Now it's time to choose a wrist computer.

[SaltyCracker]

This is a good example. Not only that mechanical devices can fail, but also how they fail.

Perhaps. However, the example posted by @gqllc007 also illustrates how a failure presents. In that case, the mechanical SPG just stuck at the reading before the failure. Generally, electronic sensors fail such that there is no question that it’s dead. They tend to report something that is so far off, there is no question.

Had the SPG failed later in the dive, it might not be as obvious. If it were to fail around 1200 psi, but not be noticed until the psi in the tank was around 700, that would be worse.

Yeah... good point.

 

[SaltyCracker]

At some point you have to accept a standard. If you wear a computer to track your NDL, you either accept its verdict or why even bother. DC have made diving a lot safer while extending the amount of time you can spend in the water. The idea of having your computer say you violated the NDL and then deciding it doesn’t apply to you is kind of like asking grandma to referee a game and then punching her because you don’t like the call.

Either respect the call or don’t ask her to referee.

Worse than that, the ignorant do not know what risk they are taking by ignoring the violation.

Lets be honest, American diving agencies, unless you step on to the 'technical rung', don't even teach decompression diving within the basic qualifications. The skippers throw there teddies out of the pram if divers over run the NDL time. You have divers racing to the surface to avoid this!
Be consistent, if you are not teaching basic decompression diving within the core training, don't advocate tools that allow you to ignore the violation of the decompression models.

Everybody has to choose their own safety standards but this just seems obvious. The idea of buying an expensive computer then deciding to ignore it is silly.

 

[waterone]

Good points. It'll be important as new divers to for us to remember that it's possible for any of our gear to malfunction and back-ups are a good idea. Thanks for pointing that out. At a certain point though, I guess a diver will just have to trust what gear they have unless they're in a position to travel with a complete redundant kit from head to toe.

I personally trust my maintained gear but at the same time I have thought about and I am prepared for failures as they do happen.

So with that said, what would be the hierarchy of redundant gear? For me I guess it would first be anything electronic then next would be my regulator/octo/SPG kit. Then what? Mask/fins/snorkel? Would anything beyond that even be practical?

This would all be quite subjective and how much you're willing to spend for gear that will most likely just sit.

I have at least doubles of everything that I would ever use for a dive, its ridiculous. I bought it most of it simply because I like gear. Somethings I upgraded even though I didn't need to, like 5 watch style dive computers in the last year and a half.

A better option than purchasing all redundant gear is having a good save a dive kit. I take my kit with me everywhere and it is in a toolbox it seems to have everything to keep me diving.

When I travel by plane I take a smaller kit. I am sure many are fine without taking anything but thays not how I roll.

In the small one I have a SPG, fin strap, mask strap, mouthpiece, light, o-rings, zip ties, batteries, multi tool and a bolt snap. I probably could add a few other things...

Of course on a trip I always have an extra computer whether it be the garmin or teric.

And yes, now that you point it out, I also agree that if I could get a decent quality AI package for near the same price as non-AI, I would jump on the bandwagon too but would still have to carry a SPG.

Since I am like most and look at my pressure often and would notice quickly if something is wrong, it is easy to deal with. With that said I would have no issues diving with just a single tx and no other spg for rec diving.

 

[dmaziuk]

Everybody has to choose their own safety standards but this just seems obvious. The idea of buying an expensive computer then deciding to ignore it is silly.

In all fairness, it's not the whole story: until recently the low-end computers all ran RGBM whose conservatism fudges are a poor fit for certain dive schedules and at least some of them are now considered questionable at best. The less "conservative" DSAT ones will lock you out just as well but that doesn't happen nearly as often because it takes much more effort to "bend" them. (And they used to cost twice as much.)

So you find yourself on a LOB running a typical DSAT schedule w/ 40-minute SIs and 4-5 dives a day, and you're wearing a Suunto Zoop, you'll have to start cutting your dives short by day 3 -- or go into mandatory deco by the computer's reckoning while nobody else in your group is anywhere near it.

 

[tbone1004]

I like the deep6 and wanted to buy it during the sale (sadly they don't ship to Europe atm), but in no way shape or form is it more capable than a peregrine??

