Cayman Aggressor - Nitrox or Air??

[ChrisA]

Actually, that's only one of the 3 reasons to use nitrox over air. The other two are to reduce surface interval or increase the margin of safety by diving a nitrox mix using air tables.

In recreational diving, the oxygen exposure issue is almost non-existent. OTUs are really only a problem with extended periods of time on very rich mixtures.

Well... I'm not sure what maximum partial pressure you're calculating, but 107' is the MOD for 32% at ppO2 of 1.4 which is a pretty standard mix. If you're using 30% or 28% you can get an MOD that's deeper, no problem.

I figured banked 32% would be the norm I get 111 feet for an MOD but still I figured most divers would plan to stay above 100 feet hence my coment. Yes you could get some .28 ad go to 130 but is this a practical option on a boat? Can they custom blend?

As for shortening SI. That is just the other side of longer NDL. It's like adding air to a beer botle by drinking the beer the two are stuck tightly together. Actually if you do take full advantage of the longer NDL SI will work out to about the same. OK sometimes you run out of gas before reaching NDL. Or if you choose an SI so that you can have a 30min botom time you SI will be shorter but if you ...

Simplest way to think of it is that if the mix has less nitrogen in it you will have lower nitrogen exposure for the same llenght of dive so you add saftey and shorter SI But if you stay down
longer you will breath more gass even if that gas has less nitrogen so what you gain is
longerbottom times Either way it is still a "win" and worth doing

PADI recently removed the part about nitrox being "safer" from the class materials. It seems there is no statistical difference. While it seems lke it should be safer but in order to make the claim you would have to observe a lowered rate of dive acidents and this was not the case. Accident rates are the same.

Argument is silly. Everyone knows that doing repetitive dives on a live abord is THE clasic example of a situation where nitrox is helpfull

 

[jakubson]

I figured banked 32% would be the norm I get 111 feet for an MOD but still I figured most divers would plan to stay above 100 feet hence my coment. Yes you could get some .28 ad go to 130 but is this a practical option on a boat? Can they custom blend?

Aggressor does banked 32%, and does not offer custom blending. Since the boat policy is to request all divers (nitrox or air) to stay to a max of 110 feet, this is not a big deal.

 

[caymaniac]

I figured banked 32% would be the norm I get 111 feet for an MOD but still I figured most divers would plan to stay above 100 feet hence my coment. Yes you could get some .28 ad go to 130 but is this a practical option on a boat? Can they custom blend?

As for shortening SI. That is just the other side of longer NDL. It's like adding air to a beer botle by drinking the beer the two are stuck tightly together. Actually if you do take full advantage of the longer NDL SI will work out to about the same. OK sometimes you run out of gas before reaching NDL. Or if you choose an SI so that you can have a 30min botom time you SI will be shorter but if you ...

Simplest way to think of it is that if the mix has less nitrogen in it you will have lower nitrogen exposure for the same llenght of dive so you add saftey and shorter SI But if you stay down
longer you will breath more gass even if that gas has less nitrogen so what you gain is
longerbottom times Either way it is still a "win" and worth doing

PADI recently removed the part about nitrox being "safer" from the class materials. It seems there is no statistical difference. While it seems lke it should be safer but in order to make the claim you would have to observe a lowered rate of dive acidents and this was not the case. Accident rates are the same.

Argument is silly. Everyone knows that doing repetitive dives on a live abord is THE clasic example of a situation where nitrox is helpfull

What we have experienced on a liveaboard was even though they might bank nitrox at 32%, the O2 sensor might read 31.3 or 32.1 or 30.6, when doing so many dives and the tanks are never really emptied and there are people that are diving on both air and nitrox the readings are never consistant but the readings are close. The crew is filling the tanks that are in your area on the boat, if it's got green on it they use nitrox, if not, air. The main thing is 111ft. is your max. with 32%. We never broke that barrier, that's the rules. When diving in 50 to 80 ft. your times/saftey margin go way up. No sense absorbing all that nitrogen if you are going to do so much repetitive diving, after all after the first day there will be plenty more diving on the second and so on, ect.....why not increase your saftey margin? :14:

 

[hex92]

Get certified for Nitrox. I am already certified (and then some), and my girlfriend is going to do the course on the boat - We are going on the Cayman Aggressor Nov 5th. I have emailed back and forth with a crew member there and he says that the time commitment for the class is very small. So it will not interefere with your diving.

The only reason you could have for not getting nitrox certified is if you are morbidly obese, uncomfortable in the water, or a complete spaz. Then you would probably hoover your air down too fast for nitrox to make a difference.

 

[scubarick314]

Go ahead and do it.My wife and I had about the same number of dives, as you and your wife have, before we went on the JULIET this year. We both took the nitrox class and it helped with the NDL. The class was easy enough and the instructor was very helpful.