Complete user nitrox and deco diving

[huskerdiver23]

Hey I am getting ready to take my nitrox course and an instructor was telling me that by taking my complete user course that I could use up to 50% oxygen mixes and that by doing so I could stay longer at depth than the tables and through careful planning breath a higher % oxygen mix on assent with out doing a "decompression" dive. Is this possible, becuase it makes sense as long as bottom time isn't excessive. I just heard this and decided to ask because as a non deco diver (yet ) it caught my attention.

 

[DandyDon]

With which agency is your course?

How many dives have you logged? (You might complete your Dive Info, as it's been expaned. See Quick Links above.)

 

[huskerdiver23]

sorry for not saying my agency......I will bet getting certified through ANDI. I have around 50 logged dives and I won't be taking the advantages of this "decompression skip" if there is one until I have more dives and more training. I just wondered if it is possible.

 

[Far_X]

Interesting! I did mine with PADI and my DSAT tables only cover up to 40%. Higher oxygen AND longer than the tables makes me wonder wether you are not heading towards oxygen toxicity!! I would say, don't dive off the tables, not just yet. Do you know the point where decompression is required? Did you notice that the higher the oxygen percentage, the shallower you have to dive to stay within the tables? Get a second opinion but these are my initial thoughts. Stay safe man and happy diving!!

 

[huskerdiver23]

yeah....I figured oxygen toxicity would be a limiting factor but I was told that breathing a 32 or 34 percent bottom gas would be used in this scenario and then using the 50% mix as a travel gas upon assent to do an "accelerated deccompression" almost like a wash gas on assent. Does that make make any sence?

 

[DepartureDiver]

Yes, any time you use any nitrox percentage you get the advantage of more bottom time, so you can stay longer without get a true ceiling or mandatory stops. But as you will learn, all dives are decompression dives since you must ascend slowly through the water back to the surface ... with some safety stops thrown in. Being certified up to 50% is nice. It doesn't mean that you will always being using 50%, just that you are allowed to do so. Any mix that is chosen can lead to O2 tox if depth is not monitored. Using 50% at 50' is the same as using 40% at 70' given the same bottom time. Anything above 50% really starts limiting your depth.

 

[Far_X]

The danger lies in using the higher oxygen at deeper levels. Using a higher percentage at shallower levels has the benefit of reducing the nitrogen in your body more quickly which is the reason why you are ascending slowly and making your stops anyway. However, I don't know the formula to overcome the no deco stop so do get a few people's opinions on it rather than just one.

 

[DepartureDiver]

. . .then using the 50% mix as a travel gas upon assent to do an "accelerated deccompression" almost like a wash gas on assent.

Yes, learning to use a higher percentage gas during stops (even safety stops) does your body good. Plus you are getting good experience to transition into extended range and deco diving if you desire.

 

[padiscubapro]

Hey I am getting ready to take my nitrox course and an instructor was telling me that by taking my complete user course that I could use up to 50% oxygen mixes and that by doing so I could stay longer at depth than the tables and through careful planning breath a higher % oxygen mix on assent with out doing a "decompression" dive. Is this possible, becuase it makes sense as long as bottom time isn't excessive. I just heard this and decided to ask because as a non deco diver (yet ) it caught my attention.

Don't worry everything that you need to know will be covered in class.. ANDI's "nitrox"class is the most complete in the industry... You can figure on about 12 hours of academics.. The class you are taking is the equivalent of most nitrox plus advanced nitrox clases plus some additional information.. the only limit that some adv nitrox classes extend is oxygen use up to 100%.. CSU is a recreational rating and there is no reason for anything above 50%..

BTW when I do open water checkouts I dive with 50% in my doubles.. This allows be to cover any dephth alowable by OW and an emergency excursion deeper than that.. Even If I did everyy dive in an OW class to 50fsw (not a real situation), by effective depth is just under 20fsw, so basically I have no (realistic) nitrogen limit to worry about..

ANDI teaches the use of a RBS and its common to put a richer mix in your backup system so that you can switch to a richer mix on ascent to help the of gassing along.. There are other options which will be discussed in the class..

 

[wedivebc]

Interesting! I did mine with PADI and my DSAT tables only cover up to 40%. Higher oxygen AND longer than the tables makes me wonder wether you are not heading towards oxygen toxicity!! I would say, don't dive off the tables, not just yet. Do you know the point where decompression is required? Did you notice that the higher the oxygen percentage, the shallower you have to dive to stay within the tables? Get a second opinion but these are my initial thoughts. Stay safe man and happy diving!!

Actually the ANDI Complete Safeair User course teaches the diver to calculate equivalent air depths and best mix by providing the simple math formulas and not having to reply on a table. Although I teach some PADI programs I feel their nitrox program lacks some important aspects so prefer to offer the ANDI course instead.