would you put a inexperienced diver on this dive

[MauiScubaSteve]

Since the OP will not give any pertinent details about the proposed dive all we can do is make up scenarios to fit our POV's. If this dive is the Deep Dive for AOW (Deep Specialty Dive #1), the profile of the dive is max depth 100'; 32% is an appropriate mix for a 100' max depth dive. If the mooring line is attached to the wreck, said attachment point is not deeper than 100' and the dive is planned to be over the wreck at less than 100' deep, the plan sounds like it could be appropriate.

 

[MauiScubaSteve]

Here is a dive report from a wreck off Virginia Beach last week; notice the temps, current and vis.

....

Both wrecks sit around 110-115 max.

Waves and current were very light. It wasn't a lake, but waves were probably 1-3 ft.

....

Temp was 79F on the top and 70F on the bottom, with thermocline at 30-50ft. Vis was pretty bad (for the area) at 10-30 ft, and full of particulate matter and millions of jellyfish. Lots of big sand tiger sharks, too! Great video dive.

But overall, because of very light waves, wind, and current, it was one of the easier days of diving out there.

 

[zenheadhunter]

If I am understanding you correctly, you were told that the diver would be using Nitrox EAN32, and that that mixture had a MOD of 134'. If 134' was given as the mod and not the planned depth of the dive, can you tell us how deep the diver is actually going to go?

FYI: According to PADI Enriched Air Diver Manual P.86,

The Maximum Depth for EAN32 (calculated for 1.4 ata) is calculated as (46.2/0.32)-33 = 111 fsw.

The Contingency Depth for EAN32 (calculated for 1.6 ata) is (52.8/0.32)-33 = 132 fsw.

The Maximum Depth is just that, the maximum recommended depth for that O2 blend. It is the depth at which the partial pressure of Oxygen (PPO2) equals 1.4 ata.

The Contingency Depth figures are there so that you can track your oxygen exposure if you accidentally exceed the Maximum Depth for some reason (PADI Enriched Air Diver Manual P.73).

Mike what i was saying in the post is for the nitrox blend the diver was talking about using (32%)nitrox .The safe pp02 for any dive is 1.4 and 1.6 is only generally used in deco and for divers pushing tech and exploration limits but the risks of cnsot and pot becomes a very real factor. As the atomic wieght of nitrogen is very close to oxygen the diver will be narcd pushing just past 1.6 not a real smart idea.The max bottom depth at the site is 134'.Hope we can agree just these factors plus the numerous others i have mentioned should be a reason not to make this dive.The diver should start with more practice dives and shallower wrecks like the indra in 70 feet of saltwater.

 

[Thalassamania]

Lets get real about MODs for a moment.

1.4 is incredibly conservative. In fact, 1.6 is rather conservative. Those are numbers pushed forward by agencies with liability concerns, physicians with liability concerns, and manufacturer's with liability concerns ... in other words, lawyers.

In the 1960s we dove to 2.0 routinely, we dove pure oxygen rebreathers to 30 feet with occasional bounces deeper, even to 60 feet and we tested our oxygen tolerance in chambers, on pure oxygen at 60 feet. There were not a whole lot of hits, all that I personally knew about were on chamber tests. So I have to admit, I am a little amused at the trepidation that diving 1.6 and decompressing at 1.8 is met with.

 

[zenheadhunter]

OK, so now I'm more confused and must make another post for you all to ignore: :mooner:



You typed the above words in the original post of this thread, so unless 3 Deep Specialty dives have already been made since you typed those words the diver in question will not be "getting his deep specialty on this dive."

If 3 deep dives have not been made, the AOW Deep Dive is the 1st dive of the Deep Specialty, and could be dived to a max depth of 110' if the Instructor has written permission from PADI to conduct AOW Deep Dives to 110' at this specific dive site.

