Excessive counterlung volume on my MEG

depth · 16th July 2007, 15:50

Hi

Today i recieved pictures from pattimegdiver in a PM. The pictures illustrate how ISC can modify your CL's to reduce the standard volume.

I have sent my CL to Leon today for the same modification, I look forward seeing the result. I will post more pictures in higher resultion when i recieve the finished CL's in a couple of weeks...

Safe diving

Christian

Explorer · 16th July 2007, 17:04

Quote: (Originally Posted by pattimegdiver)

My CL's seemed huge also, but after having ISC sew the inside seam down it was less noticable. It gives a streamline look for the front and it gives optimal volume for me. It is another option, plus I am to rough on things to have neoprene CL's
Safe diving

Patti,

How much of your CL was sewn along the bottom (can't really tell from your photos)?

Also the pictures show the sewing just above the ADV. Do you have any issues with your ADV?

Jeff

pattimegdiver · 16th July 2007, 18:06

The photo on the right show the approx start point and it is stitched all the way to the bottom of the CL. Seams only run on sides of the CL's. No top or bottom seams.
Absolutely no problem with any possible interference with the ADV.

Quote: (Originally Posted by Explorer)

Patti,

How much of your CL was sewn along the bottom (can't really tell from your photos)?

Also the pictures show the sewing just above the ADV. Do you have any issues with your ADV?

Jeff

DanDunfee · 16th July 2007, 18:35

Christian

I'm really quite surprised at, what I interpreted as, the 4.8 l that you quoted above as your personal lung tidal volume (TV)... particularly for your about-average size. Knowing a good, representative personal TV is quite important for many kinds of volume ( CLs, BCs and RMVs) , and gas-consumption calculations. I'd encourage you to recheck the value you quoted.

For my own frame (5 ft 8 in, and 205 lbs), my TV is ~ 2.2 l. There's a large body of USN data, on seasoned divers, that shows an average TV of ~ 2.1 l, with a very low percentage going over 3.0 l. This leads me to question your number.

depth · 16th July 2007, 19:31

Hi Dan

Ok, my bad, I should be more specific. The 4.8l. is my Forced Vital Capacity (FVC). FVC is defined as: "The amount of air that can be forced out of the lungs after a maximal respiration". I know that the amount of air exchanged in the lungs during normal breath is much smaller.

I should have checked the terminology before posting my question, sorry!

This is also the reason why i postet the question, I do not have much knowledge on this specific topic :-)

Quote: (Originally Posted by DanDunfee)

Christian

I'm really quite surprised at, what I interpreted as, the 4.8 l that you quoted above as your personal lung tidal volume (TV)... particularly for your about-average size. Knowing a good, representative personal TV is quite important for many kinds of volume ( CLs, BCs and RMVs) , and gas-consumption calculations. I'd encourage you to recheck the value you quoted.

For my own frame (5 ft 8 in, and 205 lbs), my TV is ~ 2.2 l. There's a large body of USN data, on seasoned divers, that shows an average TV of ~ 2.1 l, with a very low percentage going over 3.0 l. This leads me to question your number.

DanDunfee · 16th July 2007, 20:45

I think that you'll find that knowing a good, representative TV for yourself is a much more useful number than FVC for most of the calculations you'll make.

I, for one, believe that too many RBs have too large total CL volumes. This occurs for various reasons, including some modern, commercial, manufacturers designing it that way to minimize WOB, to squeak by the CE certification requirements or for marketing purposes. .

I believe that excessive CL volumes have certain penalties, including:
* Carrying excessive weight to offset the excessive buoyancy
* Greater absolute CL volume changes with depth changes, and more gas used
or dumped adjusting for the volume and buoyancy changes. .
* More trim problems in some cases.

Most, more modern, combat UBA systems use total CL free volumes in the 5-8 l range whether they use Back-mounted, OTS, or Chest-Pack CLs. . I've recently designed a single, chest-pack CL for a personal rig, which is a heavily modded RG-UF/M, and is intended to have a CL free volume of ~ 6 l.

depth · 24th July 2007, 21:15

Hi

Ass promised, here are the pictures of the modified CL’s. All images are from the right side CL. The CL inseam is only sewn in on one side.
I have not yet dived with the modified lungs, but next week I will accumulate approximately 10 hours in the Norwegian seas and I will post my feedback subsequently.

