Dive Computer Failure -- Ending the Dive

[Superlyte27]

My first mustang didn't have seat belts installed in it. Today both my Jetta and my Mustang have them. I wear the seat belts every time without fail. Progress is an interesting thing. Safety is too.

In the late 70's early 80's motorcycles started being equipped with fiberglass fairings over the front, shrouding the headlights and engine. A lot of my friends would rip the fairings off claiming that they slowed you down; you know, wind resistance and all.

Of course, as time went on and the engineering of these two examples was fully understood, all car manufacturers started installing seat belts and nearly all race bikes have fiberglass or carbon fiber fairings to slice effectively through the wing, enabling bikes to go faster. Dive Computers are the same way.

Dive computers (and I know most of you know this) aren't just a little bit better or just a little bit safer, or just allow you to dive a little bit longer. Dive computers are tremendously better. Especially if you get the right one. It's time to move out of the dark ages and move into the 21st century. Diving square profiles and tables is only costing you beautiful dive time. Wear two if you have to, but you're really missing out. Just like the early opponents of seat belts and fairings were missing out.

 

[scubastingray]

Proprietary navy tables? We paid for that information! I got mine on Ebay.

Example from the Navy dive table: 70FSW for 60 min dive requires an 8 min stop at 10fsw. This is nothing more than an extended safety stop, which is all deco is in practice, a series of extended safety stops, that are required to surface safely.

Long ago when I got certified the Navy air tables were the tables we trained on because it was all there was to use. PADI, NAUI etc. hadn't developed their own yet.

You're missing the point entirely.

In order for that to be a viable back up plan you have to be constantly profiling your depth and time. I find it hard to believe you are constantly jotting that down on a slate, and even harder to believe it's something you do in your head.

 

[AfterDark]

How is it "nothing more than an extended safety stop" if it's a required stop?

Wow! Do I really have to do this? Really? OK

Originally Posted by AfterDark
Example from the Navy dive table: 70FSW for 60 min dive requires an 8 min stop at 10fsw. This is nothing more than an extended safety stop, which is all deco is in practice, a series of extended safety stops, that are required to surface safely.

in practice means roughly that the actual doing in this case is the same. The diver hangs for a prescribed amount of time at a prescribed depth and describes it as a series of stops. The sentence then goes on to describe it as required to surface safely. The 1st sentence also states the stop is required. Simple enough?

---------- Post added July 13th, 2014 at 11:24 AM ----------

You're missing the point entirely.

In order for that to be a viable back up plan you have to be constantly profiling your depth and time. I find it hard to believe you are constantly jotting that down on a slate, and even harder to believe it's something you do in your head.

No I'm not, go back and read my posts you are operating with limited information.

 

[Superlyte27]

You're missing the point entirely.

In order for that to be a viable back up plan you have to be constantly profiling your depth and time. I find it hard to believe you are constantly jotting that down on a slate, and even harder to believe it's something you do in your head.

I missed a post or something, so bear with me if I don't understand the point.
But... if you're diving a computer, and that computer suddenly fails on a recreational dive, and you have a timer and tables, you don't need to monitor your profile. You just need to know your max depth and time, then use the table to manage your square profile. Sure, you're cutting yourself out of a lot of dive time, but you can surface safely without issue. You don't have to monitor your profile up and down and up and down, you just know that your max depth was 70' and a 70' dive you can stay down for X amount of time before it's time to surface.

What have I missed?

 

[dfx]

Wow! Do I really have to do this? Really? OK

Originally Posted by AfterDark
Example from the Navy dive table: 70FSW for 60 min dive requires an 8 min stop at 10fsw. This is nothing more than an extended safety stop, which is all deco is in practice, a series of extended safety stops, that are required to surface safely.

in practice means roughly that the actual doing in this case is the same. The diver hangs for a prescribed amount of time at a prescribed depth and describes it as a series of stops. The sentence then goes on to describe it as required to surface safely. The 1st sentence also states the stop is required. Simple enough?

No, not really. Sure, if you have experience doing deco stops, then doing safety stops won't be a problem for you. The opposite isn't true however. In practice, safety stops are rarely executed in a manner precise enough for safe deco diving, generally because divers weren't trained to do that. That's the whole point of an optional safety stop, it's good if you do them and even better if you do them correctly, but it doesn't matter much if you don't.

