MOD Stickers

[tomfcrist]

Standard gases were not determined randomly--they make just as much sense for any agency.

I am aware that it wasn’t random.

Unfortunately, they make the most sense for the primary reason they were developed, which was very much dependent upon location--and that means Florida.

It means Florida caves. The percentages make less sense when you can’t stage your deco gasses along your route...ie deep ocean diving involving extensive wreck penetration(just as likely to be a traverse as it is a circuit).

Of course, if you don't have banked EANx 32, you lose all that advantage, and you are left with other reasons for choosing those gases.

It’s alwYs been an ease of blending thing. So if you don’t have access to a bank of nitrox (like you) and you are PP blending everything anyway, why not choose more advantageous mixes for the particular profile you are diving?

 

[PfcAJ]

It’s alwYs been an ease of blending thing. So if you don’t have access to a bank of nitrox (like you) and you are PP blending everything anyway, why not choose more advantageous mixes for the particular profile you are diving?

1. You run in to the issue we’re discussing regarding MOD stickers. With standard gases you don’t have to change anything because the gases are constants.

2. Due to constantly changing gases one is unable to definitively learn and remember decompression schedules. With standard gases it’s incredibly easy to memorize decompression schedules.

3. You now have a need to keep a huge deck of tables on hand with every conceivable gas combo. With standard gases you only need tables for a few bottom gases and a few deco gases.

4. Any adjustment of the dive location renders your gases “suboptimal”. At best you’re in the same boat as the standard gas guys. Worst case your gases are inadequate. Your range is roughly 50’ with standard bottom gas and the deco gases are always the same, just add or subtract what you need.

5. Dive planning requires extra steps and (as discussed earlier) each step creates a potential for error. No such problem with standard gases. Everyone knows the deal.

6. Logistics are greatly simplified. I can’t even begin to count the times someone has snagged a bottle from another team member, and that’s not at all a problem because everyone is on the same page. Helps when traveling too, since everyone is already dialed in.

Reasons to use “best mix”:

1. Look I saved 2mins of deco!!

2. ???

 

[boulderjohn]

2. Due to constantly changing gases one is unable to definitively learn and remember decompression schedules. With standard gases it’s incredibly easy to memorize decompression schedules.

3. You now have a need to keep a huge deck of tables on hand with every conceivable gas combo. With standard gases you only need tables for a few bottom gases and a few deco gases.

A lot of people are using desktop software programs that eliminate the need to have a huge deck of tables. They can plug in their gases and get a schedule. No need for a huge deck of tables. That was actually the norm in the divers who surrounded me a decade ago. I actually don't see that much anymore, because...

A lot of people are using computers now, They don't feel an overwhelming need to memorize decompression schedules.
............

If you are doing all your decompression calculations in your head, maintaining an average depth in your head, calculating your ascent strategy based on a mathematical formula, etc., then there is no question about it--using standard gases makes all that much easier. You certainly win on that point.

 

[tomfcrist]

1. You run in to the issue we’re discussing regarding MOD stickers. With standard gases you don’t have to change anything because the gases are constants.

You see it as an issue to take the 6 seconds to mark a MOD. Got it.

2. Due to constantly changing gases one is unable to definitively learn and remember decompression schedules. With standard gases it’s incredibly easy to memorize decompression schedules.

I have no intention of “memorizing” decompression schedules...just like I don’t memorize maintenance manuals for fighter jets.

3. You now have a need to keep a huge deck of tables on hand with every conceivable gas combo. With standard gases you only need tables for a few bottom gases and a few deco gases.

Who keeps tables? Welcome to the new millennium.

4. Any adjustment of the dive location renders your gases “suboptimal”. At best you’re in the same boat as the standard gas guys. Worst case your gases are inadequate. Your range is roughly 50’ with standard bottom gas and the deco gases are always the same, just add or subtract what you need.

Which is somehow different than nearly always having suboptimal gasses?

5. Dive planning requires extra steps and (as discussed earlier) each step creates a potential for error. No such problem with standard gases. Everyone knows the deal.

I don’t see the extra steps. I can literally plan a 400’ dive in 2 minutes.

