Nitrox Class Without Tables or Math...OK?

[MikeFerrara]

Mike,

As you enter the depths into your computer the MOD is displayed. You actually dial in the MOD and then read what gas you come up with. Incredibly simple to do and you don't have to have a calculator to do it. What's more, on the newer computers we can program in non-standard PPO2s from 1.2 to 1.6, giving you control over how aggressive you want to dive.

That sounds handy but I've owned a bunch of computers from various manufacturers and none of the worked that way. To get MOD you'd have to program FO2 and go to scroll or planning mode to get the max depth on that mix. None allowed you to enter a MOD at all and would not solve for FO2. You would have to repeat the "MOD" process in a series of guesses to come up with a "best mix".

As for dives, I don't see a need to watch my student breathe... "Yup, you got that right!" Determining your MOD and measuring your gas are the skills I want them to master.

Probably no need to watch them breath but nitrox diving is a diving certification and I couldn't issue a diving cert without seeing the student dive. At one time skill assessment and remediation was a required part of every course. Since I found so many students in nitros courses that needed remediation before we could do any OW nitrox dives, I'd say that maybe you do need to watch some of them in the water.

As for OW NitrOx, NAUI allows it and I often teach the classes together for students who REALLY want to understand what they are diving with. Still, most of my students now dive with computers and NAUI never really addressed computer skills in their syllabus.

Lots of diving texts do though.

Here is the BIGGEST safety factor: computers don't get narced! The deeper you go the "stupider" you get. Your computer does not share this proclivity and will be glad to alarm you if you need that nudge to ascend. I have not learned how to set an alarm on my table!

How can you make a statement like this and argue that you don't need to dive with your nitrox students? If you expect that your students may get so narced in the depth range that you're training them for or that for any other reason they will be unable to know and follow their dive plan, don't you think you should be doing some diving with them? IMO, it's certainly something that you should be aware of prior to certifying them to go do that dive.

What makes you think that one who is too narced to monitor depth and respond to a depth guage is going to respond to a gostly far off sounding beep? Have you ever been on a dive with other folks and hear beeping all over the place through the whole dive? Maybe it's just my hearing these days but I've noticed that with a heavy hood on that I often don't hear the beeps at all and I'll bet that I'm not the only one.

Divers need to know what depth they're at and have control over it. Once the beep happens it's a mistake that can't be undone rather than a possible future mistake that we can avoid.

I don't believe that beepers are the answer. LOL just like all the beepers in Mcdonalds haven't improved the food any. It's just makes a lot of irritating noise...ever notice all the folks walking around, doing whatever, while all the beepers beep? In the past (before the beepers) when the grill person had to know when to flip a burger without being beeped at everything was much quieter and the food was better. Rather than being surprised by a beep while in the middle of something else resulting in the thing not being done on time anyway the cook was aware of the state of the meat, anticipated the comming need to turn it, planned for it and did it on time. Now the beeper tells every one within hearing distance that something should have been done but probably wasn't. LOL A beeper can't make a cook or a diver. It can, however, be used by management as justification for providing less training. I'm sure that Mcdonalds feels that the beepers were a worthwhile investment but the burgers still suck. Better burgers obviously wasn't their goal. The goal must have been to reduce training costs.

 

[redacted]

To prove this point, please tell me how being able to make the calculations increases the safety of any dive. Go ahead. I'll wait.

I got careless once with my Oceanic Data + and found myself at 65 ft with my computer blinking at me with it's displeasure of a PPO2 of about 1.5. I was diving 32% and immediately realized I had not reset the mix so my BOB (battery operated brain) was diving 50% O2 and 79% N. Knowing what was going on and able to estimate the appropriate adjustments, we were able to complete the planned dive and verify that the Oceanic was still making good PPO2 calculations thru 1.8. It was the last dive of the day but I could also estimate what effect my error would have on the planned morning dives after a 10 hr SI. It may not really be an increase in safety but I was able to satisfy myself that I had no safety problem with what I was doing.

With a background in math and science, I found the "formulas" interesting but unnecessary. But If I could find your course in my area, it would be much easier for me to convince my wife/buddy to get Nitrox certified.

