Musings about a homebuild BOB & pendulum rebreathers

montyg · 6th September 2006, 12:11

Hello all

I was reading this thread about diving a dual CCR, and wanting a 3rd rebreather(!) for bail-out:

http://www.rebreatherworld.com/rebre...ebreather.html

An I was wondering about the possibility of using the very simplest rebreather for a BOB - namely a pendulum rebreather...

Does anybody here know what the deepest depth is that a pendulum rebreather (a) can or should be used and (b) has been used?

rgds
monty

Mdemon · 6th September 2006, 12:37

Quote: (Originally Posted by montyg)

Does anybody here know what the deepest depth is that a pendulum rebreather (a) can or should be used and (b) has been used?

I think they make tiny ones for mine and submarine escapes. I can't help with depths though. The weak point in them is the pendulum itself. You are rebreathing unscrubbed air in the hose so there could be a build up of CO2.

Would make a lovely emergency O2 BOB for deco though.

Padowan · 6th September 2006, 13:29

How about an MCCR pendulum rebreather, operated in a semi-MCCR mode, to get rid of the loop CO2? So basically, you run the unit as an MCCR for a couple of minutes, then dump the loop, and start again. It's not as efficient as a non-pendulum system operating as a full CCR, but with the CO2 build up limitations of a pendulum rebreather, perhaps this would be a way of using this simple technology as a gas extender that's more efficient than traditional SCR operation methodologies?

jasondrake · 6th September 2006, 13:30

I know that Castoro type pendulum breathers were used in WWII by frogmen for long, hard, cold swims carrying mines. So the dead space issues obviously aren't that big an issue. Mind you I imagine plenty of them died! Only to depth of 10m though, as were O2 only. No idea if anyone has converted them for depth.

**Dave Sutton** · 6th September 2006, 13:38

3 loops? Are they F$%8K(%g kidding? Nobody could manage that much crap and still have time to actually dive... do these people actually go into the water ever or do they just watch fish swim around on their computer screens? Sheesh.

<Incredulous mode off>

Most capable pendulum loop is the old Royal Navy CDBA. Go look at the teardown on my website. Hardly anyone ever looks at that teardown, but there's lots to learn from it.

I've used the C96Pro in 200 feet.... hardly scientific but it's a data point.

Bailout loops MUST be actively dealt with (IE kept at least at ambient pressure) and managed all thru the dive or they leak water. My "loop in a wing" seems ideal so far since adding gas to the wings on descent is a normal action anyhow. Photos 'one day', I want to streamline it enough to make it look aerospace and not a homebrew contraption.

Working on the "4 port DSV" now... which will have two loops feeding one DSV with the on/off having three position: Off/loop1/loop2

Dave Sutton

jaap · 6th September 2006, 14:08

"3 loops? Are they F$%8K(%g kidding? Nobody could manage that much crap and still have time to actually dive..."

Look at Olivier Isler: http://home.worldcom.ch/intruder/Pic...nts/OLIV01.JPG

Three loops going solo exploring for kilometers...

"I've used the C96Pro in 200 feet.... hardly scientific but it's a data point."

No CO2 issues? How big is the deadspace?

"Working on the "4 port DSV" now... which will have two loops feeding one DSV with the on/off having three position: Off/loop1/loop2"

Very innovative!

Some pics of my latest rather improvised O2-pendelum:

Mdemon · 6th September 2006, 15:20

Got a link to your site please?

Quote: (Originally Posted by Dave Sutton)

3 loops? Are they F$%8K(%g kidding? Nobody could manage that much crap and still have time to actually dive... do these people actually go into the water ever or do they just watch fish swim around on their computer screens? Sheesh.

<Incredulous mode off>

Most capable pendulum loop is the old Royal Navy CDBA. Go look at the teardown on my website. Hardly anyone ever looks at that teardown, but there's lots to learn from it.

I've used the C96Pro in 200 feet.... hardly scientific but it's a data point.

Bailout loops MUST be actively dealt with (IE kept at least at ambient pressure) and managed all thru the dive or they leak water. My "loop in a wing" seems ideal so far since adding gas to the wings on descent is a normal action anyhow. Photos 'one day', I want to streamline it enough to make it look aerospace and not a homebrew contraption.

Working on the "4 port DSV" now... which will have two loops feeding one DSV with the on/off having three position: Off/loop1/loop2

Dave Sutton

Yankee Rebel · 6th September 2006, 15:28

Dave Suttons website:

CDBA Rebreather Teardown

that links is directly to the clearance divers teardown pages. Daves teardowns are a great resource, and a good view of understanding just how rebreathers work. its generally the first one i go to when i have questions, or want to see something specific.

Rebreathers Worldwide
if i did that right, therebreathersite.nl has a page dedicated to the CDBA as well. some of the pics are from Daves site. this is my second site for reference i use alot.

hope this is of some help.

Dave its great to know that your C-96 has been down to 200 feet.. not scientific but encouraging!!

Yankee Rebel

Duncan Price · 6th September 2006, 16:06

Quote: (Originally Posted by Mdemon)

Would make a lovely emergency O2 BOB for deco though.

I've had my P1SS to 11 m in Wookey Hole and done a 500 m (shallow) cave penetration on it.

Used to intentionally use it for O2 deco as its cheaper to run than OC O2.

Duncan

Mdemon · 6th September 2006, 16:08

Thank you!

