Which rebreather has best trim

**fireman** · 24th May 2008, 03:25

Can you still turn your valves on and off quickly.
Also, if one is diving dry you are going to have to carry some weight unless the unit is very negative, so the concept of a unit having perfect trim is sort of silly.

single tank numpty · 24th May 2008, 08:41

Quote: (Originally Posted by fireman)

Can you still turn your valves on and off quickly.
Also, if one is diving dry you are going to have to carry some weight unless the unit is very negative, so the concept of a unit having perfect trim is sort of silly.

Hi

Strange question. It is exactly like turning valves on a set of twins, they are in the same place. My back ground is tech, and I've never had a problem reaching valves. So I don't really understand your question.

In my view for anyone with a tech background, valves at the head just makes perfect sense. It means that the failure responses are that bit more intuitive as they are in line with previous training.

I'm new to rebreathers but the concept of a unit which favours good trim seems anything but silly. If a unit is valves down and has a lot of air spaces at the scrubber head or by the nature of the conter lungs then obviously it will not favour good trim. But a unit with valves up and, by design, very little airspace in the scrubber head and low profile counter lungs will encourage 'normal' trim. Seems like basic physics. Am I missing something due to my inexperience?

Maybe using very small cannisters will mean that valve down is not an issue, but I personally wanted a unit that would allow me to dive with Aluminium 80s (11Ls) in a year or so, so that I can do the deeper dives on Rebreather that I currently do on open circuit (Eventually). I think that valve down 80s would be a nightmare.

Cheers

Mike

***jradomski*** · 24th May 2008, 09:22

Quote: (Originally Posted by single tank numpty)

Hi

Strange question. It is exactly like turning valves on a set of twins, they are in the same place. My back ground is tech, and I've never had a problem reaching valves. So I don't really understand your question.

In my view for anyone with a tech background, valves at the head just makes perfect sense. It means that the failure responses are that bit more intuitive as they are in line with previous training.

I'm new to rebreathers but the concept of a unit which favours good trim seems anything but silly. If a unit is valves down and has a lot of air spaces at the scrubber head or by the nature of the conter lungs then obviously it will not favour good trim. But a unit with valves up and, by design, very little airspace in the scrubber head and low profile counter lungs will encourage 'normal' trim. Seems like basic physics. Am I missing something due to my inexperience?

Maybe using very small cannisters will mean that valve down is not an issue, but I personally wanted a unit that would allow me to dive with Aluminium 80s (11Ls) in a year or so, so that I can do the deeper dives on Rebreather that I currently do on open circuit (Eventually). I think that valve down 80s would be a nightmare.

Cheers

Mike

The motion required to turn off valves is alot easier when the vales are at your ass.. unlike OC where you have alot of gas very second on a CCR makes a difference.. You need the fastest way to shut things down..

lets use some reasonable numbers ( I can vouch that these would be reasonable since I have had my OPV on my diluent go!)

Apeks 1st stages are commonly used on rebreathers.. most of them can deliever at least 2400lpm through the lp port.. on al al 80 that means it takes about 1 minute should the OPV or a hose let go.. rebreathers typically use 3l cylinders.. filled to 200 bar thats 600 liters of gas.. that means at 15 seconds (assuming you started at a full tank) you tanks are empty!

Several years ago, I had my OPV let go while I was on a free drop on a wall in gc... I was at about 80m when this happened.. I started the dive with a new fill of dil.. all of a sudden, I heard a boom and bubbles.. I immediately reached back and shut off both 02 and dil.. This was an immediate reaction.. I didnt delay, by the time I got the valves off I had just over 50bar of dil left.. There is no way I could have shut it off as fast if the valves were at my head and this was in a wet suit.. in a dry suit forget it.. Since this incident I now only turn the dil on, two quick turns of the wrist (this is about 1/2 a turn of the valve for each twist), which is what I have always used for the o2 side.. I used to turn the dil on what would be equivalent of 2 full turns (4 quick turns of the wrist)..

