V-Planner and IBCD - BUG?

PCDiver · 9th August 2007, 08:36

Hi all,

I've been running some IBCD checks in V-planner and found some inconsistencies.

The threshold is set at 0.5 ATA for N2 spikes. The theorethical dive is 100 minutes at 30 meters with TX21/79. Bailout is air.

V-Planner gives the following profile without IBCD warning.

Dec to 30m (2) Diluent 21/79 0,70 SetPoint, 15m/min descent.
Level 30m 98:00 (100) Diluent 21/79 1,30 SetPoint, 0m ead, 3m end
Asc to 12m (102) Air -9m/min ascent.
Stop at 9m 7:00 (109) Air 0,40 ppO2, 9m ead
Stop at 6m 46:00 (155) Air 0,34 ppO2, 6m ead
Surface (155) Air -9m/min ascent.

Why is there no IBCD warning? The N2 spike is massive. What am I missing?

Thanks,

Peter

rossh · 9th August 2007, 12:11

Quote: (Originally Posted by PCDiver)

Hi all,

Why is there no IBCD warning? The N2 spike is massive. What am I missing?

Hi Peter,

Mix switches on the fly are not included in the warn test, simply because no deco time is spent there. And in real life dives, new mixes and switches are normally chosen to be used and carried out in stops.

Regards

PCDiver · 9th August 2007, 13:19

Quote: (Originally Posted by rossh)

Hi Peter,

Mix switches on the fly are not included in the warn test, simply because no deco time is spent there. And in real life dives, new mixes and switches are normally chosen to be used and carried out in stops.

Regards

Hi Ross,
Are you saying that when you bailout from CCR to OC, there is no check done on IBCD?

Peter

rossh · 9th August 2007, 13:50

Quote: (Originally Posted by PCDiver)

Hi Ross,
Are you saying that when you bailout from CCR to OC, there is no check done on IBCD?
Peter

Peter, I'll write again for you if you like ..." Mix switches on the fly are not included in the warn test, simply because no deco time is spent there". That probably includes your leap off the bottom when first starting your bail out.

If your on the fly swapping, then your also reducing depth and the ppN2/He in quick succession. That in itself can null out a lot of the big swing in pp's in short order. Hence a warning when on the move is not much value.

Your test above is a silly nonsense test... two mixes from the far ends of the map. You know those two mixes do not go together, and would not use them like that in a dive. In real life, your mixes will likely be far more complimentary to each other.

Regards

PCDiver · 9th August 2007, 14:12

Quote: (Originally Posted by rossh)

Peter, I'll write again for you if you like ..." Mix switches on the fly are not included in the warn test, simply because no deco time is spent there". That probably includes your leap off the bottom when first starting your bail out.

If your on the fly swapping, then your also reducing depth and the ppN2/He in quick succession. That in itself can null out a lot of the big swing in pp's in short order. Hence a warning when on the move is not much value.

Your test above is a silly nonsense test... two mixes from the far ends of the map. You know those two mixes do not go together, and would not use them like that in a dive. In real life, your mixes will likely be far more complimentary to each other.

Regards

What do you mean with "mix switch on the fly"?

Any way, there should be a warning that no IBCD check is done when you bailout from CCR to OC.

I know the example was not realistic. I justed wanted to see whether the program performed the check or not. And it doesn't.

rossh · 9th August 2007, 15:30

Quote: (Originally Posted by PCDiver)

What do you mean with "mix switch on the fly"?

Changes in mix at a depth where no deco stop was required. i.e. you making the mix swap whilst in the ascent.

PCDiver · 9th August 2007, 16:41

Ross,

can the check be added in future version? When you bailout from CCR you don't always go straight up. Sometimes you try to fix the problem on OC at max depth. Knowing that a gas could cause IBCD related problems might help.

