Request for opinions about standardizing on EAN80

[doctormike]

The 100% could come handy on the surface.
I normally dive with 50% and 100% but if I only have one deco gas then my choice is also 50%.

Yup, I thought of that too, but wherever I do these dives, there is always O2 on the boat.

I know that the quarry has O2 from personal experience!

 

[MegDiver792]

Rather than ask people, plug your dive into multi deco and see what the varied gases do. Calc gas requirements.

You may likely find 80% as a compromise to carrying multiple deco gases. Try 70% also.(my favorite)

 

[doctormike]

Rather than ask people, plug your dive into multi deco and see what the varied gases do. Calc gas requirements.

You may likely find 80% as a compromise to carrying multiple deco gases. Try 70% also.(my favorite)

Actually, I'm asking people because I was hoping to hear other aspects of the decision besides the differences in profiles (such as operational safety, equipment issues, O2 toxicity, etc..). That's one of the benefits of this big community of experienced divers. Sometimes people come up with stuff that I hadn't thought of.

I play with multi deco constantly and there isn't a big difference in my typical run times and deco times between 50, 80 and 100.

 

[kwinter]

I've said it many times. Reducing deco time with richer mixes is a dual edged sword. Lower DCS risk is accompanied by higher O2 risk. While the risk of OxTox may be minuscule, the consequences of a seizure underwater is virtually certain death. Spending a few more minutes with a lower O2 mix is a worthwhile trade off in my mind. If I am not as efficient in my deco, I might slightly increase my chance of getting bent. This would tend to happen after I'm back on the boat or onshore, with help and O2 available. A ride to the chamber beats a ride to the morgue any day.


iPhone. iTypo. iApologize.

 

[MegDiver792]

Actually, I'm asking people because I was hoping to hear other aspects of the decision besides the differences in profiles (such as operational safety, equipment issues, O2 toxicity, etc..). That's one of the benefits of this big community of experienced divers. Sometimes people come up with stuff that I hadn't thought of.

I play with multi deco constantly and there isn't a big difference in my typical run times and deco times between 50, 80 and 100.

then you need to read what people are telling you, like re-read my last sentence. It had nothing to do with deco times and everything to do with not carrying multiple deco gasses. Ken also adds another good point on not so rich O2 mixes. Thats why I prefer 70%. Avoids higher O2 issues, you can get on it earlier, and for dive planning and bail out, keeps me at 1 deco gas, instead of 2 without a huge penalty in deco.

 

[doctormike]

then you need to read what people are telling you, like re-read my last sentence. It had nothing to do with deco times and everything to do with not carrying multiple deco gasses. Ken also adds another good point on not so rich O2 mixes. Thats why I prefer 70%. Avoids higher O2 issues, you can get on it earlier, and for dive planning and bail out, keeps me at 1 deco gas, instead of 2 without a huge penalty in deco.

I am reading what people are telling me, and I appreciate it (see my responses above).

Not sure if I have offended you, but when you say that I should just use multi deco and not ask people here for their opinion, I don't really get what you are implying. Isn't the point of this board to ask people their opinions?

Ken's point is a good one, and I appreciate it.

You only posted one thing, which was that 80% was a good compromise to carrying multiple deco gases, which was something that I mentioned that I wasn't doing now or in the future.

Again, I don't mean to be difficult, but I don't think that you are considering the question that I asked.

 

[rossh]

To the questions:

1/ A tank of 80 needs to be drained and refilled every time, while the tank of 100 is just topped off. You need to take a full tank of 80 for every dive, but a tank of 100 can be re-used because you need less of it. A tank of 80 can be harder to make when the O2 supply is getting low, while you don't need to take a full tank of 100.

2/ For deco quality reasons and O2 exposure, its better to add the deco mixes from bottom up and not top down. When using a single deco mix, its better to use the 50 or 75 or 80, and not the 100. The 100 works best in conjunction with other deco mixes, but can be a little too aggressive when used in isolation against air only type dives.

 

[doctormike]

To the questions:

1/ A tank of 80 needs to be drained and refilled every time, while the tank of 100 is just topped off. You need to take a full tank of 80 for every dive, but a tank of 100 can be re-used because you need less of it. A tank of 80 can be harder to make when the O2 supply is getting low, while you don't need to take a full tank of 100.

True, although I can get either fairly easily where I am diving locally (and wouldn't have this issue when traveling and renting bottles). Also, the typical fill of a bottle of EAN 100 is significantly lower than a bottle of 80, so even though I'm using less, I also have less to start with.

2/ For deco quality reasons and O2 exposure, its better to add the deco mixes from bottom up and not top down. When using a single deco mix, its better to use the 50 or 75 or 80, and not the 100. The 100 works best in conjunction with other deco mixes, but can be a little too aggressive when used in isolation against air only type dives.

Thanks, that's a good point, another reason to maybe just carry EAN50 for now - can always change if I ever do trimix or start carrying two deco bottles for other reasons...

I appreciate all of the advice!

 

[nadwidny]

At the risk of repeating previous stuff-

If you have a DCI incident then you want 100% on hand. Not 80%.

When you move to CCR (because pretty much all tech divers eventually do if they stay with it long enough) you are going to be using 100%, not 80%. It's best to become familiar with it now, not later.

100% is easier to mix.

 

[doctormike]

At the risk of repeating previous stuff-

If you have a DCI incident then you want 100% on hand. Not 80%.

There is always plenty of 100% on hand where I dive.

When you move to CCR (because pretty much all tech divers eventually do if they stay with it long enough) you are going to be using 100%, not 80%. It's best to become familiar with it now, not later.

Hah! Have been struggling with THAT one all season. Pretty sure that I'm not gonna do that at this point, given my age and my time constraints... but maybe, you never know!

100% is easier to mix.

Eh. They take the same credit card for all mixes...