Standard MOD
- Thread starter iztok
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Actually its still out there but there's so little data its tough to reach any conclusions. The concept picked up a little steam (at least amongst the medical people on places like TDS) after Liz Halbach's tox death.
The presentation of N2 as what we call "narcosis" is consistent with CNS depression while O2 toxicity is obviously CNS excitation, so they are working in opposite directions.
Somewhere in the neighborhood of 40 - 50ish. Nowhere the most experienced diver. MOD markings doesn't replace analysis markings and most likely the stages are going to be the same gas mixture as whats in your back gas and will be breathed down before you touch your back gas. It has nothing to do with nickel rocketing. Mailbox letters and/or duct tape and a sharpie are cheap.
LiteHedded
Contributor
ucfdiver
Contributor
What about when you're diving with a team? *YOUR* MOD might not be *EVERYONES* MOD, and it just causes confusion.
There's also the issue of not seeing the MOD sticker and assuming it's backgas. I could see a situation where on a cleanup dive after a long weekend, a diver has a brainfart and grabs a deco gas at the wrong time.
LiteHedded
Contributor
or a dive where you use two different mixes on the bottom...
Isn't part of the whole team process knowing who's got what gas and limiting the dive based on the shallowest MOD / END? Shouldn't that be caught during the planning phase of the dive rather than during the dive?
Proper switching procedures should mitigate that. If you and your team mate aren't verifying the MOD sticker (or lack there of) and your personally verifying your analysis markings / depth, then that's a lapse in judgment that a MOD sticker can't fix.
The only reason that I could fathom that (at this point in my diving career) is if I have a helium based mix in my back gas and EAN32 in a stage. At that point the stage would be just for the recreational dive and the back gas would be apart of the rock bottom. Enlighten me.
ucfdiver
Contributor
Sometimes we setup divers to go deeper. DIR wasn't designed to do cute little 20 minute at 150ft dives. Sometimes Team A has to carry stages 5000ft back into a cave for Team B, who will be going further (and deeper). Let's say we setup Manatee springs back to 10,000ft for exploration one weekend, and at 12k we find that it goes to 150ft deep. Now *every* bottle we setup has no MOD, and is no longer useful for our team to do the next push dive. We now get to remove every single tank, then label it (like you should have to begin with), and replace it. Now you've wasted 2-4 days of diving and possible exploration over a $5 sticker. Silly.
If you don't have a sticker, there's nothing to verify. Missing a MOD sticker isn't smart, but you've got to remember that sometimes working people are rushing to do a setup dive late Friday, pushing hard on Saturday, and then doing cleanup on Sunday. By day 3 fatigue is a huge issue IMO. Put MOD's in big stickers where you never switch unless you see the MOD, don't leave room for the "I didn't see the sticker" error.
PfcAJ
Contributor
Another point to reducing ppo2s in deeper deco gases is that if you do tox deep, you're fubar'd. If you tox shallow, you've at least got a chance of your buddy or support diver bringing you up. Small chance, but better at 70 or 20 than at 190.
In regards to high ppn2s staving off CNS toxicity, well... I think I'll stick with high helium and low o2. We know that works, and it doesn't have the drawback that narcosis does.
Marking stages is really a no brainer. Clearly, we can come up with situations where its a bad idea not to mark them. Yet, we can't come up with a reason NOT to mark them, other than my personal favorite of "its cheaper". Al80s aren't that expensive, its easy to own a bunch, and even easier to own tape and markers (which is certainly inferior, imo, but acceptable). If my broke, part time job college student self can own a bunch of al80s, I'm sure you can too
Amascuba, an example of one of those dives is a place like Indian Spring (and others, even Ginnie now) where its shallow for a ways, then gets deep. Which one is the right bottom stage? MOD stickers eliminate the question, and don't require math underwater or looking at a mini analysis tape that may or may not come off during your 4000' scooter ride. My buddy knows what gas I'm breathing, I know what he's breathing, the switch procedure is rock solid, and has no question marks attached to it. It also makes equipment inventory and management easy on the surface.
Sometimes support divers will be breathing a normoxic gas, while the lead team(s) breath hypoxic gas. Both are using stages, and both need to be appropriately and clearly marked so a mistake (which is the killer) doesn't happen.
The point of these procedures is to reduce the possibility of mistake, and they work in wreck diving, cave diving, exploration, you name it.
In regards to high ppn2s staving off CNS toxicity, well... I think I'll stick with high helium and low o2. We know that works, and it doesn't have the drawback that narcosis does.
Marking stages is really a no brainer. Clearly, we can come up with situations where its a bad idea not to mark them. Yet, we can't come up with a reason NOT to mark them, other than my personal favorite of "its cheaper". Al80s aren't that expensive, its easy to own a bunch, and even easier to own tape and markers (which is certainly inferior, imo, but acceptable). If my broke, part time job college student self can own a bunch of al80s, I'm sure you can too
Amascuba, an example of one of those dives is a place like Indian Spring (and others, even Ginnie now) where its shallow for a ways, then gets deep. Which one is the right bottom stage? MOD stickers eliminate the question, and don't require math underwater or looking at a mini analysis tape that may or may not come off during your 4000' scooter ride. My buddy knows what gas I'm breathing, I know what he's breathing, the switch procedure is rock solid, and has no question marks attached to it. It also makes equipment inventory and management easy on the surface.
Sometimes support divers will be breathing a normoxic gas, while the lead team(s) breath hypoxic gas. Both are using stages, and both need to be appropriately and clearly marked so a mistake (which is the killer) doesn't happen.
The point of these procedures is to reduce the possibility of mistake, and they work in wreck diving, cave diving, exploration, you name it.
IMO, there is no proper switching procedure when you're assuming a MOD because the tank lacks the sticker. This is going to bite you in the ass the day you actually forget to label a tank or get handed somebody elses unlabeled tank from the boat.
What this "no need to label bottom stages"-stuff adds is nothing but an completely unnecessary exception to a rule (for what purpose?) and a layer of assumption to verify the MOD.
It's the same problem as with any ways of color/fO2 coding MODs that pop up from time to time - you're going to have to decode to get to the MOD you're actually interested in.
That said, I've used an unmarked bottom stage (apart from the analysis sticker) now and then and survived, and often only label the left hand (buddy) side of a bottom stage unless it's a dedicated tank, but it's not something "we do" or I'd recommend to anyone as standard.
//LN
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