I would never consider putting the tanks valves up again (I tried it and definately couldnt operate it as easily- I would have hat to move the tanks up alot), and yes I had many years of diving twins under my belt.. working on inverted valves (valves down) is ALOT easier.. if they are positioned optimally your hands fall right onto the valves..

BTW I HAVE dived with large tanks on a CCR.. AL 80s SUCKED, not because of valve positioning but because of the tank characteristics... Using 7.5l steels works nicely..

Gilles · 24th May 2008, 09:39

Quote: (Originally Posted by fireman)

Can you still turn your valves on and off quickly.
Also, if one is diving dry you are going to have to carry some weight unless the unit is very negative, so the concept of a unit having perfect trim is sort of silly.

It's been all of 2 months since I've under the waves

. Seems like forever.

I get good natural trim, valves up, and using a sidemount for bailout tanks (usually a pair of 80's) on a Meg.

With the onboard valves open two wrist-twists, it takes no more than 2 seconds to shut down both in a boom scenario.

**fireman** · 24th May 2008, 16:37

Well...
I quess the answer to the original question is "mine"

In response to the responses, I think with a meg your tanks can be much higher than some Rebreather. And in fact on some RB you couldn't reach the valves at all it they were up. And I am quite flexable.
Regardless, my point is that one must have a large change in added wieght to accomidate different diving conditions, and even if you add weight on a belt this will have an effect on your trim, so whats the point.

I suppose if the required position of the Rebreather for optimal breathing and it was hideously wieghted it could be said to have bad trim, but I don't think such a beast exists

Mark Chase · 24th May 2008, 18:11

Quote: (Originally Posted by jradomski)

The motion required to turn off valves is alot easier when the vales are at your ass.. unlike OC where you have alot of gas very second on a CCR makes a difference.. You need the fastest way to shut things down..

lets use some reasonable numbers ( I can vouch that these would be reasonable since I have had my OPV on my diluent go!)

Apeks 1st stages are commonly used on rebreathers.. most of them can deliever at least 2400lpm through the lp port.. on al al 80 that means it takes about 1 minute should the OPV or a hose let go.. rebreathers typically use 3l cylinders.. filled to 200 bar thats 600 liters of gas.. that means at 15 seconds (assuming you started at a full tank) you tanks are empty!

Several years ago, I had my OPV let go while I was on a free drop on a wall in gc... I was at about 80m when this happened.. I started the dive with a new fill of dil.. all of a sudden, I heard a boom and bubbles.. I immediately reached back and shut off both 02 and dil.. This was an immediate reaction.. I didnt delay, by the time I got the valves off I had just over 50bar of dil left.. There is no way I could have shut it off as fast if the valves were at my head and this was in a wet suit.. in a dry suit forget it.. Since this incident I now only turn the dil on, two quick turns of the wrist (this is about 1/2 a turn of the valve for each twist), which is what I have always used for the o2 side.. I used to turn the dil on what would be equivalent of 2 full turns (4 quick turns of the wrist)..

I would never consider putting the tanks valves up again (I tried it and definately couldnt operate it as easily- I would have hat to move the tanks up alot), and yes I had many years of diving twins under my belt.. working on inverted valves (valves down) is ALOT easier.. if they are positioned optimally your hands fall right onto the valves..

BTW I HAVE dived with large tanks on a CCR.. AL 80s SUCKED, not because of valve positioning but because of the tank characteristics... Using 7.5l steels works nicely..

I had a diluient cylinder let go at 90m. First reaction to the jacuzi of bubbles was to turn off the 02. By the time i had reached back and done the two turns that required the bubbles stoped. As a result i asumed the problem was on the 02 side and promptly decided exiting the cave was my first priority. Upon ariving at the exit and some 70m of water I did a life check and found 02 fine Diluient totaly empty.

So it was dill leaking not 02 and it took the time it takes to find the valve by my arse and do two turns before the dill was empty.

Sobering stuff

Fortunatly i had off board bailout plumbed in to a second inject button on the inspo so the 2.5 hours deco and ascent was not an issue.

