85m air dive

[ScubaSteve]

 

[ajduplessis]

What? I do 150 for 30 on a single deco gas @ 70' (sometimes will add O2 if it's the last dive of the day). A 120 bottle? Really? That's deeper than my first deep stop for 150.

I agree, please see post on 120 (most likely travel, bailout gas)

 

[Rainer]

I agree, please see post on 120 (most likely travel, bailout gas)

What are you talking about?? Travel gas? For a normoxic dive? That doesn't make ANY sense. While a bottom stage might be useful, a 120' deco bottle is silly as a travel gas. As bailout (rich O2 mix at depth) it makes even less sense.

 

[ajduplessis]

Please elaborate on why this looks like a setup for 150'. Especially the part about having a 120' bottle. And since this is not nearly enough gas for a 300' dive, how about you give an example of how many bottles you'd have, what the contents are and how you'd make a balanced rig out of them.

I don't do 300ft dives, but have blown a few bubbles around 200. Mix:21/40 (normoxic, not trimix), deco on 50% & 100%, 4 deep stops.

 

[Rainer]

I ... have blown a few bubbles around 200. Mix:21/40 (normoxic, not trimix),

You plan your trimix dives with a bottom PPO2 of 1.5?

Weird.

Very weird.

 

[Cave Diver]

I don't do 300ft dives, but have blown a few bubbles around 200.

Then how do you know whether the pictures posted above are appropriate for the dive or not? And how would you balance a rig when you don't know the gas requirements?

Mix:21/40 (normoxic, not trimix), deco on 50% & 100%, 4 deep stops.

Normoxic trimix is still trimix...

 

[Blackwood]

I agree, please see post on 120 (most likely travel, bailout gas)

Either way, travel gas with an MOD of 120 seems pretty unlikely.

 

[Rainer]

Normoxic trimix is still trimix...

Shhhh. That's only covered in the next course.

 

[ajduplessis]

Yes, 1.5 is not wierd. 21/40 is normoxic, not trimix. I also use 50% at 69ft and 100% at 20ft (both 1.6 PPO2).

 

[Cave Diver]

Yes, 1.5 is not wierd. 21/40 is normoxic, not trimix. I also use 50% at 69ft and 100% at 20ft (both 1.6 PPO2).

Normoxic refers to containing normal levels of [-]air[/-] oxygen.

Trimix refers to a a blend of three gasses.

The two are not mutually exclusive. If you have 21/40 that only accounts for 61% of your breathing gas. What is the remaining (third - tri) gas in your mix?