DIR- GUE 30/30

[mainedvr]

Is it common to use 30/30, or do most stick to 32% in the 100' range? Not asking cause I am thinking of using a gas I am not trained on just asking out of curiosity and the expense of HE, what folks are diving..
(Not trained on HE)
Maybe a better (or a second) question would be is it commonly use in the 100-120' range ?

 

[Jack Hammer]

Most people I know use 32% in that range. I don't recall having ever seen anyone using 30/30. I'm sure it's used in some areas or under certain conditions.

 

[sigxbill]

For the 100-130' range UTD standard gas is 25/25. If it's just a possibility that I might take a quick jaunt down to 110' max, I don't worry that I am using ean32. For planned 100-130' range dives (especially those deeper than 110'), I use 25/25 and enjoy it much more. When I am being honest with myself, I can feel narcosis starting in less than 90', and have noticed that 114' seems to consistently be the depth I notice significant narcosis on air / eanx ... cheers

 

[elgoog]

I talked to my instructor about this a couple of weeks ago because using helium in 100ft or above didn't make sense either. I was told the primary use is when you're expecting enough exertion in the 80-100ft range that the easier work of breathing, reduced CO2 and reduced narcosis is desirable. Couple of examples given to me were survey/project dives in cold water and caves with high flow. Devil's System in FL was a specific example of the latter where using 30/30 is apparently not uncommon.

I agree with @sigxbill - 25/25 makes more sense for overall utility than 30/30

 

[gobuyastick]

I know a handful of people that use 30/30 in high flow caves and on the wrecks in the 80-100ft range. I plan on getting "30/30 certified" soon since i can definitely feel the narcosis creep up on me when diving below 85ish ft. Narcosis isn't something i want when I'm dealing with the current

 

[sigxbill]

Let’s not forget that in addition to narcosis, helium helps solve co2 issues - especially in high workload situations ... such as current ...

 

[PfcAJ]

I prefer it for high flow caves, wreck penetration, and any time I'm using the RB80 in the 80-120' depth range.

 

[rddvet]

Funny this just came up. My wife and I were trimix certified earlier in the year, and just dove Ginnie on 30/30 for the first time last weekend. We hadn't even thought of diving helium at those depths until the course woke us up to the pros. I must say it was an almost scary experience. We both surfaced and had the exact same comment. We were both amazed at how much we saw in the cave that we'd never seen before. It was scary because we never realized how much narcosis we've had on the other 100 dives we've done in Ginnie on 32%.

The nice thing is you can run a 30% or 32% deco profile on 30/30. (I know this is highly debatable and not taught by many instructors)

 

[Compressor]

Funny this just came up. My wife and I were trimix certified earlier in the year, and just dove Ginnie on 30/30 for the first time last weekend. We hadn't even thought of diving helium at those depths until the course woke us up to the pros. I must say it was an almost scary experience. We both surfaced and had the exact same comment. We were both amazed at how much we saw in the cave that we'd never seen before. It was scary because we never realized how much narcosis we've had on the other 100 dives we've done in Ginnie on 32%.

The nice thing is you can run a 30% or 32% deco profile on 30/30. (I know this is highly debatable and not taught by many instructors)

Sorry for my ignorance: What part of Ginnie did you do the 30/30? The cavern that goes to 55 feet?

 

[PfcAJ]

Sorry for my ignorance: What part of Ginnie did you do the 30/30? The cavern that goes to 55 feet?

Ginnie = Devils colloquially.

It’s a hunnid in a few spots.