Do they typically use 32% or 36%?

Anyone know specifically at the Divi??

Is it worth it? Seems like deeper shore dives would mean much less surface time so especially 36 would be worth it. Input??

Mike,

You will normally have more 32% available than 36%. You will normally see more 60 feet and above so 36 will give you some extra dive time at depth but obviously restrict your depth more if you do see something interesting deeper. Is this your first trip to Bonaire? How many dives are planning to do each day and long to you expect the dives to be?

Mike,

There's not much need to go deep on Bonaire . . . you see the same stuff in more shallow water and the light is much better. The Hilma Hooker and some spots on the outer reef of the double reef system are the only places I can think of that you really need to go deeper.

Most of the dive operators typically provide 32% Nitrox; some may not have 36% available unless you request it. I'm not familiar with the Divi's operation, but I know Photo Tours, Buddy's, and some of the others sometimes offer a free upgrade to Nitrox. Is it worth the extra cost? For me, yes. I average about four dives per day when in Bonaire and I am convinced that I feed better when using Nitrox. Then again, I'm in the over 50 gang and the "geezer gas" might work better for me than some of the younger folks.

Regarding bottom time, because you will be diving more shallow on Bonaire, you are seldom limited by nitrogen absorption. You will run out of air before you reach your no decompression limit on nitrogen - and if you stay relatively shallow you can plan on a tank of air lasting you 1 to 1-1/2 hours easily.

Enjoy your upcoming trip.

Mike: Up front, I'm not big on NITROX. I dove with it on the Cayman Aggressor and I noticed no difference in how I feel versus air. I've also seen a study that concluded that those with NITROX felt no different than those with air. That said, it is my understanding that NITROX is not a deep water gas and that its primarily beneficial when used as a decompression gas on decompression dives. Maybe there's something I don't know about 36% NITROX? As I understand it you're safer down to 180 ft on air, therefore, I don't bother with the expense and hassles associated with NITROX. I've dove to 137'on air and no problems. Based on what I know about NITROX, I, personally, wouldn't do that on NITROX - again, there may be something about 36% I don't know or understand. I'd really like to hear what Walt, the tech guy, has to say on this. Have great trip!!

Nitrox is much easier on your body and you feel less tired at the end of the day. It is even supposed to have beneficial effects similar to Viagra.

I may need to go back and re-read the manual... but what I remember is that at 36%, your maximum depth is supposed to be LESS, not more - more chance of oxygen toxicity at the greater % and depth.

I'm curious Mike, what you think nitrox does?

I have read that no one has been able to prove that diving nitrox has any effect, but there is plenty of anecdotal evidence that it does. I know my husband and I prefer to dive nitrox, as we don't feel as tired after a dive as we do on air.

Mike, last trip we dove geezer gas (nitrox ;-) and I really didn't notice much difference in how I felt, but I was able to do 3 80-90 minute dives a day and wasn't totally wiped...lol...I went with Wannadive and their air mix varied. They have nitrox tanks availible if you request, they ranged from about 32% to the last fills we got were 35.2% and 35.7%. I did end up diving air a few times because I was going to go a little deeper and didn't want to have my bottom time limited.

I had to read up on this earlier this year as I had also forgotten how to calculate the maximum depth of the mixes. We do not tend to go deep as we both take pictures and most of our subjects are above 80 feet. The limits are partial pressure of 1.4ata with a contingency of 1.6ata.

For example 40% oxygen is .4 ata at the surface, .8ata at 10 metres and 1.2ata at 20 metres and 1.6ata at 30 metres.

so max depth for 32% (to 1.4ata) is 111 feet or 33.7 metres

max depth for 36% (to 1.4ata) is 95 feet or 28.8 metres

max depth for 40% (to 1.4ata) is 82 feet or 25 metres

And then there is managing your exposure to oxygen, thank god for computers.

Thanks for the detail Brian. My AOW class is going to include Nitrox and I've been pondering the benefits after signing up for it!

My understanding is that Nitrox has only one benefit and that is more bottom time. When we dove West Palm Beach with their square profiles we were at a serious disadvantage on air. Dive till your deco limit then come up.