6. Logistics are greatly simplified. I can’t even begin to count the times someone has snagged a bottle from another team member, and that’s not at all a problem because everyone is on the same page.

Cough... if that were only true.

There have been multiple incidents of divers inside and out of the WKPP of people unknowingly breathing a gas that wasn’t properly represented by the beloved Permenant MOD of a “standard gas”.

Reasons to use “best mix”:

1. Look I saved 2mins of deco!!

2. ???

That’s cute.

 

[tomfcrist]

It’s worth mentioning that it’s not unheard of for people currently and formerly associated with your associates to repurpose bottles...240 bottles becoming 300 bottles and so forth.

Additionally, while logistically it’s acceptable for someone who dives with a team of 30+ other divers that dive the same site repeatedly, all of whom have 15+ bottles of different flavors to not have to repurpose bottles very often.

Most dive teams are much looser than that, and for some of us our buddy list can be counted on one hand. That and we rarely dive the same profile consecutively...thus it’s advantageous to mix for what we are diving that day.

 

[Jack Hammer]

I like "standard" gasses simply because they are very flexible. When my sinuses wouldn't clear about 15' into a dive with 3 stages that I thumbed (much to the displeasure of my buddy), I was able to use both those stages and my backgas shortly after on some other dives that were both deeper and shallower without needing to bleed off and remix either. I've also been on several boats where we ended up going shallower/deeper than planned due to poor conditions at our intended site. Best mix would have been unsafe several times when our dives eneed up at a deeper site and I would've had to bow out of some awesome dives.

I also like being able to dive with people who are on the same deco schedule as me instead of we'll drop down together and begin our ascent together but you do your thing and I'll do mine... see ya on the surface 8|

That said, do whatever works for you, I do what works for me

 

[stuartv]

4. Any adjustment of the dive location renders your gases “suboptimal”. At best you’re in the same boat as the standard gas guys. Worst case your gases are inadequate. Your range is roughly 50’ with standard bottom gas and the deco gases are always the same, just add or subtract what you need.

I like "standard" gasses simply because they are very flexible. When my sinuses wouldn't clear about 15' into a dive with 3 stages that I thumbed (much to the displeasure of my buddy), I was able to use both those stages and my backgas shortly after on some other dives that were both deeper and shallower without needing to bleed off and remix either. I've also been on several boats where we ended up going shallower/deeper than planned due to poor conditions at our intended site. Best mix would have been unsafe several times when our dives eneed up at a deeper site and I would've had to bow out of some awesome dives.

As I said before:

Best Mixes are a superset of Standard Gases. There is no gas choice that isn't allowed by Best Mix (as practiced by me, anyway). It is only Standard Gases that are limiting.

Best Mix doesn't mean I HAVE to use the gas that will give me exactly 1.4 on my ppO2 at max depth. It just means I can. But, I can also factor in things like "what can I make with what I have?" And I can factor in "my target dive site has a max depth of 140, but I might have to divert to a different site and that has a max of 160."

I can't say that I know a huge number of tech divers. But, I don't know any that would plan a dive to one site, knowing that weather or other conditions might result in diverting to a deeper site, and insist on using gas where the MOD is the depth of the shallower site.

The result is that in ALMOST ALL cases, whether the dive is diverted to an alternate site or not, the Best Mix bottom gas is closer to optimal that if one were using Standard Gases. Examples? Any plan where one site is in the depth range of one Standard Gas and the alternate site is in a different depth range.

Site A is 140' and (alternate) Site B is 170'. If I understand Standard Gases correctly*, you'd be using a 200' gas on a 140' site. Or a 200' gas on a 170' site. With Best Mix, you'd use a 170' gas on a 140' site or a 170' site. Better in either case.

Site A is 90 feet and Site B is 130. With Standard Gases, you'd be using a 150' gas on a 130 site or a 90' site. Best Mix, you'd be using a 130' gas on either. Better in either case.

More examples? Any plan where both sites are in the same range, to use the same Standard Gas, but both sites are not at the max depth allowed for the Standard Gas. Site A is 115' and Site B is 130'. SG = 150' gas on both. BM = 130' gas on both. BM is better.

