Re: Fwd: Two more rebreather patches
On Tue, Nov 04, 2014 at 10:01:05AM +0100, Robert Helling wrote: I think these two patches have not yet been applied. Sorry about that. I like the first one, the second one is marginal but it should have no negative impact, so I took it. It didn't apply but was easy to fix. Still, please double check. /D ___ subsurface mailing list subsurface@subsurface-divelog.org http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
Re: Two more rebreather patches
[2014-10-27 15:52:59 -0700] Dirk Hohndel: On Mon, Oct 27, 2014 at 08:14:44PM +0100, Anton Lundin wrote: On 27 October, 2014 - Gaetan Bisson wrote: [2014-10-24 16:48:34 +0200] Robert Helling: what happened to Gaetan’s attempts at coming up with a UI implementation? I wanted to do something basic and Anton convinced me that would be a shame and something much better should be done instead. Since GUIs are the complete opposite to my area of expertise, I just stopped thinking about this. Something is always better then nothing. Give it a try! +1 -- if we have something then we can talk about what should be differently and make that happen. If we have nothing it's really hard for the UI experts to start working. Thanks for the motivation; I'll give this a go when I find the time, which probably won't be before a couple of weeks, but I'll get there eventually. Cheers. -- Gaetan ___ subsurface mailing list subsurface@subsurface-divelog.org http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
Re: Two more rebreather patches
On 27 Oct 2014, at 17:56, Rodrigo Severo rodr...@fabricadeideias.com wrote: For example: A one hour dive should be 20bar (60 litres) out of a standard 3 litre cylinder - just calculating 1 litre a minute. That's just way off. I always use about ~50 bar on a ~40 metre dive, so I tend to make sure I've got at least 100 bar when I jump in. (or have a missed a different method of calculating things in the various mails?) The method of calculation is just that but, as I see things, it would happen the other way around: After this dive Subsurface would show you that your oxygen SAC is 2,5 l/min (50 bar of a 3 l cylinder used on an hour dive). So on your next planning you should use 2,5 l/min for oxygen and not the usual 1 l/min. The problem here is that going from a one hour to a two hour dive doesn’t double my O2 use. I might go from 50 bar to 70 bar (i.e. Same use for the ascent aspects, another 20 bar for the extra hour). To me it sounds to me like we’d need a SAC component (litres/min) and an ascent component (litres/metre.bar). Diluent would just have a descent component (litres/metre.bar). In the example above reasonable figure might be: - O2 SAC: 1 litre/min - O2 Ascent: 30bar * 3l = 90l 90l / 40 metres = 2.25 litres/metre 2.25l / 2.5 bar (Avg. Pressure during ascent) = 0.9l / metre.bar - Diluent Descent: 50bar * 3l = 150l 150l / 40 metres = 3.75l / metre 3.75l / 2.5 bar (Avg. Pressure during descent) = 1.5l / metre.bar Paul signature.asc Description: Message signed with OpenPGP using GPGMail ___ subsurface mailing list subsurface@subsurface-divelog.org http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
Re: Two more rebreather patches
On Tue, Oct 28, 2014 at 9:36 AM, Paul Sargent paul.lions...@icloud.com wrote: On 27 Oct 2014, at 17:56, Rodrigo Severo rodr...@fabricadeideias.com wrote: For example: A one hour dive should be 20bar (60 litres) out of a standard 3 litre cylinder - just calculating 1 litre a minute. That's just way off. I always use about ~50 bar on a ~40 metre dive, so I tend to make sure I've got at least 100 bar when I jump in. (or have a missed a different method of calculating things in the various mails?) The method of calculation is just that but, as I see things, it would happen the other way around: After this dive Subsurface would show you that your oxygen SAC is 2,5 l/min (50 bar of a 3 l cylinder used on an hour dive). So on your next planning you should use 2,5 l/min for oxygen and not the usual 1 l/min. The problem here is that going from a one hour to a two hour dive doesn’t double my O2 use. I might go from 50 bar to 70 bar (i.e. Same use for the ascent aspects, another 20 bar for the extra hour). To me it sounds to me like we’d need a SAC component (litres/min) and an ascent component (litres/metre.bar). Diluent would just have a descent component (litres/metre.bar). In the example above reasonable figure might be: - O2 SAC: 1 litre/min - O2 Ascent: 30bar * 3l = 90l 90l / 40 metres = 2.25 litres/metre 2.25l / 2.5 bar (Avg. Pressure during ascent) = 0.9l / metre.bar I don't understand way the ascent component has a bar in it (and why you divided the average consumption per meter by the average pressure). Shouldn't the ascent component just be 2.25 litres/metre here? - Diluent Descent: 50bar * 3l = 150l 150l / 40 metres = 3.75l / metre 3.75l / 2.5 bar (Avg. Pressure during descent) = 1.5l / metre.bar Here again I don't understand why getting a litre/metre*bar. Why not jsut litre/metre? Rodrigo ___ subsurface mailing list subsurface@subsurface-divelog.org http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
