40% O2 mix at the safety stop

[rollerboi]

Punctuate so it makes sense: TIME FLIES YOU CAN'T THEY ARE TOO FAST.

Time flies? You can't, they are too fast.

 

[Thalassamania]

Time flies? You can't. They are too fast!

Close enough

 

[Bismark]

Pretty funny............!? Thal, ewe have two much thyme on your hands...

 

[nereas]

OK, thanks for all the input. I haven't done NITROX in years so I will probably take a course soon before diving it again. I think cave_diver summed it up good and thanks String and everyone else.

What exactly is the $$$ of this should I ever get a boat. A dedicated bottle and reg with a couple of seconds on it, equipment to suspend the bottle and the O2 fill? Is the 80-100% O2 fill $$$ (of course, if you are only using it for 3-5 minutes that tank should last for awhile-maybe not, depends on how many people used it...)

It is simply not worth the trouble of rigging a hang-tank from a boat for NDL diving.

The meer fact that you are doing a 3 min safety stop, on any gas, whether air or nitrox, is enough over-kill. For a deep dive, your safety stop should be 5 mins. NAUI has recommended doing your first 1 min at 1/2 of your max depth, ostensibly 60 ft, and your second 1 min at half that, or 30 ft, and then another 3 mins at 15 ft. Otherwise a 3 min stop will do, for shallower dives.

A hang-tank is a backup procedure for deco diving, in case the dive goes too long, and the final deco mix (normally oxygen) is exhausted, or if the final deco bottle fails somehow.

 

[nereas]

...IMHO, basic nitrox (which is enough to figure out this scenario) should really be included in basic open water training. It isn't that complicated and no more difficult to understand than regular dive tables and DCS. Perpetuating this cloak that it is somehow special just serves to make the training orgs more money by making it a seperate card with a seperate fee. But, they didn't ask me, so two classes, two fees, and two cards it is.

The salient issue is information overload for the students.

That is why EANx is more appropriate as a segment of the AOW course, rather than together with the Basic Open Water (1st) course, as you unfortunately speculated.

In college courses you have 4 months available to you to teach during the semester, and in that case, the OW1 and AOW can easily be taught together, even with a Scuba Rescue class added as well, and including EANx, all combined as a Scuba 101 course.

But in the civilian retail world, it is rough just getting people to think and read enough to pass the Basic Open Water course, as it now is. Normally people simply show up and pay their $200 bucks, and expect to be entertained like at a movie, without having to think. This is why PADI has been so successful over the years, not at teaching anything meaningful, but at entertaining and Putting Another Dollar In.

 

[tschmitt]

EANx class should be lumped with AOW for sure. But they've got a nice little business going - PADI that is. Why not create a separate class for a buck fifty? Regular OW class might be a bit overloaded especially for people like my girlfriend that had trouble at first with the Air RDPs, nevermind the blends, new tables, EAD, PO2, and O2 Clock ...

Back to the "original" thread (whatever that was :/ ), the EANx40 PO2 at 15 ft is 0.58 ata, unless your O2 Clock is at 110% for the day, I wouldn't worry about another 3-5mins at this PO2. Although it's probably all moot in that switching from 68% nitrogen to 60% nitrogen at this depth for 3 mins isn't going to do that much. For those coming off air might may sense. Actually in NITROX class (PADI) you do all kinds of calculations - first dive on 32% for 60 mins at 57 ft, second dive on 36% at 45ft what is your ABT to stay above a 65% O2TOX or NDL, blah blah - so switching blends between 21% and 40% is generally safe as long as you aren't pushing any of the limits.

 

[Thalassamania]

EANx class should be lumped with AOW for sure. But they've got a nice little business going - PADI that is. Why not create a separate class for a buck fifty? Regular OW class might be a bit overloaded especially for people like my girlfriend that had trouble at first with the Air RDPs, nevermind the blends, new tables, EAD, PO2, and O2 Clock ... ... blah blah - so switching blends between 21% and 40% is generally safe as long as you aren't pushing any of the limits.

Low risk, but almost useless.