Safe diving

Christian

Chris · 25th July 2007, 06:07

Ahh what a neat trick
So really anyone with a sewing machine can do the job, its just stitching the two seams together down the inside of the lung.

Cheers
Chriso

decoweenie · 25th July 2007, 06:13

Some thoughts...

Does the nylon CL have inner plastic CL bladder like the Inspiration, or is it a single layer ?

If inner plastic CL is inside, you could also punch holes and zip ties the side to get the exact expansion size you want. I do this on the BMCL system...

If single layer, you could also glue instead of sew and save on shipping to ISC.

Phil · 25th July 2007, 07:11

Christian,

Thanks for the pictures from what I can see they removed the inner side velcro straps and only kept the bottom one. Is this correct?

I'll wait for your diving report before I get my sewing machine running

Cheers,

16th July 2007, 17:04	#12 (permalink)
Explorer Be vewy vewy quiet.... Current Rebreather/s: Evolution Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Alberta, Canada Posts: 749	Re: Excessive counterlung volume on my MEG Quote: (Originally Posted by pattimegdiver) My CL's seemed huge also, but after having ISC sew the inside seam down it was less noticable. It gives a streamline look for the front and it gives optimal volume for me. It is another option, plus I am to rough on things to have neoprene CL's Safe diving Patti, How much of your CL was sewn along the bottom (can't really tell from your photos)? Also the pictures show the sewing just above the ADV. Do you have any issues with your ADV? Jeff __________________ TRAIN WRECKED.....
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16th July 2007, 18:06	#13 (permalink)
pattimegdiver #1 COPIS Mini Meg Girl Current Rebreather/s: Megalodon Sport Kiss Other Rebreather/s: Join Date: Nov 2005 Location: Portland Oregon Posts: 305	Re: Excessive counterlung volume on my MEG The photo on the right show the approx start point and it is stitched all the way to the bottom of the CL. Seams only run on sides of the CL's. No top or bottom seams. Absolutely no problem with any possible interference with the ADV. Quote: (Originally Posted by Explorer) Patti, How much of your CL was sewn along the bottom (can't really tell from your photos)? Also the pictures show the sewing just above the ADV. Do you have any issues with your ADV? Jeff __________________ Patti Meg Diver Remember that great love and great achievements involve great risk Last edited by pattimegdiver : 16th July 2007 at 18:15.
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16th July 2007, 18:35	#14 (permalink)
DanDunfee Custom Title Allowed! Current Rebreather/s: Other CCR Other SCR Home Build Other Rebreather/s: Not Bought Yet Other CCR Other SCR Home Build Join Date: Sep 2005 Location: Virginia, USA Posts: 204	Re: Excessive counterlung volume on my MEG Christian I'm really quite surprised at, what I interpreted as, the 4.8 l that you quoted above as your personal lung tidal volume (TV)... particularly for your about-average size. Knowing a good, representative personal TV is quite important for many kinds of volume ( CLs, BCs and RMVs) , and gas-consumption calculations. I'd encourage you to recheck the value you quoted. For my own frame (5 ft 8 in, and 205 lbs), my TV is ~ 2.2 l. There's a large body of USN data, on seasoned divers, that shows an average TV of ~ 2.1 l, with a very low percentage going over 3.0 l. This leads me to question your number. __________________ There are 'Bold' divers and old divers, but NO old, ' Bold ' divers
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16th July 2007, 19:31	#15 (permalink)
depth Custom Title Allowed! Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Aug 2006 Location: Denmark Posts: 143	Re: Excessive counterlung volume on my MEG Hi Dan Ok, my bad, I should be more specific. The 4.8l. is my Forced Vital Capacity (FVC). FVC is defined as: "The amount of air that can be forced out of the lungs after a maximal respiration". I know that the amount of air exchanged in the lungs during normal breath is much smaller. I should have checked the terminology before posting my question, sorry! This is also the reason why i postet the question, I do not have much knowledge on this specific topic :-) Quote: (Originally Posted by DanDunfee) Christian I'm really quite surprised at, what I interpreted