How Deep do you Dive?

[Solomon]

Maybe I am misunderstanding you but it appears you believe it is foolish to dive within nodecompression limits on air past 100 feet but then seem to disagree with me not wanting to spearfish at these depths on nitrox where there is a viable risk of being exposed to a PPO of 1.8 or greater. I think I know where you are trying to lead me and the answer is yes. Have not yet but probably will. You got me.

 

[Uncle Pug]

Originally posted by Solomon
You got me.

Well there are several ways to play this Solomon but lets take one at a time:

You are willing to dive air to 120 feet per your previous post...
You are also willing to spear a fish at 120 feet...
You have seen people pulled down 30 feet or more...
You have the potential of diving air at 150 feet or more while trying to control a 60lb fish pulling you deeper...

Questions:
Would you drop the gun? When?
Would you fight the fish? How long?
Would you realize what was happening?
Narcosis...

We can deal with the O2 boogeyman later.

 

[Solomon]

Like I said. You got me. My hesitation in using nitrox pretty much gives it away that, contrary to my earlier statements regarding diving air to 130 feet only, I am planning or preparing to do just that. Otherwise I should have no roblem in diving nitrox. Let me say that I have not gone deeper than 130 on air to date but to be honest I very well could while fishing. I have seen several do it many times. Not that that makes it right but . . . . Nonetheless, I still think my original point about nodecompression air dives to 130 feet is correct (although nitrox can be a safer gas within these limits).

 

[HDrider]

I have been following this post for the last few days. I have been trying to say out of it, but with the mention of shooting fish a large fish in somewhat deep water I wanted to put in my 2 cents worth.

Solomon you have stated that narcosis does not seem to effect you at 120’. I think it maybe a good idea for you to read this before the next time you have been at 120’ feet for say 10 minutes on a single AL 80, and you see a very nice large fish that you just cannot pass up.

I know the circumstances surrounding this article are different than (I would hope) anything you have ever done. But if you were to shoot a large fish at 120 and get pulled down 30 or 40 feet it could be possible to get desperately low on air without realizing and have no choice but to surface way to fast.

The narcosis that you are not feeling could just cause you to go ahead and take that shot when you really know you shouldn’t.
Reading this changed my diving quite a bit, it compelled me to take many long classes and buy lots more gear in order to be a safer diver.


Dive safe and often!
Tom

 

[MASS-Diver]

I've done a few wrecks around here (in the chilly NE) in 100-110' range on EANx32. Although I haven't felt narced at this depth, I'm sure I was a least somewhat impaired (like the guy who can't feel the 5 beers he had the bar).

Narcosis is the main thing that stops me from going deeper, I have wrecks that I want to do in the 150-200' range, but, I'm holding off for a while untill I can dive TRIMIX.

The only guy I know that got bent did it on a 60' dive well within the NDL (Cold water). I guess he took a hot shower right after the dive and he attributes that to the onset of the bends, he has made a decent recovery and still carefuly dives.

One thing that I think would help the rec "deep" diver was if 50%-100% O2 was more widely avaiable in LDS (I can only get 40% with my PADI NITROX cert and I don't have the $ to set-up my own mixing station). Still, after a 15min dive at 100' in 40deg water I would love to have a bottle an O2 bottle to breath off at 15-10'.

 

[HDrider]

Originally posted by MASS-Diver
One thing that I think would help the rec "deep" diver was if 50%-100% O2 was more widely avaiable in LDS (I can only get 40% with my PADI NITROX cert and I don't have the $ to set-up my own mixing station). Still, after a 15min dive at 100' in 40deg water I would love to have a bottle an O2 bottle to breath off at 15-10'.

At the certification level you are at that is all you should be able to get.
The classroom portion of Advanced Nitrox was the most intense classroom of any dive class I have taken. I think it was at least as intense as Nitrox Gas Blender. The reason I mention this is to point out that there is a big difference from the up to 40% certification you have and a 100% certification. This is the reason your LDS will not fill your tanks with more than 40%. I am sure if you took an advanced Nitrox course, and get at least one of your regulators O2 cleaned your LDS would be happy to give you a fill of what ever you would like.

Tom

 

[MASS-Diver]

HDrider,

The LDS around here will not fill more than 40%max, regarless of cert. level.

I really feel that rec divers that are doing non-deco diving in cold water could benefit from breathing 50-100%O2 at saftey stops. I know most board members disagree.
Maybe at my current cert level I'm just not aware of the risks of using 100% O2 (campared with 40%) and I need lots more training before even thinking about not using it, but, my understanding with 100% O2 is:

Use only O2 cleaned/safe tanks/gear
Don't breath it deeper than 10' (label the bottle clearly, use common sense and proper config to prevent from breathing at depth - this is actually properly easier for rec guys with only 1 primary reg and a backup than for tech guys dealing with multiple stage regs).

Am I missing something? I have been told that at my current level, 100% O2 is "none of my business", but, I think it would my diving alot safer.

 

[Uncle Pug]

Originally posted by MASS-Diver
Am I missing something?

Yep... several things.

First: MOD for O2 is 20 feet not 10.... and 20 feet is where it is most effective because the PO2 is 1.6 and you get the maximum oxygen window.

Second: Buoyancy skill in holding stops is very important at this point... and is also the most difficult from 20 feet on up.

Third: An Air dive with its huge nitrogen content is not going to be effectively decompressed from using a mix with 50% nitrogen.

Fourth: You are trying to solve a problem that should not exist on a dive to 100 feet for 15 minutes and adding a complication that could result in a serious accident.

Fifth: You shouldn't be diving elevated PO2s (EAN32) in your back gas past the NDL if you then need to deco with gases at a high PO2.

Sixth: Sooner or later you run the risk of handing off or taking the wrong regulator yourself at depth and getting whacked.

Seventh: You know.... HDrider is right.... you should take a decompression proceedures type class if you really want to do this safely... I would recomment DIRF followed by GUE Tech 1.

 

[WreckWriter]

Originally posted by Uncle Pug
Fourth: You are trying to solve a problem that should not exist on a dive to 100 feet for 15 minutes and adding a complication that could result in a serious accident.

All of Pug's points are good but I think this one is most important. Just dive EANx, you don't need the O2 for recreational exposures. The risks outweight the bennies in this case I think.

Tom

 

[MASS-Diver]

Well, you guys make some good points, but, I'm still not sure. You guys don't think breathing 100% O2 on a deep EANx dive which approcaed NDL limits in very cold water would add a margin of saftey (if the user is properly trained)?

What if I "mess-up" and I stay longer then my NDL (I get tangled/lost/trapped, etc.), you don't think it would advantageous for me to have a bottle of O2 to decompresses with?

I'm not sure about this and it's nice to feedback and I know for most people the answer will be a resounding no, but, I just feel with repetitive diving in cold water with air or NITROX anything that would help me end the dive with less N2 in me would be worth learning to use.