Site A is 160. Site B is 180 feet. SG = 200' gas on both. BM = 180' gas on both. BM is better.

In fact, Standard Gases are never better. And it's only "as good" when the dive is to the max depth of the range for the Standard Gas being used.

None of that is to say that you shouldn't stick to your standard gases. It's only to say that the oft-cited reason of "Standard Gases are more flexible. They will accommodate diving a different site if you need to" is bunk. A system that gives you MORE options for gas choices (including ALL the options available in the Standard Gas menu) is obviously more flexible.

If you prefer to plan and dive using a deck of tables and calculating deco in your head, Standard Gases are obviously the way to go. No dispute on that point of support for Standard Gases. No dispute on ease of mixing, either - IF you have banked NItrox32 to work with.


* I may not have the correct numbers for the range boundaries of Standard Gases. If not, plug in the correct numbers for whatever flavor of Standard Gases you use and the point remains.

 

[kelemvor]

I like "standard" gasses simply because they are very flexible. When my sinuses wouldn't clear about 15' into a dive with 3 stages that I thumbed (much to the displeasure of my buddy), I was able to use both those stages and my backgas shortly after on some other dives that were both deeper and shallower without needing to bleed off and remix either. I've also been on several boats where we ended up going shallower/deeper than planned due to poor conditions at our intended site. Best mix would have been unsafe several times when our dives ended up at a deeper site and I would've had to bow out of some awesome dives.

I also like being able to dive with people who are on the same deco schedule as me instead of we'll drop down together and begin our ascent together but you do your thing and I'll do mine... see ya on the surface 8|

That said, do whatever works for you, I do what works for me

The one time I've had to punt due to conditions at a planned site, the captain worked with us to select a new site appropriate for the gas we were carrying. That wasn't a technical dive, but we were carrying 40% so had a limited MOD. I think you've got at least several options in your scenario. Obviously, you can go back to shore and re-mix for some other dive. You can plan for a more appropriate alternate, or you could just reschedule the same dive. If you've thumbed due to sinus problems, I don't see why you wouldn't just reschedule the same dive unless you really didn't want to do that dive in the first place.

To each his own. I have to agree with Stuart, best mix is best for me. One of the great things about diving is that I can do it my way and you can do it yours.

 

[Jack Hammer]

The one time I've had to punt due to conditions at a planned site, the captain worked with us to select a new site appropriate for the gas we were carrying. That wasn't a technical dive, but we were carrying 40% so had a limited MOD. I think you've got at least several options in your scenario. Obviously, you can go back to shore and re-mix for some other dive. You can plan for a more appropriate alternate, or you could just reschedule the same dive. If you've thumbed due to sinus problems, I don't see why you wouldn't just reschedule the same dive unless you really didn't want to do that dive in the first place.

To each his own. I have to agree with Stuart, best mix is best for me. One of the great things about diving is that I can do it my way and you can do it yours.

Location is important. Not everyone lives in Florida or in coastal areas where one can more easily just make the same dive again. In our case we drove 350 miles for a weekend conference. Helium runs $2+ a cubic foot here, it costs less in the long run to use it on a shallower dive than to dump it and remix. Lake Michigan weather changes can be quick and surface conditions can be spotty and very different 10 miles away, not all wrecks in an area are close to each or at the same depths. Too many times we've gone to one site to find it too rough and ended up on a different part of the lake. It's not uncommon to show up at the dock and find out your planned site has been changed or the charter cancelled. Alternatives are always discussed among everyone.

For tech dives I generally keep 18/45 in my tanks because it's flexible enough for a lot of different sites and keeps my head much clearer.

 

[stuartv]

It's like the Standard Gases people just don't want to hear it.

Best Mix does not mean I HAVE to use a gas that gives me a ppO2 of 1.4 at my planned site. It means that I CAN use whatever gas is "Best" (in my opinion) for my total overall dive plan.

If I have to sit out a dive because something changed and my mix is too rich for the new plan, that is a fault of my planning, not a fault of Best Mix.