 

[MikeFerrara]

Sounds like we have alot of people here using an abacus or a slide rule to 'calculate' these precious formulas. According to a lot of logic here (of those opposed to this course), if you don't use the oldest available tool then you cannot possibly learn the material. Now that seems ludicrous.

I have not taken a NitrOx course (yet) and mathematical formulas do not scare me but if there is a better or easier way of accomplishing the same goal, I am all for that.

In my experiences with courses (both SCUBA and non-SCUBA), I find there is far too much time spent on crunching numbers and not enough time spent on the actual material (theories/laws/whatever) that is truely important. I can see me sitting in a NitrOx course with my instructor (who is thorough and traditional) spending 80% of the class time on grade 10 math skills (which today kids learn in grade 5) for those who are mathematically challenged and 20% on NitrOx relevant material.

Keep striving for improvement NetDoc!

No one is argueing in favor of using the oldest tools. Once you understand the concepts so that you might recognize when your chosen tool provides an incorrect answer, you can use whatever tool you'd like...pc, palm pilot, programable calculator, dive computer...no matter.

I've taught many nitrox classes and never spent anywhere near 80% of the time on simple math skills.

As to whether or not this class is any kind of improvement, I'd be happy to dive with some graduates and let you know what I think of their performance.

 

[MikeFerrara]

That might be a little tough. Most of us (on this board) want to know how it works and therefore how to protect ourselves best. Having said that, each time you fly on a jet, or step on the brakes in your car, you're mostly in the hands of a computer. If you rely on your dive computer alone, one could argue for a backup computer for safety.

I still calulate my group manually as a check during the SI, made a dive plan, and reviewed my computer for validation.

Stan

Good point. Not too long ago I baught a new truck because though my van was in great shape and ran fantastic all summer, as soon as winter would come and there was salt on the street, the speedometer would go crazy, the transmission would start acting nuts and would get stuck in one gear or another (sometimes neutral). I paid for many towings, rental cars and "repair" bills. After several dealers two regular garages, a tranmission place and an automotive electronics place failed to find and fix the problem I finally gave up and baught another truck. Gotta love that computer.

Jets may use computers but pilots still learn to fly and navigate.

 

[MikeFerrara]

To prove this point, please tell me how being able to make the calculations increases the safety of any dive. Go ahead. I'll wait.

First of all while safety is important there are other issues such as the versatility, convenience and effectiveness of planning. I can easily do planning steps that not all dive computers can do, even if I happened to have one of them with me while I'm doing the planning.

But then there is safety. I already talked about the stupid beeper thing...once it sounds it may be too late. But...I have a computer that if you don't get in the water within a few minutes of programming the FO2 it will revert to 21%. Once in the water the only clue that this has happened is the PO2 display. If you don't have an idea what the PO2 display should be reading for the gas being used and the depth you just won't know. Now if you're diving 32% and your max PO2 is set at 1.4 ATA PO2 alarm will sound at 187 ft rather than 110 ft. That's a PO2 of over 2 ATA. This alarm will be of no use to that narced diver you mentioned in an earlier post. And... you haven't even dived with him/her so you have no idea whether they have the ability to know and follow a plan in the water.

Being able to calculate or at least estimate PO2 on the fly would immediately let you know that your computer was off in left field. I'd say that's safer. Being able to calculate O2 exposure and know the MOD would allow you to continue the dive using air NDL's adding convenience possibly saving you from wasting an expensive trip.

 

[LSDeep]

Except that it seems to me that you're starting with a given gas while first the diver must decide which gas/gasses they wish to use for the planned series of dives. What about calculating a "best mix"?

i do that on my computer by typing in the mod and then see my time / gas options

 

[MikeFerrara]

i do that on my computer by typing in the mod and then see my time / gas options

That's handy but not all computers will do that. I haven't seen anything about the class that suggests that students are restricted to certain computers. They might have one like mine and it won't do that.

They could go buy another computer or they could just spend a few minutes learning the theory and then they won't care.

