Question about dive computers

[Gareth J]

The VR3 manual says otherwise:

"The VR3 uses a derivative of the Buhlmann ZHL16 algorithm. Exactly the same adaptation is used in Proplanner decompression software. The new versions of both systems employ some of the latest thinking in practical microbubble avoidance and compared to standard parallel compartment models may seem to modify the dive profile. This modification takes the form of deepwater microbubble controlling decompression stops."

The first computer I remember running unmodified Buhlmann GF was the Liquivision X1, following the release of MultiDeco. It initially ran VPM only.

I never committed to a VR3, so you are more accurate than me. Although, i think you could also get VPM on the VR3 as well (from memory).
I did use Proplanner a lot. I kind of preferred it over the later softwares, but that comes back to the devil you know.
Funnily enough, one of my buddies has finally retired his VR3.... it was his backup, and had recently become a little temperamental.

 

[rongoodman]

I also remember the VPM upgrade. I just did some digging and it looks that they used a modified version of that too. I had one of the early X1s, which forced me into my only encounter with Microsoft software. I had to install Windows XP under Parallels just to download the firmware for it on my Mac.

 

[scubadada]

Hi @KenGordon

I noticed that your Suunto decompression profile looks very different than that when running 50/80, with significantly less time at deeper stops and more time at the last stop. The Suunto profile actually looks most like 75/75, though the Buhlmann profile still has more time at the deeper stops. I find that quite interesting. All 3 profiles have nearly the same runtime and total deco time.

 

[dmaziuk]

2. Being a predominantly American based forum, decompression diving is considered too dangerous for recreational divers. Despite it being a normal progression within the core diver training for a large number of divers in the rest of the world.

I think it's mostly spotlight effect: there's a couple of regular suunto bashers and perhaps half a dozen drive-by ones, and for every one of them I've seen a dozen actual divers wearing zoops on boats. And so far nobody had a screaming fit when someone needed to stay at safety stop for an extra minute. But then again, I haven't dived in FL or MX yet, we mostly hang out with all them Dutch people...

Suuntos are relatively expensive here, more so than in rightpondia. I don't think the training progression is the problem per se, nothing's stopping you from getting tech trained if you want to do deco dives.

 

[KenGordon]

The criticism toward Suuntos seems rooted in the idea they allegedly cut short NDL's a bit, more liberal computers give you more time and still seem acceptably 'safe' so the Suunto's conservatism is viewed as 'robbing' divers of NDL for no useful purpose. If there are other computer options with liberal algorithms that Suunto has no clear advantage over, why get a Suunto?

It's not that Suunto is bad, just that a competitor may be about 'as good,' give you a little more NDL on at least some of your dives without putting you at undue risk of decompression-related problems, so why not get the competitor?

There may be good reasons, and Suunto fans may want to list them.

The business of NDLs and how long deco should be is a difficult one. Really nobody knows. In the past a bunch of people have been subject to some testing and the various computers are somewhat informed by that. But it is all a bit of a guess. One of the divers on the dive I posted above had a PFO. The profile worked for him that day and not another. He'd done a lot of dives before he got a hit.

So why get a Suunto and not a similar but more liberal computer?

First, for some people a Suunto is too liberal. People still get bent, the bloke with the PFO was diving a Suunto the day his bend happened.

Second, I am not sure the apparently more liberal computers are very different to a Suunto. I have compared a Zoop above with as hot a plan as I am prepared to dive and there is only 3 minute in it. I tried to properly compare an Oceanic for myself. It died following a single 50m chamber dive. On that dive it went into deco at the same time as all the other computers.

Why else?

They are reasonably cheap, they are available and, here at least, very common. So the chances are your buddy will have one.I find the UI on a Suunto pretty easy. Certainly easier than a Petrel/Perdix. It has more buttons so has the concept of 'back'. Although the Oceanic I have has four buttons I had to read the manual to get it out of watch mode.

The battery lasts forever. Like years. My Zoop and Helo2 use a battery commonly used in car keys. They are easy to find in the unlikely event you need one. They are easy enough to change if you've seen it done.

The display is alright but not fantastic. The small numbers like temperature or cns are a bit difficult. The serious numbers like time to surface, ndl or depth are totally easy to read.If it is vaguely dark I have a torch, with the Zoop you point the torch at it and the phosphorescence lights it up. The Helo2 needs a button press.

They are simple and cheap. I can give a random new diver one on their first ever dive and they can use it because there is nothing to do. If they destroy it or lose it then I will not be pleased but it is not £800.

