Question How to dive nitrox for the first time

[Nemrod]

I am of a mnd that many who dive an air setting on Nitrox simply do not understand how to set their computers. As I have been told several times after being asked "how you stay down so long" my answer was learning to be still, using Nitrox and setting my computer accordingly. Then I am told, "James, we are just not into the technical stuff" and the next dive both of their computers locked out.

I am thinking to begin to advocate this basically harmless practice. That way, me and the DM or my buddy or whoever is left can have often a good 20 minutes of wonderful diving and with no fins sticking ino the side of my frame. Again, priceless.

I am not advocating or bragging about this profile, it was 32% mix and I was back on deck with a solid 500+ psi with an adaptive 5 minute safety stop and a cautionary 40 foot pause (half average depth). It is a bad practice to ride the computer even knowing the deco obligation will clear on ascent. But, sometimes, there is something interesting, I had the gas and well, bad, bad, bad Nemrod . All the cool stuff shows up like right at the last minute dang it. I shot my own buoy at 40 feet and surfaced alone.

 

[Subcooled]

@KatieMac
You are fooled if you think you are reducing your nitrogen load by ascending a bit if coming close to it - well at least if we are speaking about 30m.

Actually you then may load more tissues to the max than if you do an honest dive - speaking from the model. Afaik there is some evidence that doing this increases the risk of a dcs hit.

And "extending" the safety stop has probably been a real deco stop.

Now, while I belive this answer was not in the correct place, the message is an important one and worth bringing up.

 

[Subcooled]

This is just not true in all cases. I routinely dive 32% and my buddy dives air. My bottom time is generally limited by volume not by his %O2. I dive 32% to reduce N2 loading and a clearer head. However, I always set my computer appropriately so alarms are real and actionable.

When I dive on nitrox 30,32,34 or even 40, and my dive buddy is on air we do this:

1. I declare the maximum depth (oxygen toxicity is the limiting factor over gas narcosis)
2. My dive buddy declares the dive time (his/her nitrogen load being the limiting factor)

Which ever condition is met first, will be respected.

This is a simplified model without overhead diving and all the complications that it infers.

 

[Subcooled]

Lets clarify up a few things

When you increase the O2 % in the breathing gas
1. you cannot go quite as deep
2. you can dve longer in the shallows

 

[happy-diver]

All the cool stuff shows up like right at the last minute dang it.

 

[34109411]

I got my nitrox cert in 2023 as a dry course at the end of a dive trip but haven't dove nitrox since yet. I want to try nitrox on my planned october trip to cebu (moalboal, oslob, malapascua) but honestly I don't think I remember much from the course.

I will certainly do a full review of the course materials before the trip which I think are still available because the cert was with SSI. However, from what little I do remember, apart from the theory and the science, nitrox doesn't change much "how" I dive except that I need to check the gas and set my computer to nitrox mode, right? If there's a lot more I should do in practice then I better shut up and go back to the first page of the textbook now, but I just want to get a basic sense of where I am at the moment. Thanks in advance!

read the book again.