Need backup computer advice please

[jhelmuth]

Use the other one and enjoy the rest of the trip.

Good diving, Craig

So you'd use a backup because you feel it's prudent, but then you'd do without a backup because you feel that after one failure there would statistically be no reason to do so?

I don't want to put words in your mouth - so please correct me if that is not the case.


The arguments for/on carrying a backup computer cretainly seem reasonable given the stories we've heard right here within this thread (floods, etc.)
All I'm saying is that gauges offer an additional measure of redundancy due to their nature of not having to have been on all of your previous dives should it/they fail. Gauges are replaceable anytime - computers are not (as you have to be "clear" on your N2 loading to start-over with a new computer).


Granted - to me it seems odd to be of one opinion on the one hand that - I need a backup, but then contradict that when the backup fails. I'm not a statistician, but I beleive I'm correct in stating that while it's perfectly correct to figue the odss of 2 computers failing on the same dive as being quite high, the odds are reset for a single failure on any given dive. That is to say, even if you have an extremely low chance of both computers failing on any one dive, the odds of any computer failing on any given dive do not decrease.
If I'm correct about that (any of you stats guys please chime in), then it follws (to me) that a backup computer offers a nice, safe, logical degree of redundancy on any one dive - but it doesn't offer that over a given set of dives, and it means that in the case of one failure I either have no backup or I have to go to gauges for backup.
That is why I make it my practice to use gauges for my backup.

Just to reiterate... I don't feel that computers are significantly unreliable to gauges (if proper care is taken with each one). They are a bit more unreliable, and it makes sense to have a backup to them (just my opinion). I choose to use gauges as a backup because [1] my style and SOP do not allow me to be OK with a backup on one hand but not on another, [2] gauges can be eassily replaced and do not have the requirement that I have dived them previously to be on track with my N2 loading (once clear, it doesn't matter).


Please note that I'm just presenting an argument here and I'm not trying to beat you over the haed with it. If some of the members on this thread wouldn't have misconstrued my posts, I wouldn't bother to even post this. However, since they did I just wanted to be very clear that I'm OK with whatever practice you choose. I like that freedom. If asked, I offer my opinion and analysis only to allow you to think about the problem and than come to your own conclussion.


Be safe... and have fun!


All the best,

Jim

 

[Randy43068]

You don't need a back-up computer for recreational diving!

If you must, take two on a vacation, do it. But for crying out loud, you do not need redundant computers for non deco diving.

 

[scubadada]

So you'd use a backup because you feel it's prudent, but then you'd do without a backup because you feel that after one failure there would statistically be no reason to do so?

I don't want to put words in your mouth - so please correct me if that is not the case.

Jim

Correct, I'd take a single backup computer on an important dive vacation and would use the single working computer should one fail. You're over obsessing on this topic. I have no problem with your guage backups, do as you please, I will too. You'll be diving tables when your computer goes and I'll be diving my 2nd computer. I'll meet you back on the boat when I finally come up.

Good diving, Craig

 

[GrumpyOldGuy]

Randy,

I think most of us understand a backup computer is not needed to safely complete a non-deco dive. It is not life support nor safety gear.

For most, it is like "travel insurance", it offers a degree of protection to allow sequential dives in situations where you plan multiple dives per day and the unexpected demise of a dive computer may screw the rest of the dives on that day. So you pay your extra $250 for insurance, not safety.

 

[Crush]

Randy,

I think most of us understand a backup computer is not needed to safely complete a non-deco dive. It is not life support nor safety gear.

For most, it is like "travel insurance", it offers a degree of protection to allow sequential dives in situations where you plan multiple dives per day and the unexpected demise of a dive computer may screw the rest of the dives on that day. So you pay your extra $250 for insurance, not safety.

+1. If my primary AI computer fails catastrophically during a dive I have lost all info on my tank pressure. I abort the dive, do my safety, and hit the surface. My backup computer, which is not necessary for this process, serves as a timer and depth gauge, not that I really need it as I can count out 180 seconds and my finger spool on my DSMB has knots tied on the line every 10 feet. Once on the surface I swap out the AI computer for gauges. Since my backup was with me on my wrist I can dive again that same day with no risk of not accounting for residual nitrogen.

I get your point that it is not necessary to have a backup for a single rec dive.

 

[scubafanatic]

Thanks for the reply. I asked because I do not wear a backup and wanted to understand why others do. I do not use a backup because it seems failures are rare and would consider my buddies dive computer to be a backup. If there was a failure between a series of dives I have a second computer I bring but do not wear that could be used. Of course to do that you have to know what you did on the first dive and adjust your NDL or stops. A partial sensor failure during the dive leading to shallower than actual depths does seem to be a reason to have a second computer. I have never heard of this occurring and would consider the risk low enough not to worry about it. But then apparently others think this could happen and would want a redundant computer to protect against it.

...dive buddy's computer won't be of much use to you if you get separated from each other.....

 

[jhelmuth]

Correct, I'd take a single backup computer on an important dive vacation and would use the single working computer should one fail. You're over obsessing on this topic. I have no problem with your guage backups, do as you please, I will too. You'll be diving tables when your computer goes and I'll be diving my 2nd computer. I'll meet you back on the boat when I finally come up.

Good diving, Craig

Couldn't you have just left that out? I'm OK with you doing what you want to do.

It's pretty evident that you're obsessing with trying to make me look like I'm somehow not as bright as you are... stick to what you know champ. When you get as much training and experience as I have - then you can talk that #$*!

 

[fnfalman]

Why do people worry so much about what others use for backup?

If you think that two computers are the cat's meow, then go for it.

If you think that a computer and a set of gauges are da shiznit, then go for it.

If you think that one computer with SPG or one AI computer is dandy, then go for it.

Big whoopdeedooo. Drama over nothing.

 

[watboy]

This reminds me of that joke, where a small town has a single engine fire dept. One night while the sole fire truck is out fighting one fire, a 2nd fire errupts causing much devastation. The town then buys some more trucks and to ensure that there will always be a fire truck ready, passes a law requiring that at least one truck to always be at the station.

 

[jhelmuth]

Why do people worry so much about what others use for backup?

If you think that two computers are the cat's meow, then go for it.

If you think that a computer and a set of gauges are da shiznit, then go for it.

If you think that one computer with SPG or one AI computer is dandy, then go for it.

Big whoopdeedooo. Drama over nothing.

My apologies to eveyone....

I did not intent to be a part of any drama (but I was). I admit that I don't like to have other tell me that I said something I didn't (I guess I'm just defensive that way and I've never let anyone push me around - so there it is here on an internet forum). I really wish everyone would just simply make their points and move on (me too). I'll try harder to ignore others who try to

All the best!

Jim