Teaching Computers in OW class vs tables

[ShakaZulu]

Ok, updated the info, my computer doesn't give me the time at max depth (Suunto Mosquito), the dive time indicated, would be the time of the entire dive. I did not ride the NDL curve on the first dive.

 

[perpet1]

How are you going to get onto tables after the fact?
You need to plan your dive before hand.
If you have planned your dives and adjusted the plan for

I do not agree with this line of thaught and the idea as was also mentioned that if you computer fails you need to not dive for 24 hours.

This all depends on how many dives you have done that day and where you are on your tables as a back up. I personally can off the top of my head (as I am sure most of us can) say how long and the max depth of my last few dives. Given the fact that if a computer fails you only have to go back that day you should have all the information you need (even with a computer you should have a timing device). Now plug the dives you did into a table with the SI and behold you are have the necessary data to use the table to plan your next dive.

Now because your computer does the multilevel thing and you are now stuck with a table (I would not even try to calculate the previous dives as multi level) you may be in a situation where you need a long SI but once the table gives you the bottom time you want I really do not see a problem doing that. If the previous dives violated NDL's for your tables you should then not dive for 24 hours. But other then that I can think of no reason not to switch over to the tables.

I dive with two computers most of the time for redundancy. I can however crankout the tables when I need to.

 

[Caver95]

well then.

 

[AADiveRex]

One thing that should be mentioned is that technical diving or overhead diving is totally different and what were talkign of here isnt designed for that. Tech diving requires backups, so you wont be relying on a single computer. Most tech divers dont seem to use computers at all, which makes sense in that kind of diving. I cave dive and use my computer solely, but I do single tank diving to NDLs, and so rarely does it even matter except repetive diving. I almost always have to turn based on air.

Most of my diving is fairly technical, wreck penetrations, and long decos. I do use computers, 3 of them. A Nitek He, a Nitek 3, and an old Dacor Pro Brain Air computer. Never had a failure with any of them yet. I have several hundred dives on the Niteks, and over 1500 on the Dacor. Like everything I carry into the water, they are tools to aid in my dive, and although I expect them to work, if they fail, no problem. Backup computers, backup tables... and of course my brain.

The only computer failures I have ever had were before the dive. Pre Nitek days, I had a Cochran Nemesis 3 gas, air integrated, which one day decided to just stop working. Cochran fixed it, I sold it and got the Nitek 3, then later the He, and I absolutely love them. I have never had one fail, though the possibility of course exists. BTW, up here in the North Atlantic, most of the tech divers do use computers.

I did have a buddy's computer fail on a dive. We were cave diving down at Ginnie Springs, and his Nitek 3 started to behave erratically. He is also equipped with backups, so our dive went off without a hitch. Back at the surface, we called Dive Rite and they figured it was dirty contacts, but suggested they take a look at it to give it a complete test. No sooner had we hung up the phone, did Lamar Hires, owner of Dive Rite, pull in for a dive. He was our cave instructor, is a friend, and an all around great guy. He heard our story, and gave my buddy the Nitek He right off his wrist, to keep for the week while we were down there. Talk about customer service... Lamar took my buddy's computer, and on our way home at the end of the week, we dropped off Lamar's computer at Dive Rite, and they had my buddy's unit ready to go. It was, as they predicted, simply dirty contacts, due to my buddy's failure to wash the thing regularly.

Dive Safe,
Adam

 

[AADiveRex]

Amen to most of the comments here. Although some of the agencies will end up not making the tables a compulsory part of the OW course, I believe we, as instructors, should always teach them and make sure our students learn them well. Computers should always be treated as a back up for the tables and not the other way around.

Students spend so little time learning in the OW course these days, it is important that they master the tables in order to become safe divers. Yes, computers fail too often and then divers who have zero understanding of physics rules end up conducting their dives blindly while following the 'suggestions' of a DM on a boat, or another eually unsafe diver from the shore.

I agree as well, with one exception.

I beleve that a computer can be used as a back up to the tables, or the tables can be the back up to the computer. The brain is the back up to them both. But there is no substitute for a well thought out dive plan before jumping in the water. For this, there is no back up, and there is no excuse. "Winging" a dive without forthought, and going wherever the computer OR the tables take you, is sloppy, unsafe, and inexcusable. If you do "plan the dive and dive the plan", than any problem should be able to be resolved, backed up, or the dive safely aborted.