Re: Two more rebreather patches
On Mon, Oct 27, 2014 at 12:37 PM, William Perry wmpe...@kadath.us wrote: I just finished by CCR training down in Bonaire last week so I don’t have a lot of experience, but I did find that minor depth changes did not impact the loop volume enough for me to feel the need to add diluent. My inhale was cut very slightly short (I was diving with the auto-diluent-valve off after the initial big descent). This would be equivalent to the occasional mask clear at depth. If you are doing a ton of 10 meter ascents/descents in a cave system as it winds around then those will add up quickly, but 1-2 footers is noise. Bill, I agree: 1/2 foot is noise, 10 m is significant. What value do you think we should use as limit? I just proposed 1 m on my previous email to Robert but I'm not sure if this value is big enough. What do you think? Would tracking only the size of the counter lungs be sufficient? I don't think any of this is necessary, neither counter lungs volume nor loop volume as I mentioned on my previous email. Regards, Rodrigo ___ subsurface mailing list subsurface@subsurface-divelog.org http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
Re: Two more rebreather patches
On Oct 27, 2014, at 10:42 AM, Rodrigo Severo rodr...@fabricadeideias.com wrote: On Mon, Oct 27, 2014 at 12:37 PM, William Perry wmpe...@kadath.us wrote: I just finished by CCR training down in Bonaire last week so I don’t have a lot of experience, but I did find that minor depth changes did not impact the loop volume enough for me to feel the need to add diluent. My inhale was cut very slightly short (I was diving with the auto-diluent-valve off after the initial big descent). This would be equivalent to the occasional mask clear at depth. If you are doing a ton of 10 meter ascents/descents in a cave system as it winds around then those will add up quickly, but 1-2 footers is noise. Bill, I agree: 1/2 foot is noise, 10 m is significant. What value do you think we should use as limit? I just proposed 1 m on my previous email to Robert but I'm not sure if this value is big enough. What do you think? Maybe start tracking it if they stay at the new depth for more than a certain # of samples? If I just drop down quickly to look at something I’m not going to mind a short breath or two but if I am following the contour of the reef and stay at that depth for 5-10 minutes I will probably squirt in some diluent. I’m generally not a fan of heuristics like that though. Would tracking only the size of the counter lungs be sufficient? I don't think any of this is necessary, neither counter lungs volume nor loop volume as I mentioned on my previous email. Yes, if we are just worrying about determining a SAC rate after the fact. Would some indication of loop volume help for planning these dives though? -bill ___ subsurface mailing list subsurface@subsurface-divelog.org http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
Re: Two more rebreather patches
On Oct 27, 2014, at 03:42 PM, Rodrigo Severo rodr...@fabricadeideias.com wrote: Bill, I agree: 1/2 foot is noise, 10 m is significant. What value do you think we should use as limit? I just proposed 1 m on my previous email to Robert but I'm not sure if this value is big enough. What do you think? It'd be interesting to put some code together, run it on real dive data and see how the predicted number compared with the measured one. Until you do I think it'd be difficult to know where the noise filter level needs to be set. Would tracking only the size of the counter lungs be sufficient? I don't think any of this is necessary, neither counter lungs volume nor loop volume as I mentioned on my previous email. Without knowing has much gas is in the loop (note: not counter lung size, which is part of the maximum loop volume) you can't know how much diluent to add to maintain