Dziękuję, Panowie, za zorganizowanie tego niezwykle ciekawego wykładu. Nie mogłem oglądać go na żywo i żałuję, że nie udało mi się zadać pytania o potwierdzone empirycznie działanie okna tlenowego.
Hi All, I found this really interesting as I have been using GF 30/70 and am only a recreational diver but found myself going into deco on my last dive with this setting hence why I am researching this subject. My question is does this discussion really only apply to the technical diver as after watching this amongst other videos / blogs I'm feeling a GF of 50/50 would be best for the recreational diver. Your thoughts please ;-)
If you are not planning on going into deco the only gf high matters. Using 50/50 instead of 30/70 will give you far shorter ndl times. Whether that is good or bad is up to you.
@@Justins-Adventures Thanks for the info, I normally have 30/70 set but will watch this again to try and understand why its only the GF high that is the limiting factor if not planning to go into deco. As a recreational diver I would not be performing a deco dive any time soon 👌
@@darrenbrewer7587 Basically the reason why GF low doesn't matter is because gf low determines the depth of the deepest deco stop. Because we don't do any stops during NDL diving, only gf High (the surfacing percentage of supersaturation) matters to us.
@@darrenbrewer7587 You have to be in deco before GF low comes into play. GF Low determines while in deco how close you can get to the maximum over pressure amount (M value) you are allowed to get. If it is set to say 50/50 on deco you can ride that 50% GF line. But with 30/70, when you go into deco you can only get as close to the 30% to M value until you have a low enough gas loading to surface at the GF high percentage. As an example, here is a dive I am planning, my normal GF is 60/80. With that my first stop is at 40 feet with a total deco time of 37 minutes. If I change that to 80/80, my first stop is at 30 feet with a total deco time of 36 minutes. Now that is a pretty minor difference as it is only a small change on a short nitrox deco dive. But GF low can have a major affect on deep helium dives. Now I should say I am not suggesting anyone use either of those gradient factors, or to even change them without a through understanding of what you are doing.
With this presentation in mind I would really be interested in a study where the GF low is HIGHER (!) than the GF high which would mean making even more use of quick offgassing of fast compartments but keeping your conservatisma in the shallower stops... My divecomputer won't let me set this up. Is there a dive planner where you can set GFL higher than GFH?
You just gotta love Dr Mitchell. Always getting such amazing sessions from him.
Dziękuję, Panowie, za zorganizowanie tego niezwykle ciekawego wykładu. Nie mogłem oglądać go na żywo i żałuję, że nie udało mi się zadać pytania o potwierdzone empirycznie działanie okna tlenowego.
Thanks for the presentation on this subject. Excellent content and delivery of the data and visuals!
Very informative presentation, thank you!
Amazing, thank you for sharing!
Dr Simon, thank you. Question about the Navy test: was the non deep stop algorithm the published navy air tables?
Hi All, I found this really interesting as I have been using GF 30/70 and am only a recreational diver but found myself going into deco on my last dive with this setting hence why I am researching this subject.
My question is does this discussion really only apply to the technical diver as after watching this amongst other videos / blogs I'm feeling a GF of 50/50 would be best for the recreational diver. Your thoughts please ;-)
If you are not planning on going into deco the only gf high matters. Using 50/50 instead of 30/70 will give you far shorter ndl times. Whether that is good or bad is up to you.
@@Justins-Adventures Thanks for the info, I normally have 30/70 set but will watch this again to try and understand why its only the GF high that is the limiting factor if not planning to go into deco. As a recreational diver I would not be performing a deco dive any time soon 👌
@@darrenbrewer7587 Basically the reason why GF low doesn't matter is because gf low determines the depth of the deepest deco stop. Because we don't do any stops during NDL diving, only gf High (the surfacing percentage of supersaturation) matters to us.
@@darrenbrewer7587 You have to be in deco before GF low comes into play. GF Low determines while in deco how close you can get to the maximum over pressure amount (M value) you are allowed to get. If it is set to say 50/50 on deco you can ride that 50% GF line. But with 30/70, when you go into deco you can only get as close to the 30% to M value until you have a low enough gas loading to surface at the GF high percentage.
As an example, here is a dive I am planning, my normal GF is 60/80. With that my first stop is at 40 feet with a total deco time of 37 minutes. If I change that to 80/80, my first stop is at 30 feet with a total deco time of 36 minutes. Now that is a pretty minor difference as it is only a small change on a short nitrox deco dive. But GF low can have a major affect on deep helium dives. Now I should say I am not suggesting anyone use either of those gradient factors, or to even change them without a through understanding of what you are doing.
With this presentation in mind I would really be interested in a study where the GF low is HIGHER (!) than the GF high which would mean making even more use of quick offgassing of fast compartments but keeping your conservatisma in the shallower stops... My divecomputer won't let me set this up. Is there a dive planner where you can set GFL higher than GFH?
Dr. Simon Mitchell starts @ 3:57
Questions start at 1:38:38