at the join) then you're f'ed as you get a CO2 breakthrough and it might not be immediately obvious.

Janos

7th September 2006, 05:28	#21 (permalink)
Dave1w Born Again Diver! Current Rebreather/s: Sport Kiss Dolphin Ray Home Build Other Rebreather/s: Classic Kiss Dolphin Ray Home Build Join Date: Jan 2005 Location: Singapore / UK Posts: 378	Re: Musings about a homebuild BOB & pendulum rebreathers Quote: (Originally Posted by O.C.Diver) Hmmm, hostile environment where you have to be self sufficient and equipment failure equals death. Sounds comparable to me. When you stop to think that the first moon walks were done with what is now 40+ year old technology, science, etc., whether it cost millions or "thousand millions", that it succeeded is pretty remarkable even with today's technology. Ted I thought it was all done in a studio in hollywood? Dave
(Online)

7th September 2006, 07:30	#22 (permalink)
Mdemon SiegeEngine II Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Inspiration Classic Home Build Join Date: Feb 2007 Location: SWUK Posts: 1,946	Re: Musings about a homebuild BOB & pendulum rebreathers Quote: (Originally Posted by Dave Sutton) Sorry..... i Cave Divers obviously look at life differently than wreck divers like myself, but it's just that men walked on the moon with one rebreather loop... you would think two to be sufficient anyplace... ;-) Does anyone but me remember that the original Navy Mark-15's were set up with two sets of hoses and DSV's, the second hose and DSV set was held with velcro loops on the back of the shell and the bailout mode was to have two divers on one loop? This is one of the reasons for the loop volume of the Mark-15 being what it is. I actually have one fully set up this way and can show photos if anyone wants... Dave Hi Dave, thank's for your input and I've enjoyed reading your site. I would like to see the Mk15 with 2 loops too. Did you try using this with another diver? If so, how was it? My second loop is very long and I've left the DSV free to rotate, wondering if it would be possible to bring a buddy home. I wouldn't like to try it much though... Interesting point about the moon Rebreather, but MarcT does make a valid point - there were a few dollars more spent on those than your average recreational RB! I agree with Jason that by the time you add OC bailout you feel like you might as well dive OC. However, I thought the better solution was the second independant loop and like Marc, I'm surprised at how easy it is to use in the water. And also like Marc, a third Rebreather, passoff-able, is an interesting idea to me. I like his phrase "securing the deco stops". Unlike him, my thoughts were more for a staged 3rd RB, more for other divers than myself, but it would be a nice security blanket. __________________ www.southwestmafia.com "small minds talk about people, Average Minds Talk About Events, GREAT MINDS TALK ABOUT IDEAS!" The WRONG Attitude will get you killed. "Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?"
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7th September 2006, 09:57	#23 (permalink)
Marc T hell is in the details Current Rebreather/s: RB80 / Clone Home Build Other Rebreather/s: Not Bought Yet RB80 / Clone Home Build Join Date: Sep 2005 Location: FRANCE Carcassonne Posts: 498	Re: Musings about a homebuild BOB & pendulum rebreathers Quote: (Originally Posted by paulraymaekers) you can also use a 'non-pendulum'-hose (like drager ray), and simply connect both endings at top of the scrubber: this way you don't inhale the exhaled gas from exhale-hose and your scrubber is used pendulum paul But your inhale hose receive your exhale gaz and so become a dead space no?
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7th September 2006, 10:35	#24 (permalink)
*Beanie* Gallery Administrator Current Rebreather/s: Inspiration Classic Other Rebreather/s: Inspiration Vision Join Date: Jan 2005 Location: In da house! yeah baby! Posts: 3,311	Re: Musings about a homebuild BOB & pendulum rebreathers Quote: (Originally Posted by Marc T) But your inhale hose receive your exhale gaz and so become a dead space no? worse you could in theory completly bypass the scrubber __________________ Beanie Gallery Admin & Library Assistant. www.outlawdivers.org.uk www.beandiving.co.uk www.beanengineering.co.uk
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7th September 2006, 10:45	#25 (permalink)