Now on Bonaire where you can always go up the wall when you are close to deco, the advantage of nitrox does not seem like a big deal. This next trip I will have my nitrox certification and my plan for now is to use nitrox for the Hooker and air everywhere else. We'll see how that goes.

The advantages of Nitrox vary depending on how you use it. It can be used to either extend your NDL or reduce nitrogen loading. The disadvantage is reduced maximum operating depth (MOD) and having to keep an eye on your total oxygen exposure per 24 hour period. As for feeling better, some do and some don't. Like other things in diving your own personal physiology will be the deciding factor on that. And it can also be used to speed up off gassing while sitting on the back of the truck after a dive.

Nitrox does extend dive time, however, it does limit depth (MOD) as Brian has explained. We set our computers to go off at 10 feet above our MOD for each dive so that we know we are close to our MOD. Cecil, it does have another advantage in addition to being able to stay down longer...more O2 and less nitrogen in the gas, so you potentially have less nitrogen buildup in the tissues when you dive.

Oh, I meant to say I dove air a few times because I wanted to go deeper, than 32EAN would let me (not much deeper, but I could not have done it on 32EAN)...not to extend my bottom time

I'm with Brian...thank god for computers

(Message edited by cyndelee on August 20, 2006)

The July 2006 Scuba Diving Magazine has an article entitled NITROX: Magic Gas? This is the info I used on which to make my decision not to use NITROX with the possible exception of liveaboard diving. Strongly recommend you read this article Mike before making your decision on NITROX. Once more thing, keep in mind its in the dive shop's interest that you use NITROX. Once again, have a great trip!

There is no question for me, after 360 dives *with* nitrox and more than that without, I am certain I feel better using nitrox unless I've dived it to its time limits. The issue is trying to limit how much nitrogen uptake I have. Although I can do that by diving less, staying shallow, not staying in to the limits, and by using nitrox, I prefer to dive more, and not always stay super shallow. So, the answer is, don't stay in forever, and use nitrox.

Sometimes after even just one air dive I am tired; I've never had that happen with nitrox.

If it is available, I prefer 36% because I can still go to 90 feet, and it means even less nitrogen uptake than 32% (for the same dive).

- Mel

This is a passage from the article I referenced above: "Those long and tiring drives returning from a day of diving are over!" enthuses one dive shop's web site on the benefits of diving NITROX. Is it really the "feel good" gas? The theory here is that the work of offgassing nitrogen is a major cause of diving fatique, so less of it should leave you less tired. Many nitrox divers swear it's true, but Bennett (Dr. Peter Bennett co-edited The Physiology and Medicine of Diving) cites a blinded study that proved otherwise. Using unmarked tanks, one group of divers was given nitrox, another was given air, and both were asked later how they felt. "There was no difference," says Bennett.
"Its a placeo effect." In other words, nitrox divers just think they feel better.

WOW! I started more of a discussionthan I had planned. I epxected that 36 wasn'
t widely avaialble, so I planned on 32. Although some report feeling better, to me its more the placebo effect. What I plan on using is not the deeper dives, but the ability to extend the time at MOD of aobut 90' and then reduce the offgassing time. OR, to put it another way, to be able to reduce time between boat and shore dives. Also, to get in two nice night shore dives during spawn thanks to less outgassing.

No plan on deep diving unless from a boat, where I plan on 21 anyway since everyone or at least someone else will be on that anyway (I think) so no outgassing time advantage.

Unless anyone else has input.... Of course, there might still be the option of 32 on the final boat dive of a 3 dive trip to reach the further sites.

Marcus, I can't say that I feel any better, or less tired after diving nitrox, the main reason we took the classes and switched was the extended bottom time, and the less nitrogen in the mix, so hopefully the smaller possibility of getting bent. After taking the class, I am even more convinced about this...it is a safer gas to breathe...

I do not think there is any research out there that "proves" the "feel better" theory. It is ancedotal from diver to diver.