One other point, if your computers fail so often, perhaps it's time to consider a new computer?

Dive Safe,
Adam

 

[Diver0001]

Ok, I have question for all the table dewds.......... I always log my dives to the logbook after a dive.

Diving Air

Dive 1

Dive Time - 28min
Max Depth - 99ft
Ave Depth - 62ft
Safety Stop - 3min (stayed within the NDL limits as shown by the computer)

Dive 2 (SI 1:09)

Dive Time - 25min
Depth - 85ft (last time I looked, the computer stopped working)

Immediately accended with my buddy and did a 3min safety stop. When can I do my next 85ft dive again?

How sure are you that you haven't gone over your NDL's?

R..

 

[jviehe]

How about this, an informal poll. In how many dives has your computer failed how many times? Ive used mine 100 times and had 0 power failures or misinformation. Note: Im not interested in user error here, that is a different topic.

Second, lets take a hypothetical. A dive computer will never fail. If this was the case, what would be the problems with tossing the tables and teaching OW students computers only?

 

[MikeFerrara]

How about this, an informal poll. In how many dives has your computer failed how many times? Ive used mine 100 times and had 0 power failures or misinformation. Note: Im not interested in user error here, that is a different topic.

Second, lets take a hypothetical. A dive computer will never fail. If this was the case, what would be the problems with tossing the tables and teaching OW students computers only?

I've seen many computers fail especially in the winter.

I was on my way out of Peacock after a 60 minute dive with a max depth of about 65 ft and an average of about 50/55 ft. On the way back the computer started racking up decompression. LOL I was only using it as a bottom timer and already knew what my ascent would be like but it was interesting to watch. I did a slow ascent to about 40 ft where I did a briefe stop and moved up to 30 ft to kill some time in the cavern. While at 30 ft the computer was racking up more decompression like it was going out of style. When I got to 20 ft it still wasn't taking any time off to speak of. LOL

I had to stop at about 10 ft to wait for some kids who were jumping into the spring to move and it wasn't until then that it started giving me credit.

you see the stupid machine wanted me at 10 ft and if I didn't get there I guess it was going to try to keep me in the water all day. LOL

When I got out of the water I looked at it to try and figure out what made it flip. Apparantly I bumped it or something and put it in some super duper ultra conservative mode. Of course there isn't any way to fix it or even figure that out under water so if I didn't already know exactly how I was going to do the dive I would have been at the mercy of that crazy machine.

These kinds of situations can be as much trouble as if the thing just shuts off if you're depending on it.

And then there's all the computers that lock up or go into gauge mode for 24 or 48 hours if you violate one of its rules. No computer should EVER do that. It needs to keep calculating and let you make the decisions.

 

[MikeFerrara]

How about this, an informal poll. In how many dives has your computer failed how many times? Ive used mine 100 times and had 0 power failures or misinformation. Note: Im not interested in user error here, that is a different topic.

User error isn't, IMO, another topic. The reliability of the procedures involed in oporating a computer are in part related to its design.

Second, lets take a hypothetical. A dive computer will never fail. If this was the case, what would be the problems with tossing the tables and teaching OW students computers only?

I use tables as a reference just as I would use a computer for reference if I used one. I wouldn't blindly follow/trust either one. The diver still needs to understand enough decompression theory to feel comfortable making decisions based on what the table or computer says as well as what they know about themselves and the dive that the computer doesn't know or doesn't know what to do with...

For instance...I might do a dive a little different if I know I'm going to be doing more diving later in the day. The computer has no clue what I'm going to do and therefore can't help me plan for it.

Teaching tables is one tool that can be used to teach decompression theory but the tables have some problemns too...

For instance the tables won't give you any SI credit until you begine a direct ascent to safety stop depth or the surface. While the fact is that if, after a deep dive, you use up some of your remaining gas hanging out shallow (say 30 ft or so) you're doing nothing but offgassing while under pressure halping to keep bubles small. If used as designed the table will cintinue to hike up the rep group until you end the dive. So even tables can encourage bad habits like rushing up to 10 or 15 ft after a dive.

 

[jviehe]

But do current teaching methods via the tables make students understand deco theory? You have pointed out one issue which is that its more difficult to plan a serieis of dives using a computer. Mine only scrolls current allowable NDLs, but cant tell me when to quit in order to have a certain amount of time on another dive.