6th September 2006, 12:11	#1 (permalink)
montyg Monty Guest Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Feb 2007 Location: Cape Town, South Africa Posts: 242	Musings about a homebuild BOB & pendulum rebreathers Hello all I was reading this thread about diving a dual CCR, and wanting a 3rd rebreather(!) for bail-out: http://www.rebreatherworld.com/rebre...ebreather.html An I was wondering about the possibility of using the very simplest rebreather for a BOB - namely a pendulum rebreather... Does anybody here know what the deepest depth is that a pendulum rebreather (a) can or should be used and (b) has been used? rgds monty
(Online)

6th September 2006, 12:37	#2 (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 montyg) Does anybody here know what the deepest depth is that a pendulum rebreather (a) can or should be used and (b) has been used? I think they make tiny ones for mine and submarine escapes. I can't help with depths though. The weak point in them is the pendulum itself. You are rebreathing unscrubbed air in the hose so there could be a build up of CO2. Would make a lovely emergency O2 BOB for deco though. __________________ 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?"
(Offline)

6th September 2006, 13:29	#3 (permalink)
Padowan RBW Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Exeter, UK. Posts: 526	Re: Musings about a homebuild BOB & pendulum rebreathers How about an MCCR pendulum rebreather, operated in a semi-MCCR mode, to get rid of the loop CO2? So basically, you run the unit as an MCCR for a couple of minutes, then dump the loop, and start again. It's not as efficient as a non-pendulum system operating as a full CCR, but with the CO2 build up limitations of a pendulum rebreather, perhaps this would be a way of using this simple technology as a gas extender that's more efficient than traditional SCR operation methodologies? __________________ Padowan The future's bright, the future's Yellow .....for now padowan.net - Latest Video: Scapa Flow Rebreather Diving
(Offline)

6th September 2006, 13:30	#4 (permalink)
jasondrake RBW Member Current Rebreather/s: Other CCR Dolphin Home Build Other Rebreather/s: Other CCR Dolphin Home Build Join Date: Nov 2005 Location: Completely homeless Posts: 77	Re: Musings about a homebuild BOB & pendulum rebreathers I know that Castoro type pendulum breathers were used in WWII by frogmen for long, hard, cold swims carrying mines. So the dead space issues obviously aren't that big an issue. Mind you I imagine plenty of them died! Only to depth of 10m though, as were O2 only. No idea if anyone has converted them for depth.
(Online)

6th September 2006, 13:38	#5 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Evolution Megalodon rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,907	Re: Musings about a homebuild BOB & pendulum rebreathers 3 loops? Are they F$%8K(%g kidding? Nobody could manage that much crap and still have time to actually dive... do these people actually go into the water ever or do they just watch fish swim around on their computer screens? Sheesh. <Incredulous mode off> Most capable pendulum loop is the old Royal Navy CDBA. Go look at the teardown on my website. Hardly anyone ever looks at that teardown, but there's lots to learn from it. I've used the C96Pro in 200 feet.... hardly scientific but it's a data point. Bailout loops MUST be actively dealt with (IE kept at least at ambient pressure) and managed all thru the dive or they leak water. My "loop in a wing" seems ideal so far since adding gas to the wings on descent is a normal action anyhow. Photos 'one day', I want to streamline it enough to make it look aerospace and not a homebrew contraption. Working on the "4 port DSV" now... which will have two loops feeding one DSV with the on/off having three position: Off/loop1/loop2 Dave Sutton __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
(Offline)

6th September 2006, 15:20	#7 (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 Got a link to your site please? Quote: (Originally Posted by Dave Sutton) 3 loops? Are they F$%8K(%g kidding? Nobody could manage that much crap and still have time to actually dive... do these people actually go into the water ever or do they just watch fish swim around on their computer screens? Sheesh. <Incredulous mode off> Most capable pendulum loop is the old Royal Navy CDBA. Go look at the teardown on my website. Hardly anyone ever looks at that teardown, but there's lots to learn from it. I've used the C96Pro in 200 feet.... hardly scientific but it's a data point. Bailout loops MUST be actively dealt with (IE kept at least at ambient pressure) and managed all thru the dive or they leak water. My "loop in a wing" seems ideal so far since adding gas to the wings on descent is a normal action anyhow. Photos 'one day', I want to streamline it enough to make it look aerospace and not a homebrew contraption. Working on the "4 port DSV" now... which will have two loops feeding one DSV with the on/off having three position: Off/loop1/loop2 Dave Sutton __________________ 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?"
(Offline)

6th September 2006, 15:28	#8 (permalink)
Yankee Rebel Custom Title Allowed! Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Other CCR Home Build Join Date: Jan 2006 Location: California Posts: 147	Re: Musings about a homebuild BOB & pendulum rebreathers Dave Suttons website: CDBA Rebreather Teardown that links is directly to the clearance divers teardown pages. Daves teardowns are a great resource, and a good view of understanding just how rebreathers work. its generally the first one i go to when i have questions, or want to see something specific. Rebreathers Worldwide if i did that right, therebreathersite.nl has a page dedicated to the CDBA as well. some of the pics are from Daves site. this is my second site for reference i use alot. hope this is of some help. Dave its great to know that your C-96 has been down to 200 feet.. not scientific but encouraging!! Yankee Rebel
(Offline)

6th September 2006, 16:06	#9 (permalink)
Duncan Price Sump Monster Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Feb 2005 Location: Wells, Somerset, UK Posts: 335	Re: Musings about a homebuild BOB & pendulum rebreathers Quote: (Originally Posted by Mdemon) Would make a lovely emergency O2 BOB for deco though. I've had my P1SS to 11 m in Wookey Hole and done a 500 m (shallow) cave penetration on it. Used to intentionally use it for O2 deco as its cheaper to run than OC O2. Duncan
(Offline)

6th September 2006, 16:08	#10 (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 Thank you! __________________ 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?"
(Offline)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode