Total Newb - Some Basic Questions

[DiveBZ]

Let me start by saying that I am pretty new to SCUBA, and do not claim to know ANYTHING other than the basics from OW like how to put on the gear and pretend like I can be buoyant. I have a long way to go, and a lot of time and dives left to continue learning. Please forgive me if these questions are rudimentary.

Ok, I've been up and down this board, and I can't seem to find the answer to a couple questions that I have.

I've just recently been certified, and I have some concerns.

1) All of my dive buddies use Nitrox. I, obviously, use Air, and I honestly have no plans to switch to Nitrox, for what seems like minimal gains and substantially elevated risks. (Maybe that will change in the future, but I'm good right now.)

So, that being said, if I'm on a wreck thats 100' down and I have an OOA situation, whether its free flow, complete failure of both second stages, or what have you, etc, etc, and my dive buddies are running Nitrox, am I subjecting myself to heightened risks for ascent and safety stops on Nitrox since I've been on Air for the rest of the dive? Are there any major concerns with switching to Nitrox at depth in an emergency?

As far as I can tell, as long as I don't try to continue the dive (obviously) on a share-air scenario, I should be fine, but I like to keep myself informed. The LDS owner simply stated "You'll be fine don't worry about it." Well, thats not gonna cut it, I would like to hear from some of the DM's here, since I was quite obviously worried about it.

I'm trying to decide if I should buy a pony bottle, or if the risks are so minimal that it's not worth the money. I don't plan on any deep dives, it's not really what I'm interested in, but I like to err on the side of safety.

2) Everyone keeps saying, here and at the LDS, to cut the little black pulls off of my dump valves. (I have a Sherwood Avid)

I can basically understand the idea behind it, but is it really that big of a deal? I kind of like knowing that I can get to it easily should there be an emergency requiring me to go fully positive in a last ditch emergency ascent. (I do realize that uncontrolled ascent is an absolute no-no in all but the most dire of situations, but I'm a Police Officer, I've been trained my whole life to plan for the worst.)

Thank you for your time and I am looking forward to becoming a part of the community here.

 

[MurkyRockDiver]

Hi DiveBZ welcome to the board. I dive Nitrox and do not believe it is dangerous as long as you follow a few simple rules. To answer your questions "briefly" you will be fine if you have to share air with a buddie using Nitrox, it is after all just a little more O2 and being on it a short period will not make much difference to you for you O2 levels.

A pony bottle is a good idea on deep dives or just long dives depending on where etc... it is really a personal choice, some just buy a larger tank. Lots of threads on Ponies here though so search away.

I can't help you on cutting the tabs on your dump values, I would not do it where I dive I see no point. I use mine from time to time.

Where are you on the job, we may have a few things in common

 

[BDSC]

First of all congrats on getting certified. I hope you will enjoy diving as much as I have.

I don't see any problems with breathing Nitrox in an OOA situation. At that point you will be ending the dive anyway and you and your buddy will be headed up so it shouldn't be a problem. FYI: I also don't dive Nitrox and have never seen what would be a real benefit for me to do it. I'm just fine on air.

As far as a pony bottle goes, I wouldn't waste your money on one. Especially if you won't be doing really deep dives. Every diver I know that bought one stopped using it after a year or two.

I also see no need to cut off the pulls on your BC. They are there for a reason I would think.

BDSC

 

[youngblood]

nitrox is great, it has prevented a lot of people from getting recreationally bent. The saying is that people get less tired after the dives---that may be true, I certainly feel better after diving recreationally with 36% than I do on air.

Ascending while using nitrox from 100 ' would actually be safer than doing an OOA ascent with air because of the raised levels of O2, there would be less N2 in your system, and less likely to get a DCS hit.

Stages/pony bottles are great---always carry one. You'll never know when you would need one and something like a 20 cuft to 40 cuft are so small and out of the way that it is really not bothersome at all. In fact, my rig is more balanced when I dive with stages and so I enjoy using them.

Rule of thumb: I'd rather have it and not need it than need it and not have it...within reason.

Get a EANX cert, there are little to no risks at all while diving nitrox. Just don't go past the MOD.

 

[mello-yellow]

So, that being said, if I'm on a wreck thats 100' down and I have an OOA situation, whether its free flow, complete failure of both second stages, or what have you, etc, etc, and my dive buddies are running Nitrox, am I subjecting myself to heightened risks for ascent and safety stops on Nitrox since I've been on Air for the rest of the dive? Are there any major concerns with switching to Nitrox at depth in an emergency?

As long as your buddies are diving within prescribed depth for their Nitrox mixture (a.k.a. MOD), the answer is no. In fact, your risks for ascent and safety stops become (very slightly) less. And if your buddies are NOT diving within prescribed depth for their Nitrox mixture, then you should not be their buddy to begin with!