Mike, you think you can bring up nitrox and NOT have a discussion? lol ;-)

Have a great trip

IMO, Nitrox is great for people that come up with 900+ psi after a 50 min dive at depths averaging 55 ft. I can't see how you would benefit from the decreased RNT that Nitrox provides if you use most of your tank in the process of an air dive anyway. To for any significant gains, one would have to be able to stay on the bottom longer....and if your air usage is such that you need to surface in less than 1 hr, what's the point? Nitrox tanks have the same sq/ft of gas as an air tank.

I have heard that you feel stronger after a dive with Nitrox though. I'm sure that is due to the increased paO2 a diver has after breathing an increased fiO2 at depth.

(Message edited by dave_l on August 20, 2006)

Grasshopper: I respectfully disagree. I don't believe nitrox is a safer than air due to the increased risk of Central Nervous System Oxygen Toxicity with nitrox. The risk may be small given a single tank of nitrox and strict adherence to depth limits and no decompression times but it is still a possiblity on a single nitrox tank and a possibility I am not willing to risk. That said, the nitrox depth limitations alone are enough to make me dive on air - I routinely dive to 130 ft. To each their own I guess. Have a nice day!!

Marcus doesn't like nitrox; I suggest he not use it.
I like nitrox; I'll continue to use it!

Much good science starts with anecdotal evidence, no good science stops with one study.....

From the Wikipedia:
"There is anecdotal evidence that the use of nitrox reduces post-dive fatigue, particularly in older and or obese divers; however the only known double-blind study to test this found no statistically significant reduction in reported fatigue. [1] There has, however, been some suggestion that post dive fatigue is due to sub-clinical decompression sickness (DCS) (i.e. micro bubbles in the blood insufficient to cause symptoms of DCS); the fact that the study mentioned was conducted in a dry chamber with an ideal decompression profile may have been sufficient to reduce sub-clinical DCS and prevent fatigue in both nitrox and air divers."

So the only study, the one quoted by Bennett, has reason to be questioned. I'd say the issue is still open for study!

- Mel

Mel: You make an excellent point. The issue should be still open for study and I am more than willing to consider any new evidence that may come to light. What concerns me as certfied Dive Master and an assistant instructor in training are statements made on websites that have the appearance of facts that may in fact be myths. I know of several people, myself included, who bought into the feel good gas theory and unknowingly violated the depth limitations of nitrox. My goal as a dive professional is to ensure divers have the other side of the story so they can make an informed decision - An opportunity I never had because I was never taught the facts, backed by at least some semblance of scientific evidence, on nitrox. Have a good one.

Marcus, I'm a dive professional too... PADI Master Instructor, and TDI Advanced Nitrox instructor. We need to know the facts, and make sure they are communicated accurately. I'm surprised you violated the depth limitation...the nitrox courses I'm familiar with are obsessed with making sure the student does not do this!

for your info, the study Peter Bennet quoted is:
Undersea Hyperb Med. 2003 Winter;30(4):285-91.

Measurement of fatigue following 18 msw dry chamber dives breathing air or enriched air nitrox.

Harris RJ, Doolette DJ, Wilkinson DC, Williams DJ.

Hyperbaric Medicine Unit, Royal Adelaide Hospital, Adelaide, South Australia 5000.

Many divers report less fatigue following diving breathing oxygen rich N2-O2 mixtures compared with breathing air. In this double blinded, randomized controlled study 11 divers breathed either air or Enriched Air Nitrox 36% (oxygen 36%, nitrogen 64%) during an 18 msw (281 kPa(a)) dry chamber dive for a bottom time of 40 minutes. Two periods of exercise were performed during the dive. Divers were assessed before and after each dive using the Multidimensional Fatigue Inventory-20, a visual analogue scale, Digit Span Tests, Stroop Tests, and Divers Health Survey (DHS). Diving to 18m produced no measurable difference in fatigue, attention levels, ability to concentrate or DHS scores, following dives using either breathing gas.

Great discussion going here. I love what Jim had to say about how folks "feel" after using Nitrox. And I appreciate the quotes taken from the studies that Mel mentioned. As a health care professional, the studies are interesting in terms of assessing functional scores (how people feel and function) but I'm wondering if anyone has studied the actual blood levels of gas concentrations in a variety of individuals. As each one of us has different body composition, renal function, pulmonary function, etc. we can only make educated guesses about how each of us will respond physiologically. Bottom line is more information and study would be a good thing!