ATB

Mark

rogeringebo · 25th May 2008, 12:03

Im with Mike here.....
When you reach the level where most people start looking in to CCR you would at least have done Advanced nitrox or simular. Quite often trimix level. (then you will start understanding the real costs of OC Trimix)
At this level your instructors must have had you doing hundreds of shutdown drills and you should have developed the right motor skills.
Why change that just because you get in to CCR?
The benefits are non existing.
It will put weight in the wrong place, you are stuck with one size tanks (unless you like the valves at your knees or have the Petrona towers of Kuala Lumpur over shadowing you.) I have tried that so I know

When I dive, my hands are a lot closer to my shoulders then my ass so there would be no time won there.
If you find it hard to reach the valves the back plate should be altered, the dry suit be bigger or what ever it takes. Some one must have showed you that during the OC days...
If thousands of OC teckies can do it so can we, right?
A rapid loss of gas is a nightmare for all divers but to shut down valves on CCR does not take longer as they are the same valves.

When it comes to the importance of proper trim Im with the GUE boys (but just not as anal

)
If you have any plans of doing wreck penetrations, cave diving or even dive in hard currents it will suit you well to have a good trim.
I have many OC diving friends that teach technical diving and I can see their scepticism when they hear the words trim and CCR in the same sentence. I guess they have been on to many dive boats over the years...

If you guys are happy with your rig and your trim, stick with it....

If you are not.... try something new

I used to strap weights to my webbing or back plate, wear a lead hat, sport a 15 pound nose piercing, or wear my weight belt around my neck but no more

Best regards
Rodge

jkaterenchuk · 25th May 2008, 12:46

Quote: (Originally Posted by rogeringebo)

Im with Mike here.....
When you reach the level where most people start looking in to CCR you would at least have done Advanced nitrox or simular. Quite often trimix level. (then you will start understanding the real costs of OC Trimix)
At this level your instructors must have had you doing hundreds of shutdown drills and you should have developed the right motor skills.
Why change that just because you get in to CCR?

Rodge

Your forgeting about those of us that were enlightened enough to move directly to CCR and bypass doubles.

John

***jradomski*** · 25th May 2008, 13:16

Quote: (Originally Posted by rogeringebo)

If you find it hard to reach the valves the back plate should be altered, the dry suit be bigger or what ever it takes. Some one must have showed you that during the OC days...
If thousands of OC teckies can do it so can we, right?
A rapid loss of gas is a nightmare for all divers but to shut down valves on CCR does not take longer as they are the same valves.
Best regards
Rodge

Hey rodge,

Fisrt it depends on the valves... I for one avoid thermo style valves whenever possible especially on the o2 side as these are WAY to fast to open/close.. I want a valve thats at lest 4 or 5 FULL turns to close, not the less than 2 for a thermo an many other manifold valves which have evolved to less turns to shut off.. More turns = a finer thread = slower pressurizing when opening..

Rapid loss fo an OC diver is tens of seconds, for a Rebreather diver its seconds... Regardless of which way an individual chooses to rig the valves, shutdown drills should be regularly practiced..

Certain RBs will allow placement in the valve up thats reachable but alot of them the ideal placemeny of the tanks is lower than one would easily reach.. depending on the size of doubles one need, alot of time people need the trick to reach behind and push up the cylinders, so they can shut off one side at a time, or preferrably shut the isolator down first.. with very small tanks you really want both off immediately.. If I take 15 seconds to isolate and shut down a set of twins thats fine.. I'll still have alot of gas left, 15 seconds on a CCR and I'm F***ed.. In warm water with thin undrgarments or a wet suit I can usually get my arm back far enough to use the valve to lift the tanks higher, so I can shut 1 valve an the isolator at the same time, but I still have 1 cylinder dumping.. When I'm in very heavy undergarments, I definately need to reach behind my ass to prop up the tanks...

