What if...? Computer Issues

[Jax]

Assume this is normal recreational divers who are fairly new and only have one computer each, not 3.

Perhaps I missed it -- did anyone mention that divers should keep their max depth in their mind, for just this sort of eventuality?

When mine quit, that nugget of information allowed me to transition back to tables. :yuck:

 

[Cave Diver]

Perhaps I missed it -- did anyone mention that divers should keep their max depth in their mind, for just this sort of eventuality?

No one has specifically mentioned it. It's a good idea for divers to keep track of their depth, time and gas on a regular basis. It helps them to start to draw correlations between them.

It's an even better idea for them to try and anticipate what those readings will be before they look. This will help them get to a point that they aren't relying on the information the gauges provide, they merely use it for confirmation of what they already know.

I thought you were going to ask something difficult. You and your buddy are on a dive trip and run out of beer and money, what do you do?

Answer: Don't panic.

Better answer, sell all of your buddies dive gear for more beer money.

 

[syntaxerrorsix]

Better answer, sell all of your buddies dive gear for more beer money.

Win.

You can always find more buddies. Beer is precious

 

[soltari675]

This one is an easy set.

* What would you do if your computer stopped working during a dive?
End the dive. If I kept track of my dives at all and knew how deep I went and how long, I could track where I am on a table. If not, I am done.

* What would you do if you exceeded your NDLs (table or computer)?
Done for 24 hours at least.

* What would you do if your buddies computer went into deco but yours still showed NDL time remaining?
End the dive. Not worth risking my buddy's life because I want to see a fish.

* What would you do if you were gearing up on the boat and realized you forgot your computer and no one had an extra?
Use tables that day, despite how annoying they are.

 

[Jewls]

(Long Post….sorry)

Alright, I’m the only one with fewer than 25 dives that has answered Cave Divers last question. I recently completed my AOW in December 2010. Even though I am AOW certified, I wouldn’t classify myself as an experienced diver. So I’m going to take another shot at this scenario.

I was OW certified in 2009; in my PADI Crew Pack I received the eRDPml. There were not any tables included in the pack I received. We did see the tables during our classes, but where not thoroughly trained to use the tables, just the eRDPml. I also learned that PADI eliminated the tables and replaced the tables with eRDPml in 2008. So I pulled out the eRDPml and made some new calculations.

So let’s assume that I have the eRDPml (rather than tables) back on shore. Last time I looked at my computer I had 7 minutes remaining for my NDL, that was 5 minutes ago. So I have an estimated 2 minutes remaining, if not less time. I alert my buddy and end the dive making a slow ascent with my buddy’s assistance. We make an emergency safety stop (assuming I’ve gone past my NDL) of at least 8 minutes or more to allow the excess nitrogen to release from our bodies. Deploy the SMB and ascend to the surface. Surface swim back to the shore (as explained in my earlier post).

Now I’m back on shore and see that we can consider this dive a “single” depth profile as we did not make multiple ascents to consider this a multi-level dive. (Thank you charlie99 for pointing this out). While using the eRDPml, I consider if I was deeper than my buddy at any given time, so I’m going to round up to a max depth of 85’. My NDL reads 27 minutes. Now I need to calculate my ABT, I assume that I have either reached or passed my NDL limit of 27 minutes. I enter in ABT of 27 minutes. My RDP tells me a safety stop of 3 minutes is required, not the 8 minute Emergency Safety stop I performed earlier. My PG is Q. I estimate a SI of 2 hours. My new pressure group is B. If I plan for a second dive to the same depth of 85’, my ANDL is 20 minutes. I’m conservative, so I could make a single depth dive of 15 minutes, leaving me with a pressure group of N. This dive wouldn’t be worth the shore dive. However, I could make a single depth dive of 60’ with an ANDL of 44 minutes . Diving on the conservative side, would give me about a 40 minute dive. So my answer would be Yes, I could make a second dive.

I kind of feel like I’m breaking rules though and as mentioned before these are the reasons why.