it*. Example: 5l of gas in the loop. Decend from surface to 10m (2bar). I need to double the mass of gas in the loop to maintain volume, hence I need to add 5l (surface equivalent mass**). Counter lung (maximum) volume is irrelevent, because divers try not to run maximum volume. In fact they try to run minimum volume (i.e. 1 human lung full) because doing so uses less gas and is easier to control (buoyancy). You probably need to work out an average of what this diver tends to do (like SAC) and use that in predictions. Paul * Similarly, You can't know how much O2 to add to raise the ppO2 by some amount without knowing how much gas is in the loop. Hence ascents are tricky too ** Terminology when talking about amounts of gas under pressure is hard. Really we should talk about masses of gas, but we don't. ___ subsurface mailing list subsurface@subsurface-divelog.org http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
Re: Two more rebreather patches
On Mon, Oct 27, 2014 at 11:29:47AM -0400, William Perry wrote: I just finished by CCR training down in Bonaire last week so I don’t have a lot of experience, but I did find that minor depth changes did not impact the loop volume enough for me to feel the need to add diluent. My inhale was cut very slightly short (I was diving with the auto-diluent-valve off after the initial big descent). This would be equivalent to the occasional mask clear at depth. If you are doing a ton of 10 meter ascents/descents in a cave system as it winds around then those will add up quickly, but 1-2 footers is noise. I agree: 1/2 foot is noise, 10 m is significant. What value do you think we should use as limit? I just proposed 1 m on my previous email to Robert but I'm not sure if this value is big enough. What do you think? Maybe start tracking it if they stay at the new depth for more than a certain # of samples? If I just drop down quickly to look at something I’m not going to mind a short breath or two but if I am following the contour of the reef and stay at that depth for 5-10 minutes I will probably squirt in some diluent. I’m generally not a fan of heuristics like that though. With the benefit of absolutely know subject matter expertize, I think what would make sense is to smooth out the depth graph. Something like a gliding average across one minute - that should remove jitter and the quick pop down to look at things that you describe, at the same time it should be reasonably close to what I would call the perceived depth during a dive - and I think that's what people will tend to base their change to the counter lung content on... Again, just running my mouth (errr, fingers) and making things up here :-) /D ___ subsurface mailing list subsurface@subsurface-divelog.org http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
Re: Two more rebreather patches
On Mon, Oct 27, 2014 at 2:10 PM, Dirk Hohndel d...@hohndel.org wrote: With the benefit of absolutely know subject matter expertize, I think what would make sense is to smooth out the depth graph. Something like a gliding average across one minute - that should remove jitter and the quick pop down to look at things that you describe, at the same time it should be reasonably close to what I would call the perceived depth during a dive - and I think that's what people will tend to base their change to the counter lung content on... I believe this gliding average could be a really good solution for this issue. Could it be used for anything else or would it be used just for SAC calculation of diluent on CCR dives? Rodrigo ___ subsurface mailing list subsurface@subsurface-divelog.org http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
Re: Two more rebreather patches
On Mon, Oct 27, 2014 at 08:14:44PM +0100, Anton Lundin wrote: On 27 October, 2014 - Gaetan Bisson wrote: [2014-10-24 16:48:34 +0200] Robert Helling: what happened to Gaetan’s attempts at coming up with a UI implementation? I wanted to do something basic and Anton convinced me that would be a shame and something much better should be done instead. Since GUIs are the complete opposite to my area of expertise, I just stopped thinking about this. Something is always better then nothing. Give it a try! +1 -- if we have something then we can talk about what should be differently and make that happen. If we have nothing it's really hard for the UI experts to start working. /D ___ subsurface mailing list subsurface@subsurface-divelog.org http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
