Preperation for a deep dive...

[breals]

I know that. 20ft I think is still too deep to use 100% isn't it? I was quoting the manual whar Seabear70 recommended using. I will soon know when I can find some proper tables for tech/sport divers.

No, 100% @ 20 ft is right, it's a 1.6 ppo2 which is an acceptable risk when you are decompressiong and not moving around.

The tables won't tell you WHY it's acceptable to use 100% at a given depth. A Nitrox course will explain most of this.

 

[junior diver]

Oh. Sorry. I did the maths wrong. I have to convert into feet from meters.
PS: MY 100TH POST YEEESSSS

 

[Seabear70]

I know that. 20ft I think is still too deep to use 100% isn't it? I was quoting the manual which someone recommended using. I will soon know when I can find some proper tables for tech/sport divers.

If you look at table 21-5 in the Navy dive manual, you'll see that O2 can be used at depths of up to 60ft, and is commonly used that way in treatment of DCS.

HOWEVER That is in very controlled environments, and it is not a constant use of O2. Typically there is a switch to air every 25 minutes for 5 minutes to drop the level of Oxygen in the body. This is proceeded by a full vent of the ambient air in the chamber. This is also a case where we can put another diver in to pull the oxygen mask off of a diver in a big hurry, have a medic nearby, and can control depth to a very fine degree.

 

[junior diver]

Couldn't you technically use 100% as deep as you pleased if you were in a simialar kind of suit to a WASP suit? Because you could change the pressure inside the suit so that the O2 wouldn't become toxic.

 

[Seabear70]

A wasp suit is sealed at the surface and is not supposed to drop below 1 atmosphere. It could, I suppose theoretically be pressurized to a deeper level, but there would not be much point in it, in addition, as it is running at one atmosphere, enriched air may be of some penefit, but it's not going to be for deco.

 

[RIOceanographer]

Couldn't you technically use 100% as deep as you pleased if you were in a simialar kind of suit to a WASP suit? Because you could change the pressure inside the suit so that the O2 wouldn't become toxic.

Yes, they maintain 1 atm of internal pressure so physiologically it is no different from breathing at the surface. But you don't get DCS or narcosis in them either so there isn't much use for pure O2.

It is better to think of those things as wearable submarines not dive suits.

 

[junior diver]

Talking of dive suits. What kind of exposure suit are you using for this dive?

 

[Seabear70]

Talking of dive suits. What kind of exposure suit are you using for this dive?

Most likely a dry suit, though I do not relish the Idea of four and a half hours in a sealed suit.
http://www.trelleborg.com/protective/template/T036.asp?id=635&lang=2

I've a lot of experience in Viking dry suits, and I find them to be rather rugged.

 

[junior diver]

May I recommend an undersuit? http://www.dui-online.com/newsite/dw_thinsulate.htm The 400 model keeps 85% of its insulation even on a full flood. I know people what have this suit and when they get into warmer climates they don't bother with wet suits and just use one of these instead!

 

[EIGHTWGT]

I read this post and all the replies....... some real good advice here.....

My small addition is to look back over what everyone is telling you and realize why..... This is a very difficult dive - more than you think Im sure.

Id like to suggest you go to :
http://www.gue.com

Take a look around....