I also prefer to have the bottom of the Rebreather as close to my ass as possible to prevent as much back pain as possible.. I find that if I'm diving a short RB and its up high, I have a sore back afterwards.. If I was diving something like a meg with a small can, it would probably be easier for me to rig the RB up high and invert the tanks (valve side up), but I'd get a back ache, if I put it at a compromise position my back would feel better but it would slow down valve access low and would probably be impossible to reach if they were valve side up.. Same with a sport Kiss, where it breaths the best (up high), my back hurts, down low breathing sucks.. The sport is almost long enough where the compromise position is actually acceptable..

With my body size just dropping my arms to the sides puts my hands very close to the valves.. reaching them is effortless.. on something like a rEvo, its easier than reaching the manual adds which becomes a second nature thing...

If you have a very short body with a big Rebreather low valves might be an issue.. but a majority of the RBs out there, the bottom of the RB (and the vales) end up about ass height.. the normal body proportions put someones hand when at their side around this position as well.. If my RB was higher on my back then it would end up probably being close to that of putting valves up on top..

Anders Thulin · 27th May 2008, 08:57

Roger, if you ad a drysuit to your Rebreather?

(already ordered a Pelagian :P)

24th May 2008, 03:25	#41 (permalink)
fireman rEvo combat swimmer Current Rebreather/s: rEvo Other CCR Other Rebreather/s: rEvo Other CCR Join Date: Nov 2006 Location: chicago Posts: 517	Re: Which rebreather has best trim Can you still turn your valves on and off quickly. Also, if one is diving dry you are going to have to carry some weight unless the unit is very negative, so the concept of a unit having perfect trim is sort of silly. __________________ Heres to you Capt. Bill Never Forget, and stay safe everyone.
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24th May 2008, 08:41	#42 (permalink)
single tank numpty New Member Current Rebreather/s: Pelagian Other Rebreather/s: Pelagian Join Date: Mar 2007 Location: Philippines, 10 meters from the sea :-) Posts: 43	Re: Which rebreather has best trim Quote: (Originally Posted by fireman) Can you still turn your valves on and off quickly. Also, if one is diving dry you are going to have to carry some weight unless the unit is very negative, so the concept of a unit having perfect trim is sort of silly. Hi Strange question. It is exactly like turning valves on a set of twins, they are in the same place. My back ground is tech, and I've never had a problem reaching valves. So I don't really understand your question. In my view for anyone with a tech background, valves at the head just makes perfect sense. It means that the failure responses are that bit more intuitive as they are in line with previous training. I'm new to rebreathers but the concept of a unit which favours good trim seems anything but silly. If a unit is valves down and has a lot of air spaces at the scrubber head or by the nature of the conter lungs then obviously it will not favour good trim. But a unit with valves up and, by design, very little airspace in the scrubber head and low profile counter lungs will encourage 'normal' trim. Seems like basic physics. Am I missing something due to my inexperience? Maybe using very small cannisters will mean that valve down is not an issue, but I personally wanted a unit that would allow me to dive with Aluminium 80s (11Ls) in a year or so, so that I can do the deeper dives on Rebreather that I currently do on open circuit (Eventually). I think that valve down 80s would be a nightmare. Cheers Mike
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24th May 2008, 09:22	#43 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Home Build Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Home Build Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,001	Re: Which rebreather has best trim Quote: (Originally Posted by single tank numpty) Hi Strange question. It is exactly like turning valves on a set of twins, they are in the same place. My back ground is tech, and I've never had a problem reaching valves. So I don't really understand your question. In my view for anyone with a tech background, valves at the head just makes perfect sense. It means that the failure responses are that bit more intuitive as they are in line with previous training. I'm new to rebreathers but the concept of a unit which favours good trim seems anything but silly. If a unit is valves down and has a lot of air spaces at the scrubber head or by the nature of the conter lungs then obviously it will not favour good trim. But a unit with valves up and, by design, very little airspace in the scrubber head and low profile counter lungs