Okay, I'll jump in.

According to physlink.com, plain ordinary air at sea level consists of: a little under 79% Nitrogen, a little under 21% Oxygen, and a number of trace gasses.

According to gasdiving.co.uk, EAN 32 consists of 32% Oxygen and 68% Nitrogen. [We already know about those other trace gasses.]

I use nitrox because when I am breathing this enriched air, my body absorbs less nitrogen than it would breathing regular compressed air at depth.

As for the Hilma Hooker, I do just the opposite that Cecil does:
When I dive deeper than 80 feet, I use air because I don't want to worry about oxygen toxicity when following critters deeper than planned.

When I dive in the 60 feet and shallower range, and I spend an hour-and-a-half under the water, I use nitrox. Even with the longer bottom time, my body is absorbing less nitrogen than it would breathing air at depth because there is a lower concentration of nitrogen in the nitrox I am breathing at depth.

Hope this makes sense after a glass or two of medicinal wogga,

Mare, who uses either geezer gas or air depending on the depth of the dive.

Mare, you do exactly what I do. When we did Hooker, it was regular air (along with a few other dives that started a little deeper). Age and abdominal fat are also "possibly" risk factors for DCS...so the less nitrogen in the blood...well, the better for me central nervous system toxicity is a risk factor with NITROX...but there are also a lot of other risk factors with diving "regular air."

Cynde - just starting to have a glass of wogga

Check Please!

Please people...do not use Wikipedia as a source. It has open edit policies, meaning any person who has access to a computer can edit their material. I had a student once change the president of Poland to George W. Bush. It stayed that way for weeks before someone else changed it. Some high school teachers make their students write articles and submit them to Wikipedia and they go on line as if they are fact. All you have to do to edit an entry is click on the blue word "edit." Any one can do this...therefore you should be skeptical of anything you read on Wikipedia. Rant off...now please return to your rather interesting debate on Nitrox.

Dave L makes a point above, but doesn't carry it to the next step. 32 and 36 b oth allow a return to the water much quicker than 21, effectively increasing bottom time for the day (not for any single dive). That's my point. And, agreeing with Mel, how did Marcus violate the depth limitation if he paid attention during his EAB course? There are so many safety collars built into the limitations it allows you to get right up to it but never violate.

Hi Guys I just couldn’t resist getting in to this one where there is so much myth and opinion flying. As one who has not dove air in over 6 years and having done close to 2000 dives in that time frame I think I can shed some light on this subject.

Breathing mixtures with less inert gas (Nitrogen in this case) than air are going to have many advantages and some disadvantages vs Air.

#1 advantage is less inert gas loading in your body’s tissues (be that stubborn Belly Fat or other tissues).
Read less chance of getting a ride in the chamber
Read longer bottom times vs Air
Read shorter surface intervals vs Air
Read more dives in a day vs Air
Read more time in the water - NOT waiting on shore to off gas before you can go dive again
Read Faster Decompression
Read Safer Decompression
Read probably less post dive fatigue because of a reduced chance of “Silent Micro Bubbles” which are causing sub-clinical decompression sickness (DCS). You also probably wont feel this effect if you are not doing 3 to 5 dives per day and or not pushing your computer up close to the limits.

Do you want to see a real good representation of Off Gassing/Decompression? Find 2 divers with multi-mix dive computers (NiTek computers work well for this) do a dive right up to the limit of the computers come up to 20 ft and switch one to pure O2 and watch how fast the inert gas loading drops on that computer vs one not switched to O2. This is a very graphic display of what happens when you reduce the inert gas in a mix (It would also be a good Idea for both of you to actually breathe the pure O2 or the highest Nitrox mix you can get).