 

[Superlyte27]

My Opinion of Safety Stops is below:

Is it possible to do everything properly every time and still get bent?
You're hydrated, rested, not overly task loaded. You've analyzed your gas properly, you're not obese. You're not diving after a long night of drinking. You're active, healthy, stayed within NDL, descended safely, ascended properly. You're not on meds that are bad for diving, etc. etc. etc.. YOU'VE LITERALLY DONE EVERYTHING PROPERLY... can you still get bent?

You betcha. And every training agency out there says exactly that in their slides or videos.

The safety stop was thought up to virtually eliminate all of these "undeserved" hits. So, you've done everything right, and YOU'RE still at risk of getting bent. The safety stop hopes to mitigate all of that risk. But who knows for sure....

 

[KeithG]

I missed a post or something, so bear with me if I don't understand the point.
But... if you're diving a computer, and that computer suddenly fails on a recreational dive, and you have a timer and tables, you don't need to monitor your profile. You just need to know your max depth and time, then use the table to manage your square profile. Sure, you're cutting yourself out of a lot of dive time, but you can surface safely without issue. You don't have to monitor your profile up and down and up and down, you just know that your max depth was 70' and a 70' dive you can stay down for X amount of time before it's time to surface.

What have I missed?

I think the key is that many multi level computer dives will put you way off the chart of any tables. Try 70 feet for a 60 minute dive. Very doable with a computer. So is 90 feet for 90 minutes. But neither can be applied to my copy of the us navy no decompression limits table as the 70 foot time limit is 50 minutes and the 90 foot limit is 30 minutes. Kind of hard to map back to a table as a square profile afterwards. It won't fit.

So you have 2 options:
- use a backup computer
- sit out 24 hours to off gas to ensure you can transition to tables in a know state

 

[AfterDark]

No, not really. Sure, if you have experience doing deco stops, then doing safety stops won't be a problem for you. The opposite isn't true however. In practice, safety stops are rarely executed in a manner precise enough for safe deco diving, generally because divers weren't trained to do that. That's the whole point of an optional safety stop, it's good if you do them and even better if you do them correctly, but it doesn't matter much if you don't.

Well you're either at XXFSW or you ain't, SS or deco I execute the same, SS chest @15fsw for 3min; deco stop(s) chest@ fill in the blanks.

My backup tables:

 

[ratchet04]

[sarcastic response on]




On top of that, it is a flaw to increase the failure points of the backup to three separate devices that all must work for anyone to be of use. It does not make for more security. I have seen more watches get lots than any other piece of gear because they have tiny pins holding the strap, and less hardy O-rings. Once someone moves into a proper dive rated watch, then they are getting into the amount of money that can easily buy a far more useful backup dive computer. Example: I have completely lost way more than twenty watches working as a guide, and I have blown out twice that many band pins. (I have only lost one dive computer.) This does not count watches flooding, because I long ago learned to treat watches as disposable because it there is no way to count on a watch after a battery change. And then add the fact that almost all dive computers are recoverable even after a battery compartment flood, and watches aren't, and well, dive watches just start to make less and less sense compared to computers.

.

Good point. Something to definitely consider.

---------- Post added July 13th, 2014 at 10:49 AM ----------

What the OP needs is one of these



I used to plan most of my Saudi shore dives on a profile of;

20M for 20 mins
16M for 20 mins
then 10M until I reached 50 bar then start ascent

I bought my first computer (Suunto Companion) as a back up and continued to use the wheel until around 1997.

After many years of using tables / wheel I know roughly what most of my NDLs will be before I dive.

If only they had brought out a Nitrox wheel

Now that is cool.

---------- Post added July 13th, 2014 at 10:57 AM ----------

OP, consoles are so eighties. He may not be the last "tables diver" but he is close to being the last "console diver" .

N

Ha! I'll take that under advisement. My dive shop MST used another word to describe me. CHEAP! But hey if it works and you keep up with service I'll save the money for another couple dives.

 

[ratchet04]

Hang on. This does not pass the sniff test. Are you sure this is what the manual says?
on a recreational dive, you have no deco obligation and can go directly to the surface. Since you are ending your dive early, you WILL have lots of air, so feel free to make a 3-5 minute safety stop @15 feet. But holding at 10-20 as long as air will allow? Nope. Not doing that. That could be an hour or more....

P.s. if you are computer diving, the only viable backup to a computer failure is a backup computer.

Seemed odd to me too: