Nitrox for shallow water artifact diving??

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"For example, the manual allows a diver to make a no-stop ascent after exposure to 25 fswg for less than 10 hours, before he is saturated, but there is no information on the risk if the diver is saturated at 25 fswg and is forced to make a direct ascent".


There ya go OP keep it under 10hours!
Or, from the Abstract, "No DCS occurred on shallow saturation dives between 12.0 and 20.5 feet of seawater, gauge (fswg) but incidence of DCS rose abruptly when depth was deeper than 20.5 fswg..."
@AfterDark It seems like you've shifted from claiming no DCS possible above 35 ft to arguing how long a dive can be at 25 ft. I guess that is progress.
 
There is another important factor. Looking at tables for caisson workers/sand hogs, the DCS rate is higher than what would be acceptable in a recreational environment. This is acceptable because they have chambers to treat them without having to wait hours in an ER and "hope" they can find a doc that has any idea what DCS is or where to find a chamber.
 
There is another important factor. Looking at tables for caisson workers/sand hogs, the DCS rate is higher than what would be acceptable in a recreational environment. This is acceptable because they have chambers to treat them without having to wait hours in an ER and "hope" they can find a doc that has any idea what DCS is or where to find a chamber.

Frankly speaking, the differences among commercial diving, military diving, leisure diving and others are so much that comparing tables coming from different scenarios does not make so much sense in my opinion (except for scientific/cultural reasons). It can even be dangerous.
 
Frankly speaking, the differences among commercial diving, military diving, leisure diving and others are so much that comparing tables coming from different scenarios does not make so much sense in my opinion (except for scientific/cultural reasons). It can even be dangerous.

because
1) commercial divers have immediate access to a recompression chamber
2) military divers are either very fit or in combat or #1 does apply
Is this correct?
 
Frankly speaking, the differences among commercial diving, military diving, leisure diving and others are so much that comparing tables coming from different scenarios does not make so much sense in my opinion (except for scientific/cultural reasons). It can even be dangerous.

It's not that different. Decompression tables and algorithms are a direct product of military and commercial diving research. Dr Albert Bühlmann's earliest work in decompression theory was in support of Hannes Keller deep diving experiments. Haldane's original work was commissioned by the Royal Navy.
 
In the context of the OP question, dives in the ranges he posted, would take a good bit of endurance in the OW real world to in run into DCS issues. So as I posted I wouldn't have any DCS concerns about me doing 4-5 hour dive on 21% in that range, much more time @20-25FSW than below 33FSW if I could stand the cold.
 
So as I posted I wouldn't have any DCS concerns about me doing 4-5 hour dive on 21% in that range, much more time @20-25FWS than below 33FSW if I could stand the cold.
What you actually said earlier:
OP posted 40FSW or less; with that in mind any dive above 33FSW there are no NDLs so nitrox would be no help. Above 33FSW the whole dive is a SS.

The nitrogen absorption above 33FSW is for all purposes zero. A SS can be anything above 33FSW, since the body is off gassing above 1ATM.
Air at 26FSW has no NDL, reason no nitrogen absorption.

Actual 33fsw is 2ATM absolute. For most discussions of this nature 1ATM is used but you can have it your way.

The fact is nitrox is used to extend NDLs. Above 33FSW or 2ATMA there is no NDL so nitrox is no benefit to the OP at those shallow depths. Below 33FSW is where any benefit would be incurred.
So I'm pleased that we have moved from "no NDL above 35 ft" to seeing some actual NDLs on tables and realizing that it would take some pretty long dives to incur DCS. But possible. Hence the answer to the question of whether Nitrox would help is Yes.
 
because
1) commercial divers have immediate access to a recompression chamber
2) military divers are either very fit or in combat or #1 does apply
Is this correct?

Yes, plus something more

It's not that different. Decompression tables and algorithms are a direct product of military and commercial diving research. Dr Albert Bühlmann's earliest work in decompression theory was in support of Hannes Keller deep diving experiments. Haldane's original work was commissioned by the Royal Navy.

I amis aware of that. In the end, the basic principles of human physiology are the same for everybody, but...
1) fitness level can be very different, and it has an impact on how people react to nitrogen, gas density, etc.
2) risks that people accept to take depend very much on the activity, with military personnel taking probably the highest risks, followed by commercial divers
3) support is quite different as well
4) typical dive profiles can be, again, very different

Without knowing better, I would say that tables reflect these characteristics... so I wouldn't use a military table for leisure diving
 
Why use 35FSW for 25FSW dives? The fact is there is no table information for dives less than 35FSW. Nothing in the rules says to go to the next greater depth if the original depth was not exceed.

I'd be more concern with O2tox using nitrox for shallow dives of long duration N loading is less of concern in shallow water. The O2% can be reduced to avoid that but also reduces N loading "benefit".

If I had surface supplied air and could stand the cold water I'd have no qualms about a 4-5hour dive @25fsw.
 
Why use 35FSW for 25FSW dives? The fact is there is no table information for dives less than 35FSW. Nothing in the rules says to go to the next greater depth if the original depth was not exceed.
I don't know why you are quoting yourself here, and I don't know the exact meaning of the sentence I put in bold type. But in light of your statement about nothing being in the rules about using 35 feet for a 25 foot dive, I will once again quote page 6 of the instruction book, under the title "General Rules for Using the Recreational Dive Planner." Please note that this is the fourth time (IIRC) I have quoted this rule in this thread.

2. Any dive planned to 35 feet or less should be calculated as a dive to 35 feet.​
 

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