What's the point of these 3 gas computers?

[ianr33]

I dont think its a great idea for a recreationally trained nitrox diver to be swimming around at 130 feet with a stage/pony of 50% strapped to himself. A "technically" trained diver will hopefully have appropriate MOD markings on that tank and understand better the consequences of breathing it at depth.

 

[RJP]

I dont think its a great idea for a recreationally trained nitrox diver to be swimming around at 130 feet with a stage/pony of 50% strapped to himself. A "technically" trained diver will hopefully have appropriate MOD markings on that tank and understand better the consequences of breathing it at depth.

To be clear, I'm not advocating ANYONE do a dive that is beyond the limits of their training and experience.

 

[ianr33]

It is an interesting issue.. with my SAC rate, assuming my worst case, I could easily do that dive with a 133 cf tank and two 40 cf pony's (213 cubic ft of gas) and use the three gas profile (which is shorter)..

I'm not totally clear on what you're planning here but having back mounted ponies that have different mixes than the main tank would seem to be a real bad idea. Are you 100% sure that you know exactly what is coming out of each of those 3 regs ?

Feeling Lucky? Seriously ,this is a BAD idea.

 

[Cave Bum]

Technical diving was defined at the first AquaCorp conference as diving which 'required you to switch gas supplies'. I think that's still a pretty good definition.

{It is} exclusive just a bit, though, if you consider a cave dive with no deco, just using back gas. This definition would exclude that and personally, I'd consider that a tech dive. But the greater majority of cave dives go into deco (at least mine do) so you're switching to deco gas. As a general 'test' I'd say any dive you have to switch to a different gas is definately a tech dive. That was the part I was trying to get across.

So if I did a 90min deco dive to max depth of 150', in an overhead environment, but did it all on back gas, it wouldn't be a "tech" dive?

You need to read all of the posts... No worries...

 

[Puffer Fish]

I'm not totally clear on what you're planning here but having back mounted ponies that have different mixes than the main tank would seem to be a real bad idea. Are you 100% sure that you know exactly what is coming out of each of those 3 regs ?

Feeling Lucky? Seriously ,this is a BAD idea.

You are right, what was I thinking...

Seriously...you do know that there are a lot of divers carrying pony's that do no match there main tank... right?

Look at a simple two gas dive...

You have your main tank... and you have a pony with a richer mix in it.

The richer mix has a transmitter on it.. and the hose and second stage are bright green, and just in case that is not enough, it has a tag indicating the mix.

The computer knows your pony.. knows what is in it and if you tried to use it a the wrong depth, would get very upset at you.

You do the dive (remember it is not actually a deco dive.. the computer just thinks it is)... stop at 30 ft, and the computer tells you to switch... and then checks to make sure you did. Don't switch and it continues on with the main gas.. switch and it does the calculation with the new mix

Pretty simple... just don't use the bright yellow green thing when deep.

Now add a second mix.. in this case it will be bright blue, with a bright blue second stage....and a nice id tag...different in size and shape just incase you need to switch in zero vis.

Pretty easy, and as it is not really a deco dive... pretty safe.

Oh, and black hose, black regulator is main gas.

Doing a quick plan, using 27, 40 and 80...doing a 120 ft dive that would show 25 minutes of one gas deco (in the L5 program) is a no deco dive in normal mode.

That involves three levels and by using the other two gasses, should be down to 5 minutes. I would have enough gas with me to do this entire profile more than twice.

If the system actually works.. one just swims up to the first stop.. the computer tells you to change to T2, checks that you did and recalculates your deco time..then you go to stop 2, it keeps you on the T2 tank.. you do your time and go to the last stop, where it tells you to go to T3 and again adjusts the time...

Seems pretty simple actually.. just have never tried it.

The other option is to switch to tank 2 (40% nitrox) as soon as you are above 80 ft...this would give you the shortest deco time, but there is no way to plan it with the galileo, and using L5 does not match any other deco program...might be worth seeing the difference.

 

[WarmWaterDiver]

Here's a cool use that adding a third gas mix, for the properly trained for more than one gas mix per dive, could still be useful.

Diver Gear Tests - November 2004 - DIVERNET from Diver Magazine

Glad to see several folks with equivalent training are giving the same answer in this thread as I did on a prior thread hijack.

 

[fnfalman]

I don't know about other divers, but I personally would not do multiple gas mixes and deco diving until I get some proper instruction and education into said topics. Yes, my Aeris Elite T3 has 3-gases capability. Yes, it also does deco (as with most rec computers), but no I will not be using those features until I KNOW WHAT IT'S ALL ABOUT. The computer is a tool that supplements your brain. It's not something that you put 100% faith in because it's a computer.

 

[Scared Silly]

Back to the original question - I tend to use Suunto Computers and have noticed that almost all of their computers now allow gas switching. Now for the average diver they are never going to use that feature. However, in the big scheme of things exposing that feature costs the mfg nothing really. Why? because they basically develop one computer algorithm and then install it in each computer. A very good example is the Gecko which is not downloadable but yet people have figured out a way to expose it.

So back to the marketing wizards. They see this 2-3 gas feature and say hey let use that as a marketing gimmick. You are just an average diver but not in our minds, you are better than that and as such we have the computer for you. Look three gasses - customer is now star struck buys fancy computer. Never uses the 3 gas feature but they are cool.

Kinda like people who have 4WD vehicle - 99% never put it in 4WD nor drive it on roads requiring it. But they got it.

Personally the three gas computer for the average diver does have one function. The ah crap - I forgot to set my computer to the correct mix. If they can remember how to switch underwater they could at least set mixes to 21%, 32%, and 36% and hopefully be close. Worst case dive it like air.

 

[scubafanatic]

....don't miss seeing the forest for the trees here, don't just focus on the algorithm/switching features.....your computer is a big tech 'no-no' for 2 big reasons...... it's air-integrated, and it's wireless. I've had some limited 'tech' training/classes/trips (cave diving-Akumal Mexico/wreck diving off North Carolina)...and based on my experiences, you are gonna get a lot of pushback from the tech instructors on those 'issues'. In Akumal, I was forbidden to use my 'hosed' AI Oceanic Datamax Pro Plus II...I couldn't even bring it along for the ride, as it were....they 'made me' buy a Diverite wrist mount basic computer instead.

 

[RJP]

In Akumal, I was forbidden to use my 'hosed' AI Oceanic Datamax Pro Plus II...I couldn't even bring it along for the ride, as it were....they 'made me' buy a Diverite wrist mount basic computer instead.

Man, they really saw YOU coming, huh?