Ivy Lea campground / Rockport

[cos]

You should not plan to exceed NDLs without additional training.

If you accidentally exceed NDLs, your computer will tell you what to do. Unfortunately, that will do you no good if you do not know what it is telling you. Read your manual carefully to see how your computer will guide you through an accidental decompression procedure.

Some computers are true decompression computers and can be used as such. Most computers however, will clearly state that they should not be used as such, and that the decompression information they give is for unintended violations of the NDLs.

What if the battery fails on the dive?

If you are diving near the NDL you should have a clear understanding of what you are doing. Relying on a computer for this is foolish in my opinion. Whether you are diving a computer, bottom timer, or timing & depth device, you should understand where you are going and what you are doing. Use the computer for a back-up or to affirm what you should already know.

I have done a relatively straight forward dive in my area with different divers. The dive is the "Kinghorn" in Rockport, Ontario. It is about 92' to the bottom and is square profile with an upline at the bow and stern. The thing about this dive is that NDL's come really quickly. If you are ready for it it is no big deal but I've dived it when a buddy flipped when he saw that he was at his NDL. He bugged out and raced to the line and then raced up the line until the deco obligation went away. He stopped at 40-50 foot and waited for me. I photographed him from the block shooting up and got some really great shots. For about a minute or 2 we were both alone on the dive. I had a redundant set up and he did not. I won't do that dive with him again.

 

[boulderjohn]

What if the battery fails on the dive?

The same thing you would do if your watch, depth gauge, bottom timer, pressure gauge, etc. fails.

 

[cos]

The same thing you would do if your watch, depth gauge, bottom timer, pressure gauge, etc. fails.

Proufound.

Almost as thoughtful as

"If you accidentally exceed NDLs, your computer will tell you what to do."

 

[Splitlip]

You would fall back on your plan and or tables using your ..oh, wait. never mind

 

[rfryza]

I have been on the kinghorn it was my first shipwerck dive it was very cool and I had enough time to go accross the deck(taking my time) and over the bow and back over the deck to the line up. My air did not seam to last very long at that depth.

 

[Splitlip]

groan

 

[boulderjohn]

Proufound.

Almost as thoughtful as

"If you accidentally exceed NDLs, your computer will tell you what to do."

Actually, it is profound.

If you are doing a dive on tables, and you realize that your watch or depth gauge has failed, then you should begin an immediate ascent. If you are within no decompression limits, you just need to be sure you do a relatively slow ascent and estimate as best as possible the time for a safety stop. If you are on a planned decompression dive and you have such a failure, it becomes much more challenging.

If you are using a computer, you begin by looking at the computer's planning program to determine your maximum bottom time at your planned depth. that puts you in exactly the same situation as if you were using tables. Then you do your dive. If you are doing your dive within NDLs and have a battery failure, then you are in exactly the same situation as you would be if using tables.

I don't see the difference.

If you are using tables and accidentally exceed the NDLs, what do you do if your watch or depth gauge fails after you have accidentally exceeded those limits? Most tables do not dive you any real guidance for this. You have to have memorized the formulas and then estimated the times.

If you are using your computer and accidentally exceed the NDL limits, the computer will tell you what to do about it, and if it then fails immediately after doing this, you will have to make the same estimates. You are in this case ahead of the game in this worst case scenario.

The problem comes if the computer fails IMMEDIATELY in the few seconds after going into deco--not before and not after. That would require a stroke of bad luck akin to being hit by a meteor. Even if that were to happen, the diver would be able to deal with the problem easily by giving himself a few minutes extra stop time--assuming an accidental deco only.

BTW, I rarely use a computer myself. I plan my deco dives carefully, and I measure my bottom time with a bottom timer. A bottom timer is nothing more than an overpriced computer with little functionality, and it is just as likely to fail as a real computer. I have been on two different deco dives where a teammate has had a bottom timer fail. I use a watch when I teach students, and the dive watch I used prior to the one I have now, which cost twice as much as a basic computer, failed three times during instruction before I finally replaced it.

I am not a big advocate of using computers myself, but for other reasons. The "what if the battery fails" argument is specious.

 

[cos]

Actually, it is profound.

If you are doing a dive on tables, and you realize that your watch or depth gauge has failed, then you should begin an immediate ascent. If you are within no decompression limits, you just need to be sure you do a relatively slow ascent and estimate as best as possible the time for a safety stop. If you are on a planned decompression dive and you have such a failure, it becomes much more challenging.

If you are using a computer, you begin by looking at the computer's planning program to determine your maximum bottom time at your planned depth. that puts you in exactly the same situation as if you were using tables. Then you do your dive. If you are doing your dive within NDLs and have a battery failure, then you are in exactly the same situation as you would be if using tables.

I don't see the difference.

If you are using tables and accidentally exceed the NDLs, what do you do if your watch or depth gauge fails after you have accidentally exceeded those limits? Most tables do not dive you any real guidance for this. You have to have memorized the formulas and then estimated the times.

If you are using your computer and accidentally exceed the NDL limits, the computer will tell you what to do about it, and if it then fails immediately after doing this, you will have to make the same estimates. You are in this case ahead of the game in this worst case scenario.

The problem comes if the computer fails IMMEDIATELY in the few seconds after going into deco--not before and not after. That would require a stroke of bad luck akin to being hit by a meteor. Even if that were to happen, the diver would be able to deal with the problem easily by giving himself a few minutes extra stop time--assuming an accidental deco only.

BTW, I rarely use a computer myself. I plan my deco dives carefully, and I measure my bottom time with a bottom timer. A bottom timer is nothing more than an overpriced computer with little functionality, and it is just as likely to fail as a real computer. I have been on two different deco dives where a teammate has had a bottom timer fail. I use a watch when I teach students, and the dive watch I used prior to the one I have now, which cost twice as much as a basic computer, failed three times during instruction before I finally replaced it.

I am not a big advocate of using computers myself, but for other reasons. The "what if the battery fails" argument is specious.

John, I think that is a much better explanation for a new diver with less than 24 dives who is asking about diving in a challenging area.

 

[Splitlip]

But..considering his questions, he won't get it.

Guy does not know what impacts NDL. Now we are talking about "estimates", tables, timers if his computer fails?

The OP needs more training and certainly should not rely on a computer considering his experience level, profiles and lack of basic dive science.

 

[ScubaSteve]

John, I think that is a much better explanation for a new diver with less than 24 dives who is asking about diving in a challenging area.

This is intended to be polite enough to get the point accross. Any diver with less than 20 dives really has no place diving in conditions that they consider harsh. They are still learning and getting comfortable with the gear and all of the tasks that they have yet to turn into muscle memory. The very fact that someone needs to ask what happens if their computer fails, means that their training was incomplete and they are not prepared for what could happen when diving. The thread OP needs to find a mentor and dive in conditions that they consider benign (translates into those which they certified in). This will enable them to get comfortable with the gear and the tasks, and to learn more as they go. But first and foremost, they need to approach their instructors and ask for either to sit in on some of the classes they have or a refresher because some of the fundamentals have been completely missed. I would relate it to a mechanic asking what the thing under the hood is.....not what you want to hear.