Thanks,

Peter

**DeepBlueInnovation** · 11th July 2008, 02:22

I note that this still hasn't been addressed. As CCR divers we use decompression programs for a lot of "what if" analysis, especially bailout. As such I feel that the program should warn of a IBCD danger for "on the fly switches", otherwise known as bailout. As per the instructions on v-planner bailout from CCR is calculated by using OC decompression legs with a forced depth. When this is implemented to simulate bailout at the end of bottom time no IBCD warning is given where it should be. Users shouldn't have to second guess the software - it is listed as providing IBCD warning where a PN2 or PHe shift of greater than 0.5 bar exists and should do this for all switches.

rossh · 11th July 2008, 02:53

Hello,

IBCD would seem to be a risk to dives with a significant tissue loading. That would imply the dive has many long deco stops. A mix change that occurs where no stops are present in that region, implies that the tissue loading is not yet significant, or high enough to be limiting. Further the additional distance traveled after a mix swap on the fly, implies the general gas exchange has not yet reached a limiting value, implying a reduced IBCD risk too. That is why you will not see a warning for a mix swap in the ascent.

For a plan to swap to a bail mix, check the pp graph and consider the situation from that perspective.

Regards

Loanwolf · 11th July 2008, 17:10

Ross do you ever feel like your avatar? That is when you get questioned by folks who try to put too much logic into something that is not that difficult.

9th August 2007, 08:36	#1 (permalink)
PCDiver Submerge Productions Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: Belgium Posts: 934	V-Planner and IBCD - BUG? Hi all, I've been running some IBCD checks in V-planner and found some inconsistencies. The threshold is set at 0.5 ATA for N2 spikes. The theorethical dive is 100 minutes at 30 meters with TX21/79. Bailout is air. V-Planner gives the following profile without IBCD warning. Dec to 30m (2) Diluent 21/79 0,70 SetPoint, 15m/min descent. Level 30m 98:00 (100) Diluent 21/79 1,30 SetPoint, 0m ead, 3m end Asc to 12m (102) Air -9m/min ascent. Stop at 9m 7:00 (109) Air 0,40 ppO2, 9m ead Stop at 6m 46:00 (155) Air 0,34 ppO2, 6m ead Surface (155) Air -9m/min ascent. Why is there no IBCD warning? The N2 spike is massive. What am I missing? Thanks, Peter
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9th August 2007, 12:11	#2 (permalink)
rossh Custom Title Allowed! Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Jul 2005 Location: Canada Posts: 106	Re: V-Planner and IBCD - BUG? Quote: (Originally Posted by PCDiver) Hi all, Why is there no IBCD warning? The N2 spike is massive. What am I missing? Hi Peter, Mix switches on the fly are not included in the warn test, simply because no deco time is spent there. And in real life dives, new mixes and switches are normally chosen to be used and carried out in stops. Regards __________________ Regards, Ross Hemingway V-Planner VPM-B Nitrox Trimix CCR Deco planning for Technical Divers www.v-planner.com
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9th August 2007, 13:19	#3 (permalink)
PCDiver Submerge Productions Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: Belgium Posts: 934	Re: V-Planner and IBCD - BUG? Quote: (Originally Posted by rossh) Hi Peter, Mix switches on the fly are not included in the warn test, simply because no deco time is spent there. And in real life dives, new mixes and switches are normally chosen to be used and carried out in stops. Regards Hi Ross, Are you saying that when you bailout from CCR to OC, there is no check done on IBCD? Peter
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9th August 2007, 13:50	#4 (permalink)
rossh Custom Title Allowed! Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Jul 2005 Location: Canada Posts: 106	Re: V-Planner and IBCD - BUG? Quote: (Originally Posted by PCDiver) Hi Ross, Are you saying that when you bailout from CCR to OC, there is no check done on IBCD? Peter Peter, I'll write again for you if you like ..." Mix switches on the fly are not included in the warn test, simply because no deco time is spent there". That probably includes your leap off the bottom when first starting your bail out. If your on the fly swapping, then your also reducing depth and the ppN2/He in quick succession. That in itself can null out a lot of the big swing in pp's in short order. Hence a warning when on the move is not much value. Your test above is a silly nonsense test... two mixes from the far ends of the map. You know those two mixes do not go together, and would not use them like that in a dive. In real life, your mixes will likely be far more complimentary to each other. Regards __________________ Regards, Ross Hemingway V-Planner VPM-B Nitrox Trimix CCR Deco planning for Technical Divers www.v-planner.com
(Offline)

