Feedback on recent two-tank and dive limits

[SuitableSkies]

Oh that's interesting. I wonder what they do. Maybe choose a safety stop duration so that some bubble safety metric falls below a threshold.

I suppose, with the buhlmann computer, we can just monitor surfGF and use it to inform any safety stop we might want to do.

 

[Blackcrusader]

Agreed, there is no reason to be running GF as a recreational diver. Go with preset conservatism and take a nitrox course and keep it simple.

Nonsense. Do you believe that recreational divers cannot learn or understand GF, GF99? and Surf GF?
So which nitrox course should one take? TDI ANDP?

 

[boulderjohn]

Although it is possible to ascend too slowly and thus violate NDLs, in reality, if you start and ascent within NDLs and make a continuous ascent, you would have to be pretty darn slow to cause a problem. That is why multi-level dives are possible.

When I was researching for my goal of writing on article on different NDL ascent strategies, I learned that there does not seem to be any good research showing an optimal ascent strategy. I learned that when PADI did the research that created the RDP, 60 FPM was the standard ascent rate. They did use that in their research, but they also found that going slower wasn't a problem. That is why they developed the wording "no faster than 60 FPM." So as far as the research is concerned, 60 FPM, which no one today recommends, has still been proven to be safe. RGBM will penalize you for it, though.

 

[Blackcrusader]

Why? If we are talking about computers running Buhlmann, which I believe we are (because I'm not aware of any other algorithms using GFs), then these sentences are incompatible with each other.

Perhaps you omitted the word custom from that first sentence. Computers running Buhlmann ZHL-16C may have preset conservatism levels, but they do those via GFs.

Exactly on the Peregrine divers choose a setting for conservatism and it will also show the equivalent GF setting.

 

[Blackcrusader]

Correct, recreational divers should not be customizing their GF's.

Nonsense. I am a recreational diver and choose what GF's to run on my Perdix. I also run my Perdix in Tec Mode not Rec mode as I want to be able to setup the display to what I want.

However I still have my other dive computers I can calculate on the fly with my BSAC tables from 1986.
I didn't get the 1988 BSac tables lol First one is the recreational and the second one is the technical version.

 

[Blackcrusader]

Although it is possible to ascend too slowly and thus violate NDLs, in reality, if you start and ascent within NDLs and make a continuous ascent, you would have to be pretty darn slow to cause a problem. That is why multi-level dives are possible.

I've done this but you really need to get to 1 or 0 NDL and ascend really slowly and usually only from deeper than 20m. I did deep deco dives in the Maldives, cleared the deco obligation by coming shallower then as NDL returned continued on with the multilevel dives.

 

[matt9122]

Nonsense. I am a recreational diver and choose what GF's to run on my Perdix. I also run my Perdix in Tec Mode not Rec mode as I want to be able to setup the display to what I want.

However I still have my other dive computers I can calculate on the fly with my BSAC tables from 1986.
I didn't get the 1988 BSac tables lol First one is the recreational and the second one is the technical version.

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So what's the point? If you're not doing any decompression, why do you feel the need to adjust to a custom profile? Just to extend bottom time, or to be more conservative? Because if you're just trying to adjust for maximum bottom time, this is where I might have a problem. You should read my previous post. If you want to educate yourself properly and make decisions for yourself, feel free. But in general, there is no reason for a recreational diver to adjust their profile to benefit their bottom time. Now you're taking the long-term profile that divers have been using, going into deco based on what is recommended, and ignoring the deco. But its OK, because you made your computer say that it's OK. If you want to do so, feel free, but it's not a good practice in general. I know too many friends who have taken serious decompression hits, many undeserved. I'd just keep recommending that recreational divers follow the safety standards that seem to be working just fine.

 

[scubadada]

I have posted this several times. I generally do no stop dives but about 5% of my dives are light deco, generally less than 10 minutes, always less than 15 minutes. I dive 2 computers, a Shearwater Teric running 80/95 and an Oceanic VT3 running DSAT. I have several posts comparing a GF high of 95 vs. DSAT. For light deco, these two algorithms run very similarly. I have never had a decompression ceiling below 10 feet. When doing no stop dives, I dive the more conservative of the 2 computers. For light deco, I clear one or both computers. I also use Surf GF. For no stop dives near the NDL and for light deco dives, I surface with a GF generally no higher than about 80. I've done well for over 2,500 dives; I plan to do so for as long as I can dive.

 

[Blackcrusader]

So what's the point? If you're not doing any decompression, why do you feel the need to adjust to a custom profile? Just to extend bottom time, or to be more conservative? Because if you're just trying to adjust for maximum bottom time, this is where I might have a problem. You should read my previous post. If you want to educate yourself properly and make decisions for yourself, feel free. But in general, there is no reason for a recreational diver to adjust their profile to benefit their bottom time. Now you're taking the long-term profile that divers have been using, going into deco based on what is recommended, and ignoring the deco. But its OK, because you made your computer say that it's OK. If you want to do so, feel free, but it's not a good practice in general. I know too many friends who have taken serious decompression hits, many undeserved. I'd just keep recommending that recreational divers follow the safety standards that seem to be working just fine.

Deco dives are part of recreational diving. Have been for decades with CMAS and BSAC. I do follow my training and safety standards and in near 40 years of diving have not had any incidents or DCS hits.

Why do you have a problem if I use a higher GF setting to have longer NDL times? The GF settings do not exceed dive table times do they? DSAT tables give a longer NDL than GF95. oh dear I should change my GF to 100 and extend my NDL times.

 

[scubadada]

Deco dives are part of recreational diving. Have been for decades with CMAS and BSAC. I do follow my training and safety standards and in near 40 years of diving have not had any incidents or DCS hits.

Why do you have a problem if I use a higher GF setting to have longer NDL times. The GF settings do not exceed dive table times do they? DSAT tables give a longer NDL than GF95

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I have posted many times. a GF high of 95 often has a longer NDL than DSAT on repetitive dives, especially when shallower.