I expect other brands are ok. I've know I don't like the single button ones. The basic Oceanic I didn't find easy.

 

[dmaziuk]

Of course DM5 will let you plan a dive for a Zoop

I can plan a dive in subsurface, write it down on a slate, and dive it with my Leo. I would not be comfortable doing that because nothing in the available documentation tells me a) whether Leo will get its knickers in a twist if I set it to dive (as opposed to gauge) mode for it, nor b) how it would react if I have to deviate from the plan for any reason. Presumably it won't compute me a decade of deco, but the fine manual is completely silent on the subject.

If you know how zoop would behave and your planner matches its programming, then sure, do decompression dives on a zoop in dive mode. I still doubt its calculated deco schedule will match those of Eons, but hey, it's your deco.

 

[hilljo88]

This thread may be getting a little deep in the weeds for a recently certified diver. I'd like to offer to the OP my 2 cents about disappointing support from some DC manufacturers. I had an Aeris Elite T 3 which I loved for its simple intuitive display, ease of switching to Nitrox. It did fail about every 2years, and for something like $100, the factory sent me a refurbished unit. The company no longer supports this unit. I later bought an expensive Liquivision Lynx thinking I would like the bright display. But I hated the toy like cosmetics of it and quickly sold it. The friend who bought it from me said it failed and the company is no longer supporting it. (He's still a friend, though.). Two friends, both Instructors have the very expensive Atomic Cobalt. Neither one can keep the units in service. One asked me to take a photo of his blank screen in the middle of a dive so the company would believe him that it failed. The other friend said his lights up with a lag, something like ten minutes after getting wet. The danger there is that it apparently also doesn't track his gas consumption for the first ten minutes.

I currently have a Perdix 2 and a Petrel. Knock on wood, performance and reliability are perfect. There are a lot of supporters of Shearwater on this board and based on my personal experience, I'm one of them.They may be too pricey and over engineered for a new diver but something to think about.

 

[Stormblessed]

This thread may be getting a little deep in the weeds for a recently certified diver. I'd like to offer to the OP my 2 cents about disappointing support from some DC manufacturers. I had an Aeris Elite T 3 which I loved for its simple intuitive display, ease of switching to Nitrox. It did fail about every 2years, and for something like $100, the factory sent me a refurbished unit. The company no longer supports this unit. I later bought an expensive Liquivision Lynx thinking I would like the bright display. But I hated the toy like cosmetics of it and quickly sold it. The friend who bought it from me said it failed and the company is no longer supporting it. (He's still a friend, though.). Two friends, both Instructors have the very expensive Atomic Cobalt. Neither one can keep the units in service. One asked me to take a photo of his blank screen in the middle of a dive so the company would believe him that it failed. The other friend said his lights up with a lag, something like ten minutes after getting wet. The danger there is that it apparently also doesn't track his gas consumption for the first ten minutes.

I currently have a Perdix 2 and a Petrel. Knock on wood, performance and reliability are perfect. There are a lot of supporters of Shearwater on this board and based on my personal experience, I'm one of them.They may be too pricey and over engineered for a new diver but something to think about.

I am actually enjoying the discussion here. Always happy to learn.
For my purchase, I am actually looking into computers that have been in the market for a few years. Scuba gear is pretty expensive for me locally so I was thinking of buying it from a different country. But if it fails, I won't be able to claim warranty.

 

[dmaziuk]

Scuba gear is pretty expensive for me locally so I was thinking of buying it from a different country. But if it fails, I won't be able to claim warranty.

That's depends, actually: if you can deal with the manufacturer directly, you're looking at postage fees and having to get through their support firewall, but it's doable. It is easier if you can walk into local dealer's shop with it, but for most "established" models chances are you'll never need either.

 

[dmaziuk]

Second, I am not sure the apparently more liberal computers are very different to a Suunto. I have compared a Zoop above with as hot a plan as I am prepared to dive and there is only 3 minute in it.

Here's the thing: if you dive a no-stop dive the way you want and come up when you want, and there's still NDL time left on your computer, do you even care if it's 1 minute or 5 minutes of NDL left? If you routinely overstay your no-stop times, then you have a choice of surfacing with a slightly higher tissue loading allowed by "more liberal" algorithm, or spending an extra minute or two at safety stop as required by a more "conservative" algorithm. I really fail to see what the noise is all about, as far as I'm concerned it's six of one or half a dozen of the same.