Which do you think is less dangerous at 160ft? Open-circuit air or CCR trimix?

[ginti]

Hi Ginti,

Thank you for your input. I agree that if you stretch things, you may be able to achieve Mod 2 level in under $20K which should enable you to dive to 60m on trimix. If you want to stretch things, I have no problem with that.

Let me clarify - 20k is the cost WITHOUT stretching. It's really the maximum (maybe only the GUE route could be sligymore expensive, and not much).

If one wants to stretch things, it's going to be less most likely

 

[Blackcrusader]

Obviously rebreather divers have the option for either; OC divers have no other choice than OC.

yup. I will not spend the money to learn CCR. Money is not my issue. Now as for deep dives on air.. yes this was normal with BSAC in the 1980's and these were deco planned dives. It's uncommon for me to do deep dives on air nowadays as it's not really in recreational diving. There are some dives I do in Indonesia that are to 50m on air with light back gas deco. I seem to be fortunate that I might be in that 20% of divers who don't get narced so easily. I'm also better on gas consumption than most other divers.

I am not Trimix trained. Try getting that mix anyway in some parts of Indonesia. It's hard enough getting Nitrox.

 

[Celt]

I definitely won’t be spending 20k and 2 years training to make dives I’m already making for 50 euro including fuel. People should just stop comparing narcosis to drinking alcohol, either they have no experience of narcosis or they need to get out more.

 

[ofg-1]

posting error, sorry

 

[ofg-1]

Ok boomer.

As a boomer, allow me to ask what the letters F O mean to you? You can make fun of us boomers all you want, but at least we could have sex without being wrapped in a inner tube.

Point is a moderate number of dives with $200 fills will add up faster than you think it will,

50 trimix dives may be a moderate number to you, years worth to others. My last dive partner and I tried several times to figure out the cost effectiveness of a rebreather. Couldn't make it work for us at the time. Of course, although we occasionally did, neither of us really wanted to spend more than 3 hours in the water.

From the sounds of it, it was a single test. If you have ever been narced, you will realize it isn't 100% repeatable.

I can attest that for me, this is true. We did a lot of "deep" air diving because it was all that was around. The theory at the time (1975-77) was that you built up resistance to narcosis. I don't think you had any resistance, but by repetition, you just kinda got used to it. Never got used to freezing my ass off doing air deco.

I am not a proponent of "deep" air diving, whatever that means to you. I still believe that, for the occasional deeper dive, trimix is relatively cheap.

You want a rebreather, hell, go and buy 2, you probably will anyhow when a newer model comes out. If you believe they are safer, then they are. Whatever puts you in the water with the most confidence and comfort, is fine with me.

 

[CG43]

Particularly the document provided by Angelo Farina on Raimondo Bucher. I recall seeing a documentary many years ago about the coral divers of Sardinia, made by film producer Bruno Vailati. The diver descended to well over 300ft on air to gather highly prized black coral for making jewellery. The diver appeared to use the techniques similar to those of Raimondo. His descent was very rapid by using a heavy stone connected to a line which was then used for ascent reference. He was doing these dives on a regular basis.

I was looking for this film several times . If anyone has a link , please post it

I also have a book which describes a Corsican diver called Rocco doing similar dives off Corsica (I recall 15 mins bottom times).

Here is the link to the video of the diver Rocco (Recco ? ) .

www.bing.com/videos/riverview/relatedvideo?q=the%20coral%20divers%20of%20corsica&mid=8526A0FF8B2D5D4764358526A0FF8B2D5D476435&FORM=VIRE&ajaxhist=0

 

[lostsheep]

As a boomer, allow me to ask what the letters F O mean to you? You can make fun of us boomers all you want, but at least we could have sex without being wrapped in an inner tube.

In contemporary usage FO means “find out”, it’s the second half of FAFO. I dont care what it means to a triggered geriatric.

Flippancy out of the way, dude relax. That other poster’s handle is OLDfrogman and he is espousing out dated deep air ideas.

 

[rjack321]

50 trimix dives may be a moderate number to you, years worth to others.

I know a whole lot of folks who got some sort of trimix card and had either quit or aged out of technical diving before they ever did 50 post class trimix dives.

 

[Subcooled]

So, in the dive shop, we were having this discussion about a deep cavern dive where the dive plan was 160ft... which is less dangerous?

I have been diving to 154 feet on air, sidemount, 3 feet visibility, overhead, total darkness.
The amount of gas narcosis is significant.
Only a Gopro can recall your dive - unless something truly traumatic happens.
Warning beeps from your dive computer will get registered... sometime... later.
Maybe 5-10 sec delay.
Dexterity is lost.
You think you did something.
You did not.
Add a rebreather, with air/nitrox, and if it fails at this depth, you are dead.
Do it on trimix or on open circuit. The former is better, of course, and costs more.
If your rebreather will never fail (Prayers) then it migh be safer.
Things change radically if you have a trimix CCR

Is it safer to dive with a little narcosis

Well, is it a little? The S-curve can be steep, indeed.

on a simpler system (sidemount on air with o2 deco), or is it safer to be clear headed on CCR (a rig that is trying to kill you)? (Assume the diver is trained and comfortable with both.)

A CCR will give you much more time, hence safer.
Just make sure you DO NOT have a manual nitrox CCR (Killing you softly).
If the CCR fails and you cannot cope with that, then you die.

Why the question: because helium is expensive, so open circuit trimix is not a realistic option.

How about a semi-closed?
OK, so take the risk, but instead of one dive, make it a project of 6 progessively longer dives, and please stage some emergency gas on your up line.

I could not find statistics about this, so I am asking the question.

 

[Subcooled]

And hey, one good thing about sidemount is that
when you forget to change regs regularly at 150 feet
and you run out of gas in one cylinder,
a very stupid thing to do,
I did it,
then you have at least another one to do the ascent.