Or come do a dive at the Hooker with me. You dive air I’ll dive 40% Nitrox you will see that I have about twice the available bottom time as you. I regularly do 1 hour plus dives there without going in to Deco or breaking my O2 limit (be it depth 99ft. or time). The Hooker is the perfect dive for Nitrox you have a sand bottom to stop you from going any deeper that 99 ft. without getting out your shovel. If you don’t want to have any possibility of going past a PO2 of 1.4 use 35% Nitrox even if you used 36% you are only at 1.44 if you hit 99 ft. and how often do you do that or how long do you stay there not much of a problem is it? But you get a huge % wise time advantage.

I you really want to see a difference in Inert gas loading come do a dive on Air or Nitrox and I will dive my Evolution Closed Circuit Rebreather, which mixes the Best Mix of Nitrox (based on whatever PO2 I choose) for whatever depth I am at throughout the whole dive every 6 seconds.

Below is a dive I did with the Evo. I spent 2 hours around or below 60 ft. and still had 358 minutes of no Deco time remaining at 59.1 ft. 2 hours in to the dive right before I started up for my safety stops. This really shows the advantage of using the “Right/Best Mix” for your depth.



OFF SUBJECT: Does anyone have a good Screen shot capture program I am looking for one to capture dive profiles with all the info as it does not print it all.

There are some disadvantaged (you don’t get something for nothing) to Nitrox also but the advantages far out weigh the disadvantages.

Nitrox is more expensive than air (not much these days)
Nitrox may be harder to find than air (not as hard these days as it was in the past)
Nitrox has limits based on the O2 in the mix (Depth & Time) anyone who does not have the discipline to stay with in these limits should not dive it.

Anyone who unintentionally or for no “Good?” reason busts a PO2 depth limit of 1.6 is just as stupid as someone who runs out of gas on a dive!!!

Sorry I can’t chat longer as I have to go mix gas (Trimix 20/25 & Nitrox 50%) and fill our O2 tanks for 2 - 60 meter/200ft. dives we will do Tuesday & Wednesday.

I'm in complete agreement with Walt, on the advantages, disadvantages, and caveats.

And the best of the screen-capture programs might be SnagIt, at http://www.snagit.com. Irfanview, however is free.

- Mel

Walt...THANK YOU Have a great dive

Walt

The 2 issues that you have not raised but must be factored in with 2hr bottom times:

1. E-factor - personally I get cold after 90min even with a 5-4 suit. What are you wearing for these dives?

2. P-factor - depending on your answer to the above question this might lead to a whole new level of engineering. Those believing in heavy hydration will probably have a serious interest in this ;)))

david

Last year we did a 156 minute dive in Bonaire on Lac Cai (the Tiger shark story). We had no deco. Why? We were using EAN40 (Nitrox with 40% O2). My buddy, Menno from Deep Blue View, used a nitrox computer and an air computer. His air computer showed over 20 minutes of missed deco.

(-: So if you want to see interesting stuff, you have to use Nitrox.

The Divi provides EAN 32. Been there.
Also measured some tanks at about 26% or so, so check or you may be shorted.

You should always check your percentage. We've gotten anything from 28% to 34-35% with all fractions in-between at Habitat. It seemed it varied most depending on how available the O2 was on any given day on island (if it was running low, the mix was less O2). Of course, that was over a year ago - it could be less variable now. I'll still check the mix for each tank though...

Having a dive computer which does Nitrox is definitely a plus.

Susan, we found the same thing the last trip...the mixes varied greatly as well.

Oh, and when I was talking about the effects of diving nitrox, I was talking about the "geezer gas" effects (like feeling better and less tired after diving). (What, you couldn't read my mind? )

The actual less nitrogen load, faster/safer decompression are pretty obvious.

Walt, great summary! Thanks!

Susan
PS: see you in a couple weeks... we're the tattooed geezers, in case you didn't know from my profile...

You don't check your mix on each cylinder to make sure you didn't get shorted, you check it to make sure you don't get the bends (e.g., if the mix is 26% and you thought it was 36%) or die (if the mix was 40% and you thought it was 32%).

Assume nothing, trust no one.

- Mel

Yep. You're better at reading for comprehension than I am today, Mel. As well as writing for comprehension...

I check to make sure I'm not shorted.
Pay extra to have more o2, so I want a tank that is more.

