two dive computers vs. dive tables

Dear all,

This post is inspired by Willar's post "PADI dropping dive tables?" - I did not post this as a follow-on to his thread as I did not want to detract from that thread.

A year ago I came to a personal decision that I was never going to dive tables, unless there was no other alternative. I also realized that there was a chance that a computer could fail during a dive. Therefore I bought a Sherwood Insight (wrist mount) as a backup for my Sherwood Wisdom 2 (air integrated) and take both on dives. A failure of the Wisdom 2 would mean the end of my dive (no console), but I could still dive if the Insight failed.

Personally I believe that, in the way that octo's have replaced (in the majority of cases) the need for buddy breathing (not that it shouldn't be taught or practiced), I also believe that diving with two computers will replace the need to take a dive table with you on any trip (not that a table weighs much...) Judgements on whether or not tables should be taught are directed to Willar's post.

Does anyone see a fault in this? If so, why? I am prone to missing the obvious, so I welcome feedback.

Look here

http://www.scubaboard.com/forums/ne...302322-one-dive-computer-enough-4-divers.html

For local diving when I'm doing one or possibly two dives per day, I wouldn't even bother with wearing 2 computers on a dive. It's overkill for recreational diving in my opinion. If my computer goes out in the middle of a dive, I thumb the dive, show the wonky computer to my buddy, and we ascend together. No big deal.

Wearing two computers makes a lot more sense when you're on a dive vacation doing multi-day repetitive diving. That's the only time I'll wear two. For me, it's not a safety issue...but one of convenience since the backup will track my previous nitrogen loading and oxygen exposure.

If you're going to go through the trouble of taking 2 computers with you on vacation, you might as well bring along a backup analog SPG. Then, if your Wisdom croaks, you pop the SPG on the first stage and continue diving with your Insight.

I prefer the tables simply because I don't trust anything electronic where my life is concerned. Most computer failures don't involve an obvious shutdown of the device. Most often it is the failure of but a few micro-transistors that cause a corruption of data or even a simple programming error. All computers depend on binary code; a pattern of ones and zeros. Each of the millions of transistors in a computer acts as a logic gate and the information it stores/transmits depends on whether the transistor is turned "on" (one) or "off" (zero). If a transistor shorts out, it will always read as "1", even if the data needs for it to read "0". Or, if the transistor burns out, it will always read as "0." In either case, the data corruption can cause a cascade failure of the data to the extent that the final output is in error.

Tables have no transistors to fail.

The circuitry used in a dive computer is no more sophisticated or technologically advanced than what is used in your average desktop computer and we all know how finicky they can be.

If you feel comfortable and confident that some unseen worker slaving away at an assembly line in some Asian sweatshop for slave wages has done a super bangup job of assembling mass produced parts (from another assembly line in another Asian sweatshop) into a device that you can absolutely rely on to protect your life, you've got more guts than I, my friend.

In the end, the decision whether or not to use dive computers is a purely individual choice.

Live long and prosper, my friend.

mpetryk:

Dear all,

This post is inspired by Willar's post "PADI dropping dive tables?" - I did not post this as a follow-on to his thread as I did not want to detract from that thread.

A year ago I came to a personal decision that I was never going to dive tables, unless there was no other alternative. I also realized that there was a chance that a computer could fail during a dive. Therefore I bought a Sherwood Insight (wrist mount) as a backup for my Sherwood Wisdom 2 (air integrated) and take both on dives. A failure of the Wisdom 2 would mean the end of my dive (no console), but I could still dive if the Insight failed.

Personally I believe that, in the way that octo's have replaced (in the majority of cases) the need for buddy breathing (not that it shouldn't be taught or practiced), I also believe that diving with two computers will replace the need to take a dive table with you on any trip (not that a table weighs much...) Judgements on whether or not tables should be taught are directed to Willar's post.

Does anyone see a fault in this? If so, why? I am prone to missing the obvious, so I welcome feedback.

Click to expand...

I too would like to hear of any fault in this. I started with a VEO 250 and an spg. I recently bought a Suunto Cobra 3. I also have a watch with a depth gauge. I have redundant everything along with my PADI eRDP in case of the chance of 2 computer failures. I can't think of any fault with this approach.

mpetryk, I think your idea is a good one, though tables and maybe PADI's eRDPml are obviously good planning tools. The only fault with 2 computers is many folks lost their financial shirts the last year or so.

dmoore19:

I too would like to hear of any fault in this. I started with a VEO 250 and an spg. I recently bought a Suunto Cobra 3. I also have a watch with a depth gauge. I have redundant everything along with my PADI eRDP in case of the chance of 2 computer failures. I can't think of any fault with this approach.

Click to expand...

@dmoore19: Do you wear all of this stuff on your local dives? If so, why? Are you afraid that you won't be able to safely abort a dive without a working computer? Are you diving with a buddy?

Paladin954 is a solo diver, so I can see why he'd want to be diving with backups of everything and might eschew computer doohickeys for tables. For people who buddy dive, the other diver provides complete redundancy.

Don't see a problem with redundant computers in place of dive tables at all...

That being said, you need to understand dive table planning if only to maintain a grasp of off-gassing and SI timetables, and mixture limits without having to rely on the computer to understand that for you.

For local recreational dives, I don't see the need to even have redundant computers. If you're diving deeper wrecks, technical, cave, or solo, you need redundancy (and in some cases tertiary systems).

See my next post.

I see no problem with this. It's a personal choice of course. I have two computers although I don't always wear them. I like to have two of most pieces of dive gear just to head Murphy off at the pass. It's more of a convenience really.

I don't think one should rely on computers or tables without basically having that info in your head in the first place.

It's not about not trusting a computer. You shouldn't be "trusting" a computer in the first place. You can use one however as you use a table.

"Computers" do make useful time/depth pieces.