will encourage 'normal' trim. Seems like basic physics. Am I missing something due to my inexperience? Maybe using very small cannisters will mean that valve down is not an issue, but I personally wanted a unit that would allow me to dive with Aluminium 80s (11Ls) in a year or so, so that I can do the deeper dives on Rebreather that I currently do on open circuit (Eventually). I think that valve down 80s would be a nightmare. Cheers Mike The motion required to turn off valves is alot easier when the vales are at your ass.. unlike OC where you have alot of gas very second on a CCR makes a difference.. You need the fastest way to shut things down.. lets use some reasonable numbers ( I can vouch that these would be reasonable since I have had my OPV on my diluent go!) Apeks 1st stages are commonly used on rebreathers.. most of them can deliever at least 2400lpm through the lp port.. on al al 80 that means it takes about 1 minute should the OPV or a hose let go.. rebreathers typically use 3l cylinders.. filled to 200 bar thats 600 liters of gas.. that means at 15 seconds (assuming you started at a full tank) you tanks are empty! Several years ago, I had my OPV let go while I was on a free drop on a wall in gc... I was at about 80m when this happened.. I started the dive with a new fill of dil.. all of a sudden, I heard a boom and bubbles.. I immediately reached back and shut off both 02 and dil.. This was an immediate reaction.. I didnt delay, by the time I got the valves off I had just over 50bar of dil left.. There is no way I could have shut it off as fast if the valves were at my head and this was in a wet suit.. in a dry suit forget it.. Since this incident I now only turn the dil on, two quick turns of the wrist (this is about 1/2 a turn of the valve for each twist), which is what I have always used for the o2 side.. I used to turn the dil on what would be equivalent of 2 full turns (4 quick turns of the wrist).. I would never consider putting the tanks valves up again (I tried it and definately couldnt operate it as easily- I would have hat to move the tanks up alot), and yes I had many years of diving twins under my belt.. working on inverted valves (valves down) is ALOT easier.. if they are positioned optimally your hands fall right onto the valves.. BTW I HAVE dived with large tanks on a CCR.. AL 80s SUCKED, not because of valve positioning but because of the tank characteristics... Using 7.5l steels works nicely.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated. Last edited by jradomski : 24th May 2008 at 10:26.
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24th May 2008, 09:39	#44 (permalink)
Gilles Worship the feminine Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Den Haag (Netherlands) Posts: 762	Re: Which rebreather has best trim Quote: (Originally Posted by fireman) Can you still turn your valves on and off quickly. Also, if one is diving dry you are going to have to carry some weight unless the unit is very negative, so the concept of a unit having perfect trim is sort of silly. It's been all of 2 months since I've under the waves. Seems like forever. I get good natural trim, valves up, and using a sidemount for bailout tanks (usually a pair of 80's) on a Meg. With the onboard valves open two wrist-twists, it takes no more than 2 seconds to shut down both in a boom scenario. __________________ Gilles http://www.dirrebreather.com
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24th May 2008, 16:37	#45 (permalink)
fireman rEvo combat swimmer Current Rebreather/s: rEvo Other CCR Other Rebreather/s: rEvo Other CCR Join Date: Nov 2006 Location: chicago Posts: 517	Re: Which rebreather has best trim Well... I quess the answer to the original question is "mine" In response to the responses, I think with a meg your tanks can be much higher than some Rebreather. And in fact on some RB you couldn't reach the valves at all it they were up. And I am quite flexable. Regardless, my point is that one must have a large change in added wieght to accomidate different diving conditions, and even if you add weight on a belt this will have an effect on your trim, so whats the point. I suppose if the required position of the Rebreather for optimal breathing and it was hideously wieghted it could be said to have bad trim, but I don't think such a beast exists __________________ Heres to you Capt. Bill Never Forget, and stay safe everyone.
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24th May 2008, 18:11	#46 (permalink)