All the obvious cautions....OK.

Divi has a log book for you sign, indicate % and MOD, and tank number. Also provides labels (tape) for you to put on the verified tank.

My recollection it was $8 more each.

Mike/Mel: If you had been at my "nitrox course" you'd understand why I was unaware of the depth limits while on nitrox. While on the Aggressor we were told not to go below 118' but weren't told why so on a couple of dives we violated that rule. Call it stupid if you want but we did it not knowing that the nitrox was the real reason for the depth limitation. Our logic at the time was that the recreational limit was 130' and the Aggressor was just trying to cover themselves by limiting the depth. I had a dive buddy with me on every dive that was in the same nitrox class as I was - he unknowingly did the same thing I did in violating the nitrox depth limits. Bottom line: we were not told about the nitrox depth limitations. I was hoping Walt would weigh in because he clearly knows more about this, as well as Mel, than I may ever know. My points all along were based on the fact that I don't stay in shallow water for two hours at a time, I don't do 5 dives a day and I perfer not to have my depth down to 130'limited by nitrox. That, and the fact that I really didn't notice any difference on how I felt after diving nitrox versus air and I really don't want to pay for it. Thanks Walt and Mel. I've learned something from both of you in this conversation. Have a great dive. Check Please!

Marcus, wow! Did they give you a certification card? What agency?
- Mel

Mel: Yes, they gave me the card. Don't get me wrong, the open water training at this particular shop is outstanding and the instructor is known as basically a dive god around here. Its the nitrox training beyond open water training that did not meet the standard. In fact, the shop doesn't even do the nitrox training at all anymore. I think the agency provides the proper materials; its just that the materials weren't properly presented. Since then, I have crossed over to SDI/TDI Dive Master. My position on nitrox must sound strange to you coming from a SDI/TDI guy. Later.

Thanks for more in depth info Walt! (no pun intended ) I am planning to take the class and this discussion has given me quite a lot for thought and further investigation.

(Message edited by babsoleary on August 21, 2006)

We took the PADI course. To be honest although we went to a class for it, the book alone would have sufficed - as long as you read it and do the exercises, and practice with the various tables, it sinks in (at least for us). Funny thing with all that stuff about gas mixes, we were in a class with an emergency room doctor and we did better on the final test.

There's a whole section in it "Determining the Maximum and Contingency Depth Limits for Enriched Air" (no, I don't have a photographic memory - I looked it up), close to 3 pages with example questions. That, and those big "WARNING" notations at the bottom of the Equivalent Air Depth Tables, made it pretty clear to me that being aware there are depth limitations was A Good Thing.

I'm quite surprised this wasn't taught to you, Marcus - it seems to me a pretty important bit of information.

Walt/Marcus/Mel, et al.

Tanks so much for the info. I've just cert'd on EAN last eyar and teh course was around 5 hours, so we covered everything, everything, and more. Plus the materials (PADI) were new as PADI had just completed their review of the EAN course. (Also, no dive required any longer, just a walk through pre dive.

I was taught to always check the mix and to always log in. No log or no check = no EAN: 21 only. Another reason not mentioned is shops mixing tanks, say 40 when expecting 32.

I've got a new Tec computer with variable EAN settings and an automatic MOD alarm with a 10% safety collar, so I feel relatively safe with that as backup.

That all said, seems like the 32 is just right for multiple shore dives or a boat and shore mix. Also, a full week of EAN upgrade is only US$100 at Divi in off season, so just a couple of more dives or extended bottom time is worth it. Especially getting two good night dives in one night.

Hi Marcus. You probably didn't bust the depth limit if you were diving 32% on your dives the limit for 32% is 132ft. 118 ft would be the limit for 35%.

I use Nitrox down to 180 ft. So I really don't see it as being very Depth limiting depending on your susceptibility to Narcosis. I have over 500 dives to the Windjammer guiding 1 to 4 other divers using 23% Nitrox and another rich mix to Deco out on all completed with no problems.

Deeper than 180 I prefer to be on Trimix. You just have to mix for the depth you wish to go to be it Nitrox or Trimix.