PADI Deep Diver is a cert that gives the diver a recommended operational depth of 130' so it would be pretty silly to limit the check out dives to 100' max. Dive #3 of the Deep Specialty has a max depth of 130' and where I have taught or witnessed Deep Specialty certifications, Dive #3 is at least 120'.

So your friend with only the 4 check out dives of OW has completed the non-diving Nitrox cert (?) and has at least 8 training dives scheduled. With all the required Academics of Nitrox, AOW and Deep it sounds like your friend is taking proper training seriously. It would be interesting to hear about the actual dive from someone who was actually on the dive.

halemanō,

I will try to answer your questions 1. I,m sorry if i missed your question or ignored what you wanted to know
2.The diver is finishing his aow this weekend and passed his no dive nitrox class .The so called deep dive he will make on dive 4 or 5 of aow will be in 65 ffw max since where he is taking aow this is the max depth of quarry.The dive he will be doing for #2 deep dive will be 134'

question for you : In your post are you saying you would take this diver on this dive with all the issues he has had and still having and with the amount of diver that get hurt or dead diving beyond their abilities?

thanks,
Vince

 

[zenheadhunter]

Thalassamania ,
I was wondering is this a common practice to dive above a 1.4 And if it is how far do divers push the pp02 on a dive similiar to the dive i was reffering too in the op.Thanks for the info

 

[Mike Boswell]

Lets get real about MODs for a moment.

1.4 is incredibly conservative. In fact, 1.6 is rather conservative. Those are numbers pushed forward by agencies with liability concerns, physicians with liability concerns, and manufacturer's with liability concerns ... in other words, lawyers.

In the 1960s we dove to 2.0 routinely, we dove pure oxygen rebreathers to 30 feet with occasional bounces deeper, even to 60 feet and we tested our oxygen tolerance in chambers, on pure oxygen at 60 feet. There were not a whole lot of hits, all that I personally knew about were on chamber tests. So I have to admit, I am a little amused at the trepidation that diving 1.6 and decompressing at 1.8 is met with.

Thal, it is my understanding that oxygen toxicity is both a function of the O2 partial pressure and exposure time.

In recreational situations divers are doing 3-5 dives per day for multiple days using Nitrox to extend dive times. Would a "routine" ppo2 exposure of 2.0 be safe under those conditions?

 

[kaerius]

Thal, it is my understanding that oxygen toxicity is both a function of the O2 partial pressure and exposure time.

In recreational situations divers are doing 3-5 dives per day for multiple days using Nitrox to extend dive times. Would a "routine" ppo2 exposure of 2.0 be safe under those conditions?

And in the 60s they dove exclusively on US Navy tables, which require about twice as long surface intervals as the RDP.

 

[Slamfire]

Lets get real about MODs for a moment.

1.4 is incredibly conservative. In fact, 1.6 is rather conservative. Those are numbers pushed forward by agencies with liability concerns, physicians with liability concerns, and manufacturer's with liability concerns...

I've always been skeptical of a statement that circulates in certain diving circles. It goes something like this: "I believe that the risk of oxygen toxicity is underestimated and the risk of DCS is overestimated. Therefore I prefer to dive more around 1.2 instead 1.4." I would love to see the numbers behind that asseveration, if they exist.

Knowing how these standards are set to fit a fairly low common denominator and how they are affected by the liability concerns, gives me a pretty good feeling that I will not certainly die if you go to 1.6 for a few mins. I would be very interested in seeing the statistical testing behind the NOAA tables.

 

[scubafanatic]

...to the OP, you've gone above and beyond the call of duty here, honestly, sometimes you just have to let consenting adults do what they're gonna do and step out of the way. The odds are this diver will actually survive this event, there are scads of inexperienced/incompetent divers out there diving daily, and the vast majority of them survive, despite themselves....given what I see/hear all too frequently, I'm amazed there are as few dive accidents as there are. I'd suggest you NOT participate on the dive in question, keep your distance from this potential trainwreck/lawsuit.