Mark Chase I go down for ages Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,697	Re: Which rebreather has best trim Quote: (Originally Posted by jradomski) The motion required to turn off valves is alot easier when the vales are at your ass.. unlike OC where you have alot of gas very second on a CCR makes a difference.. You need the fastest way to shut things down.. lets use some reasonable numbers ( I can vouch that these would be reasonable since I have had my OPV on my diluent go!) Apeks 1st stages are commonly used on rebreathers.. most of them can deliever at least 2400lpm through the lp port.. on al al 80 that means it takes about 1 minute should the OPV or a hose let go.. rebreathers typically use 3l cylinders.. filled to 200 bar thats 600 liters of gas.. that means at 15 seconds (assuming you started at a full tank) you tanks are empty! Several years ago, I had my OPV let go while I was on a free drop on a wall in gc... I was at about 80m when this happened.. I started the dive with a new fill of dil.. all of a sudden, I heard a boom and bubbles.. I immediately reached back and shut off both 02 and dil.. This was an immediate reaction.. I didnt delay, by the time I got the valves off I had just over 50bar of dil left.. There is no way I could have shut it off as fast if the valves were at my head and this was in a wet suit.. in a dry suit forget it.. Since this incident I now only turn the dil on, two quick turns of the wrist (this is about 1/2 a turn of the valve for each twist), which is what I have always used for the o2 side.. I used to turn the dil on what would be equivalent of 2 full turns (4 quick turns of the wrist).. I would never consider putting the tanks valves up again (I tried it and definately couldnt operate it as easily- I would have hat to move the tanks up alot), and yes I had many years of diving twins under my belt.. working on inverted valves (valves down) is ALOT easier.. if they are positioned optimally your hands fall right onto the valves.. BTW I HAVE dived with large tanks on a CCR.. AL 80s SUCKED, not because of valve positioning but because of the tank characteristics... Using 7.5l steels works nicely.. I had a diluient cylinder let go at 90m. First reaction to the jacuzi of bubbles was to turn off the 02. By the time i had reached back and done the two turns that required the bubbles stoped. As a result i asumed the problem was on the 02 side and promptly decided exiting the cave was my first priority. Upon ariving at the exit and some 70m of water I did a life check and found 02 fine Diluient totaly empty. So it was dill leaking not 02 and it took the time it takes to find the valve by my arse and do two turns before the dill was empty. Sobering stuff Fortunatly i had off board bailout plumbed in to a second inject button on the inspo so the 2.5 hours deco and ascent was not an issue. ATB Mark __________________ Is it supposed to make that noise ? I took my unit to the dive shop and demanded they bolt on every thing that would fit. Join my elite diving teem and get a Tshirt "Doing It Chasey"Hammerhead Eccr Advanced Diving System
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25th May 2008, 12:03	#47 (permalink)
rogeringebo Custom Title Allowed! Current Rebreather/s: Pelagian Other Rebreather/s: Megalodon Classic Kiss Pelagian Join Date: Sep 2005 Location: Stockholm Sweden Posts: 700	Re: Which rebreather has best trim Im with Mike here..... When you reach the level where most people start looking in to CCR you would at least have done Advanced nitrox or simular. Quite often trimix level. (then you will start understanding the real costs of OC Trimix) At this level your instructors must have had you doing hundreds of shutdown drills and you should have developed the right motor skills. Why change that just because you get in to CCR? The benefits are non existing. It will put weight in the wrong place, you are stuck with one size tanks (unless you like the valves at your knees or have the Petrona towers of Kuala Lumpur over shadowing you.) I have tried that so I know When I dive, my hands are a lot closer to my shoulders then my ass so there would be no time won there. If you find it hard to reach the valves the back plate should be altered, the dry suit be bigger or what ever it takes. Some one must have showed you that during the OC days... If thousands of OC teckies can do it so can we, right? A rapid loss of gas is a nightmare for all divers but to shut down valves on CCR does not take longer as they are the same valves. When it comes to the importance of proper trim Im with the GUE boys (but just not as anal) If you have any plans of doing wreck penetrations, cave diving or even dive in hard currents it will suit you well to have a good trim. I have many OC diving friends that teach technical diving and I can see their scepticism when they hear the words trim and CCR in the same sentence. I guess they have been on to many dive boats over the years... If you guys are happy with your rig and your trim, stick with it.... If you are not.... try something new I used to strap weights to my webbing or back plate, wear a lead hat, sport a 15 pound nose piercing, or wear my weight belt around my neck but no more Best regards Rodge