1 gas nitrox support up to 56% on the deep6

3 gas up to 100% on the peregrine, a proper backlit display, and you can actually fully customise GF.
edit: although I have to admit, if you have a need for multigas you'd probably better skip the peregrin and go straight perdix.

the next firmware is going to be full trimix, I'm diving test versions now. Will be out in a couple of months most likely

 

[Nemrod]

It is easy to equate one thing to another thing with anecdotal evidence. I have seen exacty ZERO complete failures of a mechanical SPG. I have seen them flooded, I have seen the fizz and leak to an annoying amount, even one corroded example pop the lens out, I have seen the cases (plastic) smashed to bits and the lens on even B&G gauges broken but in almost every case, even flooded, the needle continued to read the air remaining unless it was torn off. But in one month of diving I saw five computer failures inlcuding my own. I am certain that mechanical SPGs, even new ones, can and have failed but equating failures of mechanical SPGs to anything near the level of failures of computers is a big stretch at the least. I postulate about as rare as hen's teeth. Hens do grow teeth and at least one dino/paleo enthusiast wants to find and shut off the gene (sequence) that control break vs teeth development so we can have mini-raptors instead of chickens. If a chicken had teeth, would it bite you or would it peck you? Does morphology beget behavior (like ontogeny recapitulates phylogeny), in what way is behavior linked to physical expression? But as I ponder if the chicken had teeth, would it even want to cross the road, I am confident that my mechanical SPG is highly unlikely to fail me.

James

 

[Gandalf-the-Diver]

Unfortunately, for 99% of those with some form of diving qualification, that is a very bad thing.
Very few people have even a rudimentary grasp of decompression theory. Having something they can abuse, then continue diving is not a good thing.

It is all well and good to say buy the best, and you only buy once. But not every one can afford that.
Most would do better to get a good set of basic equipment, and upgrade over time as their diving (and fashion) requirements change. And, perhaps more importantly, spend the extra money actually going diving!

First on the list is a good set of regulators, but most modern CE compliant regulators are excellent. A basic set of Apex reg's will do anything you need.
Good protective clothing to suit the environment you are diving is very high on the list. I dive temperate (cold) waters. We can lend kit, either personally, or from the club. But drysuits and base layers are personal, and very few want to lend drysuits (granted, most of us will lend an old - or back up suit, old suits tend to be the 'damp' suit we no longer use).

Modern displays are certainly better than the old backlit LCD, certainly, I have upgraded my CCR unit to the newer displays, partly because my old eyes had trouble with the small typeset, and cause I broke it .

I have only just added a Shearwater Perdix to my kit. After years of diving CCR, it's nice to have a backup unit that is a CCR compatible computer. I used to use a Suunto Vytec as the backup, until I smashed it. Then an OSTC Sport, which I still carry when diving with OC buddies.
It's the first AI computer I've bought since the Suunto Eon back in the early 90's.

By the time you progress from OW to mixed gas or CCR, computer technology will have moved forward significantly. That includes what will be thought of as best decompression practice.

If one misses an obligation, the Shearwater will still continue to function, still show you tissue loading.
The Peregrine is competitively priced in it's market. The Perdix you have is expensive. The Peregrine will take one right up to, but not including Tri Mix; it also has the same wonderful size screen the Perdix has. You have to admit, it is nice to look at under water. I have a Zoop Novo as a back-up.
Speaking of not affordable, a basic set of Apex regs will be expensive in North America. I am guessing by your comments, you are on the British Islands somewhere.

 

[waterone]

I have seen exacty ZERO complete failures of a mechanical SPG. But in one month of diving I saw five computer failures inlcuding my own.

I have seen 0 txs and 0 computers fail but I can't say the same for a basic spg. That doesn't mean more hens have teeth, only s*** happens

The good thing about an ol' spg is that they are extremely simple and pretty much user proof with no batteries or seals to change, while computers probably fail a lot due to user error.

Knowing failure is possible and reading experiences like yours is why I carry an extra computer. My thoughts on this are that it doesn't matter to me if failure is common or not because failures can happen. Since I know failures do happen, I choose to be prepared.

 

[SaltyCracker]

In all fairness, it's not the whole story: until recently the low-end computers all ran RGBM whose conservatism fudges are a poor fit for certain dive schedules and at least some of them are now considered questionable at best. The less "conservative" DSAT ones will lock you out just as well but that doesn't happen nearly as often because it takes much more effort to "bend" them. (And they used to cost twice as much.)

So you find yourself on a LOB running a typical DSAT schedule w/ 40-minute SIs and 4-5 dives a day, and you're wearing a Suunto Zoop, you'll have to start cutting your dives short by day 3 -- or go into mandatory deco by the computer's reckoning while nobody else in your group is anywhere near it.

Why wouldn't you just do the recommended deco stop? This isn't a challenge but rather an honest question.

But... point well taken. I shouldn't come off as scolding others for taking risks that I wouldn't. I don't have the experience to back it up with. Only the individual knows their own skill level and risk tolerance. If that person is willing to take and educated and calculated risk then, so moat it be. I think base jumpers and free-solo climbers are nuts but who am I to hold them to my standards? Speaking only for myself though, I'm too much of a process stickler to ignore a recommended stop.

 

[dmaziuk]

Why wouldn't you just do the recommended deco stop? This isn't a challenge but rather an honest question.

I have no idea. Like I said in a previous post, likely because you don't have the gas. As the joke goes: now you have two problems...