1: If my computer fails, I should not make another dive for 24 hours.

2: I’m using my buddies dive watch to estimate my depth and time. (According to the PADI AOW manual, I should not share a computer.)

3: I think I’ve reached or passed my NDL by no more than 5 minutes and made an emergency stop of 8 minutes (just to be on the safe side). Rule # 3 on the eRDPml states if a Emergency Decompression stop is made to remain out of the water for at least 6 hours. I answered that I could make another dive after a SI of 2 hours.

So I’m confused on what the right answer is here. I can make a second dive and not follow the rules. The calculations show that I can make this dive safely. Or I can follow the rules and have a fresh start at diving tomorrow or some other day. I guess for me the answer would be to remain on the conservative side of things and follow the rules. I personally would rather skip a dive than putting myself in harm’s way. If I was a more experienced diver with more logged dives, I could change the scenario to make a second dive according to the calculation above.

 

[Charlie99]

So I’m confused on what the right answer is here. I can make a second dive and not follow the rules. The calculations show that I can make this dive safely. Or I can follow the rules and have a fresh start at diving tomorrow or some other day.

There isn't just one right answer.

It all goes back to how well you know your current decompression status.

The rule of staying out of the water for 24 hours if your computer fails is a nice, simple, conservative rule that doesn't require any calculation or thought or knowledge of your dive profile. If someone very literally followed that rule, they would stay out of the water for 24 hours if one of two computers they were wearing failed during a dive. Clearly that is nonsense, because in that case you have just as good information on your dive profile as you did before your primary computer failed.

The situation you described in your post is in between. You don't have perfect knowledge of your profile, but you do have enough to make a rational guess. And you are always free to pad your guess with as much additional safety factor as desired to account for the unknowns of your profile. Maybe you'll choose to stay out of the water for 24 hours. Maybe you'll add a couple more pressure groups to your assumed surfacing PG and extend your SI a bit more. Maybe you'll just assume you came up in the max pressure group Z. (Check it out ..... it isn't that big of penalty to make that assumption. Assuming Z rather than Q just extends your SI by 1/2 hour).

Like many things in life, it all comes back to using all of the available information. Your buddy's computer and your buddy's dive watch are bits of information that help you make a good decision. You shouldn't go diving in buddy pairs sharing one computer, but if your computer has failed, the info on your buddy's computer is one more tidbit of information that you can use to make a rational judgement.

 

[joe8mofo]

Computer Issues
* What would you do if your computer stopped working during a dive?
Continue the dive as planned as I always run dives through deco-planning software beforehand during the planning stages and I also have an analog depth gauge and alternate timing device.

* What would you do if you exceeded your NDLs (table or computer)?
Deep stop at 1/2 depth and slow ascent to whatever stops I need to do.
* What would you do if your buddies computer went into deco but yours still showed NDL time remaining?
Stick with my buddy and do the same stops they are requested to do.

* What would you do if you were gearing up on the boat and realized you forgot your computer and no one had an extra?
Rely on the profiles I had generated with deco-planning software previously including contingency profiles and bring them on a slate along with the already equipped analog depth/timer.

 

[boulderjohn]

(Long Post….sorry)
So let’s assume that I have the eRDPml (rather than tables) back on shore. Last time I looked at my computer I had 7 minutes remaining for my NDL, that was 5 minutes ago. So I have an estimated 2 minutes remaining, if not less time. I alert my buddy and end the dive making a slow ascent with my buddy’s assistance. We make an emergency safety stop (assuming I’ve gone past my NDL) of at least 8 minutes or more to allow the excess nitrogen to release from our bodies. Deploy the SMB and ascend to the surface. Surface swim back to the shore (as explained in my earlier post).

If I understand you correctly, the mistake you are making here is counting your ascent time and the safety stop time as a part of your bottom time. If you started your ascent to the surface with 2 minutes of NDL time left, then you have not violated NDLs. You do not need to do an emergency stop--the standard 3 minute stop will do nicely. You do not count either the ascent or the safety stop in your dive time.

