Should I have a backup computer?

[CT-Rich]

True but irrelevant to this conversation. It's still unsafe to use your buddy's computer. If you don't have a backup computer, of course there are other options but none are as good as having the backup computer in the first place.

It's like saying you don't need two fins because you can always just kick harder with the one.

How is this irrelevant to the conversation? His buddy helped him to safely ascend. And when need be, you kick with one fin, or do you bring a back up of those also?

 

[Joneill]

This is a basic forum and the OP with fewer than 24 dive asked if he should buy a back up computer. The answer is he probably should save his money for the moment.

Actually, I don't think that is the answer. The best answer is that one needs to understand/consider the pros/cons of not having a backup and then make an informed decision based on their personal tolerance for the impacts of a dive computer failure during a dive and the resultant impacts on subsequent planned dives.

But as a new diver with tons of task loading, a second computer is not one of them. Computer fails? Make a safe ascent.

Curious - how would carrying a backup computer affect task loading? Computer fails? Just switch to backup - no need to make an immediate safe ascent and affect your next planned dive. Neither is the right answer - but OP should be aware of the possibilities to make the decision that works for them.

Can he make a second dive? That depends. Where was he in relation to the NDL? If he was doing a couple of shallow shore dives, why not and just plan a as if the first dive was done as a square profile. Plan conservatively.

But not always your choice - as I indicated, on all boats I've been on (non-liveaboard), you are sitting out the next dive if your computer fails.

Until the 1990s that was how virtually all diving was done.

That does not make it best practice - there have been many improvements since then to aid in safety and convenience!

If you don’t know what your dive profile was previously, sit it out and wait 12 hours and get your computer battery changed.

That's true - assuming it's just a bad battery. If not, you need to find a replacement and that is sometimes easy and sometimes not, depending on where you are.

If you can’t figure out tables, go snorkeling or take a nap, no harm no shame.

I've seen that somewhat condescending line thrown out many times here on SB but, unless you are diving a perfectly square profile and mentally tracking time at various depths accurately (who actually does?), how is a newbie diver really going to really use tables effectively?

 

[DerekR]

I started diving in '71 and I not only use a computer, but I also carry a backup! Why? Because I've had computer failures on a dive! If you dive enough, it's not a question of IF it will happen, but WHEN it will happen. Wear a backup computer and don't even look at it, UNTIL you have a main computer failure!

 

[CT-Rich]

How often have you ever had a dive computer fail? My first computer still works and I replace the battery every year. My second computer was used and ten years old when I got it and it failed after my using if for seven years. My current computer failed because I put a battery in that died prematurely. I had to buy a new battery before I left for the dive boat.

Does that sound like I should spend $200 on a back up even before I have completed my first season of diving? I check gear before it goes in the car, so battery issues are dealt with early. Never had a computer flood.

For $25 I can buy a save a dive kit that will cover a dozen possible failures that are much more common, like straps and o-rings. I have had more hose failures than computer failures.

 

[Joneill]

How often have you ever had a dive computer fail? My first computer still works and I replace the battery every year. My second computer was used and ten years old when I got it and it failed after my using if for seven years. My current computer failed because I put a battery in that died prematurely. I had to buy a new battery before I left for the dive boat.

Great - so because you have never had a computer fail (nor have I), we can feel confident that they will never unexpectedly fail?

BTW - a battery dying is not a computer failure, imho. Unless it's a defective battery, I would consider that a user failure for not checking/replacing/recharging proactively before a dive/dive trip.

Does that sound like I should spend $200 on a back up even before I have completed my first season of diving?

Maybe - depends on one's risk tolerance to the impacts of a failure. It's their decision to make - not yours...

I check gear before it goes in the car, so battery issues are dealt with early. Never had a computer flood.

So your personal experience means that computers never flood - got it!

For $25 I can buy a save a dive kit that will cover a dozen possible failures that are much more common, like straps and o-rings. I have had more hose failures than computer failures.

A save a dive kit is a good idea - I have one too (along with my backup computer) as I don't want to scrub dives unnecessarily. I had a spring strap failure (my fault on improper reassembly after adjusting the length) last year when gearing up for a dive and quickly swapped back to a spare rubber strap from my kit on that fin and didn't miss a dive.