 

[Soggy]

I suggest that you give the algebraic calculations to a fourth grader to test your fallacious arguments7

Ok, 7th grade math....

So you want to predicate the entire class on using a tool that they will just leave behind? That's just dumb. It's also short sighted and elitist.

Ok, diving isn't for everyone. There, I said it. I guess I'm an elitist. It is a thinking person's sport. However, I already said that I don't object to *adding* information about computers, but leaving every calculation to your computer and having no ability to check whether those numbers that your computer is spitting out are correct or not is dangerous.

To prove this point, please tell me how being able to make the calculations increases the safety of any dive. Go ahead. I'll wait.

When said student's computer dies underwater or if there is a mistaken setting on the surface, they are fooked because they no longer have the ability to figure out what the numbers should be.

 

[Michael Schlink]

I've said it before, why does a diver diving at recreational depths(-130) need to learn anything about Nitrox at all?

I think what ND is doing sounds like a great idea, I'd take it a step further, quit pumping air, give everyone 32, tell 'em if they go below 120 they die, pat 'em on the butt and let them go diving.
The majority of diving is taking place in resorts, by divers with computers, who only dive a few times a year. I think everyone would have to agree that few use tables or remember how.

The biggest reason divers started using computers was to get a few more minutes of BT. Probably the best reason to use Nitrox is to get a few more minutes of BT. Put the two together and you have more than a few more minutes of bottom time, but not so much that people are going to try for 90 minutes dives or pushing dives more than 10 or 15 minutes, especially in the 80' +/- range, typical resort type dives.

For those of you (or us) that use Nitrox and other mixes to accomplish a COMPLETLEY different style of diving then a bit of math is in order, or you punch the numbers into the 'ole laptop and go.

Nitrox isn't that hard, it's not scary and you really don't have to know anything but how deep NOT to go. After that most divers can dive Al 80's all day long and not have to worry about 02 loading, heck you can probably do 5 a day for a week and not even have to look at your 02 clock.

Go for it ND if I were closer I 'd come watch

 

[tedtim]

I am a bit late to the discussion, but IMHO there appears to be a few of aspects to this that should be split.

1. The understanding of what Nitrox is and does for a diver is important. I can't agree that a course should just teach you to read a machine. If the intent is to educate the diver on the use of their particular type of computer for use with Nitrox, then there will be added value.

2. Having said that, once you learn how to do the calculations there may never be a need to do them again. A simple excel spreadsheet will handle it nicely.

Ok, diving isn't for everyone. There, I said it. I guess I'm an elitist. It is a thinking person's sport. However, I already said that I don't object to *adding* information about computers, but leaving every calculation to your computer and having no ability to check whether those numbers that your computer is spitting out are correct or not is dangerous.

Sorry, but I don't need to redo the calcualtion for MOD every time. I carry a simple spreadsheet with me in my log book. It has the results of the calculation for different ppo2 and MOD. Call me lazy, but I did check the math in the spreadsheet when I made it. I don't think that the math will change over time. The same can be done for bottom time if you want, although it would be table based.

3. If there is equipment failure then the "safe" approach is to get thyself to the surface. I believe that this discussion is with regard to a recreational diver. I know that there are other considerations for anyone doing tech diving or anything else in an overhead environment.

When said student's computer dies underwater or if there is a mistaken setting on the surface, they are fooked because they no longer have the ability to figure out what the numbers should be.

They also would not know when the computer died, so unless they have a backup timer and depth guage they are fooked anyway. In the flying game we learned that when flying exculsively on a backup system it was time to find the nearest safe spot to land. There were only a few situations where continuing to the destination was the only option.

Personally, if my computer died underwater on a recreational dive, I would switch to my trusty $30 timex back up timer, ascend, and call the dive. Once on the surface I could then figure out what happened. I would not be going back in until I had the computer fixed/battery replaced and waited an appropriate amount of time.

There is a consideration that the diver will be solely dependent on the computer for all aspects of planning. If they are letting the computer decide what they should do then I suggest this is an error. If they are using the computer to show the limits of their plan, then this is a good use of the tool.

2 psi