Nitrox course. What's the point?

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But with none of their history.
Of course it does, your time is on your watch till you hit the station and reset the bezel for the first stop. After that you only have to reset for each stop. Not rocket science.
 
Whereas computers vanish leaving behind a shimmering outline of the word GAMEOVER

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If you say so.
 
How do you know?

My friends who got bent would have sworn they did not make any mistakes if they had not had a computer profile of the dive to show them what mistakes they mare.

Now, I realize there is a difference between people who are perfect and mere mortals.
That’s what I trained and practiced for, that’s how I know and that old you must be perfect remark is pathetic,
 
I dunno, I find this stuff interesting! The discussion has helped me to understand things better. But let me ask you about the second method.

I don't know if some dive computers have an internal algorithm like you describe - one that converts the ambient pressure to a depth based on a specified salinity, and then compares that result to an MOD calculated from the desired maximum PPO2, known mix and salinity. But even if that were to be the case, salinity would still be irrelevant in terms of giving you an unsafe PPO2, since you are just mathematically putting the salinity constant (right or wrong) in, and then taking it back out again, right?

And yes, I agree, in the example you give, the diver would hit 95 feet (actual depth), the PPO2 would hit 1.4 and the alarm will sound, no matter what you set the salinity to. The only outcome of that salinity setting error would be that the DC display would erroneously read 98 feet, even though the diver was actually at 95 feet.

I've been away from SB. I'll try to answer your question above. If MOD is being calculated using depth then the salinity constant you refer to above must be used. I don't understand what you mean by "putting it in and taking it out". Here is the formula using depth (the constant is DPA):

MOD = ((ppO2 / fO2) - 1) x DPA

DPA = depth per atmosphere and is equal to 33 ft for salt water and 34 ft for fresh water using imperial measures.
 
Of course it does, your time is on your watch till you hit the station and reset the bezel for the first stop. After that you only have to reset for each stop. Not rocket science.
That's your run time.
  • It does not show the actual depth you were at for the deepest portion of your dive. That was another of the errors my friends made. They were sure they had stayed at a specific depth throughout the deepest portion of the dive--OK, OK, they may have dipped briefly below that from time to time. Well, the computer showed those "dips" were more significant than they would have imagined.
  • In general, it does not show the details of the mental calculations of depth and time you made before that, calculations you are remembering with dead certainty but which may not have been quite what you thought they were.
 
When I was diving on tables, I was using a mechanical depth meter with two needles. The red one was keeping the max depth, which is all what matters when diving with tables.
My Seiko watch tells me the total time from splash to the moment I reach the first deco stop, usually at 6 meters.
At that point I get the tables from the pocket and use the one for the max depth and total dive time.
Simple and very safe.
I did this for more than 1000 dives without any problem (apart the need of carrying a lot of gas for the deco).
Then I purchased a cheap and simple computer. With the same diving profile, it usually requires no deco, instead of the 15-20 minutes of deco stops I had routinely with the tables.
Is the computer practical?
Yes, definitely.
Is it safer than tables?
Probably not, as reducing or totally removing the deco stops cannot be safer...
But probably I was too much prudent when using the tables, and the computer is just "safe enough" for avoiding a DCS.
However I want to point out that both the watch and the depth gauge have "memory", you do not need to watch them continuously during the dive. Instead you need to watch often the SPG...
 
For my first years of tech diving and over I don't know how many decompression dives, I did not own or use a computer either. I personally never had a problem, but a total of 8 dives among our tech group doing using the same skills and methods for which we were trained did result in DCS.

Being an old man, I have used over many decades technologies now considered obsolete. They worked fine, but that does not mean that the technologies that replaced them aren't any better.
 
That's your run time.
  • It does not show the actual depth you were at for the deepest portion of your dive. That was another of the errors my friends made. They were sure they had stayed at a specific depth throughout the deepest portion of the dive--OK, OK, they may have dipped briefly below that from time to time. Well, the computer showed those "dips" were more significant than they would have imagined.
  • In general, it does not show the details of the mental calculations of depth and time you made before that, calculations you are remembering with dead certainty but which may not have been quite what you thought they were.
Run time is the total time elapsed since leaving the surface. For the assent I reset the bezel on the bottom and when reaching the station for each stop, the deco times are on the slate. Max depth is the first number put into the calculations and doesn’t change, for me that’s the deepest I can possibly go on any particular dive. In the event that you don’t reach the max depth it makes the dive more conservative. All my dives are planned for a max depth.
 
I am not a tech diver and I always remained within the limits of my recreational certification (50m max in air, deco only using back gas, no accelerated deco, no nitrox, no change of tank).
And the way we were trained using tables was definitely super safe, considering the max depth and the total time from splash to the first deco stop.
I have no knowledge of any undeserved DCS occurred following this approach.
Instead I know of some "undeserved" DCS occurred doing more aggressive plans, when so-called tech divers use the "average depth" instead of the max depth, or consider the dive time excluding the ascent time (as @mac64 says he is doing, and which is unsafe according to the procedure I was trained for), or shorten the deco switching to an highly oxygenated mixture, or do more than one dive every day..
 
, or consider the dive time excluding the ascent time (as @mac64 says he is doing,
No I don’t and could you please quote where I said I exclude the time to the first stop, my dives are planned from the surface which includes the decent and assent and all deco. Deco is calculated to include the decent, bottom time and assent.
 
https://www.shearwater.com/products/swift/

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