Which mixes for trimix are better for 330 feet (100 meters)?

[nereas]

Which depth you change from 12/70 to 21/35?

I used V-Planer with these mixes 12/70, 21/35, 50% and 100%, it shows that the change from 12/70 to 21/35 is too 'abrupt' with the red line, why? I think the difference between 8m ead and 32m ead is too large?

Desc à 100m (10) Trimix 12/70 10m/min Descente.
Niveau 100m 5:00 (15) Trimix 12/70 1.30 ppO2, 15m ead, 23m end
Rem. à 72m (17) Trimix 12/70 -10m/min Remontée.
Palier à 72m 0:12 (18) Trimix 12/70 0.97 ppO2, 9m ead, 14m end
Palier à 69m 1:00 (19) Trimix 12/70 0.94 ppO2, 8m ead, 13m end
Palier à 66m 2:00 (21) Triox 21/35 1.57 ppO2, 32m ead, 39m end
Palier à 63m 1:00 (22) Triox 21/35 1.51 ppO2, 30m ead, 37m end
Palier à 60m 1:00 (23) Triox 21/35 1.45 ppO2, 29m ead, 35m end
Palier à 57m 1:00 (24) Triox 21/35 1.39 ppO2, 27m ead, 33m end
Palier à 54m 1:00 (25) Triox 21/35 1.32 ppO2, 25m ead, 31m end
Palier à 51m 1:00 (26) Triox 21/35 1.26 ppO2, 24m ead, 29m end
Palier à 48m 1:00 (27) Triox 21/35 1.20 ppO2, 22m ead, 27m end
Palier à 45m 1:00 (28) Triox 21/35 1.14 ppO2, 20m ead, 25m end
Palier à 42m 1:00 (29) Triox 21/35 1.07 ppO2, 19m ead, 23m end
Palier à 39m 1:00 (30) Triox 21/35 1.01 ppO2, 17m ead, 21m end
Palier à 36m 1:00 (31) Triox 21/35 0.95 ppO2, 15m ead, 20m end
Palier à 33m 1:00 (32) Triox 21/35 0.89 ppO2, 14m ead, 18m end
Palier à 30m 1:00 (33) Triox 21/35 0.82 ppO2, 12m ead, 16m end
Palier à 27m 3:00 (36) Triox 21/35 0.76 ppO2, 10m ead, 14m end
Palier à 24m 3:00 (39) Triox 21/35 0.70 ppO2, 9m ead, 12m end
Palier à 21m 3:00 (42) Nitrox 50 1.52 ppO2, 9m ead
Palier à 18m 3:00 (45) Nitrox 50 1.37 ppO2, 7m ead
Palier à 15m 4:00 (49) Nitrox 50 1.22 ppO2, 5m ead
Palier à 12m 6:00 (55) Nitrox 50 1.07 ppO2, 4m ead
Palier à 9m 8:00 (63) Nitrox 50 0.92 ppO2, 2m ead
Palier à 6m 10:00 (73) Oxygen 1.55 ppO2, 0m ead
Palier à 3m 18:00 (91) Oxygen 1.25 ppO2, 0m ead
Surface (91) Oxygen -10m/min Remontée.

So, change your deco mix to TMX 20/40 as I said, to better control the narcosis.

Deco mixes are not carved into stone. Unless you were taught by an agency that says they are carved in stone.

But as was previously pointed out, you are not ready for this dive, yet.

And a general principle of tech-deco diving is to build up to new depths slowly. 15m increments is a good transition. You are violating this principle now by planning this deep spike dive.

 

[nereas]

We plan for all of them, just not at the same time (unless it's during your class ).

On a dive deeper than 200', if you lost all you deco bottles, and you had to deco on backgas mix, and your buddies somehow got enough backgas down to you for you to complete your deco, they could drop off the tanks to you, go to a movie and dinner, and then come back for you later. But on a three man team, you could easily dine on your buddy's deco leftovers and go to the show together. On a dive where we'd need to work all that out, I hope I'm with divers with a bunch of dives (more than 100).

Or you could hang an extra deco tank from the boat to begin with, and then not be buddy-dependent.

 

[nereas]

You need three gases!!!! End of story. You should carry three stages with 1.5 times your expected gas requirements just in case. I know you think that its only a few more feet, but the likelyhood of getting hit from 200' to 330' goes way up. Pad your deco and take a long time getting back to the surface within reasonable cns % points. It's much easier to do an extra hour of deco than 6hours of recompression, or more.
Oh and 5 minutes seriously.

Actually I would use 4 deco mixes not just 3. But definitely not only 2; I think everyone agrees on that (except maybe the back-gas-deco crowd).

 

[Tomeck]

Or you could hang an extra deco tank from the boat to begin with, and then not be buddy-dependent.

The pilot and the co-pilot are very responsible, but it is not a good idea to pilot alone, if a pilot falls ill by eating the rotted fish.

 

[jtivat]

Or you could hang an extra deco tank from the boat to begin with, and then not be buddy-dependent.

So you are going to depend on a buddy attached to a boat when you are at 330' in a open body of water???

 

[Blackwood]

Actually I would use 4 deco mixes not just 3. But definitely not only 2; I think everyone agrees on that (except maybe the back-gas-deco crowd).

Without re-reading, I don't think anyone in this thread has advocated backgas decompression from 330 feet.

 

[Scared Silly]

For some reason this quote seems appropriate -

Arguing with a grunt is like arguing with a pig. You both get dirty but the pig loves it.

 

[nereas]

So you are going to depend on a buddy attached to a boat when you are at 330' in a open body of water???

Besides 4 deco bottles comprised of TMX 20/40, TMX 30/30, EAN 50, and 100% O2, I would indeed hang another tank with 100% O2 at 20 ft under the boat, yes.

Because I believe in making good and sure I have multiple levels of redundancy.

My teacher was very conservative. He was married to a beautiful German blonde woman, with 2 beautiful kids, and he did not want any risk of not returning home to them.

The buddy is there simply to help you get untangled if that happens inside of the wreck.


Inman mentioned he draws strength from his 3-man CF even if all his bottles fail for him. I do not like CFs. I would sooner hang an extra tank. And the 3rd man in a 3-way often gets lost or left behind, in the real world.

 

[nereas]

For some reason this quote seems appropriate -

Arguing with a grunt is like arguing with a pig. You both get dirty but the pig loves it.

Where is Utha??

And is the pig hunting there good?

 

[grazie42]

Which depth you change from 12/70 to 21/35?

I used V-Planer with these mixes 12/70, 21/35, 50% and 100%, it shows that the change from 12/70 to 21/35 is too 'abrupt' with the red line, why? I think the difference between 8m ead and 32m ead is too large?

Yes, that´s why it´s red...
So you either change the gasses or accept the risks inherent in the gas-change...
risk vs. reward...

Personally I wouldn´t deco 80mins for 10 mins of bottom-time, particularly as your deco-profile is just "one big ascent" until the 30mtr mark...I don´t see that you´ll get anything out of this dive unless there´s something truly spectacular at 100mtrs...if there is, bring a camera and film it for us