 

[tursiops]

Replacing the battery significantly increases the chances of a failure due to flooding especially when done by the user, especially if they haven't done it all that often if at all.

I've seen as many floods due to diveshop battery changes as I have due to owner changes. Maybe more!

 

[islanddream]

I carry two computers. I've had computers failures twice....once when I didn't have a backup and once when I did have a backup. I'm glad I have a backup because where we dive, if you don't have a computer or some kind of timing device, you don't dive. I recently purchased a Shearwater Perdix and use one of my older computers as a backup.

 

[oly5050user]

Nah. If yours breaks use your buddy’s. You did the same dive, didn’t you?

Not necessarily. Maybe 1 diver did a previous dive and the other did not, 1 diver momentarily went deeper than another. Many different scenarios.

 

[broncobowsher]

...
Out of curiosity- since I still diver 10 year old Oceanic Air Integrated Nitrox computers which use the same algorithm as many brand new computers and do everything I need it to do- what is it that you wanted more of that you got with your new Shearwater?

Because it is easier to understand. The 1-button Oceanic computer sucks (press, wait, wait, press, wait, press and hold, missed the screen and have to wait for it to come around again, where is that manual?). Data logging the Oceanic is impossible now (it was a parallel port connection which no modern computer has). The user interface of the Shearwater works 100 times better. The Shearwater adds up your CNS and displays it. I have also transitioned into planned deco diving. It will store massive amount of logged diving, easy to download, has a battery life graph not just a battery good/bad icon. It is a completely different level of computer over the old Oceanic.

For really basic diving, the Oceanic worked fine. You got depth, and a little bar graph that climbs into warning and deco. For an occasional diver, it worked fine. For spending an hour+ in the water, with deco, and a gas switch, it is useless. That is why I got a Shearwater. Which I bring on my recreational dives as I like the info it give back better. And when doing deco diving I run a backup bottom timer and depth gauge along with a cut set of tables for the dive planned. The oceanic doesn't even come with me for those.

So while there are a lot of divers in the water with backup computers, there are most who don't. Out of all the stuff taught in an open water class, adding a second computer isn't one of them. Because for basic diving it isn't needed.

I did a liveaboard the other year. With just under 20 people for a week. All sorts of divers. From recently minted to instructors, kids, adults that needed all the toys, etc. I was the only one with 2 computers.

I'm sure there are a lot of divers out there they will tell you that it is needed, and a lot of them are probably just trying to justify to the world why they bought it. Not that they actually need it. When I got the Shearwater I didn't even think of it as a second computer, I got it as a modern replacement that could keep up with my transition into the tech world. But could still be used recreationally. When I started using it I kept the old computer just as a reference. After a little time I was comfortable with the new computer. At which point I had no need to actually remove the old computer, so it accidently became a backup. Wasn't planned that way, just happened. The used bottom timer/depth gauge was a planned backup.

Back to the title of this thread, "should I have a backup computer"
Eventually, but not now. When it comes time (if ever) you will know when it is time to get it. You won't have to ask.

 

[CT-Rich]

So you have a ten year old computer and because of that, you think purchasing two computers right away is the best investment? And two save money there is the suggestion that person that knows almost nothing about dive gear should buy it usedoff of ebay? Good plan.

How about spend some extra money on something else. I am not saying a back up computer is a bad thing, but is it a good investment? If your computer fails, you are not going to die. You have air and everything else. Go to the surface.

If you going on an expensive charter or into more advanced situations, yeah, not a bad idea, but for most divers starting out it just isn’t what I would spend money on.

I have never heard of a diver panicking and drowning because their PDC failed.

And a dead battery is a failure. You lose all your data and your current depth are lost. For $4 a battery, why should I wait until it screws with my weekend? The extra battery that I recycle pale in comparison to the 22 lbs of CO2 you generate with every gallon of gas you burn or disposable plastic bottle or straw you use.

By the way, A) the OP was asking for opinions, B) I never said they don’t flood, I just haven’t seen it happen all that often. C) I am stuck on $200 because I would never tell a newbie diver that he should trust an electronic device of unknown provenience with doing a complex calculation upon which they are going to rest their safety. If you know almost nothing about diving and deco tables, how are going to trust a used computer bought from a stranger on the internet?

And yes, I replace batteries before they fail, ‘cause that would suck to have them die while I was using them.