Nitrox training worth it w/o a computer

[tursiops]

Just so people know...

The "some Nimrods" of which he speaks are the overwhelming majority on the planet. If you don't like the Nimrod you run into in your first class, you may have a hard time finding a "real" instructor. So, while the tone of his post implies that Nimrods are rare and the real ones are in the majority, the post is actually analogous to someone telling you that if someone tries to sell you a smartphone, run away as fast as you can and find a store that will sell you a real phone, the ones with the rotary dial and the cord connected to the wall. (Okay, it''s an exaggeration, but ot that much of one.)

As an instructor, I taught students to use tables for many years. I can remember vividly the one and only time I saw a diver use one on a dive outside of instruction. It was me, and it was on my first dive trip after certification, not quite 20 years ago. It was on a DM-led multi-level dive, and I found the tables would not work on a dive like that. Another diver on the boat suggested that the tables in my hand would make a reasonable frisbee if I wanted to put them to good use.

LOL. I think tables are kinda cool, and I actually own two Wheels (which can, by the way, be used in a limited way for multi-level diving). But, then, I also have a double-hose regulator and a ScubaPro Decompression Meter (the Bend-o-Matic).

I have seen a Wheel in use, by an actual DM on an actual dive boat, in Maui. He had just taken everyone on a slightly deeper and longer dive than was the norm, and used the Wheel to determine how long a SI he should have before the next dive. The Wheel, and tables in general, easily allow one to work out the amount of SI needed, unlike almost all computers, which tell you (in Plan mode) what kind of NDL you have right now, but not an hour from now. Thankfully, the Shearwaters DO allow this look-ahead planning, which I find quite useful.

 

[Rred]

Actually, John? If you live in Florida, or the Gulf Coast, or the southeastern seaboard?

Yeah, people DO still buy wired phones. It is called "the hurricane phone" because when the storm hits and the power goes out, the wired telco's were required to have enough backup power to keep running for 3 days without mains power. Which made them obsolete wired things pretty useful.

Recently, very recently, and not at all uniformly, the cell phone carriers have gotten better about fueling each other's generators, so the cellular system is becoming as robust as the neglected landline system in some areas. But even then...a user SHOULD know how to use both.

In the Great Blackout of 2003, when NYC went dark for three days, I found my neighbors having a pow-wow in the stairwell, wondering aloud if it was another 9/11 because their phones were down. They just didn't know, if you've got a home cordless phone....it still needs mains power to work! It was just a blackout, but they couldn't tell that.

The tables will always waste my air, because the computer will be more precise. I don't care, really. That waste of air gets filed under "I'm doing a more conservative plan" for me. Now, if I wanted to do doubledives eery day, plus a night day, for a week in a row? And toss in a couple of deco dives to get more bottom time? Sure, I'd like the computer. Heck, sometimes I even use a grease pencil, because the pointy end of a #2 Ticonderoga can actually HURT if you use it too much.(VBG)

A diver can never be self-reliant, if their basic plan is relying on electronics and water seals and electricity--all of which is expected to operate UNDER WATER. All water"proofing" fails sooner or later. Ask any Rolex dealer. The question is not if it will fail, just when. No matter how you maintain it.

And what do you do then? Quit diving? Or, pull out the tables and go with Plan B?

 

[tursiops]

Actually, John? If you live in Florida, or the Gulf Coast, or the southeastern seaboard?

Yeah, people DO still buy wired phones. It is called "the hurricane phone" because when the storm hits and the power goes out, the wired telco's were required to have enough backup power to keep running for 3 days without mains power. Which made them obsolete wired things pretty useful.

Recently, very recently, and not at all uniformly, the cell phone carriers have gotten better about fueling each other's generators, so the cellular system is becoming as robust as the neglected landline system in some areas. But even then...a user SHOULD know how to use both.

In the Great Blackout of 2003, when NYC went dark for three days, I found my neighbors having a pow-wow in the stairwell, wondering aloud if it was another 9/11 because their phones were down. They just didn't know, if you've got a home cordless phone....it still needs mains power to work! It was just a blackout, but they couldn't tell that.

The tables will always waste my air, because the computer will be more precise. I don't care, really. That waste of air gets filed under "I'm doing a more conservative plan" for me. Now, if I wanted to do doubledives eery day, plus a night day, for a week in a row? And toss in a couple of deco dives to get more bottom time? Sure, I'd like the computer. Heck, sometimes I even use a grease pencil, because the pointy end of a #2 Ticonderoga can actually HURT if you use it too much.(VBG)

A diver can never be self-reliant, if their basic plan is relying on electronics and water seals and electricity--all of which is expected to operate UNDER WATER. All water"proofing" fails sooner or later. Ask any Rolex dealer. The question is not if it will fail, just when. No matter how you maintain it.

And what do you do then? Quit diving? Or, pull out the tables and go with Plan B?

Well, having defended tables in the post before yours, I feel compelled to respond to your post: tables are a useful backup to computers, but not a useful replacement. Arguing that you should never take electronics underwater because it might fail is silly; you can say the same thing of your fin strap, your tank o-ring, and your drysuit. The "self-reliant" diver does not have to be a Luddite. You plan for the unlikely event of a failure, don't you? Or do you plan for no failures? If the latter, just how do you do that?

 

[Rred]

Well, as any zen master would tell you, if you'd just learn to hold your breath for an hour or two, you wouldn't need any of that gear in the first place.