as, the 4.8 l that you quoted above as your personal lung tidal volume (TV)... particularly for your about-average size. Knowing a good, representative personal TV is quite important for many kinds of volume ( CLs, BCs and RMVs) , and gas-consumption calculations. I'd encourage you to recheck the value you quoted. For my own frame (5 ft 8 in, and 205 lbs), my TV is ~ 2.2 l. There's a large body of USN data, on seasoned divers, that shows an average TV of ~ 2.1 l, with a very low percentage going over 3.0 l. This leads me to question your number. __________________ I am not qualified to make my own meg batteries!!! I am not qualified to make my own meg batteries!!! I am not qualified to make my own meg batteries!!! I am not qualified to make my own meg batteries!!! I am not.............
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16th July 2007, 20:45	#16 (permalink)
DanDunfee Custom Title Allowed! Current Rebreather/s: Other CCR Other SCR Home Build Other Rebreather/s: Not Bought Yet Other CCR Other SCR Home Build Join Date: Sep 2005 Location: Virginia, USA Posts: 204	Re: Excessive counterlung volume on my MEG I think that you'll find that knowing a good, representative TV for yourself is a much more useful number than FVC for most of the calculations you'll make. I, for one, believe that too many RBs have too large total CL volumes. This occurs for various reasons, including some modern, commercial, manufacturers designing it that way to minimize WOB, to squeak by the CE certification requirements or for marketing purposes. . I believe that excessive CL volumes have certain penalties, including: * Carrying excessive weight to offset the excessive buoyancy * Greater absolute CL volume changes with depth changes, and more gas used or dumped adjusting for the volume and buoyancy changes. . * More trim problems in some cases. Most, more modern, combat UBA systems use total CL free volumes in the 5-8 l range whether they use Back-mounted, OTS, or Chest-Pack CLs. . I've recently designed a single, chest-pack CL for a personal rig, which is a heavily modded RG-UF/M, and is intended to have a CL free volume of ~ 6 l. __________________ There are 'Bold' divers and old divers, but NO old, ' Bold ' divers Last edited by DanDunfee : 16th July 2007 at 21:07.
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25th July 2007, 06:07	#18 (permalink)
Chris Go Nude Or Go Home Current Rebreather/s: Megalodon Other Rebreather/s: Inspiration Classic Megalodon Prism Topaz Sport Kiss Join Date: Feb 2005 Location: Perth, Western Australia Posts: 601	Re: Excessive counterlung volume on my MEG Ahh what a neat trick So really anyone with a sewing machine can do the job, its just stitching the two seams together down the inside of the lung. Cheers Chriso __________________ Megalodon Sorb and Sensors whilst in Australia www.divetub.com.au Diving & Photography @ www.uwphotog.com
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25th July 2007, 06:13	#19 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,510	Re: Excessive counterlung volume on my MEG Some thoughts... Does the nylon CL have inner plastic CL bladder like the Inspiration, or is it a single layer ? If inner plastic CL is inside, you could also punch holes and zip ties the side to get the exact expansion size you want. I do this on the BMCL system... If single layer, you could also glue instead of sew and save on shipping to ISC. __________________ "...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..." - Rebreather World PM
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25th July 2007, 07:11	#20 (permalink)
Phil Custom Title Allowed! Current Rebreather/s: Megalodon Ouroboros rEvo Other CCR Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Megalodon rEvo Other CCR Join Date: May 2005 Location: Geneva-Switzerland Posts: 169	Re: Excessive counterlung volume on my MEG Christian, Thanks for the pictures from what I can see they removed the inner side velcro straps and only kept the bottom one. Is this correct? I'll wait for your diving report before I get my sewing machine running Cheers, __________________ Phil __________________ CCR/OC Instructor CCR Training to Mixed Gas in Switzerland, France, UK & Germany on Megalodon/KISS/Ouroboros/rEvo/Inspiration/Evolution/Sentinel www.zerogravitydiving.com
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