New Shearwater Dive Modes.

[ReefHound]

But it isn't just TTS that is affected, all the Stop times will be completely wrong too. The blanket admonition is quite critical:

If you are not deco diving there are no stop times. I don't think the person with 36/32/21 and using it as convenient way to switch between the most popular rec options is going into deco.

 

[Tracy]

If you are not deco diving there are no stop times. I don't think the person with 36/32/21 and using it as convenient way to switch between the most popular rec options is going into deco.

also true. I use 3 gas mode for technical dives so I was answering based on that.

 

[Manatee Diver]

You will get nicely bent if it thinks you are carrying 100%, gives you a 5 minute stop, and instead you spend that 5 minutes on 21% and then get out.

Only if you don't wait for the computer to clear.

 

[KenE]

I believe the OC Rec provides safety stops and OC Tec does not. This was my dilemma when setting up the Perdix for recreational diving with a pony. I wanted some of the information that was not available in Rec mode but also wanted the safety stop. I decided the safety stop was not as important to me and I watch the timer after ascending past 20'. I am now curious if the new mode has both.

 

[Pavao]

If you are not deco diving there are no stop times. I don't think the person with 36/32/21 and using it as convenient way to switch between the most popular rec options is going into deco.

If you program 36/32/21 on the computer and have them turned on, the computer will calculate your NDL based on the fact you will use those 3 gasses on the dive.
But if you then do a dive to 130 ft and all you have with you is 21%, your actual NDL will be much shorter than what the computer would be telling you during the dive.

Heres an easier way to visualize it, which would have a longer NDL:
A dive to 90ft with 36%
A dive to 90ft with 21%

Having all 3 gasses on but 21% selected is not the same as telling the computer the only gas you have with you is 21%.

 

[Manatee Diver]

If you program 36/32/21 on the computer and have them turned on, the computer will calculate your NDL based on the fact you will use those 3 gasses on the dive.
But if you then do a dive to 130 ft and all you have with you is 21%, your actual NDL will be much shorter than what the computer would be telling you during the dive.

Heres an easier way to visualize it, which would have a longer NDL:
A dive to 90ft with 36%
A dive to 90ft with 21%

Having all 3 gasses on but 21% selected is not the same as telling the computer the only gas you have with you is 21%.

That isn't how SRI's NDL calculation works. The NDL during the dive exclusively uses the gas your are breathing.

The only thing that other gasses are used for NDL diving is if you use the planner.

 

[Pavao]

That isn't how SRI's NDL calculation works. The NDL during the dive exclusively uses the gas your are breathing.

The only thing that other gasses are used for NDL diving is if you use the planner.

 

[Manatee Diver]

View attachment 816850

And? It doesn't mention NDL diving in that section. I can tell you from experience NDL is purely based on what you are breathing at that moment. It doesn't give you 32% NDLs when 21% is selected.

 

[Pavao]

And? It doesn't mention NDL diving in that section. I can tell you from experience NDL is purely based on what you are breathing at that moment. It doesn't give you 32% NDLs when 21% is selected.

FFS, I even circled it red for you.

“INCLUDING NDL”

You can pull that up right from Perdix 2 RECREATIONAL MANUAL, which is separate from the technical manual.

 

[Manatee Diver]

FFS, I even circled it red for you.

“INCLUDING NDL”

You can pull that up right from Perdix 2 RECREATIONAL MANUAL, which is separate from the technical manual.

You are trying to connect a general warning with a statement specific to deco diving. The ONLY time that SRI will factor in the non-active but turned on gasses for NDL diving is when in planner mode, and you plan a dive that is too deep for the active gas. So for example if you have 32% as the active gas, and 21% turned on; and you plan a dive to 140ft. The planner will assume that you are going to switch to 21% when you hit the MOD based on 1.4 for 32%.

But during the dive it will only show the NDL for the depth you are presently at based on the gas you are currently breathing. The NDL will only change to that of the other gasses if you do a gas switch. So while below NDL, other gasses aren't really a factor.