Long but shallow profile, what kind of training do I need

[rlynch]

IMHO - which Deco gas the team chooses is highly dependent on the conditions the dive will take place in. My recommendation was given with the OP's probable dive env in mind. I.E. San Fran Shore diving where you can proceed up along a bottom to do deco as opposed to doing it in the open ocean on a line or under a bag while drifting. if you in 2-4' seas then a 50% deco is a better choice normally given the depth at which you can start it and dealing with 2-4' sea swing on a 20' stop is not great as you quickly are above your PO2 if not very careful with your depth. 50% is a more forgiving option in that situation. otherwise I would just go on O2 and get out sooner. Your team may think different, of course.

 

[decompression]

Also this profile could be done on triox, needing only 15 min of deco on back gas. So, have a look into a triox course (UTD rec 3 or TDI triox, not sure about GUE).. That could be an option for you.

 

[decompression]

So after looking at GUE rec 3, it gives you trimix and single deco with nitrox. That will easily ( and then some) cover your desired profiles.

 

[PfcAJ]

I don't have V planner on my phone but with the above profile I'd choose 50% for the sake of a few minutes and the safety. PfcAJ, for my info, is your focus on inert gas a SOP for all dives, regardless of depth/time? Thanks. I might have to take a deeper look (excuse the pun).

I use decoplanner, and I don't really know anything about iDeco. When I run it with Buhlmann 20/85, I get 17mins of deco with 100% and 23mins with 50%. Up the dive time to 80mins, and there is a 11min difference between the two. But let's say your model is correct, and offgassing starts at 60'. Why switch to a deco gas at 70'?

I always think about inert gas, because inert gas is what bends you I always start with o2 and add gases as they are needed to cut deco time or reduce min-gas. O2 time can fix a lot of problems.

---------- Post Merged at 12:47 PM ---------- Previous Post was at 12:45 PM ----------

So after looking at GUE rec 3, it gives you trimix and single deco with nitrox. That will easily ( and then some) cover your desired profiles.

switching from that 32% to 32%?

 

[nadwidny]

I use decoplanner, and I don't really know anything about iDeco. When I run it with Buhlmann 20/85, I get 17mins of deco with 100% and 23mins with 50%. Up the dive time to 80mins, and there is a 11min difference between the two. But let's say your model is correct, and offgassing starts at 60'. Why switch to a deco gas at 70'?

If using just one deco gas GIII used to recommend to go to a deco gas at 70' as opposed to waiting until O2 at 20 ft because if things went south from 70' and you can't spend a lot of time at 20', you've already done a substantial amount of your deco before things went wrong. I like that thinking so that is what I used to do for single deco gas dives. However I believe that JJ liked O2 for single deco gas dives for the reasons that PfcJ gives.

 

[decompression]

I'm sure they mean 50% nitrox.

 

[decompression]

I give the off gassing depth as you mentioned " why spend time on gassing when you can just get on to deco", with 50% at 70' you are only on gassing for another 30 seconds or so as you move to your next stop. The switch is for accelerated deco, if you stay on back gas you've got far more time in the warm waters of SanFransico.

 

[decompression]

All good points, it's great to see different views.

 

[BDub]

Simply for clarification, UTD Rec 3 certifies the student to use EAN32 or 25/25 for backgas with no deco gas, to 130fsw.

UTD Tech 1 certifies the student to use EAN32 or 25/25 for backgas, to 130fsw, and O2 for deco.

50% is introduced at the Tech 2 level (160fsw with 21/35 and 18/45 for backgas)

While backgas deco is discussed in Rec 3, it is only for contingency, and the student isn't certified to do backgas deco

 

[TSandM]

I think UTD T1 is ideal for the kind of dives you're describing. But it's never bad to have MORE training than you need. It's paying for it that can get painful.