There are concerns with doing it other way around -- diving Nitrox and switching to air at depth.

 

[SlowRain]

Hmmm.

Nitrox is like anything else in diving. If you follow the rules, you minimize the risk. As long as you are obeying the rules around using proper mix at appropriate depths, I don't see that it is any greater risk than using air. Certainly you can get yourself in trouble if you are diving a given mix and go deeper than the Maximum Operating Depth (aka MOD). That is not the gases fault, that is the operator for not following the rules. So as far as "substaintal greater risk" I would have to disagree.

If you went OOA, and were forced to breathe your buddies nitrox, you are erroring on the side of caution, again, as long as you (and your buddy) are observing the proper MOD and operating limits for the gas mix. Unless your buddy has an advanced nitrox certification, the highest mix he is going to be able to get is 40% and the MOD for that is below the 15' safety stop.

Honestly if you don't want to use Nitrox...that is an option. For about a 100 dollars you can take a basic nitrox course which I think would give you a bit of enlightenment around it and might, if nothing else, help you understand the issues around it's use. Personal choice I guess.

As far as cutting off the pull knobs? I have never contemplated doing such a thing. I agree if they are streaming out a foot from the dump valve that might be questionable but then just shorten the cord. If someone is preaching "oh they could be a snag hazard" I would worry more about hoses and valves before I would worry about a dump valve release.

Congrats on becoming a diver...good luck.

 

[Arizona]

DiveBZ,

Welcome to SB. I agree, using Nitrox (enriched air) in an out of air situation is not an issue and better than a CESA option. Nitrox does have a concern about going beyond certain depths depending on how much O2 has been added. If you find your air consumption is getting really good, well then Nitrox might be something worth looking into. Basically it will increase bottom time and lower your exposure to Nitrogen. If most of your dive buddies use it, IMO this may be another reason to look into it. You will then be able to extend your bottom time.

Consider the cost for the Nitrox cert, but also buying a computer if you don't have one already that is Nitrox compatible.

AZ

 

[fyh]

As for you switching from air to EAN during a dive, there really is no problem. If there's a situation where you need to breathe from your buddy's reg, you should be immediately aborting the dive and ascending at a safe rate anyway. At the point of you taking one of your buddies' regs and switching to Nitrox, you're actually taking in a lower partial pressure of nitrogen which, in essence, lowers the risk of a DCS hit.

You mentioned "substantially elevated risks" in relation to diving Nitrox. I imagine you're referring to the risk of taking an O2 tox hit. In the situation you're describing, there should really be no fear of that happening if you're switching to the same mix as your buddy (whose been diving at the same depth as you.)

On the other hand, if your buddy is diving Nitrox and pushing his NDL and needs to switch to your octo, he's probably more at risk (for DCS) than you were (for O2 tox) in the previously described situation.

There still seems to be lots of debate about how beneficial EAN is to a diver. You'll hear "more bottom time", "shorter SIT", "less chance of DCS", etc. All of these are true in certain situations, but not all situations.
-Where I dive, bottom time is dictated mostly by NDL, not tank capacity. So yes, I can get more bottom time on most of my dives by using EAN.
-Shorter SIT, well again, that depends on the depth, length, and mix used for your first dive, and the same for your repetitive dives. There are tables for Nitrox, just as there are for air. For the sake of simplicity, I just use a Nitrox capable computer.
-Less chance of DCS... that depends on you and your dives. If you're pushing your NDL and not paying attention to ascent rate, profile of your dive, etc., you're at just as much risk as someone doing the same on air.

If you are dead set against getting certified for Nitrox, I would at least recommend that you learn how to calculate the max depth for a Nitrox mix. Before each dive, know what mix your buddy is using, and know the max depth for that mix. That way if something does happen and you need to share his supply, you'll know what depth you should not exceed.

I'm not a DM or instructor, but I have been diving Nitrox for more than a year.

edit: Wow! you guys are quick... he had no replies when I started typing... maybe I'm just slow.

 

[Arizona]

I'm not a DM or instructor, but I have been diving Nitrox for more than a year.

fyh,

You are in the know regardless

I got my Nitrox cert very early and did not realize the full benefits till my air consumption improved.

AZ

 

[Oddsnends]

2) Everyone keeps saying, here and at the LDS, to cut the little black pulls off of my dump valves. (I have a Sherwood Avid)

I can basically understand the idea behind it, but is it really that big of a deal?

I didn't get this one either. Then a deckhand lifted my BC and tank out of the water. The pull ball wedged between the tank and the boat and tore the dump valve apart. I now dive using this modification. By using 2-4 inches of caveline you can easily grasp the line - even using 7 millimeter gloves. The trick is to make touch contact with the dump valve and grasp as you run your hand down the caveline.

Just be sure to drill this procedure. Include quickly detaching the LP hose from your BC inflator as part of the drill.