Susan: You make a good point. The instructor knowledgeable on nitrox didn't show so we "winged it" if you will with the the shop owner who was not nearly as knowledgeable on nitrox. Truth be told part of the responsibility does rest with me for accepting such a cursory look at nitrox and doing basically no studying on my own; however, some of the responsiblity has to go to the instructor - if not, that would let an instructor off the hook in basically all situations. Thanks for the info Walt and I stand corrected on the depth limiting aspects of nitrox. What you said above tells me the Aggressor episode wasn't as bad as I thought - the nitrox mix seemed to flucuate between 32% and 35% from day-to-day if memory serves and the max depth I hit was 137' on one dive I believe.

Marcus,

It seems to me that the primary responsibility related to your course was the store owner for allowing the course to be done without the properly qual'ed instructor. Bad!!

And some with divers who accepted an unqual'ed instructor.

Glen: I would agree with that.

Marcus, if "winging it" had included reading the text you would have been fine. I have always believed that the primary responsibility for getting good training rests with the individual student.

Walt, thanks for the cogent and informative posts.

If you want to go deep and stay for a while then trimix is the safe answer! TDI training in the service was demanding but interesting... Ron
Cost some bucks but worth it if that's your bag.
http://cisatlantic.com/trimix/descrip.htm Check this out...

(Message edited by ronindiana on August 21, 2006)

Seb: I have admitted I failed to meet my responsibility in this. As a military officer of over 30 years, I have spent countless hours training others and while I have told soldiers time and time again excellence is their responsibility, I have always taken steps to ensure the training they received was outstanding in nature. The ultimate responsibility for quality training fell to me, their leader/ instructor. That's what I believe. Have a nice day.

Learned one answer from Divi: they mix their own so they can mix whatever we ask for. Maybe 36 sounds right and 40 for night diving.

Mike,
Be carefull, too much O2 is not good.. Get some instruction on this subject before you put the noose around your neck... Ron

In addition to the Maximum Operating Depth, the key to use of the high-percentage Nitrox mixtures is to understand the "oxygen clock." Just as you have a maximum time you can spend at a certain depth because of the nitrogen, there is a maximum time you can spend (during each 24h period) on oxygen. Using air, the oxygen time is effectively unlimited. But using 36% at 60 feet (as an example), you only get 270 mins per 24h-day before you hit your limits. If you were using the 36% at 90 feet (its MOD), you'd only get 180 mins per day. You won't hit that on three dives, but you might if you did six dives that day. In fact, if you sit down and work it out, 5 or 6 dives per day is conservatively possible even up to 40% mixes, regardless of what depths you are diving at, so long as you stay within your MOD, and use an 80 cu ft tank....the amount of gas you carry holds down your total bottom time very nicely.

The nitrox courses (should) cover the background to this, and teach you how to make the calcuations. Your computer does the same thing...probably with fewer errors!

- Mel

"the amount of gas you carry holds down your total bottom time very nicely"

(-: Two 3 liter tanks and I can stay down for around 4 hours, and still surface with tanks half full. The benefit of a rebreather.

If you get a chance, and if you are interested in a different way of diving, give a rebreather a try, especially in Bonaire. The water is warm, so you can stay down long before getting cold and there is lots to see so you don't get bored.

I believe Walt can organize training dives and try-outs.

BTW, with a rebreather you can get very close to the fishies. It's the bubbles that scare them away.

Marcus, no offense meant, it's just that after seeing a lot of poorly trained divers, I have come to the conclusion that the buyer must be a wary and informed consumer when purchasing scuba instruction. Many people are over eager to knock off the next course on their way to a higher certification.

Seb: None taken and I agree with your conclusion.

Agree with Mel, et al. I completed my PADI EAN this spring just for such an occasion (and Wakatobi!!). Understand very well the O2 maxs. That's why air for most of the day and then 36 - 40% for two night dives. It's all in the planning!!! (and the correct mix and MOD).

The chance of the bends as you age increases, being 57 the least dangerous diving I can do is too dive with 32% nitrox using a regular air computer and making all the non nitrox safety stops!!