Should I have a backup computer?

[Neilwood]

I haven't read the entire thread (and no intention of going back and doing so) but my take is as follows:
1) Having a single computer is fine apart from certain circumstances (more below).
2) If your computer craps out on you,it is dive over IMHO. Time to make a safe ascent.
3) In extreme circumstances, it is possible to rely on a buddies computer but only if you make sure you are sticking closely together. Maintaining different depths will cause your nitrogen loadings to diverge and therefore your NDL's wont match. My first OW dive post qualification was on a shared computer (the car containing all the rented computers was held up at the ferry so didn't make it in time for the first dive). We shared but stayed close and dived conservatively (well within NDLS).
4) If you are on a challenging dive (deep or long) or on a series of dives (such as a LOB), then it might be worth bringing 2. It would have sucked going on a LOB (with 20-21 dives planned) and have to miss some because I hadn't got a working computer.

As Colliam says, my preference is a wrist computer - IMHO it is far easier to use and more likely to be checked there than a console one. Air integrated or SPG is a different decision - I like AI for the ease of checking my air.

 

[Colliam7]

the one thing that is not being debated is that having a backup computer is not mandatory.

OK, I am confused by the wording. Are you saying that having a back-up computer is mandatory, and that is a statement that is not being debated? Or, are you saying that having a back-up computer is not mandatory, and there is no debate about that? Not disagreeing or agreeing at this point, just trying to understand.

As far as you not ever having a computer failure, so what? You, and one or two other divers who posted that they never had a failure are a very small statistically insignificant sample of the diving population that does have a statistically significant number of computer mechanical failures, flooding, theft, and loss.

You need to document the basis for 'statistically significant' or else the statement is not valid. (OK, I admit, I AM a statistician, and a teacher of biostatistics, and I really am bothered when people throw around such terms without the presence of supporting data, and I am quite certain that no such data exist on this particular point.)

it's bad advice because you are projecting your own personal experiences and luck onto others

Well, I think I made it pretty clear that my statements were a matter of PERSONAL PREFERENCE. I don't see how that could not have been clear to anyone. And, I will go a step further: ALL of the arguments and positions presented are also a matter of PERSONAL PREFERENCE (which was my point). Nothing that has been said in any post in this thread provides incontrovertible documentation that one approach is objectively 'better' than the other. The only basis for applying 'better' is when there is a value foundation, and that clearly varies between individuals. Some value the money they would pay for a backup computer more than a dive they might miss. Some people value the dive more than the money they might pay for a second computer. And, I made no attempt to give advice. (I do sell advice in my particular field of expertise. But, I don't give it away.) I simply stated, this is what I do, and why.

The fact is I PERSONALLY PREFER to dive with two computers, with exceptions based on circumstances. That should NOT be a basis for anyone feeling that THEY must dive with two computers. I can articulate MY reasons, but it is still up to the individual diver to make the choice.

Your dive computer uses rechargeable batteries? How does that work exactly, do you remove the batteries and put them in a charger, or do you connect the charger to the dive computer. I'd think the latter is a great way to short out a battery in saltwater.

How? I don't recall ever recharging the battery in salt water.

YI also don't see a benefit of rechargeable dive computer batteries because most use a single lithium round battery that can last 5-10 years.

I am not aware of any data supporting a life span of '5-10 years' for such a battery. Could you provide documentation of that? In addition, YOU may not see the benefit. Apparently, others do. And, that reflects their PERSONAL PREFERENCE.

 

[Joneill]

When you respond on a forum such as this one, on a thread that starts with a question by a novice diver, your words can and probably will be taken as advice by any number of divers who may read them, regardless of whether that is your intent.

Actuially, more than anyone else in this thread, he was VERY clear that he was not giving advice:

Thanks for partially answering my question about your use of rechargeable batteries in your dive computer.

How do you charge them? What I meant was that if the charging ports are unsealed they are exposed to saltwater during a dive and that would seem to make them vulnerable to corrosion and shorting out the internal battery which is directly connected to those points.

Plenty of computers with rechargeable batteries, including the new Shearwater Teric. Some have wet contacts like the Scubapro G2, Mares Icon HD and Ratio iX3M - beyond cleaning them periodically, I've never read about any significant issues with them. However, the new Teric uses a "better" approach (imho) with inductive/wireless charging - so has no external contacts.

 

[CT-Rich]

It happens often enough that it matters for all practical purposes.

If you say “statistically significant”, then you owe statistics on the matter. That it happens enough to matter is actually the heart of the issue. You are stating a subjective opinion as proven fact, which it is not.

When you respond on a forum such as this one, on a thread that starts with a question by a novice diver, your words can and probably will be taken as advice by any number of divers who may read them, regardless of whether that is your intent.

You May take some of that advice yourself, some of your statements have a very dodgy basis fact. See your statement asserting “statistics”. Opinions can be debated, but stating them as supported “facts” misrepresents them. The eternal struggle between BP/W and other styles of BCD are opinion debates and will rage forever.... you will notice that there is no debate about safety stops, that was settled by science a long time ago. Facts and REAL statistics.