I don't say a computer can't be useful, only that in many situations it is an expense (diving is already expensive enough) and a recurrent expense (to maintain and replace) and not necessary. Having a nice "rate of ascent" instrument certainly IS damned useful at all times, but that even used to be in some dive watches.

IIRC the rates and numbers of deco incidents haven't changed in any way correlated to the use and spread of computers, have they? Have the computers actually made diving any safer for anyone except the folks pushing the edges?

 

[boulderjohn]

Actually, John? If you live in Florida, or the Gulf Coast, or the southeastern seaboard?
...

A diver can never be self-reliant, if their basic plan is relying on electronics and water seals and electricity--all of which is expected to operate UNDER WATER. All water"proofing" fails sooner or later. Ask any Rolex dealer. The question is not if it will fail, just when. No matter how you maintain it.

And what do you do then? Quit diving? Or, pull out the tables and go with Plan B?

First of all, I see no benefit in knowing how tables work in order to use a computer. For some reason, people seem to think you need to know how to use tables in order to understand the basic concepts of decompression. Mark Powell wrote an entire book about decompression without ever explaining how to use a dive table. Decompression theory is one thing; the process we use to manage decompression stress is another. It could be tables. It could be a computer.

Next, the tables rely on your use of a depth gauge and a timing device, two instruments with the same potential for failure as a computer, as your Rolex analogy implies. I have never had a computer fail, and I have never had a buddy's computer fail. I have had two dive watch failures, and each was the same insidious failure--at some point during the dive, it stopped for a while and then started again, leaving me with the very dangerous assumption that I not been diving as long as I had. Luckily, both times occurred when I was teaching a class in the pool, so the only problem was that my class schedule got thrown off. If it had been on an actual dive, I could have been bent.

Most of my diving is multi-level, as was the case in my only attempt to use tables after certification. If I use the computer on one dive, I will often find it impossible to switch to tables for the second, because the first one is likely to put me off the tables.

Finally, I carry two computers, so if one fails, I will simply carry on with the other.

I will leave you with a wild analogy. I was in parent teacher conferences for my then 9th grade son, and his English teacher was trying to explain the thinking behind the worst assignment I have ever heard of (and I was an English Teacher myself). The teacher had the students sit in class every day and copy the contents of their grammar book into a notebook. (This had been going on for weeks.) He said that doing this enabled them to carry around a grammar notebook they could use when the need arose in their daily lives. You mean, I asked, that if they ever need to know if a verb is in the subjunctive mood, they will be able to whip out their loose leaf notebooks and see? Exactly, he replied. I then asked why he did not also suggest that they walk around with a life jacket on in case the continent sinks, since I would consider those two events to be in a similar order of likelihood.

Yes, there is a very, very, very, extreme, remote, unlikely possibility that if a single computer failed during the first dive of a two tank day that the second dive could be salvaged by using tables. I'll take my chances.

 

[Rocketman3]

When you do buy your computer be sure and get the same computer for both you and your wife.
When we started diving we bought nice used gear. The computers on each set were completely different. The real issue is that because we are vacationing divers it is difficult to remember how two different computers work.

But to answer your original question, YES get Nitrox certified, we don’t use it often, but when we want/need it, I am glad we are certified.

 

[TMHeimer]

I didn't read all the posts. Agree that it is a good idea to get your own computer and be familiar with using it for nitrox. Agree that tables are a good backup, but not a good replacement as some have pointed out. The big thing with nitrox is the MOD--that you don't exceed the max depth for the % O2 you're using or you may die while convulsing. Tables and computers don't differ in that. If you rent computers you have to be shown how to use them and have them set properly for your nitrox mix. Whether it's worth taking the course when you do dive trips so infrequently is a judgement call (as opposed to just using Air). As mentioned, nitrox is beneficial for repetitive diving, so what your dive schedule usually is will play into that. I would be too nervous to dive so infrequently, nitrox or not, but you didn't ask that.

 

[Aviyes]

The advantage to having the computer before taking the course is that the instructor would most likely be able to show you how to adjust %O2 settings for that specific computer. Otherwise the Nitrox course is all about theory/MOD restrictions and how to test/mark your tanks and calc MOD. The course felt like more of a read the text, ask/clarify any questions/concerns, take a test, and here's your cert card.

 

[TMHeimer]

The advantage to having the computer before taking the course is that the instructor would most likely be able to show you how to adjust %O2 settings for that specific computer. Otherwise the Nitrox course is all about theory/MOD restrictions and how to test/mark your tanks and calc MOD. The course felt like more of a read the text, ask/clarify any questions/concerns, take a test, and here's your cert card.

Agree on all that. The instructor could probably also show all the many functions on the computer, thus skipping trying to understand all that stuff in the manual. I've had two computers so far. Setting them to nitrox was something even I could figure out, so anyone probably can.

 

[StefinSB]

Well, as any zen master would tell you, if you'd just learn to hold your breath for an hour or two, you wouldn't need any of that gear in the first place.

I don't say a computer can't be useful, only that in many situations it is an expense (diving is already expensive enough) and a recurrent expense (to maintain and replace) and not necessary. Having a nice "rate of ascent" instrument certainly IS damned useful at all times, but that even used to be in some dive watches.

IIRC the rates and numbers of deco incidents haven't changed in any way correlated to the use and spread of computers, have they? Have the computers actually made diving any safer for anyone except the folks pushing the edges?

This is like saying that real engineers should learn to use slide rulers as computers don’t work without power. I also do not see what a table really “teaches” you that a proper dive computer lecture can’t. Do you really know about decompression theory when you figured out you are in pressure group H?