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25th May 2008, 12:46	#48 (permalink)
jkaterenchuk . Current Rebreather/s: Inspiration Classic Megalodon Classic Kiss Other Rebreather/s: Join Date: May 2006 Location: Lititz, PA Posts: 827	Re: Which rebreather has best trim Quote: (Originally Posted by rogeringebo) Im with Mike here..... When you reach the level where most people start looking in to CCR you would at least have done Advanced nitrox or simular. Quite often trimix level. (then you will start understanding the real costs of OC Trimix) At this level your instructors must have had you doing hundreds of shutdown drills and you should have developed the right motor skills. Why change that just because you get in to CCR? Rodge Your forgeting about those of us that were enlightened enough to move directly to CCR and bypass doubles. John
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25th May 2008, 13:16	#49 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Home Build Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Home Build Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,001	Re: Which rebreather has best trim Quote: (Originally Posted by rogeringebo) If you find it hard to reach the valves the back plate should be altered, the dry suit be bigger or what ever it takes. Some one must have showed you that during the OC days... If thousands of OC teckies can do it so can we, right? A rapid loss of gas is a nightmare for all divers but to shut down valves on CCR does not take longer as they are the same valves. Best regards Rodge Hey rodge, Fisrt it depends on the valves... I for one avoid thermo style valves whenever possible especially on the o2 side as these are WAY to fast to open/close.. I want a valve thats at lest 4 or 5 FULL turns to close, not the less than 2 for a thermo an many other manifold valves which have evolved to less turns to shut off.. More turns = a finer thread = slower pressurizing when opening.. Rapid loss fo an OC diver is tens of seconds, for a Rebreather diver its seconds... Regardless of which way an individual chooses to rig the valves, shutdown drills should be regularly practiced.. Certain RBs will allow placement in the valve up thats reachable but alot of them the ideal placemeny of the tanks is lower than one would easily reach.. depending on the size of doubles one need, alot of time people need the trick to reach behind and push up the cylinders, so they can shut off one side at a time, or preferrably shut the isolator down first.. with very small tanks you really want both off immediately.. If I take 15 seconds to isolate and shut down a set of twins thats fine.. I'll still have alot of gas left, 15 seconds on a CCR and I'm F*ed.. In warm water with thin undrgarments or a wet suit I can usually get my arm back far enough to use the valve to lift the tanks higher, so I can shut 1 valve an the isolator at the same time, but I still have 1 cylinder dumping.. When I'm in very heavy undergarments, I definately need to reach behind my ass to prop up the tanks... I also prefer to have the bottom of the Rebreather as close to my ass as possible to prevent as much back pain as possible.. I find that if I'm diving a short RB and its up high, I have a sore back afterwards.. If I was diving something like a meg with a small can, it would probably be easier for me to rig the RB up high and invert the tanks (valve side up), but I'd get a back ache, if I put it at a compromise position my back would feel better but it would slow down valve access low and would probably be impossible to reach if they were valve side up.. Same with a sport Kiss, where it breaths the best (up high), my back hurts, down low breathing sucks.. The sport is almost long enough where the compromise position is actually acceptable.. With my body size just dropping my arms to the sides puts my hands very close to the valves.. reaching them is effortless.. on something like a rEvo, its easier than reaching the manual adds which becomes a second nature thing... If you have a very short body with a big Rebreather low valves might be an issue.. but a majority of the RBs out there, the bottom of the RB (and the vales) end up about ass height.. the normal body proportions put someones hand when at their side around this position as well.. If my RB was higher on my back then it would end up probably being close to that of putting valves up on top.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI** Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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27th May 2008, 08:57	#50 (permalink)
Anders Thulin New Member Current Rebreather/s: Pelagian Other Rebreather/s: Pelagian Join Date: Nov 2007 Location: Stockholm, Sweden Posts: 8	Re: Which rebreather has best trim Roger, if you ad a drysuit to your Rebreather? (already ordered a Pelagian :P)
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