Thanks for partially answering my question about your use of rechargeable batteries in your dive computer.

How do you charge them? What I meant was that if the charging ports are unsealed they are exposed to saltwater during a dive and that would seem to make them vulnerable to corrosion and shorting out the internal battery which is directly connected to those points.

You may want to get off your horse long enough to actually read up on a variety of computers before making global assertions about all computers.

It has been my personal experience that 3V lithium dive computer batteries last 5 years or more. I have yet to change the battery in the transmitter that is attached to my first stage and I've been using it for over 10 years.

It has been my experience that batteries may last one or two seasons, and that the manufacturer of at least one if not all my computers says replace annually. The day your transmitter stop working is the day you may say “gee, I wish I had replaced it sooner...”. And you may find that replacement you had in your damp gear bag with the save a dive kit is no longer good. (From personal experience.)

You seem to be very strident in your opinions, but there are many on this board who have been around a long time and have differing attitude grounded in experience. Feel free to disagree. Very few of the other posters here have done other than relate opinions and advice based on experience. If you feel like you are being ganged upon, it may be that offering strident opinions as fact will grate on other’s nerves.

 

[tursiops]

I'm sticking with statistically significant meaning there's a reasonable probability that it's going to happen, as you said that is the heart of the issue. At this point we are debating semantics= non productive and circular. I understand that not everyone will agree with my definition of statistically significant and I am willing to accept my definition is not accepted by many if not most.

Come on, dude; you can have your own opinions, but not your own facts or definitions.

I've seen lots of varied opinions on safety stops as some (newer) divers believe they are mandatory when (as per accepted diving principles and as stated in most manuals), they are optional.

Since the mid 90's they've been deemed mandatory for deeper dives or dives near the NDL. More recently, they've been recommended for all dives.

I haven't made any assertions about rechargeable dive computers, I clearly stated I know nothing about them and I simply asked for clarification on a few issues such as how the charging ports would work and whether they are prone to corrosion and other issues such as shorting out the internal batteries, or if the internal batteries need to be removed and recharged, and whether they are less convenient and create more tasks for a diver such as monitoring the charge levels and recharging them on a regular basis.

Maybe you could do a little research before blasting out your "I know nothing" questions. Many lights, for example the SOLAs, also have external charging contacts.

So what manufacturers support your wasteful habit of discarding perfectly good batteries every year. Doesn't mean it's any better for the environment or for the dive computer or any less damaging to the environment.

I just looked at some manuals for DiveRite, Oceanic (several models), Shearwater, and UWATEC. Battery lifetimes vary from 50-300 dives or 1-3 years, whichever is less, and Shearwater even says for their transmitter battery, annual replacement recommended. Considering the number of dive computer batteries being replaced, I doubt the environmental impact is "statistically significant," to use your definition.

Thanks Rich, but I don't feel like I'm being ganged up on at all. There are several who have agreed with me on most if not all of my points and my posts have received several "likes" for what that might be worth.

My likes have gone to those -- like CT-Rich - who have suggested you calm down and chill a little.

 

[CT-Rich]

Seems like a rather short replacement period but perhaps you probably dive a lot more than I do? You cannot possibly state with any degree of accuracy that your batteries can last more than one season since you replace them after one season.

So what manufacturers support your wasteful habit of discarding perfectly good batteries every year. Doesn't mean it's any better for the environment or for the dive computer or any less damaging to the environment. In fact it benefits the dive computer manufacturers to recommend frequent replacement of computer batteries, because the O-ring (which is often supplied by the computer manufacturer as an overpriced kit) is another revenue source for the dive computer company.

Actually, you might want to read the manual on you own dive gear. You mentioned that your battery lasts five years or something to that effect... hear is the manual for the Oceanic VT Pro.

It clearly recommends annual changes, not every five years. This would appear to be the reason you are needing the back up computer. You are effectively waiting for it to die rather than doing the basic preventative maintenance as per manufacturer recommendation. It might be that you never had the manual because you are buying it off eBay, used and on the cheap or that you understood the gear better than the manufacturer.

 

[CT-Rich]

Perhaps you should make a post that new divers should do research and not waste members time on ScubaBoard before blurting out basic questions that they can simply research on their own. Why is this forum even necessary if someone should just do their own research?
.

Might want to do some of your own research before wasting member’s time blurting out incorrect basic information that can be researched on your own. (See above).

 

[tursiops]

"Recommended for all dives" is not the same as mandatory. I have never heard of deep stops being deemed mandatory. See here we are debating safety stops!

Nobody mentioned deep stops except you. My post was about deeper dives having mandatory safety stops. And "recommended" is not the same as "optional." Suggestion: read more carefully, take two deep breaths before posting.

 

[Bob DBF]

Any time a perfectly good battery is thrown in the garbage it adds to the problem.

I recycle mine rather than toss them in the garbage.


Bob

 

[EastEndDiver]

The answer to the OPs question is simple.....Yes,No,Maybe