9th August 2007, 14:12	#5 (permalink)
PCDiver Submerge Productions Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: Belgium Posts: 934	Re: V-Planner and IBCD - BUG? Quote: (Originally Posted by rossh) Peter, I'll write again for you if you like ..." Mix switches on the fly are not included in the warn test, simply because no deco time is spent there". That probably includes your leap off the bottom when first starting your bail out. If your on the fly swapping, then your also reducing depth and the ppN2/He in quick succession. That in itself can null out a lot of the big swing in pp's in short order. Hence a warning when on the move is not much value. Your test above is a silly nonsense test... two mixes from the far ends of the map. You know those two mixes do not go together, and would not use them like that in a dive. In real life, your mixes will likely be far more complimentary to each other. Regards What do you mean with "mix switch on the fly"? Any way, there should be a warning that no IBCD check is done when you bailout from CCR to OC. I know the example was not realistic. I justed wanted to see whether the program performed the check or not. And it doesn't.
(Offline)

9th August 2007, 15:30	#6 (permalink)
rossh Custom Title Allowed! Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Jul 2005 Location: Canada Posts: 106	Re: V-Planner and IBCD - BUG? Quote: (Originally Posted by PCDiver) What do you mean with "mix switch on the fly"? Changes in mix at a depth where no deco stop was required. i.e. you making the mix swap whilst in the ascent. __________________ Regards, Ross Hemingway V-Planner VPM-B Nitrox Trimix CCR Deco planning for Technical Divers www.v-planner.com
(Offline)

9th August 2007, 16:41	#7 (permalink)
PCDiver Submerge Productions Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: Belgium Posts: 934	Re: V-Planner and IBCD - BUG? Ross, can the check be added in future version? When you bailout from CCR you don't always go straight up. Sometimes you try to fix the problem on OC at max depth. Knowing that a gas could cause IBCD related problems might help. Thanks, Peter
(Offline)

11th July 2008, 02:22	#8 (permalink)
DeepBlueInnovation Prism #007 Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Sep 2005 Location: Perth, Western Australia Posts: 351	Re: V-Planner and IBCD - BUG? I note that this still hasn't been addressed. As CCR divers we use decompression programs for a lot of "what if" analysis, especially bailout. As such I feel that the program should warn of a IBCD danger for "on the fly switches", otherwise known as bailout. As per the instructions on v-planner bailout from CCR is calculated by using OC decompression legs with a forced depth. When this is implemented to simulate bailout at the end of bottom time no IBCD warning is given where it should be. Users shouldn't have to second guess the software - it is listed as providing IBCD warning where a PN2 or PHe shift of greater than 0.5 bar exists and should do this for all switches.
(Online)

11th July 2008, 02:53	#9 (permalink)
rossh Custom Title Allowed! Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Jul 2005 Location: Canada Posts: 106	Re: V-Planner and IBCD Hello, IBCD would seem to be a risk to dives with a significant tissue loading. That would imply the dive has many long deco stops. A mix change that occurs where no stops are present in that region, implies that the tissue loading is not yet significant, or high enough to be limiting. Further the additional distance traveled after a mix swap on the fly, implies the general gas exchange has not yet reached a limiting value, implying a reduced IBCD risk too. That is why you will not see a warning for a mix swap in the ascent. For a plan to swap to a bail mix, check the pp graph and consider the situation from that perspective. Regards __________________ Regards, Ross Hemingway V-Planner VPM-B Nitrox Trimix CCR Deco planning for Technical Divers www.v-planner.com
(Offline)

11th July 2008, 17:10	#10 (permalink)
Loanwolf New Member Current Rebreather/s: rEvo Other Rebreather/s: Inspiration Classic Evolution Megalodon Classic Kiss MK 15.X Optima rEvo Join Date: Jan 2008 Location: Where I hang my hat at the moment. Posts: 36	Re: V-Planner and IBCD - BUG? Ross do you ever feel like your avatar? That is when you get questioned by folks who try to put too much logic into something that is not that difficult. __________________ Life is Short do as Much as You can in as Short of Period of Time as Possible.
(Offline)

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