Teric and Nitrox diving - Rec divers take care re method of changing gas (affects MOD).

[Jay]

You guys are really confusing.

The short story, is unless you're using more than one gas on a dive, use the Edit Gases menu only, have your breathing gas as Active, and no other gas on. Then you're sorted!

If there is an aspect of this thread that you find confusing please do holler.

 

[Chidiver1]

The short story, is unless you're using more than one gas on a dive, use the Edit Gases menu only, have your breathing gas as Active, and no other gas on. Then you're sorted!

If there is an aspect of this thread that you find confusing please do holler.

No I got it, I was referring to the back and forth. Of course, that was before you said you were arguing about two different things.

 

[JohnnyC]

I would think this would be common sense. Am I missing something?

Common sense is uncommon unfortunately. That's why it's important that we recognize what we're talking about, and refer to things correctly. I admit that I have not been clear in this thread, and also recognize that others haven't either.

People say things like it won't accurately calculate your decompression. That has some serious implications if it were true. Fortunately that is not the case. A more accurate way to say it is that it will not accurately reflect your stop times. That has an entirely different meaning, and it's a super important distinction.

Ultimately fault lies with the diver for not using his equipment correctly. I find Shearwater's implementation of things very intuitive, and don't have any issues with it. Others may not. Common sense for some is not for others.

 

[stuartv]

People say things like it won't accurately calculate your decompression. That has some serious implications if it were true. Fortunately that is not the case.

Yes. Even that quote from Shearwater said so.

If you have gases turned on that you are not carrying, it will not calculate your deco accurately.

It WILL track your inert gas tissue loading accurately.

Calculating your deco correctly means that if you need to stop for 10 min at 10', it TELLS you that you need to stop at 10 for 10. It does not tell you that you need to stop at 10 for 2 minutes, when you really need to stop for 10.

Unfortunately, that's actually what it does if you have gases turned on that you are not carrying. It calculates your deco incorrectly because the calculation includes assumptions that are incorrect. To wit, the assumption that you will use all the gases that are turned on in the computer's settings.

The inert gas loading is tracked correctly. The deco is calculated incorrectly (if you have given the computer incorrect info).

 

[JohnnyC]

We will have to disagree with the terminology being used.

Tracking inert gas IS decompression. Inaccurate stop depth time is not.

 

[Jay]

Common sense is uncommon unfortunately. ...

...I find Shearwater's implementation of things very intuitive, and don't have any issues with it. Others may not. Common sense for some is not for others.

Let's dispense with the snippety snippets shall we.

Having the gases set to On you intend to use is quite obvious. Knowing that it's On because of the (incorrect) use of the Select Gas menu is another thing all together (for a Rec diver), and this isn't about intuitively. See post 66 for that detail.

I started this thread to share something that had caught me out, and it's taken 8 pages and some good minds put together (yours included) to nut that and related aspects out.

I hope between this thread and some re-jigging (somehow) of the aspects raised in it by SW that no other Teric owner makes the same error. If it's because of this thread I'm happy.

But neither myself nor others in this thread should hear that we're lacking commonsense because something caught us out.

 

[JohnnyC]

Let's dispense with the snippety snippets shall we.

Having the gases set to On you intend to use is quite obvious. Knowing that it's On because of the (incorrect) use of the Select Gas menu is another thing all together (for a Rec diver), and this isn't about intuitively. See post 66 for that detail.

I started this thread to share something that had caught me out, and it's taken 8 pages and some good minds put together (yours included) to nut that and related aspects out.

I hope between this thread and some re-jigging (somehow) of the aspects raised in it by SW that no other Teric owner makes the same error. If it's because of this thread I'm happy.

But neither myself nor others in this thread should hear that we're lacking commonsense because something caught us out.

I'm not being "snippity," simply pointing out that what someone might consider common sense, is not what someone else might consider common sense. What someone may consider common sense may be completely out of someone else's wheelhouse. That's not an observation on their mental acuity.

 

[stuartv]

We will have to disagree with the terminology being used.

Tracking inert gas IS decompression. Inaccurate stop depth time is not.

Yes. It is just terminology. I think "tracking inert gas" as a synonym for "decompression information" is completely wrong. But, I reckon it's just my opinion and you are entitled to your different one.

Your inert gas tissue loading is tracked. It's a factual mathematical model (in the sense that the numbers produced by the model are standalone facts, which may or may not match any actual physical properties).

Your decompression requirements are a completely different thing. The computer calculates them based on the tracked inert gas tissue load, what Gradient Factor settings you have chosen, what Last Stop Depth you have chosen, and depth, plus assumptions that the computer makes like what your ascent rate will be and what gases you will switch to during the ascent.

You can call inert gas and deco the same thing, but knowing my inert gas tissue load does not tell me what stops I'm going to make and for how long. The calculations based on some defined parameters and some assumptions is what tells me where to stop and for how long.

You say decompression information is a synonym for inert gas tissue loading. I regard decompression information as a synonym for my ascent plan. Certainly, if we were planning a dive together and I said "what is your plan for deco" I would expect you to tell me stops and times, not some description of your anticipated inert gas tissue loading.

In the end, the important fact is that if you set your computer to think you are carrying gases which you are not, then the inert gas tissue load it thinks you have will be correct (with regards to the model - but may not have any correlation to your actual physical tissues). But, the ascent plan it tells you will be wrong. It will self-correct as you ascend. But, when you are on the bottom and looking at your computer and it says "go up, stop at 20 for 2, stop at 10 for 10, and you can get out within the GF parameters you have set" that info is wrong.

 

[lermontov]

In the end, the important fact is that if you set your computer to think you are carrying gases which you are not, then the inert gas tissue load it thinks you have will be correct (with regards to the model - but may not have any correlation to your actual physical tissues). But, the ascent plan it tells you will be wrong. It will self-correct as you ascend. But, when you are on the bottom and looking at your computer and it says "go up, stop at 20 for 2, stop at 10 for 10, and you can get out within the GF parameters you have set" that info is wrong.

just for clarification - and excuse me if I'm a little off track but my perdix shows me the ascent plan as you described but uneless i turn those gasses on it will still run down the time but at a lot slower pace. eg if it tells you to stop at 12m for 3 minutes and you still on 21% and you have a 50% gas "on" but not active it will time down at the equivalent time of 21% (almost twice as long) so in response to your last paragraph the depths will be correct and the numbers (times) will be correct but teh times to clear those stops is in real time longer

 

[stuartv]

just for clarification - and excuse me if I'm a little off track but my perdix shows me the ascent plan as you described but uneless i turn those gasses on it will still run down the time but at a lot slower pace. eg if it tells you to stop at 12m for 3 minutes and you still on 21% and you have a 50% gas "on" but not active it will time down at the equivalent time of 21% (almost twice as long) so in response to your last paragraph the depths will be correct and the numbers (times) will be correct but teh times to clear those stops is in real time longer

If it says 3 minutes and then it takes 6 minutes, I do not count that as correct. It may be correct with respect to a theoretical model that thinks I am carrying gas that I am not, but I need correct with respect to ME and my actual situation.