jaap Normal people worry me Current Rebreather/s: Classic Kiss Other CCR RB80 / Clone Ray Other SCR Home Build Other Rebreather/s: Other CCR RB80 / Clone Ray Other SCR Home Build Join Date: Jun 2005 Location: Stockholm Sweden Posts: 473	Re: Musings about a homebuild BOB & pendulum rebreathers Quote: (Originally Posted by Marc T) But your inhale hose receive your exhale gaz and so become a dead space no? No, not if the system is well designed. Have a look here: Italian 02 Rebreather C-96 Far down on the page there are some detailed pics of how the hoses connect to the scrubber.
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7th September 2006, 11:24	#26 (permalink)
Marc T hell is in the details Current Rebreather/s: RB80 / Clone Home Build Other Rebreather/s: Not Bought Yet RB80 / Clone Home Build Join Date: Sep 2005 Location: FRANCE Carcassonne Posts: 498	Re: Musings about a homebuild BOB & pendulum rebreathers Quote: (Originally Posted by jaap) No, not if the system is well designed. Have a look here: Italian 02 Rebreather C-96 Far down on the page there are some detailed pics of how the hoses connect to the scrubber. Thats not a pendulum Rebreather
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7th September 2006, 11:49	#27 (permalink)
Woz Custom Title Allowed! Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Jun 2005 Location: Nottingham Posts: 186	Re: Musings about a homebuild BOB & pendulum rebreathers Silly question: why not have the exhale hose running concentrically down the inside of the inhale hose. Then it will look like a pendulum Rebreather but is actually a loop. In fact you could do this for any RB. You do it concentrically because the larger dia hose doesn't have to be that much bigger than the smaller hose as the CSA increases as a squared relationship. __________________ Still punting shiny diving tatt to gullible divers www.kitfondle.co.uk
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7th September 2006, 11:50	#28 (permalink)
jaap Normal people worry me Current Rebreather/s: Classic Kiss Other CCR RB80 / Clone Ray Other SCR Home Build Other Rebreather/s: Other CCR RB80 / Clone Ray Other SCR Home Build Join Date: Jun 2005 Location: Stockholm Sweden Posts: 473	Re: Musings about a homebuild BOB & pendulum rebreathers Quote: (Originally Posted by Marc T) Thats not a pendulum Rebreather Its a semipendulum. Two hoses but the gas goes via the scrubber both ways, on inhale and exhale. Look closely on the pictures of how the inhale/exhale-hoses feed to the scrubber.
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7th September 2006, 11:51	#29 (permalink)
*Beanie* Gallery Administrator Current Rebreather/s: Inspiration Classic Other Rebreather/s: Inspiration Vision Join Date: Jan 2005 Location: In da house! yeah baby! Posts: 3,311	Re: Musings about a homebuild BOB & pendulum rebreathers Quote: (Originally Posted by Woz) Silly question: why not have the exhale hose running concentrically down the inside of the inhale hose. Then it will look like a pendulum Rebreather but is actually a loop. In fact you could do this for any RB. You do it concentrically because the larger dia hose doesn't have to be that much bigger than the smaller hose as the CSA increases as a squared relationship. Becasue manufacturing and repair cost would be silly that and you'd never know if the innerhose had failed. __________________ Beanie Gallery Admin & Library Assistant. www.outlawdivers.org.uk www.beandiving.co.uk www.beanengineering.co.uk
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7th September 2006, 11:51	#30 (permalink)
Janos "Two Sheds" Current Rebreather/s: Classic Kiss Other Rebreather/s: Classic Kiss Join Date: Feb 2005 Location: East Surrey Posts: 632	Re: Musings about a homebuild BOB & pendulum rebreathers Quote: (Originally Posted by Woz) Silly question: why not have the exhale hose running concentrically down the inside of the inhale hose. Then it will look like a pendulum Rebreather but is actually a loop. In fact you could do this for any RB. You do it concentrically because the larger dia hose doesn't have to be that much bigger than the smaller hose as the CSA increases as a squared relationship. Nice idea, but if the inner hose leaks (perhaps at the join) then you're f'ed as you get a CO2 breakthrough and it might not be immediately obvious. Janos __________________ You can lead a horse to water but you can't climb a ladder with a large bell in both hands - Vic Reeves www.hellfins.com/shed
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