Thus, you can assume a square profile dive within the limits of the eRDPml and plan a second dive normally.

 

[Jewls]

There isn't just one right answer.

It all goes back to how well you know your current decompression status.

The rule of staying out of the water for 24 hours if your computer fails is a nice, simple, conservative rule that doesn't require any calculation or thought or knowledge of your dive profile. If someone very literally followed that rule, they would stay out of the water for 24 hours if one of two computers they were wearing failed during a dive. Clearly that is nonsense, because in that case you have just as good information on your dive profile as you did before your primary computer failed.

The situation you described in your post is in between. You don't have perfect knowledge of your profile, but you do have enough to make a rational guess. And you are always free to pad your guess with as much additional safety factor as desired to account for the unknowns of your profile. Maybe you'll choose to stay out of the water for 24 hours. Maybe you'll add a couple more pressure groups to your assumed surfacing PG and extend your SI a bit more. Maybe you'll just assume you came up in the max pressure group Z. (Check it out ..... it isn't that big of penalty to make that assumption. Assuming Z rather than Q just extends your SI by 1/2 hour).

Like many things in life, it all comes back to using all of the available information. Your buddy's computer and your buddy's dive watch are bits of information that help you make a good decision. You shouldn't go diving in buddy pairs sharing one computer, but if your computer has failed, the info on your buddy's computer is one more tidbit of information that you can use to make a rational judgement.

Yes, the tidbits of information I can attain from my buddies dive watch or computer and what I can remember about my dive profile are very helpful. This would allow me to rationalize the previous dive profile in order to calculate the next. With the bits of information as provided in Cave Divers scenario, I was able to the calculate a second dive, I just had to read into it a bit more. Adding on a bit more time to the SI is a good idea and allows for any variances in the calculation, thanks for also pointing that out to me. This test really helped me to take a step back and really analyze the situation if it were to occur.

If I understand you correctly, the mistake you are making here is counting your ascent time and the safety stop time as a part of your bottom time. If you started your ascent to the surface with 2 minutes of NDL time left, then you have not violated NDLs. You do not need to do an emergency stop--the standard 3 minute stop will do nicely. You do not count either the ascent or the safety stop in your dive time.
Thus, you can assume a square profile dive within the limits of the eRDPml and plan a second dive normally.

Good point! But no, I was actually taking into account how much time has passed while at depth. If the timing wasn’t exactly 5 minutes since the last time I looked at my computer, I figured I should add a couple minutes (to be on the safe side) and I was considering the time that would pass to get my buddies attention and communicate. I agree an 8 minute safety stop is a bit much for this profile and also agree that 3 minute safety stop would have done just fine. Maybe I am a little too “conservative” in my thinking?

 

[syntaxerrorsix]

Yes, the tidbits of information I can attain from my buddies dive watch or computer and what I can remember about my dive profile are very helpful. This would allow me to rationalize the previous dive profile in order to calculate the next. With the bits of information as provided in Cave Divers scenario, I was able to the calculate a second dive, I just had to read into it a bit more. Adding on a bit more time to the SI is a good idea and allows for any variances in the calculation, thanks for also pointing that out to me. This test really helped me to take a step back and really analyze the situation if it were to occur.



Good point! But no, I was actually taking into account how much time has passed while at depth. If the timing wasn’t exactly 5 minutes since the last time I looked at my computer, I figured I should add a couple minutes (to be on the safe side) and I was considering the time that would pass to get my buddies attention and communicate. I agree an 8 minute safety stop is a bit much for this profile and also agree that 3 minute safety stop would have done just fine. Maybe I am a little too “conservative” in my thinking?

No, but you really need to work on your situational awareness if you are getting that close to NDL's. A conservative diver wouldn't push the edges of NDL's.

The three minute safety stop